--- [LDtk](https://ldtk.io/) level importer for Lua and drawing using LÖVE.
-- Support most LDtk features, and allow easy usage in LÖVE projects.
--
-- Every unit is in pixel in the API unless written otherwise.
-- Colors are reprsented as a table `{r,g,b}` where `r`,`b`,`g` in [0-1].
--
-- This modules returns a single function, @{LDtk}(path).
--
-- No mandatory dependency.
-- Optionally requires LÖVE `love.graphics` (drawing Image, SpriteBatch, Quad) for drawing only.
--
-- @module ldtk
-- @require love
-- @usage
-- local ldtk = require("ubiquitousse.ldtk")
--
-- -- load ldtk project file
-- local project = ldtk("example.ldtk")
--
-- -- can define callbacks when loading: for example to setup entities defined in LDtk
-- local callbacks = {
-- 	onAddEntity = function(entity)
-- 		-- handle entity...
-- 	end
-- }
--
-- -- load every level, with callbacks
-- for _, lvl in ipairs(project.levels) do lvl:load(callbacks) end
--
-- function love.draw()
-- 	-- draw every level
-- 	for _, lvl in ipairs(project.levels) do lvl:draw() end
-- end

-- TODO: give associated tile & color with enum values, also give enum info

--- LÖVE wrappers/placeholder
let lg = (love or {}).graphics
let newQuad
if lg then
	newQuad = lg.newQuad
else
	newQuad = (x, y, w , h, image)
		return { x, y, w, h }
	end
end

--- json helpers
let json_decode = require((...):gsub("ldtk$", "json")).decode
let readJson = (file)
	let f = assert(io.open(file, "r"))
	local t = json_decode(f:read("*a"))
	f:close()
	return t
end

--- color helpers
let parseColor = (str)
	local r, g, b = str:match("^#(..)(..)(..)")
	r, g, b = tonumber(r, 16), tonumber(g, 16), tonumber(b, 16)
	return { r/255, g/255, b/255 }
end
let white = {1,1,1}

--- returns a lua table from some fieldInstances
let toLua = (type, val)
	if val == nil then return val end
	if type:match("^Array%<") then
		local itype = type:match("^Array%<(.*)%>$")
		for i, v in ipairs(val) do
			val[i] = toLua(itype, v)
		end
	elseif type == "Color" then
		return parseColor(val)
	elseif type == "Point" then
		return { x = val.cx, y = val.cy }
	end
	return val
end
let getFields = (f)
	local t = {}
	for _, v in ipairs(f) do
		t[v.__identifier] = toLua(v.__type, v.__value)
	end
	return t
end

let tileset_mt

--- cached values
let make_cache = (new_fn)
	return setmetatable({}, {
		__mode = "v",
		__call = (cache, id)
			if not cache[id] then
				cache[id] = new_fn(id)
			end
			return cache[id]
		end
	})
end
let cache = {
	tileset = make_cache((tilesetDef)
		return tileset_mt._init(tilesetDef)
	end),
	image = make_cache((path)
		if lg then
			return lg.newImage(path)
		else
			return path
		end
	end),
}

--- Tileset object.
-- Stores the image associated with the tileset; can be shared among several layers and levels.
-- @type Tileset
tileset_mt = {
	_newQuad = :(x, y, width, height)
		return newQuad(x, y, width, height, @image)
	end,
	_getTileQuad = :(tileid, x, y, size)
		if not @_tileQuads[tileid] then
			@_tileQuads[tileid] = @_newQuad(x, y, size, size)
		end
		return @_tileQuads[tileid]
	end,
	_init = (tilesetDef)
		local t = {
			--- The tileset LÖVE image object.
			-- If LÖVE is not available, this is the path to the image (string).
			image = cache.image(tilesetDef.path),

			_tileQuads = {}
		}
		return setmetatable(t, tileset_mt)
	end
}
tileset_mt.__index = tileset_mt

--- Layer object.
--
-- Part of a @{Level}.
--
-- @type Layer
let layer_mt = {
	--- Draw the current layer.
	-- Assumes we are currently in level coordinates (i.e. level top-left is at 0,0).
	-- @require love
	draw = :()
		if @visible then
			lg.push()
				lg.translate(@offsetX, @offsetY)
				if @spritebatch then
					lg.setColor(1, 1, 1, @opacity)
					lg.draw(@spritebatch)
				elseif @intTiles then
					for _, t in ipairs(@intTiles) do
						lg.setColor(t.color)
						lg.rectangle("fill", t.x, t.y, t.layer.gridSize, t.layer.gridSize)
					end
				elseif @entities then
					for _, e in ipairs(@entities) do
						if e.draw then e:draw() end
					end
				end
			lg.pop()
		end
	end,

	_unloadCallbacks = :(callbacks)
		local onRemoveTile = callbacks.onRemoveTile
		if @tiles and onRemoveTile then
			for _, t in ipairs(@tiles) do
				onRemoveTile(t)
			end
		end
		local onRemoveIntTile = callbacks.onRemoveIntTile
		if @intTiles and onRemoveIntTile then
			for _, t in ipairs(@intTiles) do
				onRemoveIntTile(t)
			end
		end
		local onRemoveEntity = callbacks.onRemoveEntity
		if @entities and onRemoveEntity then
			for _, e in ipairs(@entities) do
				onRemoveEntity(e)
			end
		end
	end,
	_init = (layer, level, order, callbacks)
		let gridSize = layer.__gridSize
		let t = {
			--- `Level` this layer belongs to.
			-- @ftype Level
			level = level,
			--- The layer name.
			-- @ftype string
			identifier = layer.__identifier,
			--- Type of layer: IntGrid, Entities, Tiles or AutoLayer.
			-- @ftype string
			type = layer.__type,
			--- Whether the layer is visible or not.
			-- @ftype boolean
			visible = layer.visible,
			--- The layer opacity (0-1).
			-- @ftype number
			opacity = layer.opacity,
			--- The layer order: smaller order means it is on top.
			-- @ftype number
			order = order,
			--- X position of the layer relative to the level.
			-- @ftype number
			offsetX = layer.__pxTotalOffsetX,
			--- Y position of the layer relative to the level.
			-- @ftype number
			offsetY = layer.__pxTotalOffsetY,
			--- Size of the grid on this layer.
			-- @ftype number
			gridSize = gridSize,
			--- Width of the layer, in grid units.
			-- @ftype number
			gridWidth = layer.__cWid,
			--- Height of the layer, in grid units.
			-- @ftype number
			gridHeight = layer.__cHei,
			--- _(Entities layer only)_ List of `Entity` in the layer.
			-- @ftype {Entity,...}
			entities = nil,
			--- _(Tiles, AutoLayer, or IntGrid with AutoLayer rules layers only)_ List of `Tile`s in the layer.
			-- @ftype {Tile,...}
			-- @ftype nil if not applicable
			tiles = nil,
			--- _(Tiles, AutoLayer, or IntGrid with AutoLayer rules layers only)_ `Tileset` object associated with the layer.
			-- @ftype Tileset
			-- @ftype nil if not applicable
			tileset = nil,
			--- _(Tiles, AutoLayer, or IntGrid with AutoLayer rules layers only)_ [LÖVE SpriteBatch](https://love2d.org/wiki/SpriteBatch) containing the layer.
			-- @ftype SpriteBatch
			-- @ftype nil if LÖVE not available.
			-- @require love
			spritebatch = nil,
			--- _(IntGrid without AutoLayer rules layer only)_ list of `IntTile`s in the layer.
			-- @ftype {IntTile,...}
			-- @ftype nil if not applicable
			intTiles = nil,
		}
		-- Layers with an associated tileset (otherwise ignore as there is nothing to draw) (Tiles, AutoLayer & IntGrid with AutoLayer rules)
		if layer.__tilesetDefUid then
			t.tiles = {}
			local tilesetData = level.project._tilesetData[layer.__tilesetDefUid]
			t.tileset = cache.tileset(tilesetData)
			local tiles = layer.__type == "Tiles" and layer.gridTiles or layer.autoLayerTiles
			local onAddTile = callbacks.onAddTile
			if lg then t.spritebatch = lg.newSpriteBatch(t.tileset.image) end
			for _, tl in ipairs(tiles) do
				let quad = t.tileset:_getTileQuad(tl.t, tl.src[1], tl.src[2], gridSize)
				let sx, sy = 1, 1
				let x, y = tl.px[1], tl.px[2]
				--- Tile object.
				--
				-- This represent the tiles from a Tiles, AutoLayer or IntGrid with AutoLayer rules layer.
				--
				-- Can be retrived from the `Layer.tiles` list or `onAddTile` level load callback.
				--
				-- @type Tile
				let tile = {
					--- `Layer` the tile belongs to.
					-- @ftype Layer
					layer = t,
					--- X position of the tile relative to the layer.
					-- @ftype number
					x = x,
					--- Y position of the tile relative to the layer.
					-- @ftype number
					y = y,
					--- Whether the tile is flipped horizontally.
					-- @ftype boolean
					flipX = false,
					--- Whether the tile is flipped vertically.
					-- @ftype boolean
					flipY = false,
					--- Tags associated with the tile: can be used either as a list of tags or a map of activated tags tags[name] == true.
					-- @ftype {"tag",["tag"]=true,...}
					tags = tilesetData[tl.t].tags,
					--- Custom data associated with the tile, if any.
					-- @ftype string
					data = tilesetData[tl.t].data,
					--- Quad associated with the tile (relative to the layer's tileset).
					-- @ftype LÖVE Quad if LÖVE is available
					-- @ftype table { x, y, width, height } if LÖVE not available
					quad = quad
				}
				if tl.f == 1 or tl.f == 3 then
					sx = -1
					x += gridSize
					tile.flipX = true
				end
				if tl.f == 2 or tl.f == 3 then
					sy = -1
					y += gridSize
					tile.flipY = true
				end
				if t.spritebatch then t.spritebatch:add(quad, x, y, 0, sx, sy) end
				table.insert(t.tiles, tile)
				if onAddTile then onAddTile(tile) end
			end
		-- IntGrid
		elseif layer.__type == "IntGrid" then
			t.intTiles = {}
			local onAddIntTile = callbacks.onAddIntTile
			local values = level.project._layerDef[layer.layerDefUid].intGridValues
			for i, tl in ipairs(layer.intGridCsv) do
				if tl > 0 then
					let y = math.floor((i-1) / t.gridWidth) * gridSize
					let x = ((i-1) % t.gridWidth) * gridSize
					--- IntTile object.
					--
					-- This represent the tiles from a IntGrid without AutoLayer rules layer.
					--
					-- Can be retrived from the @{intTiles} list or `onAddIntTile` level load callback.
					--
					-- @type IntTile
					let tile = {
						--- `Layer` the IntTile belongs to.
						-- @ftype Layer
						layer = t,
						--- X position of the IntTile relative to the layer.
						-- @ftype number
						x = x,
						--- Y position of the IntTile relative to the layer.
						-- @ftype number
						y = y,
						--- Name of the IntTile.
						-- @ftype string
						identifier = values[tl].identifier,
						--- Integer value of the IntTile.
						-- @ftype number
						value = tl,
						--- Color of the IntTile.
						-- @ftype table {r,g,b} with r,g,b in [0-1]
						color = values[tl].color
					}
					table.insert(t.intTiles, tile)
					if onAddIntTile then onAddIntTile(tile) end
				end
			end
		end
		-- Entities layers
		if layer.__type == "Entities" then
			t.entities = {}
			local onAddEntity = callbacks.onAddEntity
			for _, e in ipairs(layer.entityInstances) do
				let entityDef = level.project._entityData[e.defUid]
				--- Entity object.
				--
				-- This represent an entity from an Entities layer.
				--
				-- Can be retrived from the @{entities} list or `onAddEntity` level load callback.
				--
				-- @type Entity
				let entity = {
					--- `Layer` this entity belongs to.
					-- @ftype Layer
					layer = t,
					--- The entity name.
					-- @ftype string
					identifier = e.__identifier,
					--- X position of the entity relative to the layer.
					-- @ftype number
					x = e.px[1],
					--- Y position of the entity relative to the layer.
					-- @ftype number
					y = e.px[2],
					--- The entity width.
					-- @ftype number
					width = e.width,
					--- The entity height.
					-- @ftype number
					height = e.height,
					--- Scale factor on x axis relative to original entity size.
					-- @ftype number
					sx = e.width / entityDef.width,
					--- Scale factor on y axis relative to original entity size.
					-- @ftype number
					sy = e.height / entityDef.height,
					--- The entity pivot point x position relative to the entity.
					-- @ftype number
					pivotX = e.__pivot[1] * e.width,
					--- The entity pivot point x position relative to the entity.
					-- @ftype number
					pivotY = e.__pivot[2] * e.height,
					--- Entity color.
					-- @ftype table {r,g,b} with r,g,b in [0-1]
					color = entityDef.color,
					--- Tile associated with the entity, if any. Is a table { tileset = associated tileset object, quad = associated quad }.
					-- `quad` is a LÖVE Quad if LÖVE is available, otherwise a table `{ x, y, width, height }`.
					-- @ftype table
					tile = nil,
					--- Map of `CustomFields` of the entity.
					-- @ftype CustomFields
					fields = getFields(e.fieldInstances),
					--- Called for the entity when drawing the associated entity layer (you will likely want to redefine it).
					--
					-- By default, this draws the tile associated with the entity if there is one, or a rectangle around the entity position otherwise.
					-- @require love
					draw = :() 
						if @tile then
							let _, _, w, h = @tile.quad:getViewport()
							lg.setColor(white)
							lg.draw(@tile.tileset.image, @tile.quad, @x-@pivotX, @y-@pivotY, 0, @width / w, @height / h)
						else
							lg.setColor(@color)
							lg.rectangle("line", @x-@pivotX, @y-@pivotY, @width, @height)
						end
					end
				}
				if e.__tile then
					local tileset = cache.tileset(level.project._tilesetData[e.__tile.tilesetUid])
					local srcRect = e.__tile.srcRect
					local quad = tileset:_newQuad(srcRect[1], srcRect[2], srcRect[3], srcRect[4])
					entity.tile = {
						tileset = tileset,
						quad = quad
					}
				end
				table.insert(t.entities, entity)
				if onAddEntity then onAddEntity(entity) end
			end
		end
		return setmetatable(t, layer_mt)
	end
}
layer_mt.__index = layer_mt

--- Level object.
--
-- Levels are not automatically loaded in order to not waste ressources if your project is large; so before drawing or operating on a level, you will need to call its @{Level:load} method.
--
-- Part of a @{Project}.
--
-- @type Level
let level_mt = {
	--- Draw this level.
	-- Assumes we are currently in world coordinates (i.e. world top-left is at 0,0).
	-- The level must be loaded.
	-- Will draw the eventual backgrounds and all the layers in the level.
	-- @require love
	draw = :()
		assert(@loaded == true, "level not loaded")
		lg.push()
			lg.translate(@x, @y)
			-- background color
			lg.setColor(@background.color)
			lg.rectangle("fill", 0, 0, @width, @height)
			-- background image
			lg.setColor(white)
			let bgImage = @background.image
			if bgImage then
				lg.draw(bgImage.image, bgImage.quad, bgImage.x, bgImage.y, 0, bgImage.sx, bgImage.sy)
			end
			-- layers
			for _, l in ipairs(@layers) do
				l:draw()
			end
		lg.pop()
	end,

	--- Load the level.
	-- Will load every layer in the level and the associated images.
	--
	-- You can optionally specify some callbacks for the loading process:
	--
	-- * `onAddLayer(layer)` will be called for every new layer loaded, with the @{Layer} as sole argument
	-- * `onAddTile(tile)` will be called for every new tile loaded, with the @{Tile} as sole argument
	-- * `onAddIntTile(tile)` will be called for every new IntGrid tile loaded, with the @{IntTile} as sole argument
	-- * `onAddEntity(entity)` will be called for every new entity loaded, with the @{Entity} as sole argument
	--
	-- These callbacks should allow you to capture all the important elements needed to use the level, so you can hopefully
	-- integrate it into your current game engine easily.
	--
	-- @tparam[opt] table callbacks
	load = :(callbacks={})
		assert(@loaded == false, "level already loaded")
		if @_json.bgRelPath then
			let pos = @_json.__bgPos
			let cropRect = pos.cropRect
			let image = cache.image(@project._directory..@_json.bgRelPath)
			@background.image = {
				image = image,
				quad = newQuad(cropRect[1], cropRect[2], cropRect[3], cropRect[4], image),
				x = pos.topLeftPx[1],
				y = pos.topLeftPx[2],
				sx = pos.scale[1],
				sy = pos.scale[1]
			}
		end
		let layerInstances
		if @_json.externalRelPath then
			layerInstances = readJson(@project._directory..@_json.externalRelPath).layerInstances
		else
			layerInstances = @_json.layerInstances
		end
		@layers = {}
		let onAddLayer = callbacks.onAddLayer
		for i=#layerInstances, 1, -1 do
			local layer = layer_mt._init(layerInstances[i], @, i, callbacks)
			table.insert(@layers, layer)
			if onAddLayer then onAddLayer(layer) end
		end
		@loaded = true
	end,
	--- Unload the level.
	-- Images loaded by the level will be freed on the next garbage collection cycle.
	--
	-- You can optionally specify some callbacks for the unloading process:
	--
	-- * `onAddLayer(layer)` will be called for every new layer unloaded, with the @{Layer} as sole argument
	-- * `onAddTile(tile)` will be called for every new tile unloaded, with the @{Tile} as sole argument
	-- * `onAddIntTile(tile)` will be called for every new IntGrid tile unloaded, with the @{IntTile} as sole argument
	-- * `onAddEntity(entity)` will be called for every new entity unloaded, with the @{Entity} as sole argument
	--
	-- @tparam[opt] table callbacks
	unload = :(callbacks={})
		assert(@loaded == true, "level not loaded")
		let onRemoveLayer = callbacks.onRemoveLayer
		for _, l in ipairs(@layers) do
			l:_unloadCallbacks(callbacks)
			if onRemoveLayer then onRemoveLayer(l) end
		end
		@loaded = false
		@background.image = nil
		@layers = nil
	end,

	_init = (level, project)
		let t = {
			--- `Project` this level belongs to.
			-- @ftype Project
			project = project,
			--- Whether this level is currently loaded or not.
			-- @ftype boolean
			loaded = false,
			--- The level name.
			-- @ftype string
			identifier = level.identifier,
			--- The level x position.
			-- @ftype number
			x = level.worldX,
			--- The level y position.
			-- @ftype number
			y = level.worldY,
			--- The level width.
			-- @ftype number
			width = level.pxWid,
			--- The level height.
			-- @ftype number
			height = level.pxHei,
			--- Map of `CustomFields` of the level (table).
			-- @ftype CustomFields
			fields = getFields(level.fieldInstances),
			--- List of `Layer`s in the level (table).
			-- @ftype {Layer,...}
			layers = nil,
			--- Level background.
			--
			-- If there is a background image, `background.image` contains a table `{image=image, x=number, y=number, sx=number, sy=number}`
			-- where `image` is the LÖVE image (or image filepath if LÖVE not available) `x` and `y` are the top-left position,
			-- and `sx` and `sy` the horizontal and vertical scale factors.
			-- @field color backrgound color {r,g,b} with r,g,b in [0-1]
			-- @field image backrgound image information, if any
			background = {
				color = parseColor(level.__bgColor),
				image = nil,
			},

			-- private
			_json = level,
		}
		return setmetatable(t, level_mt)
	end
}
level_mt.__index = level_mt

--- Project object.
--
-- Returned by @{LDtk}.
--
-- @type Project
let project_mt = {
	_init = (project, directory)
		assert(project.jsonVersion == "0.9.3", "map made for LDtk version %s":format(project.jsonVersion))
		let t = {
			--- List of `Level`s in this project.
			-- @ftype {Level,...}
			levels = nil,

			-- private
			_directory = directory,
			_layerDef = nil,
			_tilesetData = nil,
			_entityData = nil,
		}
		t.levels = [
			for _, lvl in ipairs(project.levels) do
				push level_mt._init(lvl, t)
			end
		]
		t._tilesetData = [
			for _, ts in ipairs(project.defs.tilesets) do
				@[ts.uid] = {
					path = directory..ts.relPath
				}
				local tilesetData = @[ts.uid]
				for gridx=0, ts.__cWid-1 do
					for gridy=0, ts.__cHei-1 do
						tilesetData[gridx + gridy * ts.__cWid] = {
							tags = {},
							data = nil
						}
					end
				end
				for _, custom in ipairs(ts.customData) do
					tilesetData[custom.tileId].data = custom.data
				end
				for _, tag in ipairs(ts.enumTags) do
					local value = tag.enumValueId
					for _, tileId in ipairs(tag.tileIds) do
						table.insert(tilesetData[tileId].tags, value)
						tilesetData[tileId].tags[value] = true
					end
				end
			end
		]
		t._layerDef = [
			for _, lay in ipairs(project.defs.layers) do
				@[lay.uid] = {
					intGridValues = nil
				}
				local layerDef = @[lay.uid]
				if lay.__type == "IntGrid" then
					layerDef.intGridValues = [
						for _, v in ipairs(lay.intGridValues) do
							@[v.value] = {
								color = parseColor(v.color),
								identifier = v.identifier
							}
						end
					]
				end
			end
		]
		t._entityData = [
			for _, ent in ipairs(project.defs.entities) do
				@[ent.uid] = {
					color = parseColor(ent.color),
					width = ent.width,
					height = ent.height
				}
			end
		]
		return setmetatable(t, project_mt)
	end
}
project_mt.__index = project_mt

--- Custom fields: map of each field name to its value.
--
-- LDtk allows to defined custom fields in some places (`Entity.fields`, `Level.fields`). This library allows you to access them in a table that
-- map each field name to its value `{["fieldName"]=value,...}`.
--
-- @type CustomFields

--- Type conversion.
--
-- Here is how the values are converted to Lua values:
--
-- * Integers, Floats are converted into a Lua number.
-- * Booleans are converted into a Lua boolean.
-- * Strings, Multilines are converted in a Lua string.
-- * Enum are converted into a Lua string giving the currently selected enum value.
-- * Filepath are converted into a Lua string giving the file path.
-- * Arrays are converted into a Lua table with the elements in it as a list.
-- * Points are converted into a Lua table with the fields `x` and `y`: `{ x=number, y=number }`.
-- * Colors are converted into a Lua table with the red, green and blue components in [0-1] as a list: `{r,g,b}`.
-- @doc conversion

--- LDtk module.
-- `ubiquitousse.ldtk` returns a single function, @{LDtk}.
-- @section end

--- Load a LDtk project.
-- @string path to LDtk project file (.ldtk)
-- @treturn Project the loaded LDtk project
-- @function LDtk
return (file)
	return project_mt._init(readJson(file), file:match("^(.-)[^%/%\\]+$"))
end