package ffmpeg

import (
	"bytes"
	"fmt"
	"os/exec"
	"strconv"
	"strings"
)

type VideoProcessor interface {
	GenerateThumbnail(videoData []byte) ([]byte, error)
	GetDuration(videoData []byte) (int, error)
	TrimVideo(videoData []byte, maxDuration int) ([]byte, error)
}

type videoProcessor struct {
}

func NewVideoProcessor() VideoProcessor {
	return &videoProcessor{}
}

func (vp *videoProcessor) GenerateThumbnail(videoData []byte) ([]byte, error) {
	cmd := exec.Command("ffmpeg",
		"-i", "pipe:0", // читаем из stdin
		"-ss", "00:00:01",
		"-vframes", "1",
		"-q:v", "2",
		"-f", "image2pipe", // вывод в pipe
		"-c:v", "mjpeg",
		"pipe:1", // пишем в stdout
	)

	cmd.Stdin = bytes.NewReader(videoData)
	var output bytes.Buffer
	cmd.Stdout = &output
	cmd.Stderr = &output // capture stderr for error messages

	err := cmd.Run()
	if err != nil {
		return nil, fmt.Errorf("ffmpeg failed: %s, error: %w", output.String(), err)
	}

	if output.Len() == 0 {
		return nil, fmt.Errorf("thumbnail generation produced empty output")
	}

	return output.Bytes(), nil
}

func (vp *videoProcessor) GetDuration(videoData []byte) (int, error) {
	cmd := exec.Command("ffprobe",
		"-i", "pipe:0",
		"-show_entries", "format=duration",
		"-v", "quiet",
		"-of", "csv=p=0",
	)

	cmd.Stdin = bytes.NewReader(videoData)
	output, err := cmd.Output()
	if err != nil {
		debugCmd := exec.Command("ffprobe", "-i", "pipe:0")
		debugCmd.Stdin = bytes.NewReader(videoData)
		debugOutput, _ := debugCmd.CombinedOutput()
		return 0, fmt.Errorf("ffprobe failed: %w, debug output: %s", err, string(debugOutput))
	}

	durationStr := strings.TrimSpace(string(output))
	duration, err := strconv.ParseFloat(durationStr, 64)
	if err != nil {
		return 0, fmt.Errorf("failed to parse duration '%s': %w", durationStr, err)
	}

	return int(duration), nil
}

func (vp *videoProcessor) TrimVideo(videoData []byte, maxDuration int) ([]byte, error) {
	// Сначала получаем длительность
	duration, err := vp.GetDuration(videoData)
	if err != nil {
		return nil, fmt.Errorf("failed to get video duration: %w", err)
	}

	// Если видео короче или равно лимиту, возвращаем оригинал
	if duration <= maxDuration {
		return videoData, nil
	}

	// Обрезаем видео
	cmd := exec.Command("ffmpeg",
		"-i", "pipe:0",
		"-t", strconv.Itoa(maxDuration),
		"-c", "copy",
		"-f", "mp4",
		"pipe:1",
	)

	cmd.Stdin = bytes.NewReader(videoData)
	var output bytes.Buffer
	cmd.Stdout = &output
	cmd.Stderr = &output

	err = cmd.Run()
	if err != nil {
		return nil, fmt.Errorf("ffmpeg trim failed: %s, error: %w", output.String(), err)
	}

	if output.Len() == 0 {
		return nil, fmt.Errorf("trimmed video is empty")
	}

	return output.Bytes(), nil
}