// Google / Telegram 登录的 HTTP 端点。GitHub 的在 comments.go——
// 三个 Provider 共用同一套读者会话与 upsert 逻辑，只是凭据交换方式不同：
// GitHub / Google 是授权码换 token，Telegram 是官方 widget 直接带签名资料。
package api

import (
	"encoding/json"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"time"

	"oneblog/internal/auth"
	"oneblog/internal/httpx"
	"oneblog/internal/model"
)

// authProviders 列出已配置的登录方式。
// redirect 型前端直接跳 /api/auth/{id}/login；widget 型（Telegram）
// 前端内联官方脚本，需要 bot 用户名。
func (a *API) authProviders(w http.ResponseWriter, r *http.Request) {
	providers := []map[string]any{}
	if a.GH.Enabled() {
		providers = append(providers, map[string]any{
			"id": "github", "label": "GitHub", "kind": "redirect",
		})
	}
	if a.GG.Enabled() {
		providers = append(providers, map[string]any{
			"id": "google", "label": "Google", "kind": "redirect",
		})
	}
	if a.TG.Enabled() {
		providers = append(providers, map[string]any{
			"id": "telegram", "label": "Telegram", "kind": "widget", "login": a.TG.Bot,
		})
	}
	httpx.OK(w, map[string]any{"providers": providers})
}

// issueReaderCookie 登录成功后的公共收尾：发读者会话 + 决定跳回去的地址
func (a *API) issueReaderCookie(w http.ResponseWriter, r *http.Request, readerID int64) string {
	token, _ := a.ReaderSessions.Issue(readerID)
	http.SetCookie(w, &http.Cookie{Name: auth.ReaderCookie, Value: token, Path: "/",
		HttpOnly: true, SameSite: http.SameSiteLaxMode, MaxAge: int((30 * 24 * time.Hour).Seconds())})
	// 回到发起登录的前台；没有记录（直接敲 URL 进来的）就回站点根
	back := a.Cfg.SiteURL
	if ck, err := r.Cookie(oauthBackCook); err == nil && ck.Value != "" {
		if u, err := url.Parse(ck.Value); err == nil && (u.Scheme == "http" || u.Scheme == "https") && u.Host != "" && u.Path == "" {
			back = u.Scheme + "://" + u.Host
		}
	}
	http.SetCookie(w, &http.Cookie{Name: oauthBackCook, Value: "", Path: "/", MaxAge: -1})
	return back
}

// googleLogin 跳 Google 授权页（state 防 CSRF 同 GitHub）
func (a *API) googleLogin(w http.ResponseWriter, r *http.Request) {
	if !a.GG.Enabled() {
		httpx.NotFound(w)
		return
	}
	state := randHex(16)
	http.SetCookie(w, &http.Cookie{Name: oauthStateCook, Value: state, Path: "/",
		HttpOnly: true, MaxAge: 600})
	if ref := r.Referer(); ref != "" {
		if u, err := url.Parse(ref); err == nil && u.Scheme != "" && u.Host != "" {
			http.SetCookie(w, &http.Cookie{Name: oauthBackCook,
				Value: u.Scheme + "://" + u.Host, Path: "/", HttpOnly: true, MaxAge: 600})
		}
	}
	http.Redirect(w, r, a.GG.LoginURL(a.Cfg.SiteURL+"/api/auth/callback/google", state), http.StatusFound)
}

// googleCallback 用 code 换身份：Google 用户 → upsert 读者 → 发会话
func (a *API) googleCallback(w http.ResponseWriter, r *http.Request) {
	if !a.GG.Enabled() {
		httpx.NotFound(w)
		return
	}
	ck, err := r.Cookie(oauthStateCook)
	if err != nil || ck.Value == "" || ck.Value != r.FormValue("state") {
		httpx.BadRequest(w, "state 不匹配，请重新登录")
		return
	}
	accessToken, err := a.GG.Exchange(r.Context(), r.FormValue("code"), a.Cfg.SiteURL+"/api/auth/callback/google")
	if err != nil {
		httpx.ServerError(w, err)
		return
	}
	u, err := a.GG.FetchUser(r.Context(), accessToken)
	if err != nil {
		httpx.ServerError(w, err)
		return
	}
	// handle 优先用已验证邮箱（可读），否则退回 sub（Google 的稳定唯一 id）
	handle := u.Sub
	if u.EmailVerified && u.Email != "" {
		handle = u.Email
	}
	name := u.Name
	if name == "" {
		name = handle
	}
	reader, err := a.Store.UpsertReader(model.Reader{
		Provider: "google", Handle: handle, Name: name,
		AvatarURL: u.Picture,
	})
	if err != nil {
		httpx.ServerError(w, err)
		return
	}
	http.Redirect(w, r, a.issueReaderCookie(w, r, reader.ID), http.StatusFound)
}

// telegramAuth 校验 Login Widget 回传的签名资料并登录。
// 前端把 widget 的 user 对象原样 POST 过来（见 reader.js 的 oneTelegramAuth）。
func (a *API) telegramAuth(w http.ResponseWriter, r *http.Request) {
	if !a.TG.Enabled() {
		httpx.NotFound(w)
		return
	}
	// 原样读 body：验签必须用收到的全部字段（官方规则），
	// 身份字段再单独解一次
	body, err := io.ReadAll(r.Body)
	if err != nil {
		httpx.BadRequest(w, "invalid body")
		return
	}
	var fields map[string]any
	if err := json.Unmarshal(body, &fields); err != nil || len(fields) == 0 {
		httpx.BadRequest(w, "invalid body")
		return
	}
	if err := a.TG.VerifyMap(fields); err != nil {
		httpx.Error(w, http.StatusForbidden, "Telegram 登录校验失败，请重试")
		return
	}
	var in auth.TelegramUser
	if err := json.Unmarshal(body, &in); err != nil || in.IDInt() == 0 {
		httpx.BadRequest(w, "invalid body")
		return
	}
	handle := in.Username
	if handle == "" {
		// 没有公开 username 的用户用数字 id，保证 provider+handle 稳定唯一
		handle = strconv.FormatInt(in.IDInt(), 10)
	}
	reader, err := a.Store.UpsertReader(model.Reader{
		Provider: "telegram", Handle: handle, Name: in.DisplayName(),
		AvatarURL: in.PhotoURL,
		URL:       tgProfileURL(in.Username),
	})
	if err != nil {
		httpx.ServerError(w, err)
		return
	}
	// 会话同样落 httpOnly cookie，前端 POST 完刷新 /api/auth/me 即可见
	token, _ := a.ReaderSessions.Issue(reader.ID)
	http.SetCookie(w, &http.Cookie{Name: auth.ReaderCookie, Value: token, Path: "/",
		HttpOnly: true, SameSite: http.SameSiteLaxMode, MaxAge: int((30 * 24 * time.Hour).Seconds())})
	httpx.OK(w, map[string]any{"user": map[string]any{
		"id": reader.ID, "name": reader.Name, "handle": reader.Handle,
		"avatar_url": reader.AvatarURL, "url": reader.URL,
		"provider": reader.Provider, "is_owner": false, "banned": reader.Banned,
	}})
}

func tgProfileURL(username string) string {
	if username == "" {
		return ""
	}
	return "https://t.me/" + username
}