import { useMemo, useState } from "react";
import { useQuery } from "@tanstack/react-query";
import { useNavigate, useSearchParams } from "react-router-dom";
import { fetchSsoProviders, fetchWecomConfig } from "../api/auth";
import { mapApiErrorMessage } from "../api/errorMessages";
import { isApiError } from "../api/types";
import { useAuth } from "../auth/AuthContext";
import { Button } from "../components/ui/button";
import { Input } from "../components/ui/input";
import { Label } from "../components/ui/label";
import { isWecomWebView } from "../lib/runtimeContext";
import {
  buildWecomLoginUrl,
  resolveWecomBindNotice,
  resolveWecomEntryStatus,
  resolveWecomLoginNotice,
  type WecomNotice,
} from "../lib/wecomEntry";

function resolveRedirect(searchParams: URLSearchParams) {
  const redirect = searchParams.get("redirect");
  if (!redirect || !redirect.startsWith("/") || redirect.startsWith("//")) {
    return "/portal";
  }
  return redirect;
}

function noticeClasses(tone: WecomNotice["tone"]) {
  if (tone === "success") {
    return "border-emerald-200 bg-emerald-50 text-emerald-700";
  }
  if (tone === "warning") {
    return "border-amber-200 bg-amber-50 text-amber-700";
  }
  return "border-slate-200 bg-slate-50 text-slate-700";
}

export function LoginPage() {
  const navigate = useNavigate();
  const [searchParams] = useSearchParams();
  const { login } = useAuth();

  const [identifier, setIdentifier] = useState("");
  const [password, setPassword] = useState("");
  const [submitting, setSubmitting] = useState(false);
  const [error, setError] = useState("");

  const redirectTo = resolveRedirect(searchParams);
  const isWecomContext = isWecomWebView();

  const ssoProvidersQuery = useQuery({
    queryKey: ["auth", "sso-providers"],
    queryFn: () => fetchSsoProviders(),
    staleTime: 60_000,
  });
  const oidcProvider = (ssoProvidersQuery.data ?? []).find((item) => item.id === "oidc" && item.enabled);

  const wecomConfigQuery = useQuery({
    queryKey: ["auth", "wecom-config"],
    queryFn: () => fetchWecomConfig(),
    staleTime: 60_000,
  });

  const wecomConfig = wecomConfigQuery.data;
  const wecomStatus = resolveWecomEntryStatus(wecomConfig);
  const wecomEntry = wecomConfig?.entryEnabled ? wecomConfig : null;
  const primaryMode = isWecomContext && wecomEntry?.loginUrl ? "wecom" : "password";
  const wecomNotice = useMemo(
    () => resolveWecomBindNotice(searchParams.get("wecomBind")) ?? resolveWecomLoginNotice(searchParams.get("wecom")),
    [searchParams],
  );

  async function handleSubmit(event: React.FormEvent<HTMLFormElement>) {
    event.preventDefault();
    setSubmitting(true);
    setError("");

    try {
      const result = await login(identifier.trim(), password);
      if (result.mustChangePassword) {
        navigate("/change-password", { replace: true });
      } else {
        navigate(redirectTo, { replace: true });
      }
    } catch (err) {
      if (isApiError(err)) {
        setError(mapApiErrorMessage(err.code, err.details, err.message));
      } else if (err instanceof TypeError) {
        setError("无法连接后端服务，请确认 server 已启动（http://127.0.0.1:3000）。");
      } else {
        setError("登录失败，请稍后重试。");
      }
    } finally {
      setSubmitting(false);
    }
  }

  function handleWecomLogin() {
    if (!wecomEntry?.loginUrl) {
      return;
    }
    window.location.assign(buildWecomLoginUrl(wecomEntry.loginUrl, redirectTo));
  }

  function renderPasswordPanel(testId: string, primary: boolean) {
    return (
      <div className="space-y-4 rounded-[1.5rem] border border-slate-200 bg-white p-6 shadow-sm" data-testid={testId}>
        <div>
          <div className="text-xs font-semibold uppercase tracking-[0.18em] text-slate-400">{primary ? "推荐入口" : "回退入口"}</div>
          <h2 className="mt-2 text-xl font-semibold tracking-tight text-slate-900">使用账号密码登录</h2>
          <p className="mt-2 text-sm leading-6 text-slate-600">
            {primary
              ? "适合桌面浏览器直接登录；若企业微信入口暂未开放，也可正常使用。"
              : "企业微信免登失败、未绑定或超时时，可改用账号密码继续进入。"}
          </p>
        </div>

        <form className="space-y-4" onSubmit={handleSubmit}>
          <div className="space-y-2">
            <Label htmlFor="login-identifier">账号</Label>
            <Input
              autoComplete="username"
              data-testid="login-identifier"
              id="login-identifier"
              onChange={(event) => setIdentifier(event.target.value)}
              placeholder="邮箱或手机号"
              value={identifier}
            />
          </div>

          <div className="space-y-2">
            <Label htmlFor="login-password">密码</Label>
            <Input
              autoComplete="current-password"
              data-testid="login-password"
              id="login-password"
              onChange={(event) => setPassword(event.target.value)}
              placeholder="请输入密码"
              type="password"
              value={password}
            />
          </div>

          {error ? <div className="rounded-xl border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-600">{error}</div> : null}

          <Button data-testid="login-submit" className="w-full" disabled={submitting} type="submit" variant={primary ? "default" : "secondary"}>
            {submitting ? "登录中..." : "登录并进入工作台"}
          </Button>
        </form>
      </div>
    );
  }

  return (
    <div className="card-std overflow-hidden border-slate-200 p-0 shadow-md">
      <div className="border-b border-slate-200 bg-[radial-gradient(circle_at_8%_0%,rgba(0,57,138,0.12),transparent_16rem),linear-gradient(135deg,#ffffff,#e6ecf4)] px-6 py-6 sm:px-8 sm:py-7">
        <div className="text-xs font-bold uppercase tracking-[0.2em] text-primary">统一入口</div>
        <h1 className="mt-2 text-3xl font-semibold tracking-tight text-slate-900">登录海音达工作台</h1>
        <p className="mt-3 max-w-2xl text-sm leading-6 text-slate-600">
          企业微信负责进入与提醒，真正的审批、项目、周报和团队留痕都在海音达工作台内完成。
        </p>
        <div className="mt-4 rounded-2xl border border-slate-200 bg-white/90 px-4 py-3 text-sm text-slate-600">
          {isWecomContext
            ? "当前在企业微信中打开，推荐直接使用企业微信进入工作台；失败时可随时回退到账号密码登录。"
            : "当前为浏览器场景，推荐直接使用账号密码登录；企业微信入口会作为次级入口提供。"}
        </div>
      </div>

      <div className="space-y-5 px-6 py-6 sm:px-8 sm:py-7">
        {wecomNotice ? (
          <div className={`rounded-2xl border px-4 py-3 text-sm ${noticeClasses(wecomNotice.tone)}`} data-testid="login-wecom-notice">
            <div className="font-medium">{wecomNotice.title}</div>
            <div className="mt-1 leading-6">{wecomNotice.description}</div>
          </div>
        ) : null}

        <div className="grid gap-4">
          {primaryMode === "wecom" && wecomEntry?.loginUrl ? (
            <div className="rounded-[1.5rem] border border-primary/20 bg-primary/5 p-6" data-testid="login-wecom-primary-panel">
              <div className="text-xs font-semibold uppercase tracking-[0.18em] text-primary">推荐入口</div>
              <h2 className="mt-2 text-xl font-semibold tracking-tight text-slate-900">使用企业微信进入工作台</h2>
              <p className="mt-2 text-sm leading-6 text-slate-600">当前是企业微信场景，优先使用免登入口；若未绑定或回调失效，仍可切换为账号密码登录。</p>
              <Button className="mt-5 w-full" data-testid="wecom-entry-primary" type="button" onClick={handleWecomLogin}>
                使用企业微信进入工作台
              </Button>
            </div>
          ) : null}

          {renderPasswordPanel(
            primaryMode === "password" ? "login-password-primary-panel" : "login-password-secondary-panel",
            primaryMode === "password",
          )}

          {((primaryMode !== "wecom" && wecomEntry?.loginUrl) || oidcProvider) ? (
            <div className="rounded-[1.5rem] border border-slate-200 bg-slate-50/70 p-6">
              <div className="text-xs font-semibold uppercase tracking-[0.18em] text-slate-400">补充入口</div>
              <h2 className="mt-2 text-lg font-semibold text-slate-900">其他进入方式</h2>
              <p className="mt-2 text-sm leading-6 text-slate-600">入口失败时请优先选择可理解、可回退的方式继续进入。</p>
              <div className="mt-4 grid gap-3">
                {primaryMode !== "wecom" && wecomEntry?.loginUrl ? (
                  <Button className="w-full" data-testid="wecom-entry-secondary" type="button" variant="secondary" onClick={handleWecomLogin}>
                    使用企业微信进入工作台
                  </Button>
                ) : null}

                {oidcProvider ? (
                  <Button
                    className="w-full"
                    type="button"
                    variant="secondary"
                    onClick={() => {
                      window.location.assign(`${oidcProvider.loginUrl}?returnTo=${encodeURIComponent(redirectTo)}`);
                    }}
                  >
                    使用{oidcProvider.label}
                  </Button>
                ) : null}
              </div>
            </div>
          ) : null}
        </div>

        <div className="rounded-2xl border border-slate-200 bg-slate-50 px-4 py-3 text-sm text-slate-600">
          <div className="font-medium text-slate-900">企业微信入口状态：{wecomStatus.label}</div>
          <div className="mt-1 leading-6">{wecomStatus.description}</div>
          {wecomStatus.reasonLabels.length ? (
            <ul className="mt-2 list-disc space-y-1 pl-5 text-xs text-slate-500">
              {wecomStatus.reasonLabels.map((label) => (
                <li key={label}>{label}</li>
              ))}
            </ul>
          ) : null}
        </div>
      </div>
    </div>
  );
}