package auth

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"time"

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

type Client struct {
	CorpId     string
	CorpSecret string
}

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

func NewClient(corpId, corpSecret string) *Client {
	return &Client{
		CorpId:     corpId,
		CorpSecret: corpSecret,
	}
}

func (c *Client) AccessToken(ctx context.Context) (string, error) {
	secretMd5 := md5.Sum([]byte(c.CorpSecret))
	key := fmt.Sprintf("wecom:access_token:%s:%s", c.CorpId, hex.EncodeToString(secretMd5[:])[:8])

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

	url := fmt.Sprintf(
		"https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=%s&corpsecret=%s",
		c.CorpId,
		c.CorpSecret,
	)

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return utils.StringEmpty, err
	}

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return utils.StringEmpty, err
	}
	defer resp.Body.Close()

	var result tokenResponse
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return utils.StringEmpty, err
	}
	if result.ErrCode != utils.NumberZero {
		return utils.StringEmpty, errors.New(result.ErrMsg)
	}

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