package pay

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

const jsapiPrepayPath = "/v3/pay/transactions/jsapi"

type jsapiPrepayBody struct {
	AppID         string      `json:"appid"`
	MchID         string      `json:"mchid"`
	Description   string      `json:"description"`
	OutTradeNo    string      `json:"out_trade_no"`
	TimeExpire    interface{} `json:"time_expire,omitempty"`
	Attach        string      `json:"attach,omitempty"`
	NotifyURL     string      `json:"notify_url"`
	GoodsTag      string      `json:"goods_tag,omitempty"`
	SupportFapiao *bool       `json:"support_fapiao,omitempty"`
	Amount        Amount      `json:"amount"`
	Payer         Payer       `json:"payer"`
	Detail        *Detail     `json:"detail,omitempty"`
	SceneInfo     *SceneInfo  `json:"scene_info,omitempty"`
	SettleInfo    *SettleInfo `json:"settle_info,omitempty"`
}

func (c *Client) JsapiPrepay(ctx context.Context, req *JsapiPrepayRequest) (*JsapiPrepayResponse, error) {
	if req == nil {
		return nil, fmt.Errorf("request is required")
	}
	if req.OutTradeNo == "" || req.Description == "" || req.Payer.OpenID == "" {
		return nil, fmt.Errorf("out_trade_no, description and payer.openid are required")
	}
	if req.Amount.Total <= 0 {
		return nil, fmt.Errorf("amount.total must be greater than 0")
	}

	notifyURL := req.NotifyURL
	if notifyURL == "" {
		notifyURL = c.NotifyURL
	}
	if notifyURL == "" {
		return nil, fmt.Errorf("notify_url is required")
	}

	currency := req.Amount.Currency
	if currency == "" {
		currency = "CNY"
	}

	body := jsapiPrepayBody{
		AppID:         c.AppID,
		MchID:         c.MchID,
		Description:   req.Description,
		OutTradeNo:    req.OutTradeNo,
		Attach:        req.Attach,
		NotifyURL:     notifyURL,
		GoodsTag:      req.GoodsTag,
		SupportFapiao: req.SupportFapiao,
		Amount: Amount{
			Total:    req.Amount.Total,
			Currency: currency,
		},
		Payer:      req.Payer,
		Detail:     req.Detail,
		SceneInfo:  req.SceneInfo,
		SettleInfo: req.SettleInfo,
	}
	if req.TimeExpire != nil {
		body.TimeExpire = req.TimeExpire
	}

	reqBody, err := json.Marshal(body)
	if err != nil {
		return nil, err
	}

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, c.Host+jsapiPrepayPath, bytes.NewReader(reqBody))
	if err != nil {
		return nil, err
	}

	httpReq.Header.Set("Accept", "application/json")
	httpReq.Header.Set("Content-Type", "application/json")
	if c.platformSerial != "" {
		httpReq.Header.Set("Wechatpay-Serial", c.platformSerial)
	}

	authorization, err := c.buildAuthorization(http.MethodPost, jsapiPrepayPath, reqBody)
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("Authorization", authorization)

	resp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	if !isSuccessStatus(resp.StatusCode) {
		return nil, newAPIError(resp.StatusCode, respBody)
	}

	if err := c.validateResponse(resp.Header, respBody); err != nil {
		return nil, err
	}

	var result JsapiPrepayResponse
	if err := json.Unmarshal(respBody, &result); err != nil {
		return nil, err
	}
	if result.PrepayID == "" {
		return nil, fmt.Errorf("empty prepay_id in response")
	}

	return &result, nil
}

func (c *Client) MiniProgramPay(ctx context.Context, req *JsapiPrepayRequest) (*MiniProgramPayResult, error) {
	prepay, err := c.JsapiPrepay(ctx, req)
	if err != nil {
		return nil, err
	}

	payParams, err := c.BuildMiniProgramPayParams(prepay.PrepayID)
	if err != nil {
		return nil, err
	}

	return &MiniProgramPayResult{
		PrepayID: prepay.PrepayID,
		Pay:      payParams,
	}, nil
}