local Tilemap = require("tilemap")
local Entity = require("entity")
local Player = require("player")
local Camera = require("camera")

local World = {}
World.__index = World

local GRAVITY = 9.81 * 64
local PHYSICS_DT = 1 / 60

function World:new()
    local self = setmetatable({}, World)
    self.physicsWorld = nil
    self.tilemap = nil
    self.mapData = nil
    self.groundEntities = {}
    self.player = nil
    self.enemies = {}
    self.entities = {}
    self.camera = nil
    self.groundContacts = {}
    self.contactCounts = {}
    self.contactEntity = {}
    self.contactKind = {}
    return self
end

function World:load(mapPath, tilesetPath)
    if self.physicsWorld then
        self.groundEntities = {}
    end
    self.physicsWorld = love.physics.newWorld(0, GRAVITY)
    self.physicsWorld:setCallbacks(
        function(fa, fb, contact)
            local udA, udB = fa:getUserData(), fb:getUserData()
            local nx, ny = contact:getNormal()
            self:_onBeginContact(udA, udB, nx, ny, contact)
        end,
        function(fa, fb, contact)
            local udA, udB = fa:getUserData(), fb:getUserData()
            self:_onEndContact(udA, udB, contact)
        end
    )

    self.tilemap = Tilemap:new(mapPath, tilesetPath)
    self.mapData = self.tilemap:getMapData()
    if not self.mapData then
        error("World:load - no map data from " .. tostring(mapPath))
    end

    local tileWidth = self.tilemap:getTileWidth()
    local tileHeight = self.tilemap:getTileHeight()

    local groundLayer = self.tilemap:getGroundLayer()
    if groundLayer and groundLayer.data then
        local mapW = self.mapData.width or 0
        local mapH = self.mapData.height or 0
        local data = groundLayer.data

        local solid = {}
        for row = 0, mapH - 1 do
            solid[row] = {}
            for col = 0, mapW - 1 do
                local idx = row * mapW + col + 1
                local gid = data[idx]
                solid[row][col] = (gid and gid ~= 0)
            end
        end

        for row = 0, mapH - 1 do
            local col = 0
            while col < mapW do
                if solid[row][col] then
                    local startCol = col
                    while col < mapW and solid[row][col] do
                        col = col + 1
                    end
                    local stripWidth = (col - startCol) * tileWidth
                    local x = startCol * tileWidth
                    local y = row * tileHeight
                    local strip = Entity:new(x, y, stripWidth, tileHeight)
                    strip:enablePhysics(self.physicsWorld, "static")
                    strip.fixture:setUserData("ground")
                    table.insert(self.groundEntities, strip)
                else
                    col = col + 1
                end
            end
        end
    end

    self.player = nil
    self.enemies = {}
    self.entities = {}
    local spawns = self.tilemap:getEntitiesSpawns()
    for _, spawn in ipairs(spawns) do
        local entityType = spawn:get("entity", "")
        if entityType == "Player" and not self.player then
            self.player = Player.new(self.physicsWorld, spawn.x, spawn.y)
            self.player.isPlayer = true
            table.insert(self.entities, self.player)
        else
            local e = Entity:new(spawn.x, spawn.y, spawn.width, spawn.height)
            e:setPropertiesFromOptions({ properties = spawn.properties or {}, name = spawn.name, type = spawn.type })
            if entityType ~= "" then
                table.insert(self.enemies, e)
            end
            table.insert(self.entities, e)
        end
    end

end

function World:_addContact(entity, kind)
    self.contactCounts[entity] = self.contactCounts[entity] or { floor = 0, wall = 0, ceiling = 0 }
    self.contactCounts[entity][kind] = (self.contactCounts[entity][kind] or 0) + 1
    entity.contact = entity.contact or { floor = 0, wall = 0, ceiling = 0 }
    entity.contact[kind] = 1
end

function World:_removeContact(entity, kind)
    self.contactCounts[entity] = self.contactCounts[entity] or { floor = 0, wall = 0, ceiling = 0 }
    self.contactCounts[entity][kind] = math.max(0, (self.contactCounts[entity][kind] or 0) - 1)
    entity.contact = entity.contact or { floor = 0, wall = 0, ceiling = 0 }
    entity.contact[kind] = (self.contactCounts[entity][kind] > 0) and 1 or 0
end

function World:_normalToContactType(nx, ny)
    local ax, ay = math.abs(nx), math.abs(ny)
    if ay >= ax then
        if ny < -0.3 then return "floor" end
        if ny > 0.3 then return "ceiling" end
    else
        if ax > 0.3 then return "wall" end
    end
    return nil
end

function World:_isTrackedEntity(ud)
    return type(ud) == "table" and (ud.body ~= nil or ud.x ~= nil)
end

function World:_isPlayerLike(ud)
    return type(ud) == "table" and ud.jump ~= nil
end

function World:_onBeginContact(udA, udB, nx, ny, contact)
    if udA == "ground" and self:_isTrackedEntity(udB) then
        local kind = self:_normalToContactType(nx, ny)
        if kind then
            self:_addContact(udB, kind)
            self.contactEntity[contact] = udB
            self.contactKind[contact] = kind
        end
        self.groundContacts[udB] = (self.groundContacts[udB] or 0) + 1
        if self:_isPlayerLike(udB) then udB.grounded = true end
    elseif udB == "ground" and self:_isTrackedEntity(udA) then
        local kind = self:_normalToContactType(-nx, -ny)
        if kind then
            self:_addContact(udA, kind)
            self.contactEntity[contact] = udA
            self.contactKind[contact] = kind
        end
        self.groundContacts[udA] = (self.groundContacts[udA] or 0) + 1
        if self:_isPlayerLike(udA) then udA.grounded = true end
    end
end

function World:_onEndContact(udA, udB, contact)
    local ent = self.contactEntity[contact]
    local kind = ent and self.contactKind[contact]
    if ent and kind then
        self:_removeContact(ent, kind)
        self.contactEntity[contact] = nil
        self.contactKind[contact] = nil
    end
    if udA == "ground" and self:_isTrackedEntity(udB) then
        self.groundContacts[udB] = math.max(0, (self.groundContacts[udB] or 0) - 1)
        if self:_isPlayerLike(udB) then
            udB.grounded = (self.groundContacts[udB] or 0) > 0
        end
    elseif udB == "ground" and self:_isTrackedEntity(udA) then
        self.groundContacts[udA] = math.max(0, (self.groundContacts[udA] or 0) - 1)
        if self:_isPlayerLike(udA) then
            udA.grounded = (self.groundContacts[udA] or 0) > 0
        end
    end
end

function World:setCamera(camera)
    self.camera = camera
    self.camera:setLimits(self.tilemap:getCameraLimits())
end

function World:getPlayer()
    return self.player
end

function World:getPhysicsWorld()
    return self.physicsWorld
end

function World:getMapData()
    return self.mapData
end

local function drawTileLayer(layer, tileWidth, tileHeight, tilesetImage, tileQuads)
    if not layer or not layer.visible or not layer.data then return end
    local w = layer.width or 0
    local data = layer.data
    for i, gid in ipairs(data) do
        if gid and gid ~= 0 then
            local idx = i - 1
            local tx = idx % w
            local ty = math.floor(idx / w)
            local x = tx * tileWidth
            local y = ty * tileHeight
            if tilesetImage and tileQuads and tileQuads[gid] then
                love.graphics.draw(tilesetImage, tileQuads[gid], x, y)
            else
                local r = ((gid * 17) % 256) / 255
                local g = ((gid * 31 + 50) % 256) / 255
                local b = ((gid * 47 + 100) % 256) / 255
                love.graphics.setColor(r, g, b, 1)
                love.graphics.rectangle("fill", x, y, tileWidth, tileHeight)
                love.graphics.setColor(1, 1, 1, 1)
            end
        end
    end
end

function World:draw()
    local tw = self.tilemap:getTileWidth()
    local th = self.tilemap:getTileHeight()
    local tilesetImage = self.tilemap:getTilesetImage()
    local tileQuads = self.tilemap:getTileQuads()
    
    drawTileLayer(self.tilemap:getBackgroundLayer(), tw, th, tilesetImage, tileQuads)

    drawTileLayer(self.tilemap:getGroundLayer(), tw, th, tilesetImage, tileQuads)

    for _, e in ipairs(self.entities) do
        if e.draw then e:draw() else World.drawEntityDefault(e) end
    end

    if DEBUG then
        World.drawPhysicsBodyOutlines(self.entities)
        World.drawPhysicsBodyOutlines(self.groundEntities)
    end

    drawTileLayer(self.tilemap:getForegroundLayer(), tw, th, tilesetImage, tileQuads)
end

function World.drawPhysicsBodyOutlines(entityList)
    if not entityList then return end
    love.graphics.setColor(0, 1, 0, 1)
    for _, e in ipairs(entityList) do
        local body = e.body
        if body and e.physicsWidth and e.physicsHeight then
            local cx, cy = body:getX(), body:getY()
            local x = cx - e.physicsWidth / 2
            local y = cy - e.physicsHeight / 2
            love.graphics.rectangle("line", x, y, e.physicsWidth, e.physicsHeight)
        end
    end
    love.graphics.setColor(1, 1, 1, 1)
end

function World.drawEntityDefault(entity)
    love.graphics.setColor(0.2, 0.6, 1, 1)
    if entity.isPlayer then
        love.graphics.setColor(1, 0.3, 0.2, 1)
    end
    love.graphics.rectangle("fill", entity.x, entity.y, entity.width, entity.height)
    love.graphics.setColor(1, 1, 1, 1)
end

function World:update(dt)
    if not self.physicsWorld then return end
    self.physicsWorld:update(PHYSICS_DT)

    if self.camera then 
        self.camera:setTarget(self.player)
        self.camera:update(dt) 
    end

    for _, e in ipairs(self.entities) do
        if e.body then
            e:syncFromPhysicsBody()
        end
        if e.update then e:update(dt) end
    end
end

return World