// Licensed to the LF AI & Data foundation 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 config

import "time"

const (
	HighPriority   = 1
	NormalPriority = HighPriority + 10
	LowPriority    = NormalPriority + 10
)

type ConfigManager interface {
	EvictCacheValueByFormat(keys ...string)
}

type Source interface {
	GetConfigurations() (map[string]string, error)
	GetConfigurationByKey(string) (string, error)
	GetPriority() int
	GetSourceName() string
	SetEventHandler(eh EventHandler)
	SetManager(m ConfigManager)
	UpdateOptions(opt Options)
	Close()
}

// EtcdInfo has attribute for config center source initialization
type EtcdInfo struct {
	UseEmbed   bool
	EnableAuth bool
	UserName   string
	PassWord   string
	UseSSL     bool
	Endpoints  []string
	KeyPrefix  string
	CertFile   string
	KeyFile    string
	CaCertFile string
	MinVersion string

	// DialTimeout for establishing the initial connection to etcd, read from the
	// local file/env config source (which is already loaded before the etcd
	// source is created). A non-positive value keeps the etcd client default.
	DialTimeout time.Duration

	// Pull Configuration interval, unit is second
	RefreshInterval time.Duration
}

// FileInfo has attribute for file source
type FileInfo struct {
	Files           []string
	RefreshInterval time.Duration
}

// Options hold options
type Options struct {
	FileInfo        *FileInfo
	EtcdInfo        *EtcdInfo
	EnvKeyFormatter func(string) string
}

// Option is a func
type Option func(options *Options)

// WithRequiredFiles tell archaius to manage files, if not exist will return error
func WithFilesSource(fi *FileInfo) Option {
	return func(options *Options) {
		options.FileInfo = fi
	}
}

// WithEtcdSource accept the information for initiating a remote source
func WithEtcdSource(ri *EtcdInfo) Option {
	return func(options *Options) {
		options.EtcdInfo = ri
	}
}

// WithEnvSource enable env source
// archaius will read ENV as key value
func WithEnvSource(keyFormatter func(string) string) Option {
	return func(options *Options) {
		options.EnvKeyFormatter = keyFormatter
	}
}

// EventHandler handles config change event
type EventHandler interface {
	OnEvent(event *Event)
	GetIdentifier() string
}

type simpleHandler struct {
	identity string
	onEvent  func(*Event)
}

func (s *simpleHandler) GetIdentifier() string {
	return s.identity
}

// OnEvent implements EventHandler
func (s *simpleHandler) OnEvent(event *Event) {
	s.onEvent(event)
}

func NewHandler(ident string, onEvent func(*Event)) EventHandler {
	return &simpleHandler{ident, onEvent}
}
