// Copyright 2019 Drone IO, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cache

import (
	"context"
	"fmt"

	"github.com/drone/drone/core"

	"github.com/hashicorp/golang-lru"
)

// content key pattern used in the cache, comprised of the
// repository slug, commit and path.
const contentKey = "%s/%s/%s"

// Contents returns a new FileService that is wrapped
// with an in-memory cache.
func Contents(base core.FileService) core.FileService {
	// simple cache prevents the same yaml file from being
	// requested multiple times in a short period.
	cache, _ := lru.New(25)
	return &service{
		service: base,
		cache:   cache,
	}
}

type service struct {
	cache   *lru.Cache
	service core.FileService
	user    *core.User
}

func (s *service) Find(ctx context.Context, user *core.User, repo, commit, ref, path string) (*core.File, error) {
	key := fmt.Sprintf(contentKey, repo, commit, path)
	cached, ok := s.cache.Get(key)
	if ok {
		return cached.(*core.File), nil
	}
	file, err := s.service.Find(ctx, user, repo, commit, ref, path)
	if err != nil {
		return nil, err
	}
	s.cache.Add(key, file)
	return file, nil
}