local World = require("game.world")
local Lander = require("game.lander")
local Terrain = require("game.terrain")
local Camera = require("game.camera")
local Particles = require("game.particles")
local Stars = require("game.stars")
local HUD = require("game.hud")
local HighScores = require("game.highscores")
local Palette = require("rendering.palette")
local Fonts = require("rendering.fonts")
local Sounds = require("audio.sounds")

local thrustSoundTimer = 0
local fuelWarnTimer = 0
local STATE_PAUSE = 3.0

local DIFFICULTIES = {
    {name = "CADET",     gravity = 8,  fuel = 1000, description = "TRAINING - LOW GRAVITY"},
    {name = "PILOT",     gravity = 12, fuel = 750,  description = "STANDARD MISSION"},
    {name = "COMMANDER", gravity = 16, fuel = 600,  description = "EXPERIENCED - HEAVIER PULL"},
    {name = "ASTRONAUT", gravity = 22, fuel = 500,  description = "ELITE - EXTREME GRAVITY"},
}
local difficultyIndex = 2

local function applyDifficulty(d)
    World.gravity = d.gravity
    World.startFuel = d.fuel
    World.difficultyName = d.name
end

local function startGame()
    applyDifficulty(DIFFICULTIES[difficultyIndex])
    World.state = "playing"
    World.score = 0
    World.fuel = World.startFuel
    World.time = 0
    World.stateTimer = 0

    Terrain.generate()
    Lander.init()
    Camera.reset()
    Particles.clear()
end

local function nextAttempt()
    World.stateTimer = 0
    Terrain.generate()
    Lander.init()
    Camera.reset()
    Particles.clear()
    World.state = "playing"
end

local function checkLanding()
    local l = Lander.get()
    local colPts = Lander.getCollisionPoints()

    for _, pt in ipairs(colPts) do
        local terrainY = Terrain.getHeightAt(pt.x)
        if pt.y >= terrainY then
            -- Contact! Evaluate landing
            local pad = Terrain.getPadAt(l.x)
            local vspeed = math.abs(l.vy)
            local hspeed = math.abs(l.vx)
            local tilt = math.abs(l.angle)

            if pad and vspeed < 8 and hspeed < 15 and tilt < math.rad(5) then
                -- A perfect landing — tightest tolerances
                local pts = 50 * pad.mult
                World.addScore(pts)
                World.fuel = World.fuel + 50
                World.landingResult = "CONGRATULATIONS — A PERFECT LANDING    " .. pts .. " PTS"
                World.landingPoints = pts
                World.state = "landed"
                Lander.land()
                Sounds.play("land_good")
            elseif pad and vspeed < 15 and hspeed < 30 and tilt < math.rad(15) then
                -- Good landing
                local pts = 25 * pad.mult
                World.addScore(pts)
                World.fuel = World.fuel + 25
                World.landingResult = "GOOD LANDING    " .. pts .. " PTS"
                World.landingPoints = pts
                World.state = "landed"
                Lander.land()
                Sounds.play("land_good")
            elseif pad and vspeed < 25 and hspeed < 45 and tilt < math.rad(25) then
                -- Rough but survivable on-pad landing
                local pts = 10 * pad.mult
                World.addScore(pts)
                World.landingResult = "ROUGH LANDING    " .. pts .. " PTS"
                World.landingPoints = pts
                World.state = "landed"
                Lander.land()
                Sounds.play("land_hard")
            elseif (not pad) and vspeed < 20 and hspeed < 40 and tilt < math.rad(20) then
                -- Missed the pad but touched down intact
                World.addScore(5)
                World.landingResult = "YOU MISSED THE LANDING AREA    5 PTS"
                World.landingPoints = 5
                World.state = "landed"
                Lander.land()
                Sounds.play("land_hard")
            else
                -- Destroyed
                World.landingResult = "CRAFT DESTROYED"
                World.landingPoints = 0
                World.state = "crashed"
                Particles.spawnCrash(l.x, l.y, l.vx, l.vy)
                Lander.die()
                Sounds.play("crash")
            end

            World.stateTimer = 0
            return
        end
    end
end

local function drawTitleScreen()
    local p = Palette.get()
    local sw, sh = World.screenW, World.screenH
    local t = love.timer.getTime()

    -- Background
    love.graphics.setColor(p.bg)
    love.graphics.rectangle("fill", 0, 0, sw, sh)
    Stars.draw(sw, sh)

    -- Title
    local titleY = sh * 0.15
    love.graphics.setFont(Fonts.large)
    love.graphics.setColor(p.bright)
    love.graphics.printf("OMA-LANDER", 0, titleY, sw, "center")

    -- Controls
    love.graphics.setFont(Fonts.small)
    love.graphics.setColor(p.fg[1], p.fg[2], p.fg[3], 0.4)
    love.graphics.printf("ARROWS / WASD: ROTATE & THRUST    SPACE: ABORT", 0, sh * 0.38, sw, "center")
    love.graphics.printf("LAND GENTLY ON MARKED PADS FOR POINTS", 0, sh * 0.42, sw, "center")

    -- Press Enter
    local pulse = 0.3 + math.sin(t * 3) * 0.3
    love.graphics.setFont(Fonts.medium)
    love.graphics.setColor(p.bright[1], p.bright[2], p.bright[3], pulse + 0.2)
    love.graphics.printf("PRESS ENTER TO SELECT MISSION", 0, sh * 0.52, sw, "center")

    -- High scores
    local allScores = HighScores.getScores()
    if #allScores > 0 then
        HighScores.drawTable(sw, sh, p, Fonts)
    end
end

local function drawDifficultyScreen()
    local p = Palette.get()
    local sw, sh = World.screenW, World.screenH
    local t = love.timer.getTime()

    love.graphics.setColor(p.bg)
    love.graphics.rectangle("fill", 0, 0, sw, sh)
    Stars.draw(sw, sh)

    love.graphics.setFont(Fonts.large)
    love.graphics.setColor(p.bright)
    love.graphics.printf("SELECT MISSION", 0, sh * 0.12, sw, "center")

    love.graphics.setFont(Fonts.medium)
    local lineH = Fonts.medium:getHeight() + 12
    local menuTop = sh * 0.30

    for i, d in ipairs(DIFFICULTIES) do
        local y = menuTop + (i - 1) * lineH
        local selected = (i == difficultyIndex)
        if selected then
            local pulse = 0.7 + math.sin(t * 4) * 0.3
            love.graphics.setColor(p.bright[1], p.bright[2], p.bright[3], pulse)
            love.graphics.printf("> " .. d.name .. " <", 0, y, sw, "center")
        else
            love.graphics.setColor(p.fg[1], p.fg[2], p.fg[3], 0.5)
            love.graphics.printf(d.name, 0, y, sw, "center")
        end
    end

    -- Description of selected mission
    love.graphics.setFont(Fonts.small)
    love.graphics.setColor(p.fg[1], p.fg[2], p.fg[3], 0.7)
    local d = DIFFICULTIES[difficultyIndex]
    local descY = menuTop + #DIFFICULTIES * lineH + 20
    love.graphics.printf(d.description, 0, descY, sw, "center")
    love.graphics.printf(string.format("GRAVITY %d     FUEL %d", d.gravity, d.fuel),
        0, descY + Fonts.small:getHeight() + 4, sw, "center")

    -- Instructions
    love.graphics.setColor(p.fg[1], p.fg[2], p.fg[3], 0.4)
    love.graphics.printf("UP / DOWN: CHANGE MISSION    ENTER: BEGIN    ESC: BACK",
        0, sh - Fonts.small:getHeight() - 12, sw, "center")
end

function love.load()
    love.mouse.setVisible(false)
    love.graphics.setBackgroundColor(0, 0, 0)
    love.graphics.setLineStyle("smooth")
    Palette.loadFromSystem()
    World.resize(love.graphics.getDimensions())
    Fonts.init()
    HighScores.init()
    Sounds.init()
    Stars.init()
    World.highScore = HighScores.getHighest()
    World.state = "title"
end

function love.resize(w, h)
    World.resize(w, h)
    Fonts.init()
end

function love.update(dt)
    World.ensureScale()

    if World.state == "title" or World.state == "difficulty_select" then
        return
    end

    if World.state == "playing" then
        World.time = World.time + dt
        Lander.update(dt)
        Camera.update(Lander.get(), Terrain, dt)
        Particles.update(dt)

        -- Thrust sound
        local l = Lander.get()
        if l.thrusting then
            thrustSoundTimer = thrustSoundTimer + dt
            if thrustSoundTimer > 0.2 then
                thrustSoundTimer = 0
                Sounds.play("thrust")
            end
            -- Thrust particles — spawn at engine-bell exit transformed by lander angle
            local sa, ca = math.sin(l.angle), math.cos(l.angle)
            local fx = l.x - sa * 12
            local fy = l.y + ca * 12
            Particles.spawnThrust(fx, fy, l.angle)
        else
            thrustSoundTimer = 0.15
        end

        -- Fuel warning
        if World.fuel < 150 and World.fuel > 0 then
            fuelWarnTimer = fuelWarnTimer + dt
            if fuelWarnTimer > 0.5 then
                fuelWarnTimer = 0
                Sounds.play("fuel_warn")
            end
        end

        -- Check terrain collision
        checkLanding()

    elseif World.state == "landed" or World.state == "crashed" then
        World.stateTimer = World.stateTimer + dt
        Particles.update(dt)
        Camera.update(Lander.get(), Terrain, dt)

        if World.stateTimer >= STATE_PAUSE then
            if World.fuel <= 0 then
                World.state = "game_over"
                World.stateTimer = 0
            else
                nextAttempt()
            end
        end

    elseif World.state == "game_over" then
        World.stateTimer = World.stateTimer + dt

    elseif World.state == "high_score_entry" then
        HighScores.updateEntry(dt)
    end
end

function love.draw()
    love.graphics.clear(0, 0, 0)
    local p = Palette.get()
    local sw, sh = World.screenW, World.screenH

    if World.state == "title" then
        drawTitleScreen()
        return
    end

    if World.state == "difficulty_select" then
        drawDifficultyScreen()
        return
    end

    if World.state == "high_score_entry" then
        love.graphics.setColor(p.bg)
        love.graphics.rectangle("fill", 0, 0, sw, sh)
        Stars.draw(sw, sh)
        HighScores.drawEntry(sw, sh, p, Fonts)
        return
    end

    -- Draw game world
    love.graphics.setColor(p.bg)
    love.graphics.rectangle("fill", 0, 0, sw, sh)

    -- Stars (screen space, behind everything)
    Stars.draw(sw, sh)

    -- World space
    Camera.applyTransform()

    local minX, minY, maxX, maxY = Camera.getVisibleRect()
    Terrain.draw(minX, maxX)
    Lander.draw()
    Particles.draw()

    Camera.popTransform()

    -- HUD (screen space)
    local l = Lander.get()
    local altitude = Camera.getAltitude(l.y, Terrain, l.x)
    HUD.draw(altitude, l.vx, l.vy)

    -- Landing/crash result text
    if World.state == "landed" or World.state == "crashed" then
        love.graphics.setFont(Fonts.medium)
        local flash = World.state == "landed" or
            (math.floor(World.stateTimer * 4) % 2 == 0)

        if flash then
            if World.state == "crashed" then
                love.graphics.setColor(p.warning)
            else
                love.graphics.setColor(p.bright)
            end
            love.graphics.printf(World.landingResult, 0, sh * 0.45, sw, "center")
        end
    end

    -- Game over
    if World.state == "game_over" then
        local t = love.timer.getTime()

        love.graphics.setColor(0, 0, 0, 0.5)
        love.graphics.rectangle("fill", 0, 0, sw, sh)

        if World.stateTimer > 0.5 then
            love.graphics.setFont(Fonts.large)
            local pulse = 0.7 + math.sin(t * 3) * 0.3
            love.graphics.setColor(p.bright[1], p.bright[2], p.bright[3], pulse)
            love.graphics.printf("OUT OF FUEL", 0, sh * 0.3, sw, "center")
        end

        if World.stateTimer > 1.5 then
            love.graphics.setFont(Fonts.medium)
            love.graphics.setColor(p.fg[1], p.fg[2], p.fg[3], 0.7)
            love.graphics.printf("FINAL SCORE: " .. string.format("%d", World.score), 0, sh * 0.3 + Fonts.large:getHeight() + 8, sw, "center")
        end

        if World.stateTimer > 2.5 then
            local pulse = 0.3 + math.sin(t * 3) * 0.3
            love.graphics.setFont(Fonts.small)
            love.graphics.setColor(p.bright[1], p.bright[2], p.bright[3], pulse + 0.2)
            love.graphics.printf("PRESS ENTER", 0, sh * 0.3 + Fonts.large:getHeight() + Fonts.medium:getHeight() + 24, sw, "center")
        end
    end
end

function love.keypressed(key)
    if World.state == "title" then
        if key == "return" then World.state = "difficulty_select" end
        if key == "escape" then love.event.quit() end
        return
    end

    if World.state == "difficulty_select" then
        if key == "up" or key == "w" then
            difficultyIndex = ((difficultyIndex - 2) % #DIFFICULTIES) + 1
        elseif key == "down" or key == "s" then
            difficultyIndex = (difficultyIndex % #DIFFICULTIES) + 1
        elseif key == "return" then
            startGame()
        elseif key == "escape" then
            World.state = "title"
        end
        return
    end

    if World.state == "high_score_entry" then
        local result = HighScores.keypressedEntry(key)
        if result == "done" then
            World.highScore = HighScores.getHighest()
            World.state = "title"
        end
        return
    end

    if World.state == "playing" then
        if key == "space" then
            Lander.abort()
            Sounds.play("abort")
        end
    end

    if World.state == "game_over" then
        if key == "return" and World.stateTimer > 2.0 then
            if HighScores.isHighScore(World.score) then
                World.state = "high_score_entry"
                HighScores.startEntry(World.score)
            else
                World.state = "title"
            end
            return
        end
        if key == "escape" then
            World.state = "title"
            return
        end
    end

    if key == "escape" then
        love.event.quit()
    end
end