#include <raylib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <glob.h>
#include <sys/stat.h>

#define WINDOW_WIDTH  800
#define WINDOW_HEIGHT 600
#define LOGO_HEIGHT   64
#define LOGO_SPEED    300.0f
#define GIF_FPS       20

static unsigned int hash_str(const char *s) {
    unsigned int h = 5381;
    while (*s) h = h * 33 ^ (unsigned char)*s++;
    return h;
}

static void generate_gif(const char *output_gif, const char **logo_paths, int logo_count, float switch_secs, int duration_secs) {
    if (FileExists(output_gif)) {
        TraceLog(LOG_INFO, "Skipping %s (already exists)", output_gif);
        return;
    }

    TraceLog(LOG_INFO, "Generating %s...", output_gif);

    char tmpdir[] = "/tmp/demo_gen_XXXXXX";
    if (!mkdtemp(tmpdir)) {
        perror("mkdtemp");
        return;
    }

    Texture2D *textures = (Texture2D *)malloc(logo_count * sizeof(Texture2D));
    for (int i = 0; i < logo_count; i++) {
        Image img = LoadImage(logo_paths[i]);
        ImageResize(&img, img.width * LOGO_HEIGHT / img.height, LOGO_HEIGHT);
        textures[i] = LoadTextureFromImage(img);
        UnloadImage(img);
    }

    RenderTexture2D target = LoadRenderTexture(WINDOW_WIDTH, WINDOW_HEIGHT);

    SetRandomSeed(hash_str(output_gif));

    int cur_logo = 0;
    float x = GetRandomValue(0, WINDOW_WIDTH  - textures[cur_logo].width);
    float y = GetRandomValue(0, WINDOW_HEIGHT - textures[cur_logo].height);
    float vx = LOGO_SPEED * (GetRandomValue(0, 1) ? 1.0f : -1.0f);
    float vy = LOGO_SPEED * (GetRandomValue(0, 1) ? 1.0f : -1.0f);

    int   total_frames = duration_secs * GIF_FPS;
    float frame_dt     = 1.0f / GIF_FPS;
    float logo_timer   = 0.0f;

    for (int f = 0; f < total_frames; f++) {
        Texture2D tex = textures[cur_logo];

        x += vx * frame_dt;
        y += vy * frame_dt;

        if (x < 0 || x + tex.width >= WINDOW_WIDTH) {
            vx *= -1.0f;
            x  += vx * frame_dt;
        }
        if (y < 0 || y + tex.height >= WINDOW_HEIGHT) {
            vy *= -1.0f;
            y  += vy * frame_dt;
        }

        logo_timer += frame_dt;
        if (logo_timer >= switch_secs) {
            logo_timer = 0.0f;
            cur_logo   = (cur_logo + 1) % logo_count;
        }

        BeginTextureMode(target);
        ClearBackground(BLACK);
        DrawTextureV(tex, (Vector2){x, y}, WHITE);
        EndTextureMode();

        Image frame_img = LoadImageFromTexture(target.texture);
        ImageFlipVertical(&frame_img);

        ExportImage(frame_img, TextFormat("%s/frame_%04d.png", tmpdir, f));
        UnloadImage(frame_img);

        TraceLog(LOG_INFO, "  frame %d/%d", f + 1, total_frames);
    }

    UnloadRenderTexture(target);
    for (int i = 0; i < logo_count; i++) UnloadTexture(textures[i]);
    free(textures);

    if (system(TextFormat(
        "ffmpeg -y -framerate %d -i '%s/frame_%%04d.png' "
        "-vf 'fps=%d,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse' "
        "'%s' 2>/dev/null",
        GIF_FPS, tmpdir, GIF_FPS, output_gif)) != 0)
        TraceLog(LOG_ERROR, "ffmpeg failed for %s", output_gif);

    system(TextFormat("rm -rf '%s'", tmpdir));
}

int main(void) {
    SetConfigFlags(FLAG_WINDOW_HIDDEN);
    InitWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "demo_gen");

    glob_t gl;
    if (glob("languages/*/*_logo.png", 0, NULL, &gl) != 0) {
        TraceLog(LOG_ERROR, "No logos found. Run from project root.");
        CloseWindow();
        return 1;
    }

    mkdir("docs", 0755);

    // generate docs/demo.gif (cycles all logos)
    generate_gif("docs/demo.gif", (const char **)gl.gl_pathv, (int)gl.gl_pathc, 1.0f, (int)gl.gl_pathc);

    // generate languages/**/demo.gif
    for (size_t i = 0; i < gl.gl_pathc; i++) {
        const char *path = gl.gl_pathv[i];
        char *output_path = strdup(TextFormat("%s/demo.gif", GetDirectoryPath(path)));
        generate_gif(output_path, &path, 1, 9999.0f, 4);
        free(output_path);
    }

    CloseWindow();
    globfree(&gl);
    return 0;
}