package fs

import (
	"context"
	"io/fs"
	"mime"
	"path"
	"strings"
	"text/template"

	"tildegit.org/tjp/gus"
	"tildegit.org/tjp/gus/gopher"
)

// GopherFileHandler builds a handler which serves up files from a file system.
//
// It only serves responses for paths which correspond to files, not directories.
func GopherFileHandler(fileSystem fs.FS) gus.Handler {
	return gus.HandlerFunc(func(ctx context.Context, request *gus.Request) *gus.Response {
		filepath, file, err := ResolveFile(request, fileSystem)
		if err != nil {
			return gopher.Error(err).Response()
		}

		if file == nil {
			return nil
		}

		return gopher.File(GuessGopherItemType(filepath), file)
	})
}

// GopherDirectoryDefault serves up default files for directory path requests.
//
// If any of the supported filenames are found in the requested directory, the
// contents of that file is returned as the gopher response.
//
// It returns nil for any paths which don't correspond to a directory.
//
// It requires that files from the provided fs.FS implement fs.ReadDirFile. If
// they don't, it will produce nil responses for all directory paths.
func GopherDirectoryDefault(fileSystem fs.FS, filenames ...string) gus.Handler {
	return gus.HandlerFunc(func(ctx context.Context, request *gus.Request) *gus.Response {
		dirpath, dir, err := ResolveDirectory(request, fileSystem)
		if err != nil {
			return gopher.Error(err).Response()
		}
		if dir == nil {
			return nil
		}
		defer func() { _ = dir.Close() }()

		_, file, err := ResolveDirectoryDefault(fileSystem, dirpath, dir, filenames)
		if err != nil {
			return gopher.Error(err).Response()
		}
		if file == nil {
			return nil
		}

		return gopher.File(gopher.MenuType, file)
	})
}

// GopherDirectoryListing produces a listing of the contents of any requested directories.
//
// It returns nil for any paths which don't correspond to a filesystem directory.
//
// It requires that files from the provided fs.FS implement fs.ReadDirFile. If they
// don't, it will produce nil responses for any directory paths.
//
// A template may be nil, in which case DefaultGopherDirectoryList is used instead. The
// template is then processed with RenderDirectoryListing.
func GopherDirectoryListing(fileSystem fs.FS, tpl *template.Template) gus.Handler {
	return gus.HandlerFunc(func(ctx context.Context, request *gus.Request) *gus.Response {
		dirpath, dir, err := ResolveDirectory(request, fileSystem)
		if err != nil {
			return gopher.Error(err).Response()
		}
		if dir == nil {
			return nil
		}
		defer func() { _ = dir.Close() }()

		if tpl == nil {
			tpl = DefaultGopherDirectoryList
		}
		body, err := RenderDirectoryListing(dirpath, dir, tpl, request.Server)
		if err != nil {
			return gopher.Error(err).Response()
		}

		return gopher.File(gopher.MenuType, body)
	})
}

// GopherTemplateFunctions is a map for templates providing useful functions for gophermaps.
//
// - GuessItemType: return a gopher item type for a file based on its path/name.
var GopherTemplateFunctions = template.FuncMap{
	"GuessItemType": func(filepath string) string {
		return string([]byte{byte(GuessGopherItemType(filepath))})
	},
}

// DefaultGopherDirectoryList is a template which renders a directory listing as gophermap.
var DefaultGopherDirectoryList = template.Must(
	template.New("gopher_dirlist").Funcs(GopherTemplateFunctions).Parse(
		strings.ReplaceAll(
			`
{{ $root := .FullPath -}}
{{ if eq .FullPath "." }}{{ $root = "" }}{{ end -}}
{{ $hostname := .Hostname -}}
{{ $port := .Port -}}
i{{ .DirName }}		{{ $hostname }}	{{ $port }}
i		{{ $hostname }}	{{ $port }}
{{ range .Entries -}}
{{ if .IsDir -}}
1{{ .Name }}	{{ $root }}/{{ .Name }}	{{ $hostname }}	{{ $port }}
{{- else -}}
{{ GuessItemType .Name }}{{ .Name }}	{{ $root }}/{{ .Name }}	{{ $hostname }}	{{ $port }}
{{- end }}
{{ end -}}
.
`[1:],
			"\n",
			"\r\n",
		),
	),
)

// GuessGopherItemType attempts to find the best gopher item type for a file based on its name.
func GuessGopherItemType(filepath string) gus.Status {
	ext := path.Ext(filepath)
	switch ext {
	case "txt", "gmi":
		return gopher.TextFileType
	case "gif", "png", "jpg", "jpeg":
		return gopher.ImageFileType
	case "mp4", "mov":
		return gopher.MovieFileType
	case "mp3", "aiff", "aif", "aac", "ogg", "flac", "alac", "wma":
		return gopher.SoundFileType
	case "bmp":
		return gopher.BitmapType
	case "doc", "docx", "odt":
		return gopher.DocumentType
	case "html", "htm":
		return gopher.HTMLType
	case "rtf":
		return gopher.RtfDocumentType
	case "wav":
		return gopher.WavSoundFileType
	case "pdf":
		return gopher.PdfDocumentType
	case "xml":
		return gopher.XmlDocumentType
	case "":
		return gopher.BinaryFileType
	}

	mtype := mime.TypeByExtension(ext)
	if strings.HasPrefix(mtype, "text/") {
		return gopher.TextFileType
	}

	return gopher.BinaryFileType
}