//
//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

package util

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

const (
	FileTypePDF    = "pdf"
	FileTypeDOC    = "doc"
	FileTypeVISUAL = "visual"
	FileTypeAURAL  = "aural"
	FileTypeFOLDER = "folder"
	FileTypeOTHER  = "other"
)

var (
	filenameLenLimit = 255
)

func init() {
}

func normalizeFilename(filename string) (string, bool) {
	if filename == "" {
		return "", false
	}
	base := filepath.Base(filename)
	base = strings.TrimSpace(base)
	if base == "" || len(base) > filenameLenLimit {
		return "", false
	}
	return strings.ToLower(base), true
}

func FilenameType(filename string) string {
	normalized, ok := normalizeFilename(filename)
	if !ok {
		return FileTypeOTHER
	}

	if matched, _ := regexp.MatchString(`.*\.pdf$`, normalized); matched {
		return FileTypePDF
	}

	docExtensions := []string{
		"msg", "eml", "doc", "docx", "ppt", "pptx", "yml", "xml", "htm", "json", "jsonl", "ldjson",
		"csv", "txt", "ini", "xls", "xlsx", "wps", "rtf", "hlp", "pages", "numbers", "key",
		"md", "mdx", "py", "js", "java", "c", "cpp", "h", "php", "go", "ts", "sh", "cs", "kt",
		"html", "sql", "epub",
	}
	for _, ext := range docExtensions {
		if strings.HasSuffix(normalized, "."+ext) {
			return FileTypeDOC
		}
	}

	audioExtensions := []string{
		"wav", "flac", "ape", "alac", "wv", "mp3", "aac", "ogg", "vorbis", "opus",
	}
	for _, ext := range audioExtensions {
		if strings.HasSuffix(normalized, "."+ext) {
			return FileTypeAURAL
		}
	}

	visualExtensions := []string{
		"jpg", "jpeg", "png", "tif", "gif", "pcx", "tga", "exif", "fpx", "svg", "psd", "cdr",
		"pcd", "dxf", "ufo", "eps", "ai", "raw", "WMF", "webp", "avif", "apng", "icon", "ico",
		"mpg", "mpeg", "avi", "rm", "rmvb", "mov", "wmv", "asf", "dat", "asx", "wvx", "mpe",
		"mpa", "mp4", "mkv",
	}
	for _, ext := range visualExtensions {
		if strings.HasSuffix(normalized, "."+ext) {
			return FileTypeVISUAL
		}
	}

	return FileTypeOTHER
}

func SanitizeFilename(filename string) string {
	if filename == "" {
		return ""
	}
	filename = strings.TrimSpace(filename)
	if filename == "" {
		return ""
	}

	filename = strings.ReplaceAll(filename, "\\", "/")
	filename = strings.Trim(filename, "/")

	parts := strings.Split(filename, "/")
	var sanitizedParts []string
	for _, part := range parts {
		if part != "" && part != "." && part != ".." {
			sanitizedParts = append(sanitizedParts, part)
		}
	}

	unsafeRegex := regexp.MustCompile(`[^A-Za-z0-9_\-/]`)
	for i, part := range sanitizedParts {
		sanitizedParts[i] = unsafeRegex.ReplaceAllString(part, "")
	}

	result := strings.Join(sanitizedParts, "/")
	return result
}

func GetFileExtension(filename string) string {
	ext := filepath.Ext(filename)
	if len(ext) > 0 && ext[0] == '.' {
		return strings.ToLower(ext[1:])
	}
	return strings.ToLower(ext)
}