"use strict";

const MIN_Y_DEFAULT = -31000
const MAX_Y_DEFAULT = 31000
const LIMIT_MIN = -37.5
const LIMIT_MAX = 137.5
const DRAW_MIN = LIMIT_MIN - 10
const DRAW_MAX = LIMIT_MAX + 10
const GRID_STEP = 10
const MIDPOINT = 50

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

let lastBiomeID = 0;
let biomePoints = [];
function addBiome(biomeDef) {
	biomeDef.id = lastBiomeID;
	biomePoints.push(biomeDef);
	lastBiomeID++;
}

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

function getViewY() {
	if (!inputViewY) {
		return 0;
	}
	return inputViewY.value;
}

const pointColor = "#913636";
const pointColorSelected = "#e19696";
const edgeColor = "#0f2c2e";
const gridColor = "#00000040";
const axisColor = "#000000";
const clearColor = "#ecddba";
const cellColors = [
	"#64988e",
	"#3d7085",
	"#345644",
	"#6b7f5c",
	"#868750",
	"#a7822c",
	"#a06e38",
	"#ad5f52",
	"#692f11",
	"#89542f",
	"#796e63",
	"#a17d5e",
	"#5a3f20",
	"#836299",
];

// 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 biome name for displaying it, based on heat and humidity values.
function generateBiomeName(heat, humidity) {
	return "("+heat+","+humidity+")";
}

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;
}
function voronoiPointToBiomePoint(point) {
	let newPoint = { heat: point.x, humidity: point.y, id: point[biomeIDSymbol] }
	return newPoint;
}

function putPointName(context, point) {
	let x = point.heat
	let y = point.humidity - 1
	if (x < LIMIT_MIN || x > LIMIT_MAX || y < LIMIT_MIN || y > LIMIT_MAX) {
		return;
	}
	if (x > MIDPOINT) {
		context.textAlign = "right";
		x = x-2;
	} else {
		context.textAlign = "left";
		x = x+2;
	}
	if (y < MIDPOINT) {
		context.textBaseline = "top";
	} else {
		context.textBaseline = "alphabetic";
	}
	context.font = "35% sans-serif"
	context.fillText(point.name, x, y);
}
function putPoint(context, point) {
	const ARROW_SIZE_SIDE = 2.25;
	const ARROW_SIZE_CORNER = 2.5;
	let x = point.heat
	let y = point.humidity
	// Point is out of bounds: Draw an arrow at the border
	if (x < LIMIT_MIN || x > LIMIT_MAX || y < LIMIT_MIN || y > LIMIT_MAX) {
		context.beginPath();
		// top left corner
		if (x < LIMIT_MIN && y < LIMIT_MIN) {
			context.moveTo(LIMIT_MIN, LIMIT_MIN);
			context.lineTo(LIMIT_MIN + ARROW_SIZE_CORNER, LIMIT_MIN);
			context.lineTo(LIMIT_MIN, LIMIT_MIN + ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// top right corner
		} else if (x > LIMIT_MAX && y < LIMIT_MIN) {
			context.moveTo(LIMIT_MAX, LIMIT_MIN);
			context.lineTo(LIMIT_MAX - ARROW_SIZE_CORNER, LIMIT_MIN);
			context.lineTo(LIMIT_MAX, LIMIT_MIN + ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// bottom left corner
		} else if (x < LIMIT_MIN && y > LIMIT_MAX) {
			context.moveTo(LIMIT_MIN, LIMIT_MAX);
			context.lineTo(LIMIT_MIN + ARROW_SIZE_CORNER, LIMIT_MAX);
			context.lineTo(LIMIT_MIN, LIMIT_MAX - ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// top right corner
		} else if (x > LIMIT_MAX && y > LIMIT_MAX) {
			context.moveTo(LIMIT_MAX, LIMIT_MAX);
			context.lineTo(LIMIT_MAX - ARROW_SIZE_CORNER, LIMIT_MAX);
			context.lineTo(LIMIT_MAX, LIMIT_MAX - ARROW_SIZE_CORNER);
			context.closePath();
			context.fill();
		// left side
		} else if (x < LIMIT_MIN) {
			context.moveTo(LIMIT_MIN, y);
			context.lineTo(LIMIT_MIN + ARROW_SIZE_SIDE, y + ARROW_SIZE_SIDE);
			context.lineTo(LIMIT_MIN + ARROW_SIZE_SIDE, y - ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		// right side
		} else if (x > LIMIT_MAX) {
			context.moveTo(LIMIT_MAX, y);
			context.lineTo(LIMIT_MAX - ARROW_SIZE_SIDE, y + ARROW_SIZE_SIDE);
			context.lineTo(LIMIT_MAX - ARROW_SIZE_SIDE, y - ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		// top side
		} else if (y < LIMIT_MIN) {
			context.moveTo(x, LIMIT_MIN);
			context.lineTo(x - ARROW_SIZE_SIDE, LIMIT_MIN + ARROW_SIZE_SIDE);
			context.lineTo(x + ARROW_SIZE_SIDE, LIMIT_MIN + ARROW_SIZE_SIDE);
			context.closePath();
			context.fill();
		// bottom side
		} else if (y > LIMIT_MAX) {
			context.moveTo(x, LIMIT_MAX);
			context.lineTo(x - ARROW_SIZE_SIDE, LIMIT_MAX - ARROW_SIZE_SIDE);
			context.lineTo(x + ARROW_SIZE_SIDE, LIMIT_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, 2, 0, Math.PI * 2);
		context.closePath();
		context.fill();
	}
};

function putGrid(context) {
	context.lineWidth = 0.5;
	context.strokeStyle = gridColor;
	for (let x=0; x<=LIMIT_MAX; x+=GRID_STEP) {
		context.beginPath();
		context.moveTo(x, LIMIT_MIN);
		context.lineTo(x, LIMIT_MAX);
		context.stroke();
	}
	for (let x=-GRID_STEP; x>=LIMIT_MIN; x-=GRID_STEP) {
		context.beginPath();
		context.moveTo(x, LIMIT_MIN);
		context.lineTo(x, LIMIT_MAX);
		context.stroke();
	}
	for (let y=0; y<=LIMIT_MAX; y+=GRID_STEP) {
		context.beginPath();
		context.moveTo(LIMIT_MIN, y);
		context.lineTo(LIMIT_MAX, y);
		context.stroke();
	}
	for (let y=-GRID_STEP; y>=LIMIT_MIN; y-=GRID_STEP) {
		context.beginPath();
		context.moveTo(LIMIT_MIN, y);
		context.lineTo(LIMIT_MAX, y);
		context.stroke();
	}
}

function putAxes(context) {
	context.lineWidth = 0.75;
	// heat axis (horizontal)
	context.beginPath();
	context.moveTo(LIMIT_MIN,0)
	context.lineTo(LIMIT_MAX,0)
	context.closePath();
	context.stroke();

	// humidity axis ()
	context.beginPath();
	context.moveTo(0,LIMIT_MIN)
	context.lineTo(0,LIMIT_MAX)
	context.closePath();
	context.stroke();
}

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

function getVoronoiDiagram(points, recalculate) {
	if ((cachedVoronoiDiagram === null) || recalculate) {
		let vbbox = {xl: LIMIT_MIN, xr: LIMIT_MAX, yt: LIMIT_MIN, yb: LIMIT_MAX};
		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);
		}
		diagram = voronoi.compute(sites, vbbox);
		cachedVoronoiDiagram = diagram;
		return diagram;
	} else {
		return cachedVoronoiDiagram;
	}
}

function getDrawContext() {
	let canvas = document.getElementById("voronoiCanvas");
	// TODO: Check for getContext support of browser
	return canvas.getContext("2d");
}
function drawInit() {
	let context = getDrawContext();
	context.scale(voronoiCanvas.width/(LIMIT_MAX-LIMIT_MIN), voronoiCanvas.height/(LIMIT_MAX-LIMIT_MIN));
	context.translate(-LIMIT_MIN, -LIMIT_MIN);
}
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;
}
function draw(y, recalculate) {
	let context = getDrawContext();
	// Clear draw area
	context.fillStyle = clearColor;
	context.fillRect(DRAW_MIN, DRAW_MIN, DRAW_MAX-DRAW_MIN, DRAW_MAX-DRAW_MIN);

	let points = getRenderedPoints(y);

	let diagram = getVoronoiDiagram(points, recalculate);

	// Render cell colors
	let colors = cellColors;
	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 ccol = biomeID % colors.length;

		context.fillStyle = colors[ccol];
		context.beginPath();
		for (let h=0; h<cell.halfedges.length; h++) {
			let halfedge = cell.halfedges[h]
			let start = halfedge.getStartpoint()
			let end = halfedge.getEndpoint()
			if (h === 0) {
				context.moveTo(start.x, start.y);
			} else {
				context.lineTo(start.x, start.y);
			}
			context.lineTo(end.x, end.y);
		}
		context.closePath();
		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
		context.fillStyle = colors[points[0].id % colors.length];
		context.fillRect(DRAW_MIN, DRAW_MIN, DRAW_MAX-DRAW_MIN, DRAW_MAX-DRAW_MIN);
	}

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

	// Render Voronoi cell edges
	context.lineWidth = 1;
	for (let e=0; e<diagram.edges.length; e++) {
		let edge = diagram.edges[e];
		if (edge.rSite === null) {
			context.strokeStyle = "transparent";
		} else {
			context.strokeStyle = edgeColor;
		}
		context.beginPath();
		context.moveTo(edge.va.x, edge.va.y);
		context.lineTo(edge.vb.x, edge.vb.y);
		context.closePath();
		context.stroke();
	}

	let selElemID = null;
	if (biomeSelector.selectedIndex !== -1) {
		let selElem = biomeSelector.options[biomeSelector.selectedIndex];
		let strID = selElem.id;
		if (strID.startsWith("biome_list_element_")) {
			let slice = strID.slice(19);
			if (slice) {
				selElemID = +slice;
			}
		}
	}

	// Render biome points
	for (let point of points) {
		let pointID = point.id;
		// Highlight selected point
		if (selElemID !== null && pointID === selElemID) {
			context.fillStyle = pointColorSelected;
		} else {
			context.fillStyle = pointColor;
		}
		putPoint(context, point);
	}
	// 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);
	}

	// Render a special message if there are no biomes
	if (points.length === 0) {
		context.textAlign = "center";
		context.fillStyle = "black";
		context.textBaseline = "middle";
		let msg;
		if (biomePoints.length === 0) {
			msg = "No biomes.";
		} else {
			msg = "No biomes in this Y layer.";
		}
		context.fillText(msg, MIDPOINT, MIDPOINT);
	}

}

function rewriteBiomeSelector() {
	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 newElemText = document.createTextNode(biomePoints[b].name);
		newElem.append(newElemText);
		biomeSelector.append(newElem);
	}
}

function updateWidgetStates() {
	if (biomePoints.length === 0 || biomeSelector.selectedIndex === -1) {
		removeBiomeButton.disabled = "disabled";
		inputHeat.disabled = "disabled";
		inputHumidity.disabled = "disabled";
		inputMinY.disabled = "disabled";
		inputMaxY.disabled = "disabled";
	} else {
		removeBiomeButton.disabled = "";
		inputHeat.disabled = "";
		inputHumidity.disabled = "";
		inputMinY.disabled = "";
		inputMaxY.disabled = "";
		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;
		}
	}
}

biomeSelector.onchange = function() {
	draw(getViewY(), 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();
}

function onChangeBiomeValueWidget(pointField, value) {
	if (value === null) {
		return;
	}
	if (biomeSelector.selectedIndex === -1) {
		return;
	}
	let selected = biomeSelector.options[biomeSelector.selectedIndex];
	if (selected === null) {
		return;
	}
	let point = biomePoints[biomeSelector.selectedIndex];
	point[pointField] = +value;
	point.name = generateBiomeName(point.heat, point.humidity);
	selected.innerText = point.name;
	draw(getViewY(), true);
}

inputHeat.onchange = function() {
	onChangeBiomeValueWidget("heat", this.value);
}
inputHumidity.onchange = function() {
	onChangeBiomeValueWidget("humidity", this.value);
}
inputMinY.onchange = function() {
	onChangeBiomeValueWidget("min_y", this.value);
}
inputMaxY.onchange = function() {
	onChangeBiomeValueWidget("max_y", this.value);
}
inputViewY.onchange = function() {
	draw(getViewY(), true);
}

addBiomeButton.onclick = function() {
	let he = Math.round(Math.random()*100);
	let hu = Math.round(Math.random()*100);
	let newPoint = {
		id: lastBiomeID,
		name: generateBiomeName(he, hu),
		heat: he,
		min_y: MIN_Y_DEFAULT,
		max_y: MAX_Y_DEFAULT,
		humidity: hu,
	};
	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(getViewY(), 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(getViewY(), true);
	updateWidgetStates();
}

function selectPoint(point) {
	for (let elem of biomeSelector.options) {
		let strID = elem.id;
		let elemID = null;
		if (strID.startsWith("biome_list_element_")) {
			let slice = strID.slice(19);
			if (slice) {
				elemID = +slice;
			}
		}
		if (elemID !== null) {
			if (point.id === elemID) {
				if (elem.selected) {
					console.log("Already selected!");
					return [true, true];
				}
				elem.selected = "selected";
				draw(getViewY(), true);
				updateWidgetStates();
				return [true, false];
			}
		}
	}
	return [false, false];
}
function getDistance(x1, y1, x2, y2) {
	return Math.sqrt((x2 - x1)**2 + (y2 - y1)**2);
}
function canvasPixelCoordsToBiomeCoords(x, y) {
	let w = (voronoiCanvas.width/(LIMIT_MAX-LIMIT_MIN));
	let h = (voronoiCanvas.height/(LIMIT_MAX-LIMIT_MIN));
	let heat = Math.round((x + LIMIT_MIN * w) / w);
	let humidity = Math.round((y + LIMIT_MIN * w) / w);
	return [heat, humidity];
}
function biomeCoordsToCanvasPixelCoords(heat, humidity) {
	let w = (voronoiCanvas.width/(LIMIT_MAX-LIMIT_MIN));
	let h = (voronoiCanvas.height/(LIMIT_MAX-LIMIT_MIN));
	let pixelX = heat * w - LIMIT_MIN * w;
	let pixelY = humidity * h - LIMIT_MIN * h;
	return [pixelX, pixelY];
}

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;
	}
}
let mouseIsDown = false;
let dragDropPointID = null;
let dragDropPos = null;

function updatePointWhenDragged(pointID) {
	if (pointID !== null) {
		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;
				selectedPoint.name = generateBiomeName(newHeat, newHumidity);
				draw(getViewY(), true);
				updateWidgetStates();
				for (let elem of biomeSelector.options) {
					let strID = elem.id;
					let elemID = null;
					if (strID.startsWith("biome_list_element_")) {
						let slice = strID.slice(19);
						if (slice) {
							elemID = +slice;
						}
					}
					if (elemID !== null && points[i].id === elemID) {
						elem.innerText = selectedPoint.name;
						break;
					}
				}
				return;
			}
		}
	}
}

voronoiCanvas.onmousemove = function(event) {
	// drag-n-drop
	if (mouseIsDown) {
		updatePointWhenDragged(dragDropPointID);
	}
	// show coordinates
	let [heat, humidity] = canvasPixelCoordsToBiomeCoords(event.offsetX, event.offsetY);
	let html = "heat="+heat+"; humidity="+humidity;
	coordinateDisplay.innerHTML = html;
}
voronoiCanvas.onmouseenter = function(event) {
	// show coordinates
	let [heat, humidity] = canvasPixelCoordsToBiomeCoords(event.offsetX, event.offsetY);
	let html = "heat="+heat+"; humidity="+humidity;
	coordinateDisplay.innerHTML = html;
}

voronoiCanvas.onmousedown = function(event) {
	// select point by clicking.
	// initiate drag-n-drop if already selected.
	mouseIsDown = true;
	let nearest = getNearestPointFromCanvasPos(event.offsetX, event.offsetY, 25);
	if (nearest !== null) {
		let success, alreadySelected
		[success, alreadySelected] = selectPoint(nearest);
		if (alreadySelected) {
			dragDropPointID = nearest.id;
		}
	}
}
voronoiCanvas.onmouseup = function(event) {
	// end drag-n-drop
	updatePointWhenDragged(dragDropPointID);
	mouseIsDown = false;
	dragDropPos = null;
	dragDropPointID = null;
}
voronoiCanvas.onmouseleave = function() {
	// end drag-n-drop
	mouseIsDown = false;
	dragDropPointID = null;
	dragDropPos = null;
	coordinateDisplay.innerHTML = "&nbsp;";
}


window.addEventListener("load", drawInit);
window.addEventListener("load", function() {
	draw(getViewY(), true);
})
window.addEventListener("load", rewriteBiomeSelector);
window.addEventListener("load", updateWidgetStates);