package gpaste

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
)

type FSFileStore struct {
	dir      string
	metadata map[string]*File
}

func NewFSFileStore(dir string) (*FSFileStore, error) {
	s := &FSFileStore{
		dir:      dir,
		metadata: make(map[string]*File),
	}

	err := s.readMetadata()

	return s, err
}
func (s *FSFileStore) Store(f *File) error {
	defer f.Body.Close()

	metadata := &File{
		ID:               f.ID,
		OriginalFilename: f.OriginalFilename,
		MaxViews:         f.MaxViews,
		ExpiresOn:        f.ExpiresOn,
	}

	path := filepath.Join(s.dir, f.ID)
	dst, err := os.Create(path)
	if err != nil {
		return err
	}
	defer dst.Close()

	if _, err := io.Copy(dst, f.Body); err != nil {
		return err
	}
	s.metadata[f.ID] = metadata
	if err := s.writeMetadata(); err != nil {
		delete(s.metadata, f.ID)
		return err
	}
	return nil
}

func (s *FSFileStore) Get(id string) (*File, error) {
	metadata, ok := s.metadata[id]
	if !ok {
		return nil, fmt.Errorf("no such item")
	}

	path := filepath.Join(s.dir, id)
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	metadata.Body = f
	return metadata, nil
}

func (s *FSFileStore) Delete(id string) error {
	path := filepath.Join(s.dir, id)
	if err := os.Remove(path); err != nil {
		return err
	}
	delete(s.metadata, id)
	return nil
}

func (s *FSFileStore) List() ([]string, error) {
	var results []string
	for k := range s.metadata {
		results = append(results, k)
	}
	return results, nil
}

func (s *FSFileStore) writeMetadata() error {
	path := filepath.Join(s.dir, "metadata.json")
	f, err := os.Create(path)
	if err != nil {
		return err
	}
	defer f.Close()

	encoder := json.NewEncoder(f)
	if err := encoder.Encode(s.metadata); err != nil {
		return err
	}
	return nil
}

func (s *FSFileStore) readMetadata() error {
	path := filepath.Join(s.dir, "metadata.json")
	f, err := os.Open(path)
	if err != nil {
		// TODO: Handle errors better
		return nil
	}
	defer f.Close()

	decoder := json.NewDecoder(f)
	if err := decoder.Decode(&s.metadata); err != nil {
		return err
	}
	return nil
}