#!/usr/bin/env python3
"""
GIF → RGB565 raw sprite pack 转换脚本

用法：
    python3 gif_to_rgb565.py input.gif output.bin [width] [height] [max_frames]

示例：
    python3 gif_to_rgb565.py happy.gif sprite_test.bin 200 200      # 全帧
    python3 gif_to_rgb565.py happy.gif sprite_test.bin 200 200 15   # 抽帧到 15 帧

依赖：
    pip install Pillow
"""

import sys
import struct
import os
from PIL import Image, ImageSequence


def gif_to_sprite_bin(gif_path, bin_path, target_w=200, target_h=200, max_frames=0, name='test'):
    img = Image.open(gif_path)
    total_frames = getattr(img, 'n_frames', 1)
    print(f"原始 GIF: {img.size}, 共 {total_frames} 帧")

    # 先扫描所有原始帧的 duration（保持总循环时长一致）
    original_durations = []
    for frame in ImageSequence.Iterator(img):
        original_durations.append(frame.info.get('duration', 100))
    total_original_ms = sum(original_durations)
    img.seek(0)  # 回到第一帧

    # 抽帧策略：均匀抽取
    if max_frames > 0 and total_frames > max_frames:
        step = total_frames / max_frames
        keep_indices = set(int(i * step) for i in range(max_frames))
        print(f"抽帧: {total_frames} → {len(keep_indices)} 帧（步长 {step:.2f}）")
    else:
        keep_indices = None  # 保留全部

    frames_rgb565 = []
    frame_durations = []

    for idx, frame in enumerate(ImageSequence.Iterator(img)):
        if keep_indices is not None and idx not in keep_indices:
            continue

        # 转 RGBA 处理透明度 → 缩放 → 黑底合成（去 Alpha）
        f_rgba = frame.convert('RGBA').resize((target_w, target_h), Image.LANCZOS)
        rgb = Image.new('RGB', (target_w, target_h), (0, 0, 0))
        rgb.paste(f_rgba, mask=f_rgba.split()[3])

        # RGB888 → RGB565 大端（ESP32 LCD 通常用大端字节序）
        raw = bytearray()
        for r, g, b in rgb.getdata():
            rgb565 = ((r >> 3) << 11) | ((g >> 2) << 5) | (b >> 3)
            raw += struct.pack('>H', rgb565)

        frames_rgb565.append(bytes(raw))
        frame_durations.append(frame.info.get('duration', 100))

    frame_count = len(frames_rgb565)
    # FPS 计算：保持总循环时长与原 GIF 一致
    # fps = 保留帧数 / 总时长（秒）
    if total_original_ms > 0:
        fps = max(1, round(frame_count / (total_original_ms / 1000.0)))
    else:
        fps = 10
    print(f"原 GIF 总时长 {total_original_ms} ms,抽帧后 FPS = {fps}（保持循环时长一致）")
    frame_size = target_w * target_h * 2
    total_frame_data = frame_size * frame_count

    print(f"\n转换信息:")
    print(f"  目标尺寸: {target_w}x{target_h}")
    print(f"  帧数: {frame_count}")
    print(f"  平均 FPS: {fps}")
    print(f"  单帧大小: {frame_size / 1024:.1f} KB")
    print(f"  帧数据总大小: {total_frame_data / 1024:.1f} KB")

    # ============ 文件格式（简化版，单情绪 PoC） ============
    # 文件头 64 字节（与正式格式兼容）
    HEADER_SIZE = 64
    TABLE_SIZE = 20  # 单个情绪索引项（8+2+2+4+4 = 20）
    FRAME_DATA_OFFSET = HEADER_SIZE + TABLE_SIZE  # 84

    header = struct.pack(
        '<8sIHHBBBBIIIII4s20s',
        b'SPRITES\0',          # 8B magic
        1,                      # 4B version
        target_w, target_h,     # 2+2B size
        0,                      # 1B pixel_format: 0=RGB565_BE
        1,                      # 1B emotion_count
        0,                      # 1B motion_count
        1,                      # 1B mouth_levels
        HEADER_SIZE,            # 4B emotion_table_offset
        0,                      # 4B motion_table_offset
        FRAME_DATA_OFFSET,      # 4B frame_data_offset
        frame_count,            # 4B total_frames
        total_frame_data,       # 4B total_size of frames
        b'\0\0\0\0',           # 4B checksum 占位
        b'\0' * 20,            # 20B reserved
    )
    # 8+4+2+2+1+1+1+1+4+4+4+4+4+4+20 = 64
    assert len(header) == 64, f"header size = {len(header)}, expected 64"

    # 情绪索引表（16 字节）
    entry = struct.pack(
        '<8sHHII',
        name.encode('ascii').ljust(8, b'\0')[:8],
        frame_count,
        fps,
        0,                      # first_frame_idx
        0,                      # flags
    )
    assert len(entry) == 20

    # 写文件
    with open(bin_path, 'wb') as f:
        f.write(header)
        f.write(entry)
        for raw in frames_rgb565:
            f.write(raw)

    total_size = os.path.getsize(bin_path)
    print(f"\n✓ 输出: {bin_path}")
    print(f"  总大小: {total_size / 1024:.1f} KB ({total_size} bytes)")


if __name__ == '__main__':
    if len(sys.argv) < 3:
        print(__doc__)
        sys.exit(1)

    gif_path = sys.argv[1]
    bin_path = sys.argv[2]
    w = int(sys.argv[3]) if len(sys.argv) > 3 else 200
    h = int(sys.argv[4]) if len(sys.argv) > 4 else 200
    max_frames = int(sys.argv[5]) if len(sys.argv) > 5 else 0

    if not os.path.exists(gif_path):
        print(f"错误: 找不到 {gif_path}")
        sys.exit(1)

    gif_to_sprite_bin(gif_path, bin_path, w, h, max_frames)