package mimetype

import (
	"mime"
	"path/filepath"
	"strings"
)

var extraMIMETypes = map[string]string{
	// --- Text ---
	".txt":   "text/plain; charset=utf-8",
	".log":   "text/plain; charset=utf-8",
	".md":    "text/markdown; charset=utf-8",
	".csv":   "text/csv; charset=utf-8",
	".tsv":   "text/tab-separated-values",
	".css":   "text/css",
	".htm":   "text/html",
	".html":  "text/html",
	".shtml": "text/html",
	".xml":   "application/xml",
	".yaml":  "application/x-yaml",
	".yml":   "application/x-yaml",

	// --- JavaScript / JSON ---
	".js":     "application/javascript",
	".mjs":    "application/javascript",
	".json":   "application/json",
	".jsonld": "application/ld+json",

	// --- Images ---
	".jpg":  "image/jpeg",
	".jpeg": "image/jpeg",
	".png":  "image/png",
	".gif":  "image/gif",
	".svg":  "image/svg+xml",
	".webp": "image/webp",
	".bmp":  "image/bmp",
	".ico":  "image/x-icon",
	".tif":  "image/tiff",
	".tiff": "image/tiff",
	".avif": "image/avif",
	".heif": "image/heif",
	".heic": "image/heic",

	// --- Audio ---
	".mp3":  "audio/mpeg",
	".wav":  "audio/wav",
	".aac":  "audio/aac",
	".flac": "audio/flac",
	".ogg":  "audio/ogg",
	".oga":  "audio/ogg",
	".m4a":  "audio/mp4",
	".mid":  "audio/midi",
	".midi": "audio/midi",

	// --- Video ---
	".mp4":  "video/mp4",
	".mov":  "video/quicktime",
	".avi":  "video/x-msvideo",
	".wmv":  "video/x-ms-wmv",
	".flv":  "video/x-flv",
	".mkv":  "video/x-matroska",
	".webm": "video/webm",
	".mpeg": "video/mpeg",
	".mpg":  "video/mpeg",

	// --- Archives ---
	".zip": "application/zip",
	".rar": "application/vnd.rar",
	".tar": "application/x-tar",
	".gz":  "application/gzip",
	".tgz": "application/gzip",
	".bz":  "application/x-bzip",
	".bz2": "application/x-bzip2",
	".7z":  "application/x-7z-compressed",

	// --- Documents ---
	".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",

	// --- Code / Config / Dev ---
	".go":   "text/plain",
	".py":   "text/x-python",
	".java": "text/x-java-source",
	".c":    "text/x-c",
	".cpp":  "text/x-c++",
	".h":    "text/x-c",
	".hpp":  "text/x-c++",
	".rs":   "text/plain",
	".php":  "text/x-php",
	".sql":  "application/sql",
	".env":  "text/plain",
	".ini":  "text/plain",

	// --- Fonts ---
	".woff":  "font/woff",
	".woff2": "font/woff2",
	".ttf":   "font/ttf",
	".otf":   "font/otf",
	".eot":   "application/vnd.ms-fontobject",

	// --- Vector / CAD ---
	".psd": "image/vnd.adobe.photoshop",
	".ai":  "application/postscript",
	".eps": "application/postscript",

	// --- Binary / Program ---
	".exe": "application/vnd.microsoft.portable-executable",
	".bin": "application/octet-stream",
	".dll": "application/x-msdownload",
	".apk": "application/vnd.android.package-archive",
	".dmg": "application/x-apple-diskimage",
	".iso": "application/x-iso9660-image",

	// --- Misc ---
	".rtf":  "application/rtf",
	".wasm": "application/wasm",
	".swf":  "application/x-shockwave-flash",
	".map":  "application/json",
}

// GetContentType 根据文件名/扩展名获取 Content-Type
func GetContentType(filename string) string {
	ext := strings.ToLower(filepath.Ext(filename))
	if ext == "" {
		return "application/octet-stream"
	}

	// 1. 标准库优先
	if ct := mime.TypeByExtension(ext); ct != "" {
		return ct
	}

	// 2. 补充表
	if ct, ok := extraMIMETypes[ext]; ok {
		return ct
	}

	// 3. 默认值
	return "application/octet-stream"
}