-- LUALOCALS < ---------------------------------------------------------
local ipairs, math, minetest, pairs, tonumber, type
    = ipairs, math, minetest, pairs, tonumber, type
local math_atan2, math_ceil, math_cos, math_pi, math_random, math_sin,
      math_sqrt
    = math.atan2, math.ceil, math.cos, math.pi, math.random, math.sin,
      math.sqrt
-- LUALOCALS > ---------------------------------------------------------

local modname = minetest.get_current_modname()

local defaults = {
	cycletime = 20, -- time between cycles
	hudtime = 4, -- duration to display HUD
	hudreshow = 60, -- interval to re-display HUD
	hudmargin = 0, -- bottom margin for HUD

	dummyradius = 80, -- max radius for dummy cam
	dummyheight = 32, -- max height for dummy cam
	dummymin = 0.25, -- min radius (of max) for dummy cam
	dummyclear = 16, -- min clear sight for dummy cam

	vellead = -4, -- ratio of player vel for camera pos "leading/chasing"
	facelead = -2, -- ratio of player facing for camera pos lead/chase
	camdistset = 4, -- initial target distance from player to set camera
	camdistmin = 1, -- min distance from player to allow camera
	camdistmax = 16, -- max distance from player to allow camera
	camfov = 72, -- assume camera fov for angle check

	camlocktime = 1, -- min time to lock camera after moving
	minlight = 4, -- min light level to not affect cam time
	maxidle = 10, -- max idle time before penalty
	idlepenalty = 6, -- extra countdown speed for being idle

	actvig = 0.5, -- vignette when active
	actdark = 0, -- darken when active
	dummyvig = 0.75, -- vignette when dummycam
	dummydark = 0.3, -- darken when dummycam
}

local config
local enabled_players
local waypoints

local function reconfigure()
	config = {}
	for k in pairs(defaults) do
		config[k] = tonumber(minetest.settings:get(modname .. "_" .. k)) or defaults[k]
	end
	enabled_players = {}
	for _, n in pairs((minetest.settings:get(modname .. "_players") or ""):split(',')) do
		if n ~= "" then
			enabled_players[n] = true
		end
	end
	waypoints = {}
	local wpstr = minetest.settings:get(modname .. "_waypoints") or ""
	if wpstr == "" then wpstr = minetest.settings:get("static_spawn") or "" end
	for _, n in pairs(wpstr:split(';')) do
		local xyz = n:split(",")
		if #xyz == 3 then
			waypoints[#waypoints + 1] = vector.new(xyz[1], xyz[2], xyz[3])
		end
	end
	if #waypoints < 1 then waypoints[1] = vector.new(0, 0, 0) end
	return true, modname .. " config reloaded"
end
reconfigure()

minetest.register_chatcommand(modname, {
		description = "Reload " .. modname .. " config from settings",
		privs = {server = true},
		func = reconfigure
	})

local function setcamera(player, pos, target)
	local delta = vector.normalize(vector.subtract(target, pos))
	player:set_look_horizontal(math_atan2(delta.z, delta.x) - math_pi / 2)
	player:set_look_vertical(-math_atan2(delta.y, math_sqrt(
				delta.x ^ 2 + delta.y ^ 2)))
	pos.y = pos.y - player:get_properties().eye_height
	return player:set_pos(pos)
end

local allow
local fluidmedium
do
	local allow_drawtypes = {
		airlike = true,
		torchlike = true,
		signlike = true,
		raillike = true,
		plantlike = true,
		firelike = true,
		liquid = true,
		flowingliquid = true,
		glasslike = true,
		glasslike_framed = true,
		glasslike_framed_optional = true,
		allfaces = true,
		allfaces_optional = true,
	}
	local allow_nodes = {
		ignore = true
	}
	local fluids = {}
	minetest.after(0, function()
			for k, v in pairs(minetest.registered_nodes) do
				if allow_drawtypes[v.drawtype]
				and v.paramtype == "light" then
					allow_nodes[k] = true
				end
				if v.sunlight_propagates then
					fluids[k] = "CLEAR"
				else
					fluids[k] = v.liquid_alternative_source or k
				end
			end
		end)
	allow = function(pos)
		return allow_nodes[minetest.get_node(pos).name]
	end
	fluidmedium = function(pos)
		return fluids[minetest.get_node(pos).name]
	end
end

local function sightblocked(from, to)
	local fsrc = fluidmedium(from)
	for pt in minetest.raycast(from, to, false, true) do
		if pt.type == "node" then
			if fluidmedium(pt.under) ~= fsrc then
				return pt.above
			end
		end
	end
	if fluidmedium(to) ~= fsrc then return to end
end

local getdata
do
	local datastore = {}
	function getdata(p)
		local pname = type(p) == "string" and p or p:get_player_name()
		local data = datastore[pname]
		if not data then
			data = {}
			datastore[pname] = data
		end
		return data
	end
	minetest.register_on_leaveplayer(function(player)
			datastore[player:get_player_name()] = nil
		end)
end

local function hudset(player, data, key, def)
	local hud = data[key]
	if hud then
		if hud.text == def.text then return end
		player:hud_change(hud.id, "text", def.text)
		hud.text = def.text
	else
		data[key] = {
			id = player:hud_add(def),
			text = def.text
		}
	end
end

local function dimhuds(player, data, darken, vignette)
	hudset(player, data, "darken", {
			hud_elem_type = "image",
			position = {x = 0.5, y = 0.5},
			text = darken == 0 and "" or (
				"[combine:1x1^[noalpha^[opacity:"
				.. math_ceil(255 * darken)),
			direction = 0,
			scale = {x = -100, y = -100},
			offset = {x = 0, y = 0},
			quick = true
		})
	hudset(player, data, "vignette", {
			hud_elem_type = "image",
			position = {x = 0.5, y = 0.5},
			text = vignette == 0 and "" or (
				"szutil_cinecam_vignette.png^[opacity:"
				.. math_ceil(255 * vignette)),
			direction = 0,
			scale = {x = -100, y = -100},
			offset = {x = 0, y = 0},
			quick = true
		})
end

local function camdummy(player, data, dtime)
	data.dummycam = (data.dummycam or 0) - dtime
	if data.dummycam > 0 then
		local pos = player:get_pos()
		pos.y = pos.y + player:get_properties().eye_height
		if allow(pos) then return end
	end

	local theta = math_random() * math_pi * 2
	local dummyradius = config.dummyradius
	local dpos = {
		x = math_cos(theta) * dummyradius,
		y = math_random() * config.dummyheight,
		z = math_sin(theta) * dummyradius
	}
	local dummymin = config.dummymin
	dpos = vector.multiply(dpos, dummymin + math_random() * (1 - dummymin))

	local wp = waypoints[math_random(1, #waypoints)] or vector.new(0, 0, 0)
	local cpos = vector.add(wp, dpos)

	if not allow(cpos) then return end

	local len = vector.length(dpos)
	local tpos = vector.add(wp, vector.multiply(dpos, (len - config.dummyclear) / len))

	if sightblocked(cpos, tpos) then return end

	dimhuds(player, data, config.dummydark, config.dummyvig)
	setcamera(player, cpos, tpos)
	data.targethud = nil
	data.dummycam = config.cycletime
end

local function camcheck(player, dtime)
	local data = getdata(player)

	if player:get_fov() ~= config.camfov then
		player:set_fov(config.camfov)
	end

	local text = data.targethud or ""
	if data.tiptext ~= text then data.tiptime = 0 end
	data.tiptext = text
	if data.tiptime > config.hudtime then text = "" end
	data.tiptime = data.tiptime + dtime
	if data.tiptime > config.hudreshow then
		data.tiptime = data.tiptime - config.hudreshow
	end
	hudset(player, data, "tip", {
			hud_elem_type = "text",
			position = {x = 0.5, y = 1},
			text = text,
			number = 0xFFFFFF,
			alignment = {x = 0, y = -1},
			offset = {x = 0, y = -config.hudmargin},
		})

	if data.locked then
		data.locked = data.locked - dtime
		if data.locked > 0 then return end
		data.locked = nil
	end

	if data.tracktime then
		data.tracktime = data.tracktime - dtime
		if data.tracktime <= 0 then data.tracktime = nil end
	end
	local target = data.tracktime and data.target
	target = target and minetest.get_player_by_name(target)
	if not target then
		data.target = nil
		if not (data.queue and #data.queue > 0) then
			local q = {}
			local pname = player:get_player_name()
			for _, p in ipairs(minetest.get_connected_players()) do
				local n = p:get_player_name()
				if n ~= pname then
					local props = p:get_properties()
					local vs = props and props.visual_size
					if vs and vs.x > 0 and vs.y > 0 then
						q[#q + 1] = n
					end
				end
			end
			if #q < 1 then return camdummy(player, data, dtime) end
			data.queue = q
		end
		data.target = data.queue[#data.queue]
		data.queue[#data.queue] = nil
		data.tracktime = config.cycletime

		target = minetest.get_player_by_name(data.target)
		if not target then return camdummy(player, data, dtime) end

		data.dummycam = nil
	end

	local pos = player:get_pos()
	pos.y = pos.y + player:get_properties().eye_height
	local tpos = target:get_pos()
	tpos.y = tpos.y + target:get_properties().eye_height

	local tidle = getdata(target).idletime or 0
	if tidle >= config.maxidle then
		data.tracktime = data.tracktime - dtime * config.idlepenalty
	end

	local camdistset = config.camdistset
	local camdistmax = config.camdistmax
	local function newcam()
		local theta = math_random() * math_pi * 2
		local trypos = vector.add(tpos, vector.multiply({
					x = math_cos(theta),
					y = math_random() * 2 - 0.5,
					z = math_sin(theta)
				}, camdistmax))
		trypos = vector.add(trypos, vector.multiply(
				target:get_velocity(), config.vellead))
		trypos = vector.add(trypos, vector.multiply(
				target:get_look_dir(), config.facelead))
		local dist = vector.distance(trypos, tpos)
		if dist > camdistset then
			trypos = vector.add(tpos, vector.multiply(
					vector.direction(tpos, trypos), camdistset))
		end

		local bpos = sightblocked(tpos, trypos)
		if bpos and vector.distance(tpos, bpos) < config.camdistmin then
			return
		end
		trypos = bpos or trypos
		if sightblocked(trypos, tpos) then
			return
		end

		if not allow(trypos) then return end

		dimhuds(player, data, config.actdark, config.actvig)
		setcamera(player, trypos, tpos)

		data.targethud = "Watching: " .. data.target
		data.moved = 0
		data.locked = config.camlocktime
	end

	if not allow(pos) then return newcam() end

	local tlight = nodecore and nodecore.get_node_light(tpos)
	or minetest.get_node_light(tpos)
	local minlight = config.minlight
	if tlight and tlight < minlight then
		data.tracktime = data.tracktime - dtime * minlight / tlight
	end

	local dist = vector.distance(pos, tpos)
	if dist < 1 or dist > camdistmax then return newcam() end

	local look = player:get_look_dir()
	local angle = vector.angle(vector.direction(pos, tpos), look)
	if angle > config.camfov / 2/180 * math_pi then return newcam() end

	if sightblocked(pos, tpos) then return newcam() end

	data.moved = (data.moved or 0) + dtime
	if data.moved > config.cycletime then return newcam() end
end

minetest.register_globalstep(function(dtime)
		local players = minetest.get_connected_players()
		for _, player in ipairs(players) do
			local pos = player:get_pos()
			local look = player:get_look_dir()
			local ctl = player:get_player_control()
			local data = getdata(player)
			if not (ctl.up or ctl.down or ctl.left or ctl.right
				or ctl.jump or ctl.LMB or ctl.RMB) and data.idlepos
			and data.idlelook and vector.equals(pos, data.idlepos)
			and vector.equals(look, data.idlelook) then
				data.idletime = (data.idletime or 0) + dtime
			else
				data.idletime = 0
			end
			data.idlepos = pos
			data.idlelook = look
		end
		for _, player in ipairs(players) do
			if enabled_players[player:get_player_name()] then
				camcheck(player, dtime)
			end
		end
	end)