#include "pxl8_sdl3.h"
#include "pxl8_atlas.h"
#include "pxl8_game.h"
#include "pxl8_macros.h"

#define SDL_MAIN_USE_CALLBACKS
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>

typedef struct pxl8_sdl3_context {
    SDL_Texture* atlas_texture;
    SDL_Texture* framebuffer_texture;
    SDL_Renderer* renderer;
    SDL_Window* window;

    u32* rgba_buffer;
    size_t rgba_buffer_size;

    u32 atlas_width;
    u32 atlas_height;
} pxl8_sdl3_context;

static void* sdl3_create(pxl8_color_mode mode, pxl8_resolution resolution,
                         const char* title, i32 win_w, i32 win_h) {
    (void)mode;

    pxl8_sdl3_context* ctx = (pxl8_sdl3_context*)SDL_calloc(1, sizeof(*ctx));
    if (!ctx) {
        pxl8_error("Failed to allocate SDL3 context");
        return NULL;
    }

    i32 fb_w, fb_h;
    switch (resolution) {
        case PXL8_RESOLUTION_240x160: fb_w = 240; fb_h = 160; break;
        case PXL8_RESOLUTION_320x180: fb_w = 320; fb_h = 180; break;
        case PXL8_RESOLUTION_320x240: fb_w = 320; fb_h = 240; break;
        case PXL8_RESOLUTION_640x360: fb_w = 640; fb_h = 360; break;
        case PXL8_RESOLUTION_640x480: fb_w = 640; fb_h = 480; break;
        case PXL8_RESOLUTION_800x600: fb_w = 800; fb_h = 600; break;
        case PXL8_RESOLUTION_960x540: fb_w = 960; fb_h = 540; break;
        default: fb_w = 640; fb_h = 360; break;
    }

    ctx->window = SDL_CreateWindow(title, win_w, win_h, SDL_WINDOW_RESIZABLE);
    if (!ctx->window) {
        pxl8_error("Failed to create window: %s", SDL_GetError());
        SDL_free(ctx);
        return NULL;
    }

    ctx->renderer = SDL_CreateRenderer(ctx->window, NULL);
    if (!ctx->renderer) {
        pxl8_error("Failed to create renderer: %s", SDL_GetError());
        SDL_DestroyWindow(ctx->window);
        SDL_free(ctx);
        return NULL;
    }

    if (!SDL_SetRenderVSync(ctx->renderer, 1)) {
        pxl8_error("Failed to enable vsync: %s", SDL_GetError());
    }

    SDL_SetRenderLogicalPresentation(ctx->renderer, fb_w, fb_h,
                                     SDL_LOGICAL_PRESENTATION_INTEGER_SCALE);

    ctx->framebuffer_texture = SDL_CreateTexture(ctx->renderer,
                                                  SDL_PIXELFORMAT_RGBA32,
                                                  SDL_TEXTUREACCESS_STREAMING,
                                                  fb_w, fb_h);
    if (!ctx->framebuffer_texture) {
        pxl8_error("Failed to create framebuffer texture: %s", SDL_GetError());
        SDL_DestroyRenderer(ctx->renderer);
        SDL_DestroyWindow(ctx->window);
        SDL_free(ctx);
        return NULL;
    }

    SDL_SetTextureScaleMode(ctx->framebuffer_texture, SDL_SCALEMODE_NEAREST);

    ctx->rgba_buffer = NULL;
    ctx->rgba_buffer_size = 0;

    return ctx;
}

static void sdl3_destroy(void* platform_data) {
    if (!platform_data) return;

    pxl8_sdl3_context* ctx = (pxl8_sdl3_context*)platform_data;

    if (ctx->rgba_buffer) {
        SDL_free(ctx->rgba_buffer);
    }
    if (ctx->atlas_texture) {
        SDL_DestroyTexture(ctx->atlas_texture);
    }
    if (ctx->framebuffer_texture) {
        SDL_DestroyTexture(ctx->framebuffer_texture);
    }
    if (ctx->renderer) {
        SDL_DestroyRenderer(ctx->renderer);
    }
    if (ctx->window) {
        SDL_DestroyWindow(ctx->window);
    }

    SDL_free(ctx);
}

static u64 sdl3_get_ticks(void) {
    return SDL_GetTicksNS();
}


static void sdl3_present(void* platform_data) {
    if (!platform_data) return;

    pxl8_sdl3_context* ctx = (pxl8_sdl3_context*)platform_data;

    SDL_SetRenderDrawColor(ctx->renderer, 0, 0, 0, 255);
    SDL_RenderClear(ctx->renderer);

    if (ctx->framebuffer_texture) {
        SDL_RenderTexture(ctx->renderer, ctx->framebuffer_texture, NULL, NULL);
    }

    SDL_RenderPresent(ctx->renderer);
}

static void sdl3_upload_framebuffer(void* platform_data, const u8* fb,
                                    i32 w, i32 h, const u32* palette,
                                    pxl8_color_mode mode) {
    if (!platform_data || !fb) return;

    pxl8_sdl3_context* ctx = (pxl8_sdl3_context*)platform_data;

    if (mode == PXL8_COLOR_MODE_HICOLOR) {
        SDL_UpdateTexture(ctx->framebuffer_texture, NULL, fb, w * 4);
    } else {
        size_t needed_size = w * h;

        if (ctx->rgba_buffer_size < needed_size) {
            ctx->rgba_buffer = (u32*)SDL_realloc(ctx->rgba_buffer, needed_size * 4);
            ctx->rgba_buffer_size = needed_size;
        }

        if (!ctx->rgba_buffer) return;

        u32 palette_size;
        switch (mode) {
            case PXL8_COLOR_MODE_FAMI: palette_size = 64; break;
            case PXL8_COLOR_MODE_MEGA: palette_size = 512; break;
            case PXL8_COLOR_MODE_GBA: palette_size = 32768; break;
            case PXL8_COLOR_MODE_SNES: palette_size = 32768; break;
            default: palette_size = 256; break;
        }

        for (i32 i = 0; i < w * h; i++) {
            u8 index = fb[i];
            ctx->rgba_buffer[i] = (index < palette_size) ? palette[index] : 0xFF000000;
        }

        SDL_UpdateTexture(ctx->framebuffer_texture, NULL, ctx->rgba_buffer, w * 4);
    }
}

static void sdl3_upload_atlas(void* platform_data, const pxl8_atlas* atlas,
                               const u32* palette, pxl8_color_mode mode) {
    if (!platform_data || !atlas) return;

    pxl8_sdl3_context* ctx = (pxl8_sdl3_context*)platform_data;

    if (!pxl8_atlas_is_dirty(atlas)) return;

    u32 atlas_w = pxl8_atlas_get_width(atlas);
    u32 atlas_h = pxl8_atlas_get_height(atlas);
    const u8* atlas_pixels = pxl8_atlas_get_pixels(atlas);

    if (!ctx->atlas_texture || ctx->atlas_width != atlas_w || ctx->atlas_height != atlas_h) {
        if (ctx->atlas_texture) {
            SDL_DestroyTexture(ctx->atlas_texture);
        }

        ctx->atlas_texture = SDL_CreateTexture(
            ctx->renderer,
            SDL_PIXELFORMAT_RGBA32,
            SDL_TEXTUREACCESS_STREAMING,
            atlas_w,
            atlas_h
        );

        if (!ctx->atlas_texture) {
            pxl8_error("Failed to create atlas texture: %s", SDL_GetError());
            return;
        }

        SDL_SetTextureScaleMode(ctx->atlas_texture, SDL_SCALEMODE_NEAREST);
        SDL_SetTextureBlendMode(ctx->atlas_texture, SDL_BLENDMODE_BLEND);

        ctx->atlas_width = atlas_w;
        ctx->atlas_height = atlas_h;
    }

    if (mode == PXL8_COLOR_MODE_HICOLOR) {
        SDL_UpdateTexture(ctx->atlas_texture, NULL, atlas_pixels, atlas_w * 4);
    } else {
        size_t needed_size = atlas_w * atlas_h;

        if (ctx->rgba_buffer_size < needed_size) {
            ctx->rgba_buffer = (u32*)SDL_realloc(ctx->rgba_buffer, needed_size * 4);
            ctx->rgba_buffer_size = needed_size;
        }

        if (!ctx->rgba_buffer) return;

        u32 palette_size;
        switch (mode) {
            case PXL8_COLOR_MODE_FAMI: palette_size = 64; break;
            case PXL8_COLOR_MODE_MEGA: palette_size = 512; break;
            case PXL8_COLOR_MODE_GBA: palette_size = 32768; break;
            case PXL8_COLOR_MODE_SNES: palette_size = 32768; break;
            default: palette_size = 256; break;
        }

        for (u32 i = 0; i < atlas_w * atlas_h; i++) {
            u8 index = atlas_pixels[i];
            ctx->rgba_buffer[i] = (index < palette_size) ? palette[index] : 0x00000000;
        }

        SDL_UpdateTexture(ctx->atlas_texture, NULL, ctx->rgba_buffer, atlas_w * 4);
    }
}

SDL_AppResult SDL_AppInit(void** appstate, int argc, char* argv[]) {
    if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS)) {
        pxl8_error("SDL_Init failed: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    pxl8_game* game = (pxl8_game*)SDL_calloc(1, sizeof(pxl8_game));
    if (!game) {
        pxl8_error("Failed to allocate game instance");
        SDL_Quit();
        return SDL_APP_FAILURE;
    }

    game->hal = &pxl8_hal_sdl3;

    pxl8_game_result result = pxl8_init(game, argc, argv);
    if (result != PXL8_GAME_CONTINUE) {
        SDL_free(game);
        SDL_Quit();
        return SDL_APP_FAILURE;
    }

    *appstate = game;
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void* appstate) {
    pxl8_game* game = (pxl8_game*)appstate;

    if (!game) {
        return SDL_APP_FAILURE;
    }

    pxl8_game_result update_result = pxl8_update(game);
    if (update_result == PXL8_GAME_FAILURE) {
        return SDL_APP_FAILURE;
    }
    if (update_result == PXL8_GAME_SUCCESS) {
        return SDL_APP_SUCCESS;
    }

    pxl8_game_result frame_result = pxl8_frame(game);
    if (frame_result == PXL8_GAME_FAILURE) {
        return SDL_APP_FAILURE;
    }

    return (frame_result == PXL8_GAME_SUCCESS) ? SDL_APP_SUCCESS : SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppEvent(void* appstate, SDL_Event* event) {
    pxl8_game* game = (pxl8_game*)appstate;

    if (!game) {
        return SDL_APP_CONTINUE;
    }

    switch (event->type) {
        case SDL_EVENT_QUIT:
            game->running = false;
            break;

        case SDL_EVENT_KEY_DOWN: {
#ifdef DEBUG
            if (event->key.key == SDLK_ESCAPE) {
                game->running = false;
            }
#endif

            SDL_Scancode scancode = event->key.scancode;
            if (scancode < 256) {
                if (!game->input.keys_down[scancode]) {
                    game->input.keys_pressed[scancode] = true;
                }
                game->input.keys_down[scancode] = true;
                game->input.keys_released[scancode] = false;
            }
            break;
        }

        case SDL_EVENT_KEY_UP: {
            SDL_Scancode scancode = event->key.scancode;
            if (scancode < 256) {
                game->input.keys_down[scancode] = false;
                game->input.keys_pressed[scancode] = false;
                game->input.keys_released[scancode] = true;
            }
            break;
        }

        case SDL_EVENT_MOUSE_BUTTON_DOWN: {
            u8 button = event->button.button - 1;
            if (button < 3) {
                if (!game->input.mouse_buttons_down[button]) {
                    game->input.mouse_buttons_pressed[button] = true;
                }
                game->input.mouse_buttons_down[button] = true;
                game->input.mouse_buttons_released[button] = false;
            }
            break;
        }

        case SDL_EVENT_MOUSE_BUTTON_UP: {
            u8 button = event->button.button - 1;
            if (button < 3) {
                game->input.mouse_buttons_down[button] = false;
                game->input.mouse_buttons_pressed[button] = false;
                game->input.mouse_buttons_released[button] = true;
            }
            break;
        }

        case SDL_EVENT_MOUSE_MOTION: {
            if (!game->gfx) break;

            i32 window_mouse_x = (i32)event->motion.x;
            i32 window_mouse_y = (i32)event->motion.y;

            SDL_Window* window = SDL_GetWindowFromID(event->motion.windowID);
            if (!window) break;

            i32 window_width, window_height;
            SDL_GetWindowSize(window, &window_width, &window_height);

            i32 render_width, render_height;
            pxl8_gfx_get_resolution_dimensions(game->resolution, &render_width, &render_height);

            pxl8_bounds window_bounds = {0, 0, window_width, window_height};
            pxl8_viewport vp = pxl8_gfx_viewport(window_bounds, render_width, render_height);

            game->input.mouse_x = (i32)((window_mouse_x - vp.offset_x) / vp.scale);
            game->input.mouse_y = (i32)((window_mouse_y - vp.offset_y) / vp.scale);
            break;
        }

        case SDL_EVENT_MOUSE_WHEEL: {
            game->input.mouse_wheel_x = (i32)event->wheel.x;
            game->input.mouse_wheel_y = (i32)event->wheel.y;
            break;
        }
    }

    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void* appstate, SDL_AppResult result) {
    (void)result;

    pxl8_game* game = (pxl8_game*)appstate;
    if (game) {
        pxl8_quit(game);
        SDL_free(game);
    }

    SDL_Quit();
}

const pxl8_hal pxl8_hal_sdl3 = {
    .create = sdl3_create,
    .destroy = sdl3_destroy,
    .get_ticks = sdl3_get_ticks,
    .present = sdl3_present,
    .upload_atlas = sdl3_upload_atlas,
    .upload_framebuffer = sdl3_upload_framebuffer,
};