package sync

import (
	"bufio"
	"bytes"
	"encoding/base32"
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"strings"

	"srs.epita.fr/fic-server/libfic"

	"github.com/dchest/blake2b"
)

type Importer interface {
	Kind() string
	exists(filename string) bool
	toURL(filename string) string
	getFile(filename string, writer *bufio.Writer) error
	listDir(filename string) ([]string, error)
}

var GlobalImporter Importer

func getFile(i Importer, URI string, writer *bufio.Writer) error {
	// Import file if it exists
	if i.exists(URI) {
		return i.getFile(URI, writer)
	}

	// Try to find file parts
	dirname := path.Dir(URI)
	if i.exists(dirname) {
		filename := path.Base(URI)
		if files, err := i.listDir(dirname); err != nil {
			return err
		} else {
			for _, fname := range []string{filename, filename + "."} {
				found := false
				for _, file := range files {
					if matched, _ := path.Match(fname + "[0-9][0-9]", file); matched {
						found = true
						if err := i.getFile(path.Join(dirname, file), writer); err != nil {
							return err
						}
					}
				}

				if found {
					return nil
				}
			}
		}
	}

	return errors.New(fmt.Sprintf("%q: no such file or directory", i.toURL(URI)))
}

func getFileContent(i Importer, URI string) (string, error) {
	cnt := bytes.Buffer{}

	if err := getFile(i, URI, bufio.NewWriter(io.Writer(&cnt))); err != nil {
		return "", err
	} else {
		return strings.TrimSpace(cnt.String()), nil
	}
}

func ImportFile(URI string, next func(string, string) (interface{}, error)) (interface{}, error) {
	hash := blake2b.Sum512([]byte(URI))
	dest := path.Join(fic.FilesDir, strings.ToLower(base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(hash[:])), path.Base(URI))

	// If the present file is still valide, don't erase it
	if _, err := os.Stat(dest); !os.IsNotExist(err) {
		if r, err := next(dest, URI); err == nil {
			return r, err
		}

		if err := os.Remove(dest); err != nil {
			return nil, err
		}
	}

	// Ensure no more file is registered with this path
	if f, err := fic.GetFileByPath(dest); err == nil {
		f.Delete()
	}

	if err := os.MkdirAll(path.Dir(dest), 0755); err != nil {
		return nil, err
	}

	// Write file
	if fdto, err := os.Create(dest); err != nil {
		return nil, err
	} else {
		defer fdto.Close()
		writer := bufio.NewWriter(fdto)
		if err := getFile(GlobalImporter, URI, writer); err != nil {
			os.Remove(dest)
			return nil, err
		}
	}

	return next(dest, URI)
}