package loader

import (
	"encoding/json"
	"encoding/xml"
	"gitee.com/h79/goutils/common/bus"
	"gitee.com/h79/goutils/common/coder"
	cJSON "gitee.com/h79/goutils/common/json"
	"gitee.com/h79/goutils/common/system"
	cXML "gitee.com/h79/goutils/common/xml"
	cYAML "gitee.com/h79/goutils/common/yaml"
	"gopkg.in/yaml.v3"
	"sync"
	"sync/atomic"
	"time"
)

type LoadFunc func() (interface{}, error)

type Loader struct {
	stop         chan bool
	update       chan bool
	reading      bool
	watch        int32
	upChan       chan bool
	second       time.Duration
	format       string //xml,json,yaml
	topic        string
	cmd          string
	data         interface{}
	rm           sync.RWMutex
	loadFunc     LoadFunc
	unmarshal    coder.Unmarshal //默认json
	publisher    bus.Publisher
	watchRunning system.RunningCheck
}

const (
	defCmd   = "load"
	defTopic = "load.data"
)

func CreateLoader() Loader {
	return Loader{
		cmd:       defCmd,
		topic:     defTopic,
		format:    "json",
		watch:     0,
		update:    make(chan bool),
		stop:      make(chan bool),
		second:    time.Second * 5,
		reading:   false,
		data:      nil,
		loadFunc:  nil,
		publisher: nil,
		unmarshal: cJSON.DefaultCoder,
	}
}

func New() *Loader {
	l := CreateLoader()
	return &l
}

// Deprecated: this function simply calls [Data].
func (load *Loader) Get() interface{} {
	return load.Data()
}

func (load *Loader) Data() interface{} {
	load.rm.RLock()
	defer load.rm.RUnlock()
	return load.data
}

func (load *Loader) JSON() (string, error) {
	load.rm.RLock()
	defer load.rm.RUnlock()
	buf, err := json.Marshal(load.data)
	if err != nil {
		return "", err
	}
	return string(buf), nil
}

func (load *Loader) XML() (string, error) {
	load.rm.RLock()
	defer load.rm.RUnlock()
	buf, err := xml.Marshal(load.data)
	if err != nil {
		return "", err
	}
	return string(buf), nil
}

func (load *Loader) YAML() (string, error) {
	load.rm.RLock()
	defer load.rm.RUnlock()
	buf, err := yaml.Marshal(load.data)
	if err != nil {
		return "", err
	}
	return string(buf), nil
}

func (load *Loader) WithFormat(format string) *Loader {
	load.format = format
	if format == JsonFormat {
		load.unmarshal = cJSON.DefaultCoder
	} else if format == XmlFormat {
		load.unmarshal = cXML.DefaultCoder
	} else if format == YamlFormat {
		load.unmarshal = cYAML.DefaultCoder
	} else {
		load.unmarshal = coder.UnmarshalFunc(func(content []byte, v interface{}) error {
			return ErrNotDefined
		})
	}
	return load
}

func (load *Loader) WithCmd(cmd string) *Loader {
	load.cmd = cmd
	return load
}

func (load *Loader) WithTopic(topic string) *Loader {
	load.topic = topic
	return load
}

func (load *Loader) WithSecond(second time.Duration) *Loader {
	load.second = second
	return load
}

func (load *Loader) WithLoadFunc(l LoadFunc) *Loader {
	load.loadFunc = l
	return load
}

func (load *Loader) WithUnmarshal(l coder.Unmarshal) *Loader {
	load.unmarshal = l
	return load
}

func (load *Loader) WithPublisher(p bus.Publisher) *Loader {
	load.publisher = p
	return load
}

func (load *Loader) Update(async bool) {
	if async {
		if atomic.LoadInt32(&load.watch) > 0 {
			load.watchRunning.GoRunning(load.watchLoad)
			load.update <- true
		} else {
			system.ChildRunning(load.read)
		}
	} else {
		load.read()
	}
}

func (load *Loader) Reset() {
	load.reading = false
}

func (load *Loader) Watch() {
	if atomic.LoadInt32(&load.watch) == 0 {
		atomic.StoreInt32(&load.watch, 1)
		load.watchRunning.GoRunning(load.watchLoad)
	}
}

func (load *Loader) WatchChan() <-chan bool {
	if atomic.LoadInt32(&load.watch) == 0 {
		atomic.StoreInt32(&load.watch, 2)
		load.upChan = make(chan bool)
	} else if atomic.LoadInt32(&load.watch) == 1 {
		atomic.StoreInt32(&load.watch, 2)
		load.upChan = make(chan bool)
	}
	load.watchRunning.GoRunning(load.watchLoad)

	return load.upChan
}

func (load *Loader) Stop() {
	if atomic.LoadInt32(&load.watch) == 2 {
		close(load.upChan)
	}
	atomic.StoreInt32(&load.watch, 0)
	close(load.stop)
}

func (load *Loader) Read() (error, bool) {
	if load.loadFunc == nil {
		return nil, false
	}
	if load.reading {
		return nil, false
	}
	load.reading = true
	data, err := load.loadFunc()
	load.reading = false
	if err != nil {
		return err, false
	}
	load.rm.Lock()
	load.data = data
	load.rm.Unlock()
	return nil, true
}

func (load *Loader) watchLoad() {
	defer atomic.StoreInt32(&load.watch, 0)
	ticker := time.NewTicker(load.second)
	for {
		select {
		case _ = <-load.stop:
			return
		case _ = <-load.update:
			if load.readV2() && atomic.LoadInt32(&load.watch) == 2 {
				load.upChan <- true
			}
		case _ = <-ticker.C:
			if load.readV2() && atomic.LoadInt32(&load.watch) == 2 {
				load.upChan <- true
			}
		case <-system.Closed():
			return
		}
	}
}

func (load *Loader) readV2() bool {
	// 打开文件
	// 为什么使用匿名函数？ 当匿名函数退出时可用defer去关闭文件
	// 如果不用匿名函数，在循环中不好关闭文件，一不小心就内存泄露
	err, fUpdate := load.Read()
	if err != nil {
		return false
	}
	if !fUpdate {
		return false
	}
	load.publish()
	return true
}

func (load *Loader) read() {
	load.readV2()
}

func (load *Loader) publish() {
	if load.publisher == nil {
		return
	}
	topic := load.topic
	if len(topic) == 0 {
		topic = defTopic
	}
	cmd := load.cmd
	if len(cmd) == 0 {
		cmd = defCmd
	}
	load.publisher.Publish(topic, bus.Event{Cmd: cmd, Data: load.data})
}