/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 aggregate

import (
	"github.com/apache/servicecomb-service-center/datasource/etcd/state/kvstore"
	"github.com/apache/servicecomb-service-center/pkg/util"
)

// Cache implements kvstore.CacheReader.
// Cache is a multi-CacheReader, it reads cache from all CacheReaders.
type Cache []kvstore.CacheReader

func (c Cache) Name() string {
	if len(c) == 0 {
		return ""
	}
	return c[0].Name()
}

func (c Cache) Size() (s int) {
	for _, cache := range c {
		s += cache.Size()
	}
	return s
}
func (c Cache) Get(k string) (kv *kvstore.KeyValue) {
	for _, cache := range c {
		if kv = cache.Get(k); kv != nil {
			return
		}
	}
	return
}
func (c Cache) GetAll(arr *[]*kvstore.KeyValue) (s int) {
	exists := make(map[string]struct{})
	for _, item := range c {
		var tmp []*kvstore.KeyValue
		if l := item.GetAll(&tmp); l == 0 {
			continue
		}
		s += c.append(tmp, arr, exists)
	}
	return
}
func (c Cache) GetPrefix(prefix string, arr *[]*kvstore.KeyValue) (s int) {
	exists := make(map[string]struct{})
	for _, item := range c {
		var tmp []*kvstore.KeyValue
		if l := item.GetPrefix(prefix, &tmp); l == 0 {
			continue
		}
		s += c.append(tmp, arr, exists)
	}
	return
}

func (c Cache) append(tmp []*kvstore.KeyValue, arr *[]*kvstore.KeyValue,
	exists map[string]struct{}) (s int) {
	for _, kv := range tmp {
		key := util.BytesToStringWithNoCopy(kv.Key)
		if _, ok := exists[key]; ok {
			continue
		}
		exists[key] = struct{}{}
		if arr != nil {
			*arr = append(*arr, kv)
		}
		s++
	}
	return
}

func (c Cache) ForEach(iter func(k string, v *kvstore.KeyValue) (next bool)) {
	exists := make(map[string]struct{})
	for _, item := range c {
		item.ForEach(func(k string, v *kvstore.KeyValue) bool {
			if _, ok := exists[k]; ok {
				return true
			}
			exists[k] = struct{}{}
			return iter(k, v)
		})
	}
}