package utils

import (
	"path/filepath"
	"strings"
)

// GetExtension 获取文件扩展名(不含点号, 全小写)
// 例如: "photo.JPG" -> "jpg"
func GetExtension(filename string) string {
	ext := filepath.Ext(filename)
	if ext == "" {
		return ""
	}
	return strings.ToLower(ext[1:]) // 去掉开头的点号
}

// GetMimeType 根据文件扩展名获取MIME类型
// 简单映射, 覆盖常见文件类型
func GetMimeType(extension string) string {
	mimeMap := map[string]string{
		// 图片
		"jpg":  "image/jpeg",
		"jpeg": "image/jpeg",
		"png":  "image/png",
		"gif":  "image/gif",
		"bmp":  "image/bmp",
		"webp": "image/webp",
		"svg":  "image/svg+xml",
		"ico":  "image/x-icon",

		// 文档
		"pdf":  "application/pdf",
		"doc":  "application/msword",
		"docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
		"xls":  "application/vnd.ms-excel",
		"xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
		"ppt":  "application/vnd.ms-powerpoint",
		"pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",

		// 文本
		"txt":  "text/plain",
		"html": "text/html",
		"htm":  "text/html",
		"css":  "text/css",
		"js":   "application/javascript",
		"json": "application/json",
		"xml":  "application/xml",
		"csv":  "text/csv",
		"md":   "text/markdown",

		// 压缩包
		"zip": "application/zip",
		"rar": "application/x-rar-compressed",
		"7z":  "application/x-7z-compressed",
		"tar": "application/x-tar",
		"gz":  "application/gzip",

		// 音视频
		"mp3":  "audio/mpeg",
		"wav":  "audio/wav",
		"mp4":  "video/mp4",
		"avi":  "video/x-msvideo",
		"mov":  "video/quicktime",
		"wmv":  "video/x-ms-wmv",
		"flv":  "video/x-flv",
		"mkv":  "video/x-matroska",
	}

	if mime, ok := mimeMap[extension]; ok {
		return mime
	}
	return "application/octet-stream"
}

// IsImageFile 判断是否为图片文件
func IsImageFile(extension string) bool {
	imageExts := []string{"jpg", "jpeg", "png", "gif", "bmp", "webp", "svg", "ico"}
	for _, ext := range imageExts {
		if extension == ext {
			return true
		}
	}
	return false
}

// IsVideoFile 判断是否为视频文件
func IsVideoFile(extension string) bool {
	videoExts := []string{"mp4", "avi", "mov", "wmv", "flv", "mkv"}
	for _, ext := range videoExts {
		if extension == ext {
			return true
		}
	}
	return false
}

// IsDocumentFile 判断是否为文档文件
func IsDocumentFile(extension string) bool {
	docExts := []string{"pdf", "doc", "docx", "xls", "xlsx", "ppt", "pptx", "txt", "md", "csv"}
	for _, ext := range docExts {
		if extension == ext {
			return true
		}
	}
	return false
}