package storage

import (
	"io"
	"net/http"
	"os"
	"strconv"
	"strings"
)

func contentType2Ext(contentType string) string {
	if strings.Contains(contentType, "image/jpeg") {
		return "jpg"
	} else if strings.Contains(contentType, "audio/mpeg") {
		return "mp3"
	} else if strings.Contains(contentType, "video/mp4") {
		return "mp4"
	}
	return ""
}

func ext2ContentType(ext string) string {
	ext = strings.ToLower(ext)
	switch ext {
	// 图片格式
	case "jpg", "jpeg":
		return "image/jpeg"
	case "png":
		return "image/png"
	case "gif":
		return "image/gif"
	case "webp":
		return "image/webp"
	case "bmp":
		return "image/bmp"
	case "svg", "svgz":
		return "image/svg+xml"
	case "ico":
		return "image/x-icon"
	case "tiff", "tif":
		return "image/tiff"
	case "avif":
		return "image/avif"
	case "apng":
		return "image/apng"
	// 音频格式
	case "mp3":
		return "audio/mpeg"
	case "wav":
		return "audio/wav"
	case "ogg":
		return "audio/ogg"
	case "flac":
		return "audio/flac"
	case "aac":
		return "audio/aac"
	case "m4a":
		return "audio/mp4"
	// 视频格式
	case "mp4":
		return "video/mp4"
	case "avi":
		return "video/x-msvideo"
	case "mov", "qt":
		return "video/quicktime"
	case "webm":
		return "video/webm"
	case "flv":
		return "video/x-flv"
	case "mkv":
		return "video/x-matroska"
	case "wmv":
		return "video/x-ms-wmv"
	case "m3u8":
		return "application/vnd.apple.mpegurl"
	case "ts":
		return "video/mp2t"
	// 文档格式
	case "pdf":
		return "application/pdf"
	case "doc":
		return "application/msword"
	case "docx":
		return "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
	case "xls":
		return "application/vnd.ms-excel"
	case "xlsx":
		return "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
	case "ppt":
		return "application/vnd.ms-powerpoint"
	case "pptx":
		return "application/vnd.openxmlformats-officedocument.presentationml.presentation"
	case "txt":
		return "text/plain"
	case "html", "htm":
		return "text/html"
	case "css":
		return "text/css"
	case "js":
		return "application/javascript"
	case "json":
		return "application/json"
	case "xml":
		return "application/xml"
	case "zip":
		return "application/zip"
	case "rar":
		return "application/x-rar-compressed"
	case "7z":
		return "application/x-7z-compressed"
	case "gz":
		return "application/gzip"
	default:
		return ""
	}
}

// detectContentType 从文件内容检测 MIME 类型
func detectContentType(filePath string) string {
	f, err := os.Open(filePath)
	if err != nil {
		return ""
	}
	defer f.Close()

	// 读取前 512 字节用于检测
	buf := make([]byte, 512)
	n, err := f.Read(buf)
	if err != nil && err != io.EOF {
		return ""
	}

	return http.DetectContentType(buf[:n])
}

func Download(url, path string) error {
	f, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	stat, err := f.Stat()
	if err != nil {
		return err
	}
	defer f.Close()

	req, _ := http.NewRequest("GET", url, nil)
	req.Header.Set("Range", "bytes="+strconv.FormatInt(stat.Size(), 10)+"-")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	_, err = io.Copy(f, resp.Body)
	if err != nil {
		return err
	}

	return nil
}