-- NAME: Lunar Lander
-- DESC: Land safely with limited fuel

-- Game states
local STATE_MENU = 0
local STATE_PLAYING = 1
local STATE_LANDED = 2
local STATE_CRASHED = 3

-- Game constants
local GRAVITY = 0.15
local THRUST_POWER = 0.3
local MAX_FUEL = 100
local SAFE_LANDING_SPEED = 1.5

function init()
    game.vars.state = STATE_MENU
    game.vars.score = 0
    
    -- Lander
    game.vars.lander_x = game.width() / 2
    game.vars.lander_y = 10
    game.vars.lander_vel_y = 0
    game.vars.fuel = MAX_FUEL
    game.vars.thrusting = false
    
    -- Terrain
    game.vars.landing_zone_x = game.width() / 2 - 20
    game.vars.landing_zone_w = 40
    game.vars.terrain_y = game.height() - 15
    
    -- Enable continuous updates
    game.set_frame_updates(true)
    
    print("Lunar Lander initialized")
end

function update(event)
    local state = game.vars.state
    
    if state == STATE_MENU then
        if event.type == INPUT.TOUCH_DOWN or event.type == INPUT.BUTTON_0 or event.type == INPUT.BUTTON_1 then
            reset_game()
            game.vars.state = STATE_PLAYING
            return true
        end
    
    elseif state == STATE_PLAYING then
        -- Handle thrust input
        if event.type == INPUT.TOUCH_DOWN or event.type == INPUT.TOUCH_MOVE then
            if game.vars.fuel > 0 then
                game.vars.thrusting = true
                game.vars.fuel = game.vars.fuel - 1
            else
                game.vars.thrusting = false
            end
        else
            game.vars.thrusting = false
        end
        
        -- Update physics on frame tick
        if event.type == INPUT.FRAME_TICK then
            update_lander()
            check_landing()
            return true
        end
    
    elseif state == STATE_LANDED or state == STATE_CRASHED then
        if event.type == INPUT.TOUCH_DOWN or event.type == INPUT.BUTTON_0 or event.type == INPUT.BUTTON_1 then
            game.vars.state = STATE_MENU
            return true
        end
    end
    
    return false
end

function draw()
    renderer.clear(false)
    
    local state = game.vars.state
    
    if state == STATE_MENU then
        renderer.text_scaled(game.width() / 2 - 50, game.height() / 2 - 30, "LUNAR LANDER", true, 2)
        renderer.text_scaled(game.width() / 2 - 70, game.height() / 2 - 5, "Land in the zone safely", true, 2)
        renderer.text_scaled(game.width() / 2 - 50, game.height() / 2 + 20, "Tap to Start", true, 2)
    
    elseif state == STATE_PLAYING or state == STATE_LANDED or state == STATE_CRASHED then
        -- Draw terrain
        renderer.rect(0, game.vars.terrain_y, game.width(), game.height() - game.vars.terrain_y, true, true)
        
        -- Draw landing zone (outline)
        renderer.rect(game.vars.landing_zone_x, game.vars.terrain_y - 2, game.vars.landing_zone_w, 2, true, true)
        
        -- Draw lander (triangle)
        local lander_w = 8
        local lander_h = 6
        renderer.line(game.vars.lander_x - lander_w / 2, game.vars.lander_y + lander_h, 
                     game.vars.lander_x, game.vars.lander_y, true, 1)
        renderer.line(game.vars.lander_x, game.vars.lander_y, 
                     game.vars.lander_x + lander_w / 2, game.vars.lander_y + lander_h, true, 1)
        renderer.line(game.vars.lander_x - lander_w / 2, game.vars.lander_y + lander_h,
                     game.vars.lander_x + lander_w / 2, game.vars.lander_y + lander_h, true, 1)
        
        -- Draw thrust flame
        if game.vars.thrusting then
            renderer.line(game.vars.lander_x - 2, game.vars.lander_y + lander_h,
                         game.vars.lander_x - 1, game.vars.lander_y + lander_h + 3, true, 1)
            renderer.line(game.vars.lander_x + 2, game.vars.lander_y + lander_h,
                         game.vars.lander_x + 1, game.vars.lander_y + lander_h + 3, true, 1)
        end
        
        -- Draw stats
        renderer.text_scaled(5, 5, "Fuel: " .. tostring(math.floor(game.vars.fuel)), true, 2)
        renderer.text_scaled(5, 15, "Speed: " .. tostring(math.floor(game.vars.lander_vel_y * 10)), true, 2)
        
        if state == STATE_LANDED then
            renderer.text_scaled(game.width() / 2 - 40, game.height() / 2 - 20, "LANDED!", true, 2)
            renderer.text_scaled(game.width() / 2 - 30, game.height() / 2, "Score: " .. tostring(game.vars.score), true, 2)
            renderer.text_scaled(game.width() / 2 - 60, game.height() / 2 + 20, "Tap to Menu", true, 2)
        end
        
        if state == STATE_CRASHED then
            renderer.text_scaled(game.width() / 2 - 40, game.height() / 2 - 20, "CRASHED!", true, 2)
            renderer.text_scaled(game.width() / 2 - 60, game.height() / 2 + 20, "Tap to Menu", true, 2)
        end
    end
end

function update_lander()
    -- Apply gravity
    game.vars.lander_vel_y = game.vars.lander_vel_y + GRAVITY
    
    -- Apply thrust
    if game.vars.thrusting then
        game.vars.lander_vel_y = game.vars.lander_vel_y - THRUST_POWER
    end
    
    -- Update position
    game.vars.lander_y = game.vars.lander_y + game.vars.lander_vel_y
end

function check_landing()
    -- Check if lander reached terrain
    if game.vars.lander_y + 6 >= game.vars.terrain_y then
        local lander_left = game.vars.lander_x - 4
        local lander_right = game.vars.lander_x + 4
        local zone_left = game.vars.landing_zone_x
        local zone_right = game.vars.landing_zone_x + game.vars.landing_zone_w
        
        -- Check if in landing zone
        if lander_left >= zone_left and lander_right <= zone_right then
            -- Check landing speed
            if game.vars.lander_vel_y <= SAFE_LANDING_SPEED then
                game.vars.state = STATE_LANDED
                game.vars.score = 100 + math.floor(game.vars.fuel)
            else
                game.vars.state = STATE_CRASHED
            end
        else
            game.vars.state = STATE_CRASHED
        end
    end
end

function reset_game()
    game.vars.lander_x = game.width() / 2
    game.vars.lander_y = 10
    game.vars.lander_vel_y = 0
    game.vars.fuel = MAX_FUEL
    game.vars.thrusting = false
    game.vars.score = 0
end