package main

import (
	"camli/blobref"
	"fmt"
	"regexp"
	"os"
)

type diskStorage struct {
	Root string
}

func (ds *diskStorage) Fetch(blob blobref.BlobRef) (blobref.ReadSeekCloser, int64, os.Error) {
	fileName := BlobFileName(blob)
	stat, err := os.Stat(fileName)
	if err == os.ENOENT {
		return nil, 0, err
	}
	file, err := os.Open(fileName, os.O_RDONLY, 0)
	if err != nil {
		return nil, 0, err
	}
	return file, stat.Size, nil
}

func newDiskStorage(root string) *diskStorage {
	return &diskStorage{Root: root}
}

var kGetPutPattern *regexp.Regexp = regexp.MustCompile(`^/camli/([a-z0-9]+)-([a-f0-9]+)$`)

func BlobFileBaseName(b blobref.BlobRef) string {
	return fmt.Sprintf("%s-%s.dat", b.HashName(), b.Digest())
}

func BlobDirectoryName(b blobref.BlobRef) string {
	d := b.Digest()
	return fmt.Sprintf("%s/%s/%s/%s", *flagStorageRoot, b.HashName(), d[0:3], d[3:6])
}

func BlobFileName(b blobref.BlobRef) string {
	return fmt.Sprintf("%s/%s-%s.dat", BlobDirectoryName(b), b.HashName(), b.Digest())
}

func BlobFromUrlPath(path string) blobref.BlobRef {
	return blobref.FromPattern(kGetPutPattern, path)
}