"use client";

import Link from "next/link";
import { useRouter, useSearchParams } from "next/navigation";
import { useEffect, useState } from "react";
import AuthShell from "@/components/AuthShell";
import { AuthField, AuthPasswordField } from "@/components/AuthFields";
import { postLoginHref, useAuth } from "@/components/AuthProvider";
import { ApiError, getAccessToken, getRefreshToken } from "@/lib/meshkee-api";
import { toE164CellNumber } from "@/lib/cellNumber";
import {
  getAdminDashboardOrigin,
  getCustomerDashboardOrigin,
  hostAppFor,
} from "@/lib/host";
import styles from "@/components/AuthShell.module.css";

const websiteUrl =
  process.env.NEXT_PUBLIC_WEBSITE_URL?.replace(/\/$/, "") ||
  "http://localhost:3000";

const tenantDomain =
  process.env.NEXT_PUBLIC_MESHKEE_TENANT_DOMAIN?.trim() ||
  (() => {
    try {
      return new URL(websiteUrl).hostname;
    } catch {
      return "iranbay.com";
    }
  })();

type AuthMode = "login" | "register";

function isSafeWebsiteReturn(next: string) {
  try {
    const url = new URL(next);
    const allowed = new URL(websiteUrl);
    return url.origin === allowed.origin;
  } catch {
    return false;
  }
}

function websiteHandoffUrl(next: string) {
  const access = getAccessToken();
  const refresh = getRefreshToken();
  if (!access || !refresh) return null;

  const target = new URL(next);
  const hash = new URLSearchParams({
    access,
    refresh,
    next: `${target.pathname}${target.search}${target.hash}` || "/register",
  }).toString();

  return `${target.origin}/auth/handoff#${hash}`;
}

function splitName(fullName: string) {
  const parts = fullName.trim().split(/\s+/).filter(Boolean);
  const firstName = parts[0] || "";
  const lastName = parts.length > 1 ? parts.slice(1).join(" ") : firstName;
  return { firstName, lastName };
}

async function finishAuth(
  dashboard: "super_admin" | "business" | "customer",
  returnToWebsite: string | null,
  router: ReturnType<typeof useRouter>,
) {
  if (returnToWebsite) {
    const handoff = websiteHandoffUrl(returnToWebsite);
    if (handoff) {
      window.location.href = handoff;
      return;
    }
  }

  const href = postLoginHref(dashboard);
  if (href.startsWith("http")) {
    window.location.href = href;
  } else {
    router.push(href);
  }
}

export default function LoginForm() {
  const router = useRouter();
  const searchParams = useSearchParams();
  const { login, register } = useAuth();
  const [error, setError] = useState("");
  const [isSubmitting, setIsSubmitting] = useState(false);
  const [hostReady, setHostReady] = useState(false);
  const [app, setApp] = useState<"admin" | "customer" | "business">("admin");
  const [adminLoginHref, setAdminLoginHref] = useState("");

  const nextParam = searchParams.get("next");
  const returnToWebsite =
    nextParam && isSafeWebsiteReturn(nextParam) ? nextParam : null;
  const modeParam = searchParams.get("mode");
  const [mode, setMode] = useState<AuthMode>(() =>
    modeParam === "register" ? "register" : "login",
  );

  useEffect(() => {
    const host = window.location.host;
    const next = hostAppFor(host);
    setApp(next);
    setHostReady(true);
    setAdminLoginHref(`${getAdminDashboardOrigin()}/login`);
    if (next === "business") {
      const loginUrl = new URL(`${getCustomerDashboardOrigin()}/login`);
      if (returnToWebsite) loginUrl.searchParams.set("next", returnToWebsite);
      if (mode === "register") loginUrl.searchParams.set("mode", "register");
      window.location.replace(loginUrl.toString());
    }
  }, [returnToWebsite, mode]);

  useEffect(() => {
    if (modeParam === "register") setMode("register");
    if (modeParam === "login") setMode("login");
  }, [modeParam]);

  if (!hostReady || app === "business") {
    return (
      <div
        style={{
          minHeight: "100vh",
          display: "grid",
          placeItems: "center",
          background: "#f6f6f6",
          fontSize: 12,
          letterSpacing: "0.2em",
          textTransform: "uppercase",
          color: "#8e8e8e",
        }}
      >
        Redirecting to login…
      </div>
    );
  }

  const isRegister = mode === "register" && app === "customer";
  const titleLine1 = isRegister ? "Create" : "Login To";
  const titleLine2 = app === "customer" ? "Account" : "IranBay";

  return (
    <AuthShell
      titleLine1={titleLine1}
      titleLine2={titleLine2}
      footerNote={
        isRegister ? (
          <button
            type="button"
            className={styles.noteLink}
            onClick={() => {
              setError("");
              setMode("login");
            }}
          >
            Already have an account? Login
          </button>
        ) : (
          <Link href="/forgot-password">Forgot password?</Link>
        )
      }
    >
      <form
        className={styles.form}
        autoComplete="off"
        key={isRegister ? "register" : "login"}
        onSubmit={async (e) => {
          e.preventDefault();
          setError("");
          setIsSubmitting(true);

          const form = new FormData(e.currentTarget);
          const phone = String(form.get("phone") ?? "");
          const password = String(form.get("password") ?? "");

          try {
            if (isRegister) {
              const name = String(form.get("name") ?? "");
              const email = String(form.get("email") ?? "").trim();
              const { firstName, lastName } = splitName(name);

              if (firstName.length < 2) {
                throw new ApiError("Please enter your full name.", 400);
              }

              const dashboard = await register({
                cellNumber: toE164CellNumber(phone),
                password,
                firstName,
                lastName: lastName.length >= 2 ? lastName : firstName,
                email: email || undefined,
                domain: tenantDomain,
              });
              await finishAuth(dashboard, returnToWebsite, router);
            } else {
              const dashboard = await login(toE164CellNumber(phone), password);
              await finishAuth(dashboard, returnToWebsite, router);
            }
          } catch (err) {
            if (err instanceof ApiError) {
              setError(err.message);
            } else {
              setError(
                isRegister
                  ? "Unable to create account. Is Meshkee API running?"
                  : "Unable to sign in. Is Meshkee API running?",
              );
            }
          } finally {
            setIsSubmitting(false);
          }
        }}
      >
        {error ? (
          <p className={styles.error} role="alert">
            {error}
            {app === "customer" &&
            adminLoginHref &&
            error.includes("super admin access") ? (
              <>
                {" "}
                <a href={adminLoginHref}>Go to admin login</a>
              </>
            ) : null}
          </p>
        ) : null}

        {returnToWebsite ? (
          <p className={styles.hint}>
            {isRegister
              ? "Create an account to continue business registration"
              : "Sign in to continue business registration"}
          </p>
        ) : null}

        {isRegister ? (
          <AuthField
            label="Name"
            name="name"
            autoComplete="name"
            required
            disabled={isSubmitting}
          />
        ) : null}

        <AuthField
          label={isRegister ? "Cell Number" : "Phone Number"}
          name="phone"
          type="tel"
          autoComplete="off"
          dir="ltr"
          required
          disabled={isSubmitting}
        />

        {isRegister ? (
          <AuthField
            label="Email Address"
            name="email"
            type="email"
            autoComplete="email"
            required
            disabled={isSubmitting}
          />
        ) : null}

        <AuthPasswordField
          label="Password"
          name="password"
          autoComplete={isRegister ? "new-password" : "current-password"}
          required
          disabled={isSubmitting}
        />

        <div className={styles.actions}>
          {app === "customer" ? (
            isRegister ? (
              <button
                type="button"
                className={styles.secondaryBtn}
                disabled={isSubmitting}
                onClick={() => {
                  setError("");
                  setMode("login");
                }}
              >
                Login instead
              </button>
            ) : (
              <button
                type="button"
                className={styles.secondaryBtn}
                disabled={isSubmitting}
                onClick={() => {
                  setError("");
                  setMode("register");
                }}
              >
                Create account
              </button>
            )
          ) : null}
          <button
            type="submit"
            className={`outline-btn ${styles.primaryBtn}`}
            disabled={isSubmitting}
          >
            {isSubmitting ? "…" : isRegister ? "REGISTER" : "LOGIN"}
          </button>
        </div>
      </form>
    </AuthShell>
  );
}