package util

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

var (
	// AllowedMIMEPrefixes 允许的文本类 MIME 类型前缀
	AllowedMIMEPrefixes = []string{
		"text/",
		"application/json",
		"application/xml",
		"application/javascript",
		"application/x-yaml",
		"application/yaml",
		"application/toml",
		"application/x-httpd-php",
		"application/x-sh",
		"application/x-python",
		"application/x-perl",
		"application/x-ruby",
	}

	// BannedExtensions 禁止的文件扩展名
	BannedExtensions = map[string]bool{
		".png": true, ".jpg": true, ".jpeg": true, ".gif": true, ".bmp": true,
		".webp": true, ".svg": true, ".ico": true, ".tiff": true, ".tif": true,
		".mp3": true, ".wav": true, ".ogg": true, ".flac": true, ".aac": true,
		".wma": true, ".m4a": true,
		".mp4": true, ".avi": true, ".mkv": true, ".mov": true, ".wmv": true,
		".flv": true, ".webm": true,
		".tar": true, ".gz": true, ".rar": true, ".7z": true,
		".exe": true, ".dll": true, ".so": true, ".bin": true, ".dat": true,
		".class": true, ".pyc": true,
		".pdf": true, ".doc": true, ".docx": true, ".xls": true, ".xlsx": true,
		".ppt": true, ".pptx": true,
	}

	symbolCleaner = regexp.MustCompile(`[\x00-\x08\x0B\x0C\x0E-\x1F]`)
	multiNewlines = regexp.MustCompile(`\n{3,}`)
)

// SanitizeURL 清洗 URL 字符串
func SanitizeURL(raw string) string {
	s := strings.TrimSpace(raw)
	s = strings.Trim(s, "`\"")
	return s
}

// CleanSymbols 清洗文本中的控制字符和多余空行
func CleanSymbols(text string) string {
	text = symbolCleaner.ReplaceAllString(text, "")
	text = strings.ReplaceAll(text, "\r\n", "\n")
	text = strings.ReplaceAll(text, "\r", "\n")
	text = multiNewlines.ReplaceAllString(text, "\n\n")
	return strings.TrimSpace(text)
}

// IsBannedExtension 判断是否为禁止的文件扩展名
func IsBannedExtension(url string) bool {
	ext := extractExtension(url)
	return BannedExtensions[ext]
}

// IsZipExtension 判断是否为 zip 文件
func IsZipExtension(url string) bool {
	ext := extractExtension(url)
	return ext == ".zip"
}

// IsReadableContentType 判断是否为可读的文本类型
func IsReadableContentType(contentType string) bool {
	if contentType == "" {
		return false
	}

	ct := strings.ToLower(contentType)
	for _, prefix := range AllowedMIMEPrefixes {
		if strings.HasPrefix(ct, prefix) {
			return true
		}
	}

	return false
}

// extractExtension 提取文件扩展名并清理查询参数
func extractExtension(url string) string {
	ext := strings.ToLower(filepath.Ext(url))
	if idx := strings.Index(ext, "?"); idx != -1 {
		ext = ext[:idx]
	}
	return ext
}