package game 

import "core:strings"
import "core:math/rand"
import rl "vendor:raylib"

VIEWPORT_W   :: 640
VIEWPORT_H   :: 360
WINDOW_TITLE :: "Pong"

Resolution :: struct {
    width:  i32,
    height: i32,
    label:  cstring,
}

// Preset window dimensions
RESOLUTIONS := [?]Resolution{
    {1280, 720,  "1280x720"},
    {1920, 1080, "1920x1080"},
    {2560, 1440, "2560x1440"},
    {3840, 2160, "3840x2160"},
}

Game :: struct {
    viewport:     rl.RenderTexture2D,
    bg_texture:   rl.Texture2D, 
    crt_shader:   rl.Shader,
    scene_stack:  [dynamic]Scene,
    should_close: bool,
    audio:        Audio_Manager,

    // Camera state for screen effects / screen shake
    camera:       rl.Camera2D,
    shake_intensity: f32,
    shake_timer: f32,

    // resolution state
    window_w: i32,
    window_h: i32,
    res_index: int
}

// AO: lets me load this at compile time!
gamepad_compat := #load("../gamecontrollerdb.txt", string)

// ------------------------------------------------------------------------------
// Game Lifecycle
// ------------------------------------------------------------------------------
game_init :: proc(game: ^Game) {
    rl.SetConfigFlags({.WINDOW_ALWAYS_RUN, .MSAA_4X_HINT})
    game.res_index = 2
    game.window_w  = RESOLUTIONS[game.res_index].width
    game.window_h  = RESOLUTIONS[game.res_index].height

    rl.InitWindow(game.window_w, game.window_h, WINDOW_TITLE)
    rl.SetTargetFPS(60)
    rl.SetExitKey(.KEY_NULL)

    gamepad_cstr := strings.clone_to_cstring(gamepad_compat)
    defer delete(gamepad_cstr)
    rl.SetGamepadMappings(gamepad_cstr)

    // init any global managers
    audio_init(&game.audio)

    // allocate some event capacity to stop early dynamic reallocations 
    GLOBAL_EVENTS = make([dynamic]Event, 0, 16)

    game.scene_stack = make([dynamic]Scene, 0, 8)
    game.viewport = rl.LoadRenderTexture(VIEWPORT_W, VIEWPORT_H)

    // Look into texture filters
    rl.SetTextureFilter(game.viewport.texture, .BILINEAR)

    // Generate soft CRT background radial texture once on startup
    bg_center := rl.Color{22, 28, 36, 255}
    bg_corner := rl.Color{6, 8, 12, 255}
    bg_img    := rl.GenImageGradientRadial(VIEWPORT_W, VIEWPORT_H, 0.3, bg_center, bg_corner)
    game.bg_texture = rl.LoadTextureFromImage(bg_img)
    rl.UnloadImage(bg_img) // Free CPU memory

    game.crt_shader = rl.LoadShader(nil, "assets/shaders/crt.fs")

    // Setup 2D camera matching the 640x360 viewport center
    game.camera = rl.Camera2D{
        target   = rl.Vector2{VIEWPORT_W / 2.0, VIEWPORT_H / 2.0},
        offset   = rl.Vector2{VIEWPORT_W / 2.0, VIEWPORT_H / 2.0},
        rotation = 0.0,
        zoom     = 1.0,
    }

    game.should_close = false
    set_root_scene(game, make_main_menu()) 
}

game_update :: proc(game: ^Game) {
    dt := rl.GetFrameTime()
    input := poll_input()

    // -------------------------------------------------------------------------
    // Update Camera Shake
    // -------------------------------------------------------------------------
    base_center := rl.Vector2{VIEWPORT_W / 2.0, VIEWPORT_H / 2.0}

    if game.shake_timer > 0 {
        game.shake_timer -= dt

        // Generate random offset within current intensity bounds
        offset_x := (f32(rand.float32()) * 2.0 - 1.0) * game.shake_intensity
        offset_y := (f32(rand.float32()) * 2.0 - 1.0) * game.shake_intensity

        game.camera.target = base_center + rl.Vector2{offset_x, offset_y}

        if game.shake_timer <= 0 {
            game.shake_intensity = 0.0
            game.camera.target = base_center
        }
    } else {
        game.camera.target = base_center
    }

    active_scene := get_active_scene(game)
    if active_scene != nil {
        scene_update(active_scene, game, input, dt)
    }

    // background music buffer streaming
    audio_update(&game.audio, dt)

    // flush any events triggered in this loop
    flush_events()
}

game_render :: proc(game: ^Game) {
    rl.BeginDrawing()
    rl.ClearBackground(rl.BLACK)

    rl.BeginTextureMode(game.viewport)

        rl.DrawTexture(game.bg_texture, 0, 0, rl.WHITE)        

        // World/Scene objects rendered through 2D camera space
        rl.BeginMode2D(game.camera)        
            // Render all active items on the stack from bottom to top
            for &scene in game.scene_stack {
                scene_render(&scene)
            }
        rl.EndMode2D()

    rl.EndTextureMode()

    render_game_to_window(game)

    rl.DrawFPS(10, game.window_h - 20)
    rl.EndDrawing()
}


game_quit :: proc(game: ^Game) {
    audio_manager_quit(&game.audio)
    scene_manager_quit(game)
    event_manager_quit(game)

    rl.UnloadShader(game.crt_shader)
    rl.UnloadTexture(game.bg_texture)
    rl.UnloadRenderTexture(game.viewport)
    rl.CloseWindow()
}

game_should_run :: proc(game: Game) -> bool {
    return !game.should_close && !rl.WindowShouldClose()
}

game_trigger_shake :: proc(game: ^Game, intensity: f32, duration: f32 = 0.15) {
    game.shake_intensity = max(game.shake_intensity, intensity)
    game.shake_timer = duration 
}

// ------------------------------------------------------------------------------
// Window Upscale Render 
// ------------------------------------------------------------------------------
game_set_resolution :: proc(game: ^Game, res_index: int) {
    game.res_index = clamp(res_index, 0, len(RESOLUTIONS) - 1)
    
    target_w := RESOLUTIONS[game.res_index].width
    target_h := RESOLUTIONS[game.res_index].height

    monitor  := rl.GetCurrentMonitor()
    screen_w := rl.GetMonitorWidth(monitor)
    screen_h := rl.GetMonitorHeight(monitor)

    // Clamp window size so it doesn't exceed physical screen limits
    game.window_w = min(target_w, screen_w)
    game.window_h = min(target_h, screen_h)

    rl.SetWindowSize(game.window_w, game.window_h)
}

render_game_to_window :: proc(game: ^Game) {
    texture := game.viewport.texture

    rl.BeginShaderMode(game.crt_shader)
        rl.DrawTexturePro(
            texture, 
            // src: inverted y coordinate flips opengl texture buffer correctly
            rl.Rectangle{0, 0, f32(texture.width), -f32(texture.height)},
            // dst: scales viewport canvas to fill window resolution
            rl.Rectangle{0, 0, f32(game.window_w), f32(game.window_h)},
            rl.Vector2{},
            0,
            rl.WHITE,
        ) 
    rl.EndShaderMode()
}