package srvdata

import (
	"crypto/md5"
	"encoding/hex"
	"errors"
	"os"
	"strings"
)

var fileSignMap = make(map[string]string)

type DataLoader interface {
	Load(fileFullPath string) error
	Reload(fileFullPath string) error
}

type DataHolder interface {
	unmarshal([]byte) error
	reunmarshal([]byte) error
}

type JsonDataLoader struct {
	dh DataHolder
}

func (this *JsonDataLoader) Load(fileFullPath string) error {
	buf, err := os.ReadFile(fileFullPath)
	if err != nil {
		return err
	}

	h := md5.New()
	_, err = h.Write(buf)
	if err != nil {
		return err
	}
	fileSign := hex.EncodeToString(h.Sum(nil))
	fileSignMap[fileFullPath] = fileSign

	if this.dh != nil {
		err = this.dh.unmarshal(buf)
	}

	return err
}

func (this *JsonDataLoader) Reload(fileFullPath string) error {
	buf, err := os.ReadFile(fileFullPath)
	if err != nil {
		return err
	}

	h := md5.New()
	_, err = h.Write(buf)
	if err != nil {
		return err
	}
	fileSign := hex.EncodeToString(h.Sum(nil))
	if preSign, exist := fileSignMap[fileFullPath]; exist {
		if preSign == fileSign {
			return nil
		}
	}
	fileSignMap[fileFullPath] = fileSign

	if this.dh != nil {
		err = this.dh.reunmarshal(buf)
	}

	return err
}

type ProtobufDataLoader struct {
	dh DataHolder
}

func (this *ProtobufDataLoader) Load(fileFullPath string) error {
	buf, err := os.ReadFile(fileFullPath)
	if err != nil {
		return err
	}

	h := md5.New()
	_, err = h.Write(buf)
	if err != nil {
		return err
	}
	fileSign := hex.EncodeToString(h.Sum(nil))
	fileSignMap[fileFullPath] = fileSign

	if this.dh != nil {
		err = this.dh.unmarshal(buf)
	}

	return err
}

func (this *ProtobufDataLoader) Reload(fileFullPath string) error {
	buf, err := os.ReadFile(fileFullPath)
	if err != nil {
		return err
	}

	h := md5.New()
	_, err = h.Write(buf)
	if err != nil {
		return err
	}
	fileSign := hex.EncodeToString(h.Sum(nil))
	if preSign, exist := fileSignMap[fileFullPath]; exist {
		if preSign == fileSign {
			return errors.New("content no modify")
		}
	}
	fileSignMap[fileFullPath] = fileSign

	if this.dh != nil {
		err = this.dh.reunmarshal(buf)
	}

	return err
}

var DataMgr = &dataMgr{
	loaders:      make(map[string]DataLoader),
	afterLoaders: make(map[string][]DataLoader),
}

type dataMgr struct {
	loaders      map[string]DataLoader
	afterLoaders map[string][]DataLoader
}

// register 注册数据加载器,这个应该只是自动生产的代码中会用到,其它地方用不到
func (this *dataMgr) register(name string, loader DataLoader) {
	this.loaders[strings.ToLower(name)] = loader
}

// RegisterLoader 注册数据加载器,如果需要依赖配置表再生成新结构的数据用这个
// loader的方法调用会在配置表加载之后调用
func (this *dataMgr) RegisterLoader(name string, loader DataLoader) {
	this.afterLoaders[strings.ToLower(name)] = append(this.afterLoaders[strings.ToLower(name)], loader)
}

func (this *dataMgr) GetLoader(name string) []DataLoader {
	var ret []DataLoader
	if loader, exist := this.loaders[strings.ToLower(name)]; exist {
		ret = append(ret, loader)
	}
	if loader, exist := this.afterLoaders[strings.ToLower(name)]; exist {
		ret = append(ret, loader...)
	}
	return ret
}