package adapters

import (
	"errors"
	"mime"
	"os"
	"path/filepath"
	"strings"
	"time"
)

func SafeRel(root, requested string) (string, error) {
	s := requested
	if after, ok := strings.CutPrefix(s, "/"); ok {
		s = after
	}
	full := filepath.Join(root, filepath.FromSlash(s))
	rel, err := filepath.Rel(root, full)
	if err != nil {
		return "", err
	}
	if rel == "." {
		return "/", nil
	}
	sep := string(filepath.Separator)
	if strings.HasPrefix(rel, "..") || strings.Contains(rel, ".."+sep) {
		return "", errors.New("path escapes root")
	}
	return "/" + filepath.ToSlash(rel), nil
}

func ResponsePath(root, full string) string {
	rel, err := filepath.Rel(root, full)
	if err != nil || rel == "." {
		return "/"
	}
	return "/" + filepath.ToSlash(rel)
}

func sizeOrZero(fi os.FileInfo) int64 {
	if fi == nil {
		return 0
	}
	return fi.Size()
}

func modTimeOrZero(fi os.FileInfo) time.Time {
	if fi == nil {
		return time.Time{}
	}
	return fi.ModTime()
}

var textPlainExtensions = map[string]bool{
	".txt":  true,
	".log":  true,
	".json": true,
	".yaml": true,
	".yml":  true,
	".toml": true,
	".xml":  true,
	".csv":  true,
}

func contentTypeFor(name string) string {
	ext := strings.ToLower(filepath.Ext(name))
	switch ext {
	case ".md", ".markdown", ".mdown":
		return "application/markdown"
	}
	if ct := mime.TypeByExtension(ext); ct != "" {
		return ct
	}
	if textPlainExtensions[ext] {
		return "text/plain; charset=utf-8"
	}
	return "application/octet-stream"
}