package auth

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"time"

	"lone-services/pkg/redis"
	"lone-services/pkg/utils"

	jsoniter "github.com/json-iterator/go"
)

const accessTokenURL = "https://api.weixin.qq.com/cgi-bin/token"

type AccessTokenResult struct {
	AccessToken string `json:"access_token"`
	ExpiresIn   int    `json:"expires_in"`
	ErrCode     int    `json:"errcode"`
	ErrMsg      string `json:"errmsg"`
}

func (c *Client) AccessToken(ctx context.Context) (*AccessTokenResult, error) {
	if c == nil || c.AppID == utils.StringEmpty || c.Secret == utils.StringEmpty {
		return nil, fmt.Errorf("wechat app config missing")
	}
	if ctx == nil {
		ctx = context.Background()
	}

	secretMd5 := md5.Sum([]byte(c.Secret))
	key := fmt.Sprintf("wechat:access_token:%s:%s", c.AppID, hex.EncodeToString(secretMd5[:])[:8])

	token, err := redis.Client.Get(ctx, key).Result()
	if err == nil && token != utils.StringEmpty {
		return &AccessTokenResult{AccessToken: token}, nil
	}

	body, err := utils.Curl(accessTokenURL).SetData(map[string]string{
		"grant_type": "client_credential",
		"appid":      c.AppID,
		"secret":     c.Secret,
	}).Get("")
	if err != nil {
		return nil, err
	}

	var result AccessTokenResult
	if err := jsoniter.UnmarshalFromString(body, &result); err != nil {
		return nil, err
	}
	if result.ErrCode != utils.NumberZero {
		return nil, fmt.Errorf("wechat access_token: %d %s", result.ErrCode, result.ErrMsg)
	}
	if result.AccessToken == utils.StringEmpty {
		return nil, fmt.Errorf("wechat access_token empty")
	}

	expire := time.Duration(result.ExpiresIn-300) * time.Second
	if expire > 0 {
		_ = redis.Client.Set(ctx, key, result.AccessToken, expire).Err()
	}
	return &result, nil
}