import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { Check, ChevronLeft, ChevronRight, Loader2, Send } from "lucide-react";
import { api } from "../lib/api";
import { setLanguage, type LangCode } from "../i18n";
import LanguageSwitcher from "./LanguageSwitcher";

// First-run install wizard. Shown by App.tsx while the instance is unconfigured. The one-time
// setup token comes from the URL the app printed to the container logs (?token=…); every step
// posts it back as the X-Setup-Token header. On finish the instance flips to configured, the
// wizard disappears, and the operator signs in with the admin account they just created.
type StepId = "intro" | "admin" | "google" | "smtp" | "finish";

const PASSWORD_MIN = 10;

export default function SetupWizard() {
  const { t, i18n } = useTranslation();
  const [token] = useState(() => new URLSearchParams(window.location.search).get("token") ?? "");
  const [info, setInfo] = useState<{ secrets_manageable: boolean } | null>(null);
  const [tokenError, setTokenError] = useState(false);

  useEffect(() => {
    if (!token) {
      setTokenError(true);
      return;
    }
    api.setupInfo(token).then(setInfo).catch(() => setTokenError(true));
  }, [token]);

  // Step state.
  const [stepIdx, setStepIdx] = useState(0);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState("");
  // Admin account.
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  // Google OAuth (optional).
  const [gid, setGid] = useState("");
  const [gsecret, setGsecret] = useState("");
  // SMTP (optional).
  const [smtp, setSmtp] = useState({ host: "", port: "587", user: "", from: "", password: "" });
  const [testTo, setTestTo] = useState("");
  const [testState, setTestState] = useState<"idle" | "sending" | "ok" | "fail">("idle");

  if (tokenError) return <Centered><TokenError /></Centered>;
  if (!info) return <Centered><Loader2 className="w-6 h-6 animate-spin text-muted" /></Centered>;

  // Steps adapt to the instance: Google + SMTP need encrypted secret storage (TOKEN_ENCRYPTION_KEY).
  const steps: StepId[] = [
    "intro",
    "admin",
    ...(info.secrets_manageable ? (["google", "smtp"] as StepId[]) : []),
    "finish",
  ];
  const step = steps[stepIdx];
  const go = (delta: number) => {
    setError("");
    setStepIdx((i) => Math.min(steps.length - 1, Math.max(0, i + delta)));
  };

  // Each step's "Next" action persists what it collected, then advances. Optional steps with empty
  // fields just advance (skip). Errors surface inline (the setup calls use the quiet flag).
  async function next() {
    setError("");
    setBusy(true);
    try {
      if (step === "admin") {
        if (!/^[^@\s]+@[^@\s]+\.[^@\s]+$/.test(email))
          throw { detail: t("setup.admin.invalidEmail") };
        if (password.length < PASSWORD_MIN)
          throw { detail: t("setup.admin.shortPassword", { n: PASSWORD_MIN }) };
        await api.setupAdmin(token, email, password);
      } else if (step === "google" && (gid.trim() || gsecret.trim())) {
        if (!gid.trim() || !gsecret.trim()) throw { detail: t("setup.google.bothRequired") };
        await api.setupConfig(token, { google_client_id: gid.trim(), google_client_secret: gsecret.trim() });
      } else if (step === "smtp" && smtp.host.trim()) {
        await api.setupConfig(token, {
          smtp_host: smtp.host.trim(),
          smtp_port: Number(smtp.port) || 587,
          smtp_user: smtp.user.trim(),
          smtp_from: smtp.from.trim(),
          smtp_password: smtp.password,
        });
      } else if (step === "finish") {
        await api.setupFinish(token);
        window.location.href = "/"; // configured now → reloads into the login page
        return;
      }
      go(1);
    } catch (e: any) {
      setError(e?.detail ?? t("setup.genericError"));
    } finally {
      setBusy(false);
    }
  }

  async function sendTest() {
    setTestState("sending");
    try {
      // Persist the SMTP fields first so the test uses them, then send.
      if (smtp.host.trim())
        await api.setupConfig(token, {
          smtp_host: smtp.host.trim(),
          smtp_port: Number(smtp.port) || 587,
          smtp_user: smtp.user.trim(),
          smtp_from: smtp.from.trim(),
          smtp_password: smtp.password,
        });
      await api.setupTestEmail(token, testTo.trim());
      setTestState("ok");
    } catch {
      setTestState("fail");
    }
  }

  const inputCls =
    "w-full bg-card border border-border rounded-xl px-3 py-2 text-sm outline-none focus:border-accent";

  return (
    <Centered>
      <div className="w-full max-w-lg">
        <div className="flex items-center justify-between mb-4">
          <div className="text-xl font-bold tracking-tight">
            Sift<span className="text-accent">lode</span>
          </div>
          <LanguageSwitcher value={i18n.language as LangCode} onChange={setLanguage} />
        </div>

        {/* Step progress dots */}
        <div className="flex items-center gap-1.5 mb-4">
          {steps.map((s, i) => (
            <div
              key={s}
              className={`h-1.5 flex-1 rounded-full transition ${
                i <= stepIdx ? "bg-accent" : "bg-border"
              }`}
            />
          ))}
        </div>

        <div className="glass rounded-2xl p-6">
          {step === "intro" && (
            <Section title={t("setup.intro.title")} desc={t("setup.intro.body")} />
          )}

          {step === "admin" && (
            <Section title={t("setup.admin.title")} desc={t("setup.admin.desc")}>
              <input
                type="email"
                value={email}
                onChange={(e) => setEmail(e.target.value)}
                placeholder={t("setup.admin.email")}
                autoComplete="username"
                className={inputCls}
              />
              <input
                type="password"
                value={password}
                onChange={(e) => setPassword(e.target.value)}
                placeholder={t("setup.admin.password", { n: PASSWORD_MIN })}
                autoComplete="new-password"
                className={inputCls}
              />
            </Section>
          )}

          {step === "google" && (
            <Section title={t("setup.google.title")} desc={t("setup.google.desc")}>
              <input value={gid} onChange={(e) => setGid(e.target.value)} placeholder={t("setup.google.clientId")} className={inputCls} />
              <input value={gsecret} onChange={(e) => setGsecret(e.target.value)} placeholder={t("setup.google.clientSecret")} className={inputCls} />
              <p className="text-xs text-muted">{t("setup.google.skipHint")}</p>
            </Section>
          )}

          {step === "smtp" && (
            <Section title={t("setup.smtp.title")} desc={t("setup.smtp.desc")}>
              <input value={smtp.host} onChange={(e) => setSmtp({ ...smtp, host: e.target.value })} placeholder={t("setup.smtp.host")} className={inputCls} />
              <div className="flex gap-2">
                <input value={smtp.port} onChange={(e) => setSmtp({ ...smtp, port: e.target.value })} placeholder={t("setup.smtp.port")} className={`${inputCls} w-24`} />
                <input value={smtp.user} onChange={(e) => setSmtp({ ...smtp, user: e.target.value })} placeholder={t("setup.smtp.user")} className={inputCls} />
              </div>
              <input value={smtp.from} onChange={(e) => setSmtp({ ...smtp, from: e.target.value })} placeholder={t("setup.smtp.from")} className={inputCls} />
              <input type="password" value={smtp.password} onChange={(e) => setSmtp({ ...smtp, password: e.target.value })} placeholder={t("setup.smtp.password")} className={inputCls} />
              {smtp.host.trim() && (
                <div className="flex items-center gap-2 pt-1">
                  <input value={testTo} onChange={(e) => setTestTo(e.target.value)} placeholder={t("setup.smtp.testTo")} className={inputCls} />
                  <button
                    type="button"
                    onClick={sendTest}
                    disabled={testState === "sending" || !testTo.trim()}
                    className="shrink-0 glass-card glass-hover inline-flex items-center gap-1.5 px-3 py-2 rounded-xl text-sm disabled:opacity-50 transition"
                  >
                    <Send className={`w-4 h-4 ${testState === "sending" ? "animate-pulse" : ""}`} />
                    {t("setup.smtp.test")}
                  </button>
                </div>
              )}
              {testState === "ok" && <p className="text-xs text-emerald-500">{t("setup.smtp.testOk")}</p>}
              {testState === "fail" && <p className="text-xs text-red-400">{t("setup.smtp.testFail")}</p>}
              <p className="text-xs text-muted">{t("setup.smtp.skipHint")}</p>
            </Section>
          )}

          {step === "finish" && (
            <Section title={t("setup.finish.title")} desc={t("setup.finish.body")} />
          )}

          {error && <p className="text-sm text-red-400 mt-3">{error}</p>}

          <div className="flex items-center justify-between mt-6">
            <button
              onClick={() => go(-1)}
              disabled={stepIdx === 0 || busy}
              className="glass-card glass-hover inline-flex items-center gap-1 px-3 py-2 rounded-xl text-sm disabled:opacity-40 transition"
            >
              <ChevronLeft className="w-4 h-4" />
              {t("setup.nav.back")}
            </button>
            <button
              onClick={next}
              disabled={busy}
              className="inline-flex items-center gap-1.5 px-4 py-2 rounded-xl text-sm bg-accent text-accent-fg font-medium shadow-md shadow-accent/20 disabled:opacity-50 transition"
            >
              {busy ? (
                <Loader2 className="w-4 h-4 animate-spin" />
              ) : step === "finish" ? (
                <Check className="w-4 h-4" />
              ) : null}
              {step === "finish" ? t("setup.nav.finish") : t("setup.nav.next")}
              {step !== "finish" && !busy && <ChevronRight className="w-4 h-4" />}
            </button>
          </div>
        </div>
      </div>
    </Centered>
  );
}

function Centered({ children }: { children: React.ReactNode }) {
  return (
    <div className="min-h-screen bg-bg text-fg grid place-items-center p-4">{children}</div>
  );
}

function Section({
  title,
  desc,
  children,
}: {
  title: string;
  desc: string;
  children?: React.ReactNode;
}) {
  return (
    <div className="space-y-3">
      <div>
        <h2 className="text-lg font-semibold">{title}</h2>
        <p className="text-sm text-muted leading-relaxed mt-1">{desc}</p>
      </div>
      {children}
    </div>
  );
}

function TokenError() {
  const { t } = useTranslation();
  return (
    <div className="max-w-md glass rounded-2xl p-6 text-center">
      <h2 className="text-lg font-semibold">{t("setup.token.title")}</h2>
      <p className="text-sm text-muted leading-relaxed mt-2">{t("setup.token.body")}</p>
    </div>
  );
}