"use strict";

// Default values for the min. and max. Y of biomes
const MIN_Y_DEFAULT = -31000
const MAX_Y_DEFAULT = 31000

// Draw a grid line every GRID_STEP units
const GRID_STEP = 10

// Size of the resizing corner
const RESIZE_CORNER = 14;

// Minimum canvas side length (px)
const MIN_CANVAS_SIZE = 100;

// Minimum required distance of canvas from the right page side
const CANVAS_PAGE_MARGIN_RIGHT = 20

// Grid widths. We use lower grid widths
// as the grid becomes more crammed.
// There are 4 levels from 0 to 3.
// Level 3 is the full width, level 1 is the
// smallest with and level 0 renders no grid lines
// when the grid would become too crammed.
const GRID_WIDTH_LEVEL_3 = 2; // full width
const GRID_WIDTH_LEVEL_2 = 1; // reduced width
const GRID_WIDTH_LEVEL_1 = 0.5; // more reduced width
// the grid thesholds are the "grid lines to pixel"
// ratio. The more grid lines therere are per pixel,
// the lower the grid level.
// e.g. grid level 2 triggers if ratio is above
// GRID_THRESHOLD_LEVEL_2. Grid level 3 is used
// if no grid thresholds are triggered.
const GRID_THRESHOLD_LEVEL_2 = 0.08;
const GRID_THRESHOLD_LEVEL_1 = 0.16;
const GRID_THRESHOLD_LEVEL_0 = 0.24; // this will disable grid rendering

// Distance from the point's center in which a point can
// be selected by clicking on it
const POINT_SELECT_DISTANCE = 25

// Distance a point has to be dragged after a single click
// before drag-n-drop starts.
// Normally, the user can drag-n-drop a point
// when clickong and dragging it *after* it has already been
// selected; there's no distance requirement.
// But it is also possible to select the point (by clicking
// on it) and dragging it with the same mouse click. But for
// this method, the mouse had to move the distance below
// from the point coordinates (in pixels) before drag-n-drop
// activates.
const ONE_CLICK_DRAG_DROP_DISTANCE = 30

// Name to display if empty
const FALLBACK_NAME = "(no name)"

// Symbol for storing the biome ID in site objects
// for the Voronoi script
const biomeIDSymbol = Symbol("Biome ID");

// Colors (mostly self-explanatory)
const POINT_COLOR = "#913636";
const POINT_COLOR_SELECTED = "#e19696";
const EDGE_COLOR = "#0f2c2e";
const GRID_COLOR = "#00000040";
const AXIS_COLOR = "#000000";
// Color to be used when the diagram is cleared
const CLEAR_COLOR = "#ecddba";
// list of possible cell colors
// note: These MUST be in "#xxxxxx" format
// for the hexColorToRGBColor function to work.
const CELL_COLORS = [
	"#64988e",
	"#3d7085",
	"#345644",
	"#6b7f5c",
	"#868750",
	"#a7822c",
	"#a06e38",
	"#ad5f52",
	"#692f11",
	"#89542f",
	"#796e63",
	"#a17d5e",
	"#5a3f20",
	"#836299",
];
const CELL_COLOR_NEUTRAL = "#888888";
const COLOR_BUTTON_BORDER_SELECTED = "#FF0000";

/* Status variables for the diagram calculations */

// Min. and max. mathematically possible values for heat and humidity
let limit_heat_min, limit_heat_max;
let limit_humidity_min, limit_humidity_max;
// Draw area. Slightly larger than the value area to avoid
// ugly edge rendering problems
const DRAW_OFFSET = 10
let draw_heat_min, draw_heat_max;
let draw_humidity_min, draw_humidity_max;
// The point that is considered the middle of heat/humidity;
// mathematically this value is the most probable.
let midpoint_heat;
let midpoint_humidity;

// Biome noise settings
const NOISE_OFFSET_DEFAULT = 50;
const NOISE_SCALE_DEFAULT = 50;
const NOISE_PERSISTENCE_DEFAULT = 0.5;
const NOISE_OCTAVES_DEFAULT = 3;
const NOISE_ABSVALUE_DEFAULT = false;

// Current noise values
let noises = {
	heat: {
		offset: NOISE_OFFSET_DEFAULT,
		scale: NOISE_SCALE_DEFAULT,
		octaves: NOISE_OCTAVES_DEFAULT,
		persistence: NOISE_PERSISTENCE_DEFAULT,
		absvalue: NOISE_ABSVALUE_DEFAULT,
	},
	humidity: {
		offset: NOISE_OFFSET_DEFAULT,
		scale: NOISE_SCALE_DEFAULT,
		octaves: NOISE_OCTAVES_DEFAULT,
		persistence: NOISE_PERSISTENCE_DEFAULT,
		absvalue: NOISE_ABSVALUE_DEFAULT,
	},

};

function updateAreaVarsFor(noiseType) {
	let noise = noises[noiseType];

	let is_absolute = noise.absvalue === true
	// Calculate min. and max. possible values
	// Octaves
	let [o_min, o_max] = [0, 0]
	for (let o=1; o<=noise.octaves; o++) {
		let exp = o-1
		// Calculate the two possible extreme values
		// with the octave value being either at 1 or -1.
		let limit1 = (1 * noise.persistence ** exp)
		let limit2
		if (!is_absolute) {
			limit2 = (-1 * noise.persistence ** exp)
		} else {
			// If absvalue is set, one of the
			// limits is always 0 because we
			// can't get lower.
			limit2 = 0
		}

		// To add to the maximum, pick the higher value
		if (limit1 > limit2) {
			o_max = o_max + limit1
		} else {
			o_max = o_max + limit2
		}

		// To add to the minimum, pick the LOWER value
		if (limit1 > limit2) {
			o_min = o_min + limit2
		} else {
			o_min = o_min + limit1
		}
	}
	// Add offset and scale to min/max value (final step)
	let min_value = noise.offset + noise.scale * o_min
	let max_value = noise.offset + noise.scale * o_max

	// Bring the 2 values in the correct order
	// (min_value might be bigger for negative scale)
	if (min_value > max_value) {
		[min_value, max_value] = [max_value, min_value]
	}

	// Update globals
	let limit_min = min_value;
	let limit_max = max_value;
	let draw_min = limit_min - DRAW_OFFSET
	let draw_max = limit_max + DRAW_OFFSET
	let midpoint = min_value + (max_value - min_value) / 2
	if (noiseType === "heat") {
		limit_heat_min = limit_min;
		limit_heat_max = limit_max;
		draw_heat_min = draw_min;
		draw_heat_max = draw_max;
		midpoint_heat = midpoint;
	} else if (noiseType === "humidity") {
		limit_humidity_min = limit_min;
		limit_humidity_max = limit_max;
		draw_humidity_min = draw_min;
		draw_humidity_max = draw_max;
		midpoint_humidity = midpoint;
	} else {
		console.log("ERROR! updateAreaVars() called with wrong noise_type!")
	}
}
function updateAreaVars() {
	updateAreaVarsFor("heat");
	updateAreaVarsFor("humidity");
	// Update element
	rangeDisplay.innerHTML = "heat range: <span class='statHeat'>["+(+limit_heat_min)+", "+(+limit_heat_max)+"]</span>; " +
		"humidity range: <span class='statHumidity'>["+(+limit_humidity_min)+", "+(+limit_humidity_max)+"]</span>";
}
updateAreaVars();

// If true, point names are shown in diagram
let showNames = true;
// If true, points are shown in diagram
let showPoints = true;
// If true, cells are colorized in diagram
let showCellColors = true;
// If true, show the grid in the diagram
let showGrid = true;
// If true, show the heat/humidity axes
let showAxes = false;

// Set to true if the draw canvas currently shows an error message
let drawError = false;

// The last ID assigned to a biome (0 = none assigned yet).
let lastBiomeID = 0;
let biomePoints = [];
// Add a biome to the biome list
function addBiome(biomeDef) {
	biomeDef.id = lastBiomeID;
	biomeDef.colorIndex = lastBiomeID % CELL_COLORS.length;
	biomePoints.push(biomeDef);
	// The biome ID is just a simple ascending number
	lastBiomeID++;
}

// Current cursor position on the canvas
let canvas_cursor_x = null;
let canvas_cursor_y = null;

// Add a default biome at the midpoint
addBiome({name: "default", heat:midpoint_heat, humidity:midpoint_humidity, min_y: MIN_Y_DEFAULT, max_y: MAX_Y_DEFAULT})

// Get the Y vale of the widget to set the Y altitude
function getViewY() {
	if (!inputViewY) {
		return 0;
	}
	return inputViewY.value;
}
// Returns the biome point by its given ID
// or null if it couldn't be found
function getBiomeByID(id) {
	for(let b=0; b<biomePoints.length; b++) {
		let biome = biomePoints[b];
		if (biome.id === id) {
			return biome;
		}
	}
	return null;
}

// Returns a new biome name for displaying
function generateBiomeName(id) {
	return String(id);
}

// Converts a biome point to a point object to be passed to the Voronoi API
function biomePointToVoronoiPoint(point) {
	// Apart from x and y, we also add the biome ID to the Voronoi point
	// so we can re-identify to which biome it belongs to when the
	// object is returned from the Voronoi script output.
	let newPoint = { x: point.heat, y: point.humidity, [biomeIDSymbol]: point.id }
	return newPoint;
}
// Converts a point object for the Voronoi API to a biome point
function voronoiPointToBiomePoint(point) {
	let newPoint = { heat: point.x, humidity: point.y, id: point[biomeIDSymbol] }
	return newPoint;
}

/***** Draw functions *****/
/* Note: All of these need a draw context. */

/* Render the "resize corner", a couple of diagonal lines in the corner
indicating the canvas can be resized */
function putResizeCorner(context) {
	if (canvas_cursor_x !== null) {
		context.beginPath();
		context.moveTo(voronoiCanvas.width, voronoiCanvas.height - RESIZE_CORNER);
		context.lineTo(voronoiCanvas.width - RESIZE_CORNER, voronoiCanvas.height);
		context.lineTo(voronoiCanvas.width, voronoiCanvas.height);
		context.fillStyle = "#80808080";
		context.closePath();
		context.fill();

		context.beginPath();
		context.lineWidth = 1;
		for (let c = RESIZE_CORNER; c>0; c-=4) {
			context.moveTo(voronoiCanvas.width, voronoiCanvas.height - c);
			context.lineTo(voronoiCanvas.width - c, voronoiCanvas.height);
		}
		context.strokeStyle = "#00000080";
		context.closePath();
		context.stroke();
	}
}

/* Put the name of the given point on the draw context */
function putPointName(context, point) {
	let he = point.heat
	let hu = point.humidity
	if (he < limit_heat_min || he > limit_heat_max || hu < limit_humidity_min || hu > limit_humidity_max) {
		return;
	}
	let [x, y] = biomeCoordsToCanvasPixelCoords(he, hu);
	let w = voronoiCanvas.width;
	let h = voronoiCanvas.height;
	if (x > w/2) {
		context.textAlign = "right";
		x = x-5;
	} else {
		context.textAlign = "left";
		x = x+5;
	}
	if (y < h/2) {
		context.textBaseline = "top";
	} else {
		context.textBaseline = "alphabetic";
	}
	context.font = "120% sans-serif"
	let displayName = point.name;
	if (displayName === "") {
		displayName = FALLBACK_NAME;
	}
	context.fillText(displayName, x, y);
}

/* Put the given point on the draw context */
function putPoint(context, point) {
	const ARROW_SIZE_SIDE = 7;
	const ARROW_SIZE_CORNER = 9;
	let he = point.heat
	let hu = point.humidity
	let [x, y] = biomeCoordsToCanvasPixelCoords(he, hu);
	let w = voronoiCanvas.width;
	let h = voronoiCanvas.height;
	let [limit_x_min, limit_y_min] = biomeCoordsToCanvasPixelCoords(limit_heat_min, limit_humidity_min);
	let [limit_x_max, limit_y_max] = biomeCoordsToCanvasPixelCoords(limit_heat_max, limit_humidity_max);
	// Point is out of bounds: Draw an arrow at the border
	if (he < limit_heat_min || he > limit_heat_max || hu < limit_humidity_min || hu > limit_humidity_max) {
		context.beginPath();
		// bottom left corner
		if (he < limit_heat_min && hu < limit_humidity_min) {
			context.moveTo(limit_x_min, limit_y_min);
			context.lineTo(limit_x_min + ARROW_SIZE_CORNER, limit_y_min);
			context.lineTo(limit_x_min, limit_y_min - ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// bottom right corner
		} else if (he > limit_heat_max && hu < limit_humidity_min) {
			context.moveTo(limit_x_max, limit_y_min);
			context.lineTo(limit_x_max - ARROW_SIZE_CORNER, limit_y_min);
			context.lineTo(limit_x_max, limit_y_min - ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// top left corner
		} else if (he < limit_heat_min && hu > limit_humidity_max) {
			context.moveTo(limit_x_min, limit_y_max);
			context.lineTo(limit_x_min + ARROW_SIZE_CORNER, limit_y_max);
			context.lineTo(limit_x_min, limit_y_max + ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// top right corner
		} else if (he > limit_heat_max && hu > limit_humidity_max) {
			context.moveTo(limit_x_max, limit_y_max);
			context.lineTo(limit_x_max - ARROW_SIZE_CORNER, limit_y_max);
			context.lineTo(limit_x_max, limit_y_max + ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// left side
		} else if (he < limit_heat_min) {
			context.moveTo(limit_x_min, y);
			context.lineTo(limit_x_min + ARROW_SIZE_SIDE, y + ARROW_SIZE_SIDE);
			context.lineTo(limit_x_min + ARROW_SIZE_SIDE, y - ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		// right side
		} else if (he > limit_heat_max) {
			context.moveTo(limit_x_max, y);
			context.lineTo(limit_x_max - ARROW_SIZE_SIDE, y + ARROW_SIZE_SIDE);
			context.lineTo(limit_x_max - ARROW_SIZE_SIDE, y - ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		// bottom side
		} else if (hu < limit_humidity_min) {
			context.moveTo(x, limit_y_min);
			context.lineTo(x - ARROW_SIZE_SIDE, limit_y_min - ARROW_SIZE_SIDE);
			context.lineTo(x + ARROW_SIZE_SIDE, limit_y_min - ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		// top side
		} else if (hu > limit_humidity_max) {
			context.moveTo(x, limit_y_max);
			context.lineTo(x - ARROW_SIZE_SIDE, limit_y_max + ARROW_SIZE_SIDE);
			context.lineTo(x + ARROW_SIZE_SIDE, limit_y_max + ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		}
	// Point is in bounds: Draw a dot
	} else {
		context.beginPath();
		context.moveTo(0, 0);
		context.arc(x, y, 5, 0, Math.PI * 2);
		context.closePath();
		context.fill();
	}
};

/* Put the grid on the draw context */
function putGrid(context) {
	let [limit_x_min, limit_y_min] = biomeCoordsToCanvasPixelCoords(limit_heat_min, limit_humidity_min);
	let [limit_x_max, limit_y_max] = biomeCoordsToCanvasPixelCoords(limit_heat_max, limit_humidity_max);

	// Calculate the "grid lines pixel ratio" to reduce the
	// width of grid lines or even disable rendering them.
	// A high ratio means that a LOT of grid lines would render
	// on the canvas.
	// This code will effectively trigger if the value range
	// is very high.
	let xGridLinesPerPixel = (limit_heat_max-limit_heat_min) / voronoiCanvas.width / GRID_STEP;
	let yGridLinesPerPixel = (limit_humidity_max-limit_humidity_min) / voronoiCanvas.height/ GRID_STEP;
	let xWidth = GRID_WIDTH_LEVEL_3;
	let yWidth = GRID_WIDTH_LEVEL_3;
	if (xGridLinesPerPixel > GRID_THRESHOLD_LEVEL_0) {
		xWidth = null;
	} else if (xGridLinesPerPixel > GRID_THRESHOLD_LEVEL_1) {
		xWidth = GRID_WIDTH_LEVEL_1;
	} else if (xGridLinesPerPixel > GRID_THRESHOLD_LEVEL_2) {
		xWidth = GRID_WIDTH_LEVEL_2;
	}
	if (yGridLinesPerPixel > GRID_THRESHOLD_LEVEL_0) {
		yWidth = null;
	} else if (yGridLinesPerPixel > GRID_THRESHOLD_LEVEL_1) {
		yWidth = GRID_WIDTH_LEVEL_1;
	} else if (xGridLinesPerPixel > GRID_THRESHOLD_LEVEL_2) {
		yWidth = GRID_WIDTH_LEVEL_2;
	}
	context.strokeStyle = GRID_COLOR;
	if (xWidth !== null) {
		context.lineWidth = xWidth;
		for (let he=0; he<=limit_heat_max; he+=GRID_STEP) {
			let [x, _] = biomeCoordsToCanvasPixelCoords(he, 0);
			context.beginPath();
			context.moveTo(x, limit_y_min);
			context.lineTo(x, limit_y_max);
			context.stroke();
		}
		for (let he=-GRID_STEP; he>=limit_heat_min; he-=GRID_STEP) {
			let [x, _] = biomeCoordsToCanvasPixelCoords(he, 0);
			context.beginPath();
			context.moveTo(x, limit_y_min);
			context.lineTo(x, limit_y_max);
			context.stroke();
		}
	}
	if (yWidth !== null) {
		context.lineWidth = yWidth;
		for (let hu=0; hu<=limit_humidity_max; hu+=GRID_STEP) {
			let [_, y] = biomeCoordsToCanvasPixelCoords(0, hu);
			context.beginPath();
			context.moveTo(limit_x_min, y);
			context.lineTo(limit_x_max, y);
			context.stroke();
		}
		for (let hu=-GRID_STEP; hu>=limit_humidity_min; hu-=GRID_STEP) {
			let [_, y] = biomeCoordsToCanvasPixelCoords(0, hu);
			context.beginPath();
			context.moveTo(limit_x_min, y);
			context.lineTo(limit_x_max, y);
			context.stroke();
		}
	}
}

/* Put the labelled heat/humidity axes on the draw context */
function putAxes(context) {
	// Size of arrows (px)
	const AXIS_ARROW_SIZE = 8;
	// Offset that arrows have from the border (px)
	const ARROW_OFFSET = 1;
	// Minimum distance (px) that axis must have from the border
	const AXIS_BORDER_OFFSET = 10;
	// Maximum distance (px) from certain borders at which the axis
	// labels and ticks will be put on the other sides
	const AXIS_LABEL_FLIP_OFFSET = 40;

	context.lineWidth = 2;
	context.strokeStyle = AXIS_COLOR;
	let [x0, y0] = biomeCoordsToCanvasPixelCoords(0, 0);
	let tick_heat = (limit_heat_max - limit_heat_min) * (100/175);
	let tick_humidity = (limit_humidity_max - limit_humidity_min) * (100/175);
	let [tx, ty] = biomeCoordsToCanvasPixelCoords(tick_heat, tick_humidity);
	let w = voronoiCanvas.width;
	let h = voronoiCanvas.height;

	// If axis would go out of bounds, force them to
	// be rendered at the side instead.
	let other_side_x = false;
	let other_side_y = false;
	if (x0 <= AXIS_BORDER_OFFSET) {
		x0 = AXIS_BORDER_OFFSET;
	} else if (x0 >= w - AXIS_BORDER_OFFSET) {
		x0 = w - AXIS_BORDER_OFFSET;
	}
	if (y0 <= AXIS_BORDER_OFFSET) {
		y0 = AXIS_BORDER_OFFSET;
	} else if (y0 >= h - AXIS_BORDER_OFFSET) {
		y0 = h - AXIS_BORDER_OFFSET;
	}
	// Flip axis labels if coming close to certain sides
	if (x0 <= AXIS_LABEL_FLIP_OFFSET) {
		other_side_y = true;
	}
	if (y0 >= h - AXIS_LABEL_FLIP_OFFSET) {
		other_side_x = true;
	}


	// horizontal axis
	context.beginPath();
	context.moveTo(0, y0);
	context.lineTo(w, y0);
	// tick
	if (other_side_x) {
		context.moveTo(tx, y0 - AXIS_ARROW_SIZE);
		context.lineTo(tx, y0);
	} else {
		context.moveTo(tx, y0);
		context.lineTo(tx, y0 + AXIS_ARROW_SIZE);
	}
	// arrow
	context.moveTo(w-ARROW_OFFSET, y0);
	context.lineTo(w-ARROW_OFFSET - AXIS_ARROW_SIZE, y0 - AXIS_ARROW_SIZE);
	context.moveTo(w-ARROW_OFFSET, y0);
	context.lineTo(w-ARROW_OFFSET - AXIS_ARROW_SIZE, y0 + AXIS_ARROW_SIZE);
	context.stroke();
	context.closePath();

	// vertical axis
	context.beginPath();
	context.moveTo(x0, 0);
	context.lineTo(x0, h);
	// tick
	if (other_side_y) {
		context.moveTo(x0 + AXIS_ARROW_SIZE, ty);
		context.lineTo(x0, ty);
	} else {
		context.moveTo(x0, ty);
		context.lineTo(x0 - AXIS_ARROW_SIZE, ty);
	}
	// arrow
	context.moveTo(x0, ARROW_OFFSET);
	context.lineTo(x0 - AXIS_ARROW_SIZE, ARROW_OFFSET+AXIS_ARROW_SIZE);
	context.moveTo(x0, ARROW_OFFSET);
	context.lineTo(x0 + AXIS_ARROW_SIZE, ARROW_OFFSET+AXIS_ARROW_SIZE);
	context.stroke();
	context.closePath();

	// axis+tick labels
	context.fillStyle = "black";

	// heat label
	context.font = "100% sans-serif";

	let lx, ly, ttx, tty;
	if (other_side_x) {
		context.textBaseline = "bottom";
		context.textAlign = "right";
		lx = w - AXIS_ARROW_SIZE*2;
		ly = y0 - 4;
		tty = y0 - AXIS_ARROW_SIZE;
	} else {
		context.textBaseline = "top";
		context.textAlign = "right";
		lx = w - AXIS_ARROW_SIZE*2;
		ly = y0 + 4;
		tty = y0 + AXIS_ARROW_SIZE;
	}
	context.fillText("heat", lx, ly);

	context.textAlign = "center";
	context.fillText(Math.round(tick_heat), tx, tty);

	// humidity label
	context.font = "100% sans-serif";
	context.save();
	context.rotate(-Math.PI/2);
	if (other_side_y) {
		context.textBaseline = "top";
		context.textAlign = "right";
		lx = -AXIS_ARROW_SIZE*2;
		ly = x0 + 4;
	} else {
		context.textBaseline = "bottom";
		context.textAlign = "right";
		lx = -AXIS_ARROW_SIZE*2;
		ly = x0 - 4;
	}
	context.fillText("humidity", lx, ly);
	context.restore();
	if (other_side_y) {
		context.textAlign = "left";
		ttx = x0 + AXIS_ARROW_SIZE-2;
	} else {
		context.textAlign = "right";
		ttx = x0 - AXIS_ARROW_SIZE-2;
	}
	context.textBaseline = "middle";
	context.fillText(Math.round(tick_humidity), ttx, ty);
}

// Cache diagram object for performance boost
let cachedVoronoiDiagram = null;

/* Given the list of biome points, returns a Voronoi diagram object
(which may have been cached). If recalculate is true, a recalculation is forced. */
function getVoronoiDiagram(points, recalculate) {
	// Calculate bounding box, defaults to heat/humidity limits ...
	let vbbox = {xl: limit_heat_min, xr: limit_heat_max, yb: limit_humidity_max, yt: limit_humidity_min};
	const BUFFER_ZONE = 1;
	// ... unless a point is out of bounds,
	// then we increase the bounding box size
	for (let p of points) {
		if (p.heat < vbbox.xl) {
			vbbox.xl = p.heat - BUFFER_ZONE;
		} else if (p.heat > vbbox.xr) {
			vbbox.xr = p.heat + BUFFER_ZONE;
		}
		if (p.humidity < vbbox.yt) {
			vbbox.yt = p.humidity - BUFFER_ZONE;
		} else if (p.humidity > vbbox.yb) {
			vbbox.yb = p.humidity + BUFFER_ZONE;
		}
	}
	if ((cachedVoronoiDiagram === null) || recalculate) {
		let sites = []
		for (let p of points) {
			sites.push(biomePointToVoronoiPoint(p));
		}
		let voronoi = new Voronoi();
		let diagram = null;
		if (cachedVoronoiDiagram && recalculate) {
			diagram = cachedVoronoiDiagram;
			// This should improve performance
			voronoi.recycle(diagram);
		}
		try {
			diagram = voronoi.compute(sites, vbbox);
			cachedVoronoiDiagram = diagram;
			return diagram;
		} catch {
			cachedVoronoiDiagram = null;
			return null;
		}
	} else {
		return cachedVoronoiDiagram;
	}
}

/* Returns the context object required to draw on the canvas */
function getDrawContext() {
	let canvas = document.getElementById("voronoiCanvas");
	if (canvas.getContext) {
		return canvas.getContext("2d");
	} else {
		return null;
	}
}

// Clear draw area
function clear(context) {
	if (!context) {
		context = getDrawContext();
		if (!context) {
			return false;
		}
	}
	context.fillStyle = CLEAR_COLOR;
	context.fillRect(-DRAW_OFFSET, -DRAW_OFFSET, voronoiCanvas.width+DRAW_OFFSET, voronoiCanvas.height+DRAW_OFFSET);
	return true;
}

/* Returns all biome points except those whose Y limits fall out of the
given y value */
function getRenderedPoints(y) {
	let points = [];
	for (let p=0; p<biomePoints.length; p++) {
		let point = biomePoints[p];
		if (y >= point.min_y && y <= point.max_y) {
			points.push(point);
		}
	}
	return points;
}

/* Given a biome ID, returns the matching HTML element from the
biome list widget or null if none */
function getBiomeIDFromHTMLElement(elem) {
	let strID = elem.id;
	if (strID && strID.startsWith("biome_list_element_")) {
		let slice = strID.slice(19);
		if (slice) {
			return +slice;
		}
	}
	return null;
}

/* Returns both the ID of selected biome and the associated HTML element from
the biome list widget, or null if nothing is selected.
Result is returned in the form [id, htmlElement] or [null, null] */
function getSelectedBiomeIDAndElement() {
	if (biomeSelector.selectedIndex === -1) {
		return [null, null];
	}
	let elem = biomeSelector.options[biomeSelector.selectedIndex];
	let biomeID = getBiomeIDFromHTMLElement(elem);
	if (biomeID !== null) {
		return [biomeID, elem];
	}
	return [null, null];
}

/* Draws the diagram on the voronoiCanvas.
Will (re-)calculate the Voronoi diagram if recalculate is true;
otherwise it may re-use a previous diagram for performance reasons. */
function draw(recalculate) {
	let context = getDrawContext();
	let w = voronoiCanvas.width;
	let h = voronoiCanvas.height;
	let y = getViewY();

	// shorter function name (for "convert")
	let conv = biomeCoordsToCanvasPixelCoords

	if (!context) {
		if (!voronoiCanvas.hidden) {
			voronoiCanvas.hidden = true;
			coordinateDisplay.hidden = true;
			altitudeDisplay.hidden = true;
			rangeDisplay.hidden = true;
			configDiv.hidden = true;

			errorMessage.innerText = "ERROR: Could not get the canvas context which means this tool won't work for you. Maybe your browser does not support the HTML canvas element properly.";
		}
		return false;
	}
	clear(context);

	let showDiagramMessage = function(context, text) {
		context.textAlign = "center";
		context.fillStyle = "black";
		context.textBaseline = "middle";
		if (voronoiCanvas.width < 300) {
			context.font = "100% sans-serif";
		} else if (voronoiCanvas.width < 450) {
			context.font = "150% sans-serif";
		} else {
			context.font = "200% sans-serif";
		}
		context.fillText(text, voronoiCanvas.width/2, voronoiCanvas.height/2);
		updateAltitudeText();
	}

	// Render a special message if the value range is tiny
	if ((limit_heat_max - limit_heat_min < 0.01) || (limit_humidity_max - limit_humidity_min < 0.01)) {
		showDiagramMessage(context, "Value range is too small.");
		drawError = true;
		putResizeCorner(context);
		return true;
	}

	let points = getRenderedPoints(y);
	// Render a special message if there are no biomes
	if (points.length === 0) {
		if (biomePoints.length === 0) {
			showDiagramMessage(context, "No biomes.");
		} else {
			showDiagramMessage(context, "No biomes in this Y altitude.");
		}
		drawError = true;
		putResizeCorner(context);
		return true;
	}

	updateAltitudeText();

	let voronoiError = function() {
		showDiagramMessage(context, "Error in Javascript-Voronoi!");
		drawError = true;
		putResizeCorner(context);
	}

	let diagram = getVoronoiDiagram(points, recalculate);

	if (!diagram) {
		voronoiError();
		drawError = true;
		return true;
	}
	drawError = false;

	let createHalfedgesPath = function(context, cell) {
		context.beginPath();
		for (let h=0; h<cell.halfedges.length; h++) {
			let halfedge = cell.halfedges[h]
			let start = halfedge.getStartpoint()
			let end = halfedge.getEndpoint()
			let [cx1, cy1] = conv(start.x, start.y);
			let [cx2, cy2] = conv(end.x, end.y);
			if (h === 0) {
				context.moveTo(cx1, cy1);
			} else {
				context.lineTo(cx1, cy1);
			}
			context.lineTo(cx2, cy2);
		}
		context.closePath();
	}

	// Render cell colors
	if (showCellColors) {
		let colors = CELL_COLORS;

		/* Before we paint the cells,
		we paint the cell (half)edges in their
		cell color. Painting the cells alone
		leaves a tiny little space between the
		cells unpainted, so there is an ugly boundary
		between space. Painting the edges before
		painting the cells should ensure these ugly
		boundaries are gone */
		for (let c=0; c<diagram.cells.length; c++) {
			let cell = diagram.cells[c];
			// We use the biomeID to select a color
			let biomeID = cell.site[biomeIDSymbol];
			// This works because the biome ID is a number
			let biome = getBiomeByID(biomeID);
			if (biome.colorIndex !== null) {
				context.strokeStyle = CELL_COLORS[biome.colorIndex];
			} else {
				let ccol = biomeID % CELL_COLORS.length;
				context.strokeStyle = CELL_COLORS[ccol];
			}
			/* The line can be quite thick because
			most of it will be painted over by the
			actual cell themselves anyway */
			context.lineWidth = 6;

			createHalfedgesPath(context, cell);

			context.stroke();
		}

		// Paint the cells
		for (let c=0; c<diagram.cells.length; c++) {
			let cell = diagram.cells[c];
			// We use the biomeID to select a color
			let biomeID = cell.site[biomeIDSymbol];
			// This works because the biome ID is a number

			let biome = getBiomeByID(biomeID);
			if (biome.colorIndex !== null) {
				context.fillStyle = CELL_COLORS[biome.colorIndex];
			} else {
				let ccol = biomeID % CELL_COLORS.length;
				context.fillStyle = CELL_COLORS[ccol];
			}

			createHalfedgesPath(context, cell);

			context.fill();
		}
		// If there's only 1 cell, we have to manually colorize it because
		// the Voronoi script doesn't return that area in this special case.
		if (points.length === 1 && diagram.cells.length === 1) {
			// 1 cell means the whole area is filled

			let cell = diagram.cells[0];
			let biomeID = cell.site[biomeIDSymbol];
			let biome = getBiomeByID(biomeID);
			if (biome.colorIndex !== null) {
				context.fillStyle = CELL_COLORS[biome.colorIndex];
			} else {
				let ccol = biomeID % CELL_COLORS.length;
				context.fillStyle = CELL_COLORS[ccol];
			}
			context.fillRect(-DRAW_OFFSET, -DRAW_OFFSET, w+DRAW_OFFSET, h+DRAW_OFFSET);
		}
	} else {
		// Use a "neutral" background color for the whole area if cell colors are disabled
		context.fillStyle = CELL_COLOR_NEUTRAL;
		context.fillRect(-DRAW_OFFSET, -DRAW_OFFSET, w+DRAW_OFFSET, h+DRAW_OFFSET);
	}

	if (points.length > 0) {
		if (showGrid) {
			putGrid(context);
		}
		if (showAxes) {
			putAxes(context);
		}
	}

	// Render Voronoi cell edges
	context.lineWidth = 2.5;
	for (let e=0; e<diagram.edges.length; e++) {
		let edge = diagram.edges[e];
		if (edge.rSite === null) {
			context.strokeStyle = "transparent";
		} else {
			context.strokeStyle = EDGE_COLOR;
		}
		let [eax, eay] = conv(edge.va.x, edge.va.y);
		let [ebx, eby] = conv(edge.vb.x, edge.vb.y);
		context.beginPath();
		context.moveTo(eax, eay);
		context.lineTo(ebx, eby);
		context.closePath();
		context.stroke();
	}

	let [selElemID, _] = getSelectedBiomeIDAndElement();

	// Render biome points
	if (showPoints) {
		for (let point of points) {
			let pointID = point.id;
			// Highlight selected point
			if (selElemID !== null && pointID === selElemID) {
				context.fillStyle = POINT_COLOR_SELECTED;
			} else {
				context.fillStyle = POINT_COLOR;
			}
			putPoint(context, point);
		}
	}
	if (showNames) {
		// Render biome point names
		for (let point of points) {
			let pointID = point.id;
			// Highlight selected point
			if (selElemID !== null && pointID === selElemID) {
				context.fillStyle = "#FF8888FF";
			} else {
				context.fillStyle = "#FFFFFFAA";
			}
			putPointName(context, point);
		}
	}

	putResizeCorner(context);

	return true;
}

/* Clears the biome list widget and (re-adds) the list elements
for the biomes from scratch. */
function repopulateBiomeSelector() {
	biomeSelector.innerHTML = "";
	for (let b=0; b<biomePoints.length; b++) {
		let num = b+1;
		let newElem = document.createElement("option");
		newElem.value = num;
		newElem.id = "biome_list_element_" + biomePoints[b].id;
		let displayName = biomePoints[b].name;
		if (displayName === "") {
			displayName = FALLBACK_NAME;
		}
		let newElemText = document.createTextNode(displayName);
		newElem.append(newElemText);
		biomeSelector.append(newElem);
	}
}

/* Update the status (like disabled or value) of all widgets that
affect the diagram, based on the internal data */
function updateWidgetStates() {
	let state;
	if (biomePoints.length === 0 || biomeSelector.selectedIndex === -1) {
		state = "disabled";
	} else {
		state = "";
	}
	inputHeat.disabled = state;
	inputHumidity.disabled = state;
	inputMinY.disabled = state;
	inputMaxY.disabled = state;
	inputBiomeName.disabled = state;
	removeBiomeButton.disabled = state;
	for (let c=0; c<CELL_COLORS.length; c++) {
		let elem = document.getElementById("inputBiomeColor"+c);
		if (elem) {
			elem.disabled = state;
			elem.style.borderColor = "";
			elem.innerHTML = "&nbsp;";
		}
	}
	if (biomeSelector.selectedIndex !== -1) {
		let selected = biomeSelector.options[biomeSelector.selectedIndex];
		let point = biomePoints[biomeSelector.selectedIndex];
		inputHeat.value = point.heat;
		inputHumidity.value = point.humidity;
		inputMinY.value = point.min_y;
		inputMaxY.value = point.max_y;
		inputBiomeName.value = point.name;
		let colorIndex = point.colorIndex;
		for (let c=0; c<CELL_COLORS.length; c++) {
			let elem = document.getElementById("inputBiomeColor"+c);
			if (elem) {
				if (c === colorIndex) {
					// Add a symbol for selected color
					elem.innerHTML = "&#9679;"; // Unicode: BLACK CIRCLE
				} else {
					// Blank out non-selected color
					elem.innerHTML = "&nbsp;";
				}
			}
		}
	}
	inputNoiseHeatOffset.value = noises.heat.offset;
	inputNoiseHeatScale.value = noises.heat.scale;
	inputNoiseHeatOctaves.value = noises.heat.octaves;
	inputNoiseHeatPersistence.value = noises.heat.persistence;
	inputNoiseHumidityOffset.value = noises.humidity.offset;
	inputNoiseHumidityScale.value = noises.humidity.scale;
	inputNoiseHumidityOctaves.value = noises.humidity.octaves;
	inputNoiseHumidityPersistence.value = noises.humidity.persistence;
}

/* To be called when a biome value like heat was changed.
Will update internal data, biome list and the diagram.
* pointField: Name of the field it affects (same as in biomePoints)
* value: The value to set */
function onChangeBiomeValueWidget(pointField, value) {
	if (biomeSelector.selectedIndex === -1) {
		return;
	}
	let selected = biomeSelector.options[biomeSelector.selectedIndex];
	if (selected === null) {
		return;
	}
	let point = biomePoints[biomeSelector.selectedIndex];
	point[pointField] = value;
	let displayName = point.name;
	if (displayName === "") {
		displayName = FALLBACK_NAME;
	}
	selected.innerText = displayName;
	draw(true);
}

// Select the given point.
// point is a point from biomePoints.
// returns [selected, alreadySelected]
// where seleted is true if the point has been selected
// and alreadySelected is true if the point was selected before
function selectPoint(point) {
	for (let elem of biomeSelector.options) {
		let strID = elem.id;
		let elemID = null;
		let biomeID = getBiomeIDFromHTMLElement(elem);
		if ((biomeID !== null) && (point.id === biomeID)) {
			if (elem.selected === true) {
				return [true, true];
			}
			elem.selected = "selected";
			draw(false);
			updateWidgetStates();
			return [true, false];
		}
	}
	return [false, false];
}

// Returns the distance between the two 2D points (x1, y1) and (x2, y2)
function getDistance(x1, y1, x2, y2) {
	return Math.sqrt((x2 - x1)**2 + (y2 - y1)**2);
}

// Converts (x, y) canvas pixel coordinates to biome coordinates;
// returns [heat, humidity]
function canvasPixelCoordsToBiomeCoords(x, y) {
	let w = (voronoiCanvas.width/(limit_heat_max-limit_heat_min));
	let h = (voronoiCanvas.height/(limit_humidity_max-limit_humidity_min));
	let heat = Math.round((x + limit_heat_min * w) / w);
	// This also flips the Y axis
	let humidity = limit_humidity_min + (limit_humidity_max - (Math.round((y + limit_humidity_min * h) / h)));
	return [heat, humidity];
}
// Converts heat and humidity coordinates to canvas pixel coordinates;
// returns [x, y]
function biomeCoordsToCanvasPixelCoords(heat, humidity) {
	let w = (voronoiCanvas.width/(limit_heat_max-limit_heat_min));
	let h = (voronoiCanvas.height/(limit_humidity_max-limit_humidity_min));
	let pixelX = heat * w - limit_heat_min * w;
	// This also flips the Y axis
	let pixelY = voronoiCanvas.height - (humidity * h - limit_humidity_min * h);
	return [pixelX, pixelY];
}

// Given a (x, y) pixel positition on the canvas, returns
// the point that is nearest to it or null if none.
// maxDist is the maximum allowed point distance,
// if it is exceeded, null is returned.
function getNearestPointFromCanvasPos(x, y, maxDist) {
	let nearestPoint = null;
	let nearestDist = null;
	let points = getRenderedPoints(getViewY());
	for (let i=0; i<points.length; i++) {
		let point = points[i];
		let [pixelX, pixelY] = biomeCoordsToCanvasPixelCoords(point.heat, point.humidity);
		let dist = getDistance(x, y, pixelX, pixelY);
		if (nearestPoint === null) {
			nearestPoint = point;
			nearestDist = dist;
		} else if (dist < nearestDist) {
			nearestPoint = point;
			nearestDist = dist;
		}
	}
	if (nearestDist < maxDist) {
		return nearestPoint;
	} else {
		return null;
	}
}

// Whether the mouse is currently pressed
let mouseIsDown = false;
// Whether the canvas is being resized
let resizing = false;
// Start coordinates of canvas resize or null if not resizing
let resizing_start_pos_x = null;
let resizing_start_pos_y = null;
// Start size of canvas when resizing or null if not resizing
let resizing_start_size_x = null;
let resizing_start_size_y = null;

// Coordinates of where the drag-n-drop started
// or is about to start
let dragDropStartPos = null;

// ID of point being currently dragged by the user
// or null if none.
let dragDropPointID = null;

// Current drag-n-drop state:
// 0 = no drag-n-drop
// 1 = preparing drag-n-drop right after selection
// 2 = drag-n-drop active
let dragDropState = 0;

/* Move and update the biome point while the user
is dragging it */
function updatePointWhenDragged(pointID) {
	if (pointID !== null && !drawError) {
		let selectedPoint = null;
		let points = getRenderedPoints(getViewY());
		for (let i=0; i<points.length; i++) {
			if (points[i].id === dragDropPointID) {
				selectedPoint = points[i];
				let [newHeat, newHumidity] = canvasPixelCoordsToBiomeCoords(event.offsetX, event.offsetY);
				selectedPoint.heat = newHeat;
				selectedPoint.humidity = newHumidity;
				draw(true);
				updateWidgetStates();
				let [elemID, elem] = getSelectedBiomeIDAndElement();
				if (elemID !== null && points[i].id === elemID) {
					let displayName = selectedPoint.name;
					if (displayName === "") {
						displayName = FALLBACK_NAME;
					}
					elem.innerText = displayName;
					break;
				}
				return;
			}
		}
	}
}

/* Updates the text showing the current altitude (Y height)
the diagram currently applies */
function updateAltitudeText() {
	altitudeDisplay.innerHTML = "showing diagram for altitude Y=<span class='statAltitude'>"+inputViewY.value+"</span>";
}


/* Update the text that shows the biome coordinates
of the cursor when it's on the diagram */
function updateCoordinateDisplay(pixelX, pixelY) {
	if (pixelX === null || pixelY === null) {
		coordinateDisplay.innerHtml = "&nbsp;";
		return;
	}
	// show coordinates
	let [heat, humidity] = canvasPixelCoordsToBiomeCoords(pixelX, pixelY);
	if (!drawError) {
		let html = "cursor coordinates: heat=<span class='statHeat'>"+heat+"</span>; humidity=<span class='statHumidity'>"+humidity+"</span>";
		coordinateDisplay.innerHTML = html;
	} else {
		coordinateDisplay.innerHTML = "&nbsp;";
	}
}

/* Updates and changes the cursor type on the diagram
canvas depending on whether we can select, drag or do nothing
at the pointed position */
function updateCanvasCursorStatus(x, y) {
	// Show resize cursor at the bottom right corner
	if (resizing || (x > voronoiCanvas.width - RESIZE_CORNER && y > voronoiCanvas.height - RESIZE_CORNER)) {
		voronoiCanvas.style.cursor = "nwse-resize";
		return
	}

	if (drawError || !showPoints) {
		// a special message is shown; use auto cursor
		voronoiCanvas.style.cursor = "auto";
		return
	}

	let nearest = getNearestPointFromCanvasPos(x, y, POINT_SELECT_DISTANCE);
	if (nearest !== null) {
		let [id, elem] = getSelectedBiomeIDAndElement();
		if (id !== null && nearest.id === id) {
			// This cursor indicates we can grab the point
			voronoiCanvas.style.cursor = "grab";
		} else {
			// This cursor indicates we can select the point
			voronoiCanvas.style.cursor = "crosshair";
		}
	} else {
		// Default cursor when a click doesn't to anything
		voronoiCanvas.style.cursor = "auto";
	}
}

/* Initializes checkbox variables of the view settings */
function checkboxVarsInit() {
	showNames = inputCheckboxNames.checked;
	showPoints = inputCheckboxPoints.checked;
	showCellColors = inputCheckboxCellColors.checked;
	showGrid = inputCheckboxGrid.checked;
	showAxes = inputCheckboxAxes.checked;
}

/* Collapses/Expands a config section */
function toggleConfigSectionDisplay(headerLink, container) {
	if (container.style.display !== "none") {
		headerLink.innerText = "▶";
		container.style.display = "none";
	} else {
		headerLink.innerText = "▼";
		container.style.display = "block";
	}
}

/* Unhide the main content. Used to disable the noscript
handling because the website starts with the main content
container hidden so the noscript version of the page
isn't cluttered. */
function unhideContent() {
	mainContentContainer.hidden = false;
	/* Also hide the container holding the noscript error
	message to avoid spacing issues */
	noscriptContainer.hidden = true;
}

function initBiomeColorSelectors() {
	for (let c=0; c<CELL_COLORS.length; c++) {
		let button = document.createElement("button");
		button.type = "button";
		button.style.backgroundColor = CELL_COLORS[c];
		button.style.width = "2em";
		button.style.height = "2em";
		button.innerHTML = "&nbsp;";
		button.id = "inputBiomeColor"+c;
		button.className = "biomeColorButton";
		biomeColorSection.append(button);

		button.onclick = function() {
			onChangeBiomeValueWidget("colorIndex", c);
			updateWidgetStates();
		}
	}
}

function fitCanvasInBody() {
	// Get x,y position of canvas
	let bodyRect = document.body.getBoundingClientRect();
	let canvasRect = voronoiCanvas.getBoundingClientRect();
	let cx = canvasRect.left - bodyRect.left;
	let cy = canvasRect.top - bodyRect.top;

	// Calculate new size
	let rx = window.innerWidth - cx - CANVAS_PAGE_MARGIN_RIGHT;

	let oldWidth = voronoiCanvas.width;
	let newWidth = Math.max(MIN_CANVAS_SIZE, rx);
	if (newWidth < oldWidth) {
		// Resize
		if (voronoiCanvas.height === voronoiCanvas.width) {
			voronoiCanvas.height = newWidth;
		}
		voronoiCanvas.width = newWidth;
		draw(false);
	}
}

/***** EVENTS *****/


/* Body events */
window.onresize = function(event) {
	fitCanvasInBody();
}
document.body.onmousemove = function(event) {
	if (resizing) {
		// Get x,y position of canvas
		let bodyRect = document.body.getBoundingClientRect();
		let canvasRect = voronoiCanvas.getBoundingClientRect();
		let cx = canvasRect.left - bodyRect.left;
		let cy = canvasRect.top - bodyRect.top;

		// Calculate new size
		let rx = event.pageX - resizing_start_pos_x - cx;
		let ry = event.pageY - resizing_start_pos_y - cy;

		// Limit the width
		let maxX = (bodyRect.width - cx) - CANVAS_PAGE_MARGIN_RIGHT;

		// Resize
		voronoiCanvas.width = Math.min(maxX, Math.max(MIN_CANVAS_SIZE, resizing_start_size_x + rx));

		// Holding down Shift preserves aspect ratio
		if (event.shiftKey) {
			voronoiCanvas.height = voronoiCanvas.width;
		} else {
			voronoiCanvas.height = Math.max(MIN_CANVAS_SIZE, resizing_start_size_y + ry);
		}
		draw(false);
		return;
	}
}
document.body.onmouseup = function(event) {
	if (resizing) {
		resizing = false;
		updateCanvasCursorStatus(event.offsetX, event.offsetY);
	}
}
document.body.onmouseleave = function(event) {
	if (resizing) {
		resizing = false;
		updateCanvasCursorStatus(event.offsetX, event.offsetY);
	}
}

/* Canvas events */
voronoiCanvas.onmousemove = function(event) {
	if (resizing) {
		updateCoordinateDisplay(event.offsetX, event.offsetY);
		updateCanvasCursorStatus(event.offsetX, event.offsetY);
		canvas_cursor_x = event.offsetX;
		canvas_cursor_y = event.offsetY;
		draw(false);
		return
	}
	// update drag-n-drop state
	if (dragDropState !== 2 && dragDropPointID !== null && mouseIsDown && dragDropStartPos !== null) {
		let dist = getDistance(dragDropStartPos.x, dragDropStartPos.y, event.offsetX, event.offsetY)
		if (dragDropState === 1 && dist >= 1) {
			dragDropState = 2;
		} else if ((dragDropState === 0 || dragDropState === 1) && dist > ONE_CLICK_DRAG_DROP_DISTANCE) {
			dragDropState = 2;
		}
	}
	// drag-n-drop
	if (dragDropState === 2) {
		updatePointWhenDragged(dragDropPointID);
	}
	updateCoordinateDisplay(event.offsetX, event.offsetY);
	updateCanvasCursorStatus(event.offsetX, event.offsetY);
	canvas_cursor_x = event.offsetX;
	canvas_cursor_y = event.offsetY;
	draw(false);
}
voronoiCanvas.onmouseenter = function(event) {
	updateCoordinateDisplay(event.offsetX, event.offsetY);
	updateCanvasCursorStatus(event.offsetX, event.offsetY);
	canvas_cursor_x = event.offsetX;
	canvas_cursor_y = event.offsetY;
	draw(false);
}

voronoiCanvas.onmousedown = function(event) {
	// select point by clicking.
	// initiate drag-n-drop if already selected.
	mouseIsDown = true;

	// Resizing the canvas
	if (event.offsetX > voronoiCanvas.width - RESIZE_CORNER && event.offsetY > voronoiCanvas.height - RESIZE_CORNER) {
		resizing_start_pos_x = event.offsetX;
		resizing_start_pos_y = event.offsetY;
		resizing_start_size_x = +this.width;
		resizing_start_size_y = +this.height;
		resizing = true;
		return;
	}

	if (drawError || !showPoints) {
		// Points need to be shown for drag-n-drop to work
		return;
	}
	let nearest = getNearestPointFromCanvasPos(event.offsetX, event.offsetY, POINT_SELECT_DISTANCE);
	if (nearest !== null) {
		let success, alreadySelected
		[success, alreadySelected] = selectPoint(nearest);
		dragDropPointID = nearest.id;
		if (success) {
			let [x, y] = biomeCoordsToCanvasPixelCoords(nearest.heat, nearest.humidity);
			dragDropStartPos = { x: x, y: y };
		}
		if (alreadySelected) {
			dragDropState = 1;
		}
		updateCanvasCursorStatus(event.offsetX, event.offsetY);
	}
}
voronoiCanvas.onmouseup = function(event) {
	// end drag-n-drop
	if (dragDropState === 2) {
		updatePointWhenDragged(dragDropPointID);
	}
	mouseIsDown = false;
	dragDropStartPos = null;
	dragDropPointID = null;
	dragDropState = 0;
}
voronoiCanvas.onmouseleave = function() {
	// end drag-n-drop
	mouseIsDown = false;
	dragDropStartPos = null;
	dragDropPointID = null;
	dragDropState = 0;
	canvas_cursor_x = null;
	canvas_cursor_y = null;
	coordinateDisplay.innerHTML = "&nbsp;";
	draw(false);
}

/* Biome list events */

biomeSelector.onchange = function() {
	draw(false);
	if (biomeSelector.selectedIndex !== -1) {
		let selected = biomeSelector.options[biomeSelector.selectedIndex];
		let point = biomePoints[biomeSelector.selectedIndex];
		inputHeat.value = point.heat;
		inputHumidity.value = point.humidity;
		inputMinY.value = point.min_y;
		inputMaxY.value = point.max_y;
	}
	updateWidgetStates();
}

addBiomeButton.onclick = function() {
	let he = Math.round(limit_heat_min + Math.random() * (limit_heat_max - limit_heat_min));
	let hu = Math.round(limit_humidity_min + Math.random() * (limit_humidity_max - limit_humidity_min));
	let newPoint = {
		id: lastBiomeID,
		name: generateBiomeName(lastBiomeID),
		heat: he,
		humidity: hu,
		min_y: MIN_Y_DEFAULT,
		max_y: MAX_Y_DEFAULT,
		colorIndex: lastBiomeID % CELL_COLORS.length,
	};
	biomePoints.push(newPoint);
	let num = biomePoints.length

	let newElem = document.createElement("option");
	newElem.id = "biome_list_element_" + lastBiomeID;
	newElem.value = "" + num;

	let newElemText = document.createTextNode(newPoint.name);
	newElem.append(newElemText);
	biomeSelector.append(newElem);
	newElem.selected = "selected";

	draw(true);
	updateWidgetStates();

	lastBiomeID++;
}
removeBiomeButton.onclick = function() {
	if (biomeSelector.selectedOptions.length === 0) {
		return;
	}
	let firstIndex = null;
	for (let o=0; o<biomeSelector.selectedOptions.length; o++) {
		let opt = biomeSelector.selectedOptions[o]
		let index = opt.index
		if (firstIndex === null) {
			firstIndex = index;
		}
		biomePoints.splice(index, 1);
		opt.remove();
	}
	if (firstIndex !== null && biomePoints.length > 0) {
		let newIndex = firstIndex-1;
		if (newIndex < 0) {
			newIndex = 0;
		}
		biomeSelector.options[newIndex].selected = "selected";
	}

	draw(true);
	updateWidgetStates();
}

/* Biome editing widgets events */

inputHeat.oninput = function() {
	onChangeBiomeValueWidget("heat", +this.value);
}
inputHumidity.oninput = function() {
	onChangeBiomeValueWidget("humidity", +this.value);
}
inputMinY.oninput = function() {
	onChangeBiomeValueWidget("min_y", +this.value);
}
inputMaxY.oninput = function() {
	onChangeBiomeValueWidget("max_y", +this.value);
}
inputBiomeName.oninput = function() {
	onChangeBiomeValueWidget("name", this.value);
}

/* Diagram view settings events */

inputViewY.oninput = function() {
	draw(true);
	updateAltitudeText();
}
inputCheckboxNames.onchange = function() {
	showNames = this.checked;
	draw(false);
}
inputCheckboxPoints.onchange = function() {
	showPoints = this.checked;
	draw(false);
}
inputCheckboxCellColors.onchange = function() {
	showCellColors = this.checked;
	draw(false);
}
inputCheckboxGrid.onchange = function() {
	showGrid = this.checked;
	draw(false);
}
inputCheckboxAxes.onchange = function() {
	showAxes = this.checked;
	draw(false);
}

/* Noise parameters events */

inputNoiseHeatScale.oninput = function() {
	noises.heat.scale = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHeatOffset.oninput = function() {
	noises.heat.offset = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHeatPersistence.oninput = function() {
	noises.heat.persistence = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHeatOctaves.oninput = function() {
	noises.heat.octaves = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHumidityScale.oninput = function() {
	noises.humidity.scale = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHumidityOffset.oninput = function() {
	noises.humidity.offset = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHumidityPersistence.oninput = function() {
	noises.humidity.persistence = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseHumidityOctaves.oninput = function() {
	noises.humidity.octaves = +this.value;
	clear();
	updateAreaVars();
	draw(true);
}
inputNoiseReset.onclick = function() {
	noises.heat.offset = NOISE_OFFSET_DEFAULT;
	noises.heat.scale = NOISE_SCALE_DEFAULT;
	noises.heat.octaves = NOISE_OCTAVES_DEFAULT;
	noises.heat.persistence = NOISE_PERSISTENCE_DEFAULT;
	noises.heat.absvalue = NOISE_ABSVALUE_DEFAULT;
	inputNoiseHeatOffset.value = noises.heat.offset;
	inputNoiseHeatScale.value = noises.heat.scale;
	inputNoiseHeatOctaves.value = noises.heat.octaves;
	inputNoiseHeatPersistence.value = noises.heat.persistence;

	noises.humidity.offset = NOISE_OFFSET_DEFAULT;
	noises.humidity.scale = NOISE_SCALE_DEFAULT;
	noises.humidity.octaves = NOISE_OCTAVES_DEFAULT;
	noises.humidity.persistence = NOISE_PERSISTENCE_DEFAULT;
	noises.humidity.absvalue = NOISE_ABSVALUE_DEFAULT;
	inputNoiseHumidityOffset.value = noises.humidity.offset;
	inputNoiseHumidityScale.value = noises.humidity.scale;
	inputNoiseHumidityOctaves.value = noises.humidity.octaves;
	inputNoiseHumidityPersistence.value = noises.humidity.persistence;

	clear();
	updateAreaVars();
	draw(true);
}

/* Export events */
inputExportLua.onclick = function() {
	let str = "";
	for (let b=0; b<biomePoints.length; b++) {
		let biome = biomePoints[b];

		// escape the name for Lua
		let escapedName = biome.name;
		// escape backslash
		escapedName = escapedName.replace(/\\/g, '\\\\');
		// escape quotation mark
		escapedName = escapedName.replace(/"/g, '\\\"');

		str += "minetest.register_biome({\n";
		str += `    name = \"${escapedName}\",\n`;
		str += `    heat_point = ${biome.heat},\n`;
		str += `    humidity_point = ${biome.humidity},\n`;
		str += `    y_min = ${biome.min_y},\n`;
		str += `    y_max = ${biome.max_y},\n`;
		str += "})\n";
	}
	exportSectionText.innerText = str;
	if (str === "") {
		exportSectionText.hidden = true;
		exportLabel.innerText = "Export is empty.";
	} else {
		exportSectionText.hidden = false;
		exportLabel.innerText = "Exported biomes (as Lua code):";
	}
	exportSectionOuter.hidden = false;
}
inputExportJSON.onclick = function() {
	// Convert the biome points to a new table
	let jsonPoints = [];
	for (let b=0; b<biomePoints.length; b++) {
		let biome = biomePoints[b];
		let jsonPoint = {};
		// Use different field names for the
		// JSON export to match the Lua field
		// names exactly.
		jsonPoint.name = biome.name;
		jsonPoint.heat_point = biome.heat;
		jsonPoint.humidity_point  = biome.humidity;
		jsonPoint.y_min = biome.min_y;
		jsonPoint.y_max = biome.max_y;
		jsonPoints.push(jsonPoint);
	}

	let str = JSON.stringify(jsonPoints, undefined, 4);
	exportSectionText.innerText = str;
	if (str === "") {
		exportSectionText.hidden = true;
		exportLabel.innerText = "Export is empty.";
	} else {
		exportSectionText.hidden = false;
		exportLabel.innerText = "Exported biomes (as JSON):";
	}
	exportSectionOuter.hidden = false;
}

// Assuming that hexColor is a string of the form
// "#xxxxxx" (where x is a hexadecimal digit),
// returns an object of the form { r: 0, g: 0, b: 0 }
function hexColorToRGBColor(hexColor) {
	if (typeof hexColor !== "string") {
		return null;
	}
	let rh = hexColor.slice(1,3);
	let gh = hexColor.slice(3,5);
	let bh = hexColor.slice(5,7);
	if (rh === "" || gh === "" || bh === "") {
		return null;
	}
	let r = Number("0x"+rh)
	let g = Number("0x"+gh)
	let b = Number("0x"+bh)
	if (typeof r !== "number" || typeof g !== "number" || typeof b !== "number") {
		return null;
	}
	return { r:r, g:g, b:b }
}

inputExportAmidstForMinetest.onclick = function() {
	let jsonOut = {};
	jsonOut.name = "MiBPoV Export";
	let jsonPoints = [];
	for (let b=0; b<biomePoints.length; b++) {
		let biome = biomePoints[b];
		let jsonPoint = {};
		jsonPoint.name = biome.name;
		let color = hexColorToRGBColor(CELL_COLORS[biome.colorIndex]);
		if (color !== null) {
			jsonPoint.color = color;
		} else {
			jsonPoint.color = { r: 255, g: 255, b: 255 };
		}
		jsonPoint.y_min = biome.min_y;
		jsonPoint.y_max = biome.max_y;
		jsonPoint.heat_point = biome.heat;
		jsonPoint.humidity_point  = biome.humidity;
		jsonPoints.push(jsonPoint);
	}
	jsonOut.biomeList = jsonPoints;

	let str = JSON.stringify(jsonOut, undefined, 4);
	exportSectionText.innerText = str;
	if (str === "") {
		exportSectionText.hidden = true;
		exportLabel.innerText = "Export is empty.";
	} else {
		exportSectionText.hidden = false;
		exportLabel.innerText = "Exported biomes (as Amidst for Minetest biome profile):";
	}
	exportSectionOuter.hidden = false;
}
inputExportClear.onclick = function() {
	exportSectionOuter.hidden = true;
	exportSectionText.innerText = "";
}
/* Import */

inputImportSubmit.onclick = function() {
	let importMessage = function(message) {
		importResultOuter.hidden = false;
		importResultMessage.innerText = message;
	}
	let importStr = inputImport.value;

	// Do the JSON parse
	let reviver = function(key, value) {
		if (key === "name" && ((typeof value) === "string")) {
			return value;
		} else if (((typeof value) === "number") && (
				key === "humidity_point" ||
				key === "heat_point" ||
				key === "y_min" ||
				key === "y_max")) {
			return value;
		} else {
			return value;
		}
	}

	let parsedJSON;
	try {
		parsedJSON = JSON.parse(importStr, reviver);
	} catch {
		importMessage("Import failed. Not a valid JSON object.");
	}
	if (typeof parsedJSON !== "object") {
		importMessage("Import failed. Not a valid JSON object.");
		return;
	}

	// Populate the temporary newPoints that MAY
	// set the biomePoints if successful
	let newPoints = [];
	lastBiomeID = 0;
	let fieldsToCheck = [
		{ fieldName: "name", type: "string" },
		{ fieldName: "heat_point", type: "number" },
		{ fieldName: "humidity_point", type: "number" },
		{ fieldName: "y_min", type: "number" },
		{ fieldName: "y_max", type: "number" },
	]
	for (let p=0; p<parsedJSON.length; p++) {
		let parsedPoint = parsedJSON[p];
		// Type checking
		for (let f=0; f<fieldsToCheck.length; f++) {
			let field = fieldsToCheck[f].fieldName;
			let wantType = fieldsToCheck[f].type;
			let gotType = typeof parsedPoint[field];
			if (gotType === "undefined") {
				importMessage(`Import failed. attribute "${field}" of biome #${p} is undefined.`)
				return;
			} else if (gotType !== wantType) {
				importMessage(`Import failed. attribute "${field}" of biome #${p} is of type "${gotType}" but "${wantType}" expected.`)
				return;
			}
		}

		let newPoint = {
			id: lastBiomeID,
			name: parsedPoint.name,
			heat: parsedPoint.heat_point,
			humidity: parsedPoint.humidity_point,
			min_y: parsedPoint.y_min,
			max_y: parsedPoint.y_max,
			colorIndex: lastBiomeID % CELL_COLORS.length,
		};
		lastBiomeID++;
		newPoints.push(newPoint);
	}
	// Replace the biomes
	biomePoints = newPoints;
	repopulateBiomeSelector();
	updateWidgetStates();
	draw(true);
	if (biomePoints.length === 1) {
		importMessage("Import successful. 1 biome imported.");
	} else {
		importMessage(`Import successful. ${biomePoints.length} biomes imported.`);
	}
}

/* Events for collapsing/extending config section with the arrow thingie */

biomeConfigHeaderLink.onclick = function() {
	toggleConfigSectionDisplay(this, biomeConfigContainer);
}
viewConfigHeaderLink.onclick = function() {
	toggleConfigSectionDisplay(this, viewConfigContainer);
}
noiseConfigHeaderLink.onclick = function() {
	toggleConfigSectionDisplay(this, noiseConfigContainer);
}
importHeaderLink.onclick = function() {
	toggleConfigSectionDisplay(this, importContainer);
}
exportHeaderLink.onclick = function() {
	toggleConfigSectionDisplay(this, exportContainer);
}

/* Load events */

window.addEventListener("load", initBiomeColorSelectors);
window.addEventListener("load", checkboxVarsInit);
window.addEventListener("load", function() {
	draw(true);
})
window.addEventListener("load", repopulateBiomeSelector);
window.addEventListener("load", updateWidgetStates);
window.addEventListener("load", updateAltitudeText);
window.addEventListener("load", unhideContent);
window.addEventListener("load", fitCanvasInBody);