import subprocess
import os
from typing import Optional
try:
    import cv2
    import numpy as np
except Exception:
    cv2 = None
    np = None


class FFmpegWrapper:
    """FFmpeg命令行包装工具"""
    
    def __init__(self):
        self.ffmpeg_path = "ffmpeg"  # 假设ffmpeg已在系统PATH中
    
    def extract_audio(self, video_path: str, output_audio_path: str) -> bool:
        """
        从视频中提取音频轨道
        
        Args:
            video_path: 视频文件路径
            output_audio_path: 输出音频文件路径
            
        Returns:
            bool: 操作是否成功
        """
        try:
            cmd = [
                self.ffmpeg_path,
                "-i", video_path,
                "-vn",  # 禁用视频
                "-acodec", "pcm_s16le",  # 16位PCM
                "-ar", "16000",  # 16kHz采样率
                "-ac", "1",  # 单声道
                "-y",  # 覆盖输出文件
                output_audio_path
            ]
            
            subprocess.run(cmd, check=True, capture_output=True, text=True)
            return True
        except subprocess.CalledProcessError as e:
            raise Exception(f"音频提取失败: {e.stderr}")
    
    def convert_audio(self, input_audio_path: str, output_audio_path: str) -> bool:
        """
        转换音频格式为16k/16bit/mono wav
        
        Args:
            input_audio_path: 输入音频文件路径
            output_audio_path: 输出音频文件路径
            
        Returns:
            bool: 操作是否成功
        """
        try:
            cmd = [
                self.ffmpeg_path,
                "-i", input_audio_path,
                "-acodec", "pcm_s16le",
                "-ar", "16000",
                "-ac", "1",
                "-y",
                output_audio_path
            ]
            
            subprocess.run(cmd, check=True, capture_output=True, text=True)
            return True
        except subprocess.CalledProcessError as e:
            raise Exception(f"音频转换失败: {e.stderr}")
    
    def extract_keyframes(self, video_path: str, output_dir: str, interval: int = 60, diff_threshold: Optional[float] = None) -> list:
        """
        从视频中提取关键帧
        
        Args:
            video_path: 视频文件路径
            output_dir: 输出目录
            interval: 提取间隔（秒）
            
        Returns:
            list: 提取的关键帧文件路径列表
        """
        try:
            # 确保输出目录存在
            os.makedirs(output_dir, exist_ok=True)
            
            # 提取关键帧（按固定频率导出帧）
            output_pattern = os.path.join(output_dir, "frame_%06d.jpg")
            cmd = [
                self.ffmpeg_path,
                "-i", video_path,
                "-vf", f"fps=1/{interval}",  # 每 interval 秒一张
                "-y",
                output_pattern
            ]
            
            subprocess.run(cmd, check=True, capture_output=True, text=True)
            
            # 收集提取的帧
            frames = []
            for file in os.listdir(output_dir):
                if file.startswith("frame_") and file.endswith(".jpg"):
                    frames.append(os.path.join(output_dir, file))

            frames = sorted(frames)

            # 如果未提供差异阈值，直接返回所有按固定频率提取的帧
            if diff_threshold is None:
                return frames

            # 检查依赖
            if cv2 is None or np is None:
                raise Exception("OpenCV (opencv-python) 和 numpy 需要安装以启用帧差法（pip install opencv-python numpy）")

            # 使用 OpenCV 的灰度图像计算帧差，比较当前帧与上一个边界帧（pre），当差异>=阈值时标记为关键帧
            # 首先读取所有帧（彩色），以便能使用 cvtColor 按要求比较
            imgs = []
            for frame_path in frames:
                try:
                    img = cv2.imread(frame_path)  # BGR
                    imgs.append(img)
                except Exception:
                    imgs.append(None)

            filtered = []
            # 为了加速计算，统一缩放尺寸 (width, height)
            resize_to = (320, 240)

            # 找到第一个有效帧作为初始关键帧
            pre = None
            for idx, img in enumerate(imgs):
                if img is not None:
                    filtered.append(frames[idx])
                    pre = idx
                    break

            if pre is None:
                return []

            # 从下一个帧开始，比较当前帧与 imgs[pre]
            for i in range(pre + 1, len(imgs)):
                curr = imgs[i]
                if curr is None:
                    continue
                prev = imgs[pre]
                try:
                    prev_gray = cv2.cvtColor(prev, cv2.COLOR_BGR2GRAY)
                    curr_gray = cv2.cvtColor(curr, cv2.COLOR_BGR2GRAY)
                    if resize_to is not None:
                        prev_gray = cv2.resize(prev_gray, resize_to, interpolation=cv2.INTER_AREA)
                        curr_gray = cv2.resize(curr_gray, resize_to, interpolation=cv2.INTER_AREA)

                    diff_val = np.mean(np.abs(curr_gray.astype(int) - prev_gray.astype(int)))
                except Exception:
                    continue

                if diff_val >= float(diff_threshold):
                    filtered.append(frames[i])
                    pre = i

            return filtered
        except subprocess.CalledProcessError as e:
            raise Exception(f"关键帧提取失败: {e.stderr}")