package handler

import (
	"errors"
	"net/http"

	"github.com/gin-gonic/gin"

	"wx_service/internal/common/wechat_official/service"
	"wx_service/internal/model"
)

type OAuthHandler struct {
	oaService *service.WeChatOAService
}

func NewOAuthHandler(oaService *service.WeChatOAService) *OAuthHandler {
	return &OAuthHandler{oaService: oaService}
}

type codeToUserRequest struct {
	Code         string `json:"code" binding:"required"`
	WithUserInfo *bool  `json:"with_userinfo"`
}

// CodeToUser 使用微信公众号网页授权 code 换取 openid，并可选拉取用户信息（需要 snsapi_userinfo 授权）。
func (h *OAuthHandler) CodeToUser(c *gin.Context) {
	var req codeToUserRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, "请求参数错误"))
		return
	}

	withUserInfo := true
	if req.WithUserInfo != nil {
		withUserInfo = *req.WithUserInfo
	}

	token, err := h.oaService.ExchangeCode(c.Request.Context(), req.Code)
	if err != nil {
		switch {
		case errors.Is(err, service.ErrWeChatOANotConfigured):
			c.JSON(http.StatusServiceUnavailable, model.Error(http.StatusServiceUnavailable, "未配置公众号服务，请联系管理员"))
		case errors.Is(err, service.ErrWeChatOACodeRequired):
			c.JSON(http.StatusBadRequest, model.Error(http.StatusBadRequest, "code 不能为空"))
		default:
			var apiErr *service.WeChatOAError
			if errors.As(err, &apiErr) {
				c.JSON(http.StatusBadGateway, model.Error(http.StatusBadGateway, "微信接口异常，请稍后重试"))
				return
			}
			c.JSON(http.StatusInternalServerError, model.Error(http.StatusInternalServerError, "获取 openid 失败，请稍后重试"))
		}
		return
	}

	payload := gin.H{
		"openid":     token.OpenID,
		"unionid":    token.UnionID,
		"scope":      token.Scope,
		"expires_in": token.ExpiresIn,
	}

	if withUserInfo {
		info, err := h.oaService.FetchUserInfo(c.Request.Context(), token.AccessToken, token.OpenID)
		if err != nil {
			// 可能是 scope 不够（snsapi_base），此时仍返回 openid，并给出提示。
			payload["userinfo_error"] = "未获取到用户信息（可能未授权 snsapi_userinfo）"
		} else {
			// 统一从 userinfo 里回填 unionid（如果有）
			if info.UnionID != "" {
				payload["unionid"] = info.UnionID
			}
			payload["userinfo"] = info
		}
	}

	// 为安全起见，这里不向前端返回 access_token/refresh_token。
	c.JSON(http.StatusOK, model.Success(payload))
}