package tal

import (
	"bufio"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strings"
)

var metaRegex = regexp.MustCompile(`^#([a-zA-Z]+) (.*)$`)

type Repo struct {
	URL    string
	Path   string
	Update bool
	Books  []Book
}

func (lr *Repo) GetMeta() map[string]map[string][]Book {
	meta := map[string]map[string][]Book{}
	for _, book := range lr.Books {
		if book.Meta["DELETED"] != "" {
			continue
		}
		for key, value := range book.Meta {
			if meta[key] == nil {
				meta[key] = map[string][]Book{}
			}
			meta[key][value] = append(meta[key][value], book)
		}
	}
	return meta
}

func (lr *Repo) Scan() error {
	books := lr.scanTree(lr.Path, 1, 3, ".muse")

	if len(books) == 0 {
		return errors.New(fmt.Sprintf("No library found at %s", lr.Path))
	}

	for _, p := range books {
		meta, err := readMeta(p)
		if err != nil {
			continue
		}

		lr.Books = append(lr.Books, Book{
			Path: p,
			Base: strings.TrimSuffix(path.Base(p), ".muse"),
			Meta: meta,
		})
	}

	return nil
}

func (lr *Repo) scanTree(p string, dirlen uint8, max uint8, suffix string) []string {
	var paths []string

	files, err := ioutil.ReadDir(p)
	if err != nil {
		return paths
	}

	for _, entry := range files {
		name := entry.Name()
		subdir := filepath.Join(p, name)

		if dirlen == max {
			if strings.HasSuffix(name, suffix) {
				paths = append(paths, subdir)
			}
		} else {
			if !entry.IsDir() || len(name) != int(dirlen) {
				continue
			}
			paths = append(paths, lr.scanTree(subdir, dirlen+1, max, suffix)...)
		}
	}

	return paths
}

func readMeta(p string) (map[string]string, error) {
	meta := map[string]string{}

	f, err := os.Open(p)
	if err != nil {
		return nil, err
	}

	scanner := bufio.NewScanner(f)

	for scanner.Scan() {
		line := scanner.Text()

		if len(line) > 0 && line[0] == '#' {
			result := metaRegex.FindStringSubmatch(line)

			if len(result) > 0 {
				tag := strings.TrimSpace(result[1])
				value := strings.TrimSpace(result[2])
				meta[tag] = value
			}
		} else {
			break
		}
	}

	f.Close()

	return meta, nil
}