package weixin

import (
	"context"
	"fmt"
	"github.com/wechatpay-apiv3/wechatpay-go/core"
	"github.com/wechatpay-apiv3/wechatpay-go/core/auth"
	"github.com/wechatpay-apiv3/wechatpay-go/core/auth/verifiers"
	"github.com/wechatpay-apiv3/wechatpay-go/core/option"
	"github.com/wechatpay-apiv3/wechatpay-go/utils"
	"sync"
)

type Server struct {
	MchID                      string `json:"mch_id"`
	MchCertificateSerialNumber string `json:"mch_certificate_serial_number"`
	MchAPIv3Key                string `json:"mch_ap_iv_3_key"`
	PrivateKey                 string `json:"private_key"`
	PrivateKeyPath             string `json:"private_key_path"`
}

type manager struct {
	once    sync.Once
	mutex   sync.RWMutex
	clients map[string]*core.Client
}

var instance manager

func init() {
	instance = manager{
		clients: make(map[string]*core.Client),
	}
}

func client(ctx context.Context, c *Server) (*core.Client, error) {
	mchPrivateKey, err := utils.LoadPrivateKey(c.PrivateKey)
	if err != nil {
		return nil, fmt.Errorf("MchID[%s] load merchant private key error:%v", c.MchID, err)
	}
	opts := []core.ClientOption{
		option.WithWechatPayAutoAuthCipher(c.MchID, c.MchCertificateSerialNumber, mchPrivateKey, c.MchAPIv3Key),
	}
	cl, err := core.NewClient(ctx, opts...)
	if err != nil {
		return nil, fmt.Errorf("MchID[%s]  new wechat pay client err:%v", c.MchID, err)
	}
	return cl, nil
}

func New(ctx context.Context, c *Server) (*core.Client, error) {
	instance.mutex.Lock()
	defer instance.mutex.Unlock()
	if instance.clients[c.MchID] != nil {
		return instance.clients[c.MchID], nil
	}
	var err error
	instance.once.Do(func() {
		instance.clients[c.MchID], err = client(ctx, c)
	})
	if err != nil {
		return nil, err
	}
	return instance.clients[c.MchID], nil
}

func (s *Server) Verify(ctx context.Context, message, signature string) error {
	var verifier auth.Verifier
	verifier = verifiers.NewSHA256WithRSAVerifier(nil)
	return verifier.Verify(ctx, s.MchCertificateSerialNumber, message, signature)
}