/**
 * GetStartedView - Main view for the get-started flow
 *
 * Supports multiple handoff scenarios from eligibility check:
 *
 * 1. Verified handoff (?verified=true):
 *    - User already completed OTP on eligibility page
 *    - SessionStorage has: sessionToken, accountStatus, prefill, email
 *    - Skip directly to complete-account step
 *
 * 2. Unverified handoff (?handoff=true):
 *    - User came from eligibility check success page or SF email
 *    - Email is pre-filled but NOT verified yet
 *    - User must complete OTP verification
 *    - SessionStorage may have: handoff-token for prefill data
 */

"use client";

import { useState, useCallback, useEffect } from "react";
import { useSearchParams } from "next/navigation";
import { AuthLayout } from "@/components/templates/AuthLayout";
import { GetStartedForm } from "../components";
import {
  useGetStartedStore,
  type GetStartedStep,
  type GetStartedAddress,
} from "../stores/get-started.store";
import type { AccountStatus, VerifyCodeResponse } from "@customer-portal/domain/get-started";

// Session data staleness threshold (5 minutes)
const SESSION_STALE_THRESHOLD_MS = 5 * 60 * 1000;

export function GetStartedView() {
  const searchParams = useSearchParams();
  const {
    updateFormData,
    goToStep,
    setHandoffToken,
    setSessionToken,
    setAccountStatus,
    setPrefill,
  } = useGetStartedStore();
  const [meta, setMeta] = useState({
    title: "Get Started",
    subtitle: "Enter your email to begin",
  });
  const [initialized, setInitialized] = useState(false);

  // Helper to clear all get-started sessionStorage items
  const clearGetStartedSessionStorage = () => {
    sessionStorage.removeItem("get-started-session-token");
    sessionStorage.removeItem("get-started-account-status");
    sessionStorage.removeItem("get-started-prefill");
    sessionStorage.removeItem("get-started-email");
    sessionStorage.removeItem("get-started-timestamp");
    sessionStorage.removeItem("get-started-handoff-token");
  };

  // Check for handoff from eligibility check on mount
  useEffect(() => {
    if (initialized) return;

    // Check for verified handoff (user already completed OTP on eligibility page)
    const verifiedParam = searchParams.get("verified");

    if (verifiedParam === "true") {
      // Read all session data at once
      const storedSessionToken = sessionStorage.getItem("get-started-session-token");
      const storedAccountStatus = sessionStorage.getItem("get-started-account-status");
      const storedPrefillRaw = sessionStorage.getItem("get-started-prefill");
      const storedEmail = sessionStorage.getItem("get-started-email");
      const storedTimestamp = sessionStorage.getItem("get-started-timestamp");

      // Validate timestamp to prevent stale data
      const isStale =
        !storedTimestamp ||
        Date.now() - Number.parseInt(storedTimestamp, 10) > SESSION_STALE_THRESHOLD_MS;

      // Clear sessionStorage immediately after reading
      clearGetStartedSessionStorage();

      if (storedSessionToken && !isStale) {
        // Parse prefill data
        let prefill: VerifyCodeResponse["prefill"] | null = null;
        if (storedPrefillRaw) {
          try {
            prefill = JSON.parse(storedPrefillRaw);
          } catch {
            // Ignore parse errors
          }
        }

        // Set session data in store
        setSessionToken(storedSessionToken);
        if (storedAccountStatus) {
          setAccountStatus(storedAccountStatus as AccountStatus);
        }
        if (prefill) {
          setPrefill(prefill);
          // Also update form data with prefill
          updateFormData({
            email: storedEmail || prefill.email || "",
            firstName: prefill.firstName || "",
            lastName: prefill.lastName || "",
            phone: prefill.phone || "",
            address: (prefill.address as GetStartedAddress) || {},
          });
        } else if (storedEmail) {
          updateFormData({ email: storedEmail });
        }

        // Skip directly to complete-account (email already verified)
        goToStep("complete-account");
        setInitialized(true);
        return;
      }
      // If stale or no token, fall through to normal flow
    }

    // Check for unverified handoff (from success page CTA or SF email)
    const emailParam = searchParams.get("email");
    const handoffParam = searchParams.get("handoff");
    const storedHandoffToken = sessionStorage.getItem("get-started-handoff-token");
    const storedEmail = sessionStorage.getItem("get-started-email");

    // Clear handoff-related sessionStorage after reading
    sessionStorage.removeItem("get-started-handoff-token");
    sessionStorage.removeItem("get-started-email");

    const email = emailParam || storedEmail;
    const isHandoff = handoffParam === "true" || !!storedHandoffToken;

    if (email && isHandoff) {
      // User came from eligibility check - email is NOT verified yet
      // Pre-fill email and let user verify via OTP
      updateFormData({ email });

      // Store handoff token if available - will be used during OTP verification
      if (storedHandoffToken) {
        setHandoffToken(storedHandoffToken);
      }

      // Stay at email step - user needs to verify their email
      // Don't call goToStep - let the form start at its default step
      // The email is pre-filled so user just clicks "Send Code"
    } else if (email) {
      // Just email param (from SF email link without handoff)
      updateFormData({ email });
    }

    setInitialized(true);
  }, [
    initialized,
    searchParams,
    updateFormData,
    setHandoffToken,
    goToStep,
    setSessionToken,
    setAccountStatus,
    setPrefill,
  ]);

  const handleStepChange = useCallback(
    (_step: GetStartedStep, stepMeta: { title: string; subtitle: string }) => {
      setMeta(stepMeta);
    },
    []
  );

  return (
    <AuthLayout title={meta.title} subtitle={meta.subtitle} wide>
      <GetStartedForm onStepChange={handleStepChange} />
    </AuthLayout>
  );
}

export default GetStartedView;
