"use client";
import React, { Suspense, useEffect, useMemo, useState } from "react";
import { useSearchParams, useRouter } from "next/navigation";
import { useAuth } from "@/hooks/useAuth";
import { apiFetch } from "@/lib/api";
import { Navbar } from "@/components/layout/Navbar";
import { Footer } from "@/components/layout/Footer";
import { FileText } from "lucide-react";

// Types for form fields
type FormField = { id: string; type: 'yes_no'|'text'|'date'|'numeric'|'statement'|'paragraph'; label: string; isRequired?: boolean; helpText?: string|null };

function FormsContent() {
  const search = useSearchParams();
  const router = useRouter();
  const { token } = useAuth();
  const registrationId = search.get("registrationId");

  const [registration, setRegistration] = useState<any | null>(null);
  const [eventForm, setEventForm] = useState<{ isRequired: boolean; fields: FormField[] } | null>(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [info, setInfo] = useState<string | null>(null);

  // Local entry state for new responses
  const [formsData, setFormsData] = useState<Record<number, Record<string, string>>>({});

  useEffect(() => {
    (async () => {
      if (!registrationId) return;
      setLoading(true);
      setError(null);
      setInfo(null);
      try {
        // authToken optional — guests access via registrationId alone
        const reg = await apiFetch<any>(`/api/registrations/${encodeURIComponent(registrationId)}`, { authToken: token || undefined });
        setRegistration(reg);
        const ev = await apiFetch<any>(`/api/events/${encodeURIComponent(reg.eventId)}`);
        if (ev?.form) setEventForm(ev.form);
        // Load any saved draft to prefill fields
        try {
          const draft = await apiFetch<any>(`/api/registrations/${encodeURIComponent(registrationId)}/forms/draft`, { authToken: token || undefined });
          if (draft && draft.data && typeof draft.data === 'object') setFormsData(draft.data);
        } catch {}
      } catch (e: any) {
        setError(e?.message || 'Failed to load registration');
      } finally {
        setLoading(false);
      }
    })();
  }, [token, registrationId]);

  const submittedCount = useMemo(() => {
    return (registration?.formResponses || []).length;
  }, [registration]);

  const requiredCount = useMemo(() => {
    if (!registration) return 0;
    try {
      return (registration.registrationOptions || [])
        .filter((ro: any) => ro.eventOption?.isMainTicket)
        .reduce((s: number, ro: any) => s + (ro.quantity || 0), 0);
    } catch {
      return 0;
    }
  }, [registration]);

  const remaining = Math.max(0, requiredCount - submittedCount);

  // Determine if all required fields are filled for each attendee form to be submitted
  const canSubmit = useMemo(() => {
    if (!eventForm || remaining <= 0) return false;
    const reqFields = (eventForm.fields || [])
      .filter(f => !!f.isRequired && f.type !== 'statement' && f.type !== 'paragraph')
      .map(f => f.id);
    for (let i = 0; i < remaining; i++) {
      const data = formsData[i] || {};
      for (const fid of reqFields) {
        const v = data[fid];
        if (v === undefined || v === null || String(v).trim() === '') {
          return false;
        }
      }
    }
    return true;
  }, [eventForm, formsData, remaining]);

  const submit = async () => {
    if (!registrationId) return;
    try {
      setError(null); setInfo(null);
      const payload: any[] = [];
      for (let i = 0; i < remaining; i++) {
        payload.push({ answers: formsData[i] || {} });
      }
      if (payload.length === 0) {
        // Nothing left to submit – still go to success page to continue the flow
        const totalDue = (registration?.registrationOptions || []).reduce((s: number, ro: any) => s + ((ro.eventOption?.price || 0) * (ro.quantity || 0)), 0);
        router.push(`/registration/success?registrationId=${encodeURIComponent(registrationId)}${totalDue>0?`&totalDue=${encodeURIComponent(totalDue.toFixed(2))}`:''}`);
        return;
      }
      await apiFetch(`/api/registrations/${encodeURIComponent(registrationId)}/forms/responses`, {
        method: 'POST',
        authToken: token || undefined,
        body: { responses: payload }
      });
      // On success, redirect to the success page
      const totalDue = (registration?.registrationOptions || []).reduce((s: number, ro: any) => s + ((ro.eventOption?.price || 0) * (ro.quantity || 0)), 0);
      router.push(`/registration/success?registrationId=${encodeURIComponent(registrationId)}${totalDue>0?`&totalDue=${encodeURIComponent(totalDue.toFixed(2))}`:''}`);
    } catch (e: any) {
      setError(e?.message || 'Failed to submit forms');
    }
  };

  const saveDraft = async () => {
    if (!registrationId) return;
    try {
      setError(null); setInfo(null);
      await apiFetch(`/api/registrations/${encodeURIComponent(registrationId)}/forms/draft`, {
        method: 'PUT',
        authToken: token || undefined,
        body: { data: formsData }
      });
      setInfo('Draft saved. You can come back and finish later.');
      if (!token || !registrationId) return;
      try {
        // Redirect to the success page
        const totalDue = (registration?.registrationOptions || []).reduce((s: number, ro: any) => s + ((ro.eventOption?.price || 0) * (ro.quantity || 0)), 0);
        router.push(`/registration/success?registrationId=${encodeURIComponent(registrationId)}${totalDue>0?`&totalDue=${encodeURIComponent(totalDue.toFixed(2))}`:''}`);
      } catch (e: any) {
        setError(e?.message || 'Failded to go to next step');
      }
    } catch (e: any) {
      setError(e?.message || 'Failed to save draft');
    }
  };

  const skip = async () => {
    if (!registrationId) return;
    try {
      // Redirect to the success page
      const totalDue = (registration?.registrationOptions || []).reduce((s: number, ro: any) => s + ((ro.eventOption?.price || 0) * (ro.quantity || 0)), 0);
      router.push(`/registration/success?registrationId=${encodeURIComponent(registrationId)}${totalDue>0?`&totalDue=${encodeURIComponent(totalDue.toFixed(2))}`:''}`);
    } catch (e: any) {
      setError(e?.message || 'Failded to skip');
    }
  };

  if (!registrationId) {
    return (
      <div className="min-h-screen flex flex-col">
        <Navbar />
        <main className="flex-1 px-4 py-10 max-w-2xl mx-auto w-full">
          <div className="border rounded-xl p-6 bg-white shadow-sm text-gray-700">Missing registrationId.</div>
        </main>
        <Footer />
      </div>
    );
  }

  return (
    <div className="min-h-screen flex flex-col">
      <Navbar />
      <main className="flex-1 px-4 py-10 max-w-2xl mx-auto w-full">
      <div className="flex items-center justify-between mb-4">
        <div className="flex items-center gap-3">
          <div className="w-10 h-10 rounded-xl bg-brand-50 flex items-center justify-center shrink-0">
            <FileText className="w-5 h-5 text-brand-600" />
          </div>
          <h1 className="text-2xl font-semibold text-gray-900">Attendee forms</h1>
        </div>
        <button className="px-3 py-1.5 text-sm rounded-lg bg-gray-100 hover:bg-gray-200 transition-colors" onClick={skip}>Skip for now</button>
      </div>

      {loading && <div className="text-sm text-gray-600 mb-2">Loading…</div>}
      {error && <div className="text-sm text-red-600 mb-2">{error}</div>}
      {info && <div className="text-sm text-emerald-700 mb-2">{info}</div>}

      {registration && (
        <div className="border rounded p-3 mb-4 bg-white">
          <div className="font-medium">{registration.event?.title || registration.eventId}</div>
          <div className="text-xs text-gray-600">Registration #{registration.id.slice(0,8)}</div>
          <div className="text-sm mt-1">Forms submitted: {submittedCount} / {requiredCount}</div>
        </div>
      )}

      {/* Existing responses (read-only list) */}
      {registration && (registration.formResponses || []).length > 0 && (
        <div className="border rounded p-3 mb-4 bg-gray-50">
          <div className="text-sm font-medium mb-2">Submitted responses</div>
          <ul className="space-y-2">
            {(registration.formResponses || []).map((resp: any, idx: number) => (
              <li key={resp.id} className="bg-white border rounded p-2">
                <div className="font-medium text-sm mb-1">Attendee {idx + 1}</div>
                {(resp.answers || []).length === 0 ? (
                  <div className="text-xs text-gray-600">No answers recorded.</div>
                ) : (
                  <ul className="text-xs list-disc pl-5 space-y-0.5">
                    {resp.answers.map((a: any) => (
                      <li key={a.id}>
                        <span className="text-gray-600">{eventForm?.fields.find(f => f.id === a.fieldId)?.label || (`Field ${a.fieldId}`)}</span>: {a.value}
                      </li>
                    ))}
                  </ul>
                )}
              </li>
            ))}
          </ul>
        </div>
      )}

      {/* Remaining forms to fill */}
      {eventForm && remaining > 0 && (
        <div className="border rounded p-3 bg-gray-50">
          <div className="text-sm font-medium mb-2">Fill remaining attendee details ({remaining})</div>
          <div className="space-y-4">
            {Array.from({ length: remaining }, (_, idx) => (
              <div key={idx} className="bg-white border rounded p-3">
                <div className="font-medium mb-2">Attendee {submittedCount + idx + 1}</div>
                {eventForm.fields.map((f) => (
                  <div key={f.id} className="mb-2">
                    {f.type === 'statement' ? (
                      <div className="text-sm text-gray-700 whitespace-pre-line">{f.label}</div>
                    ) : f.type === 'paragraph' ? (
                      <div className="text-sm text-gray-700">
                        {f.label && <div className="font-medium mb-1 whitespace-pre-line">{f.label}</div>}
                        {f.helpText && <div className="whitespace-pre-line">{f.helpText}</div>}
                      </div>
                    ) : (
                      <>
                        <label className="block text-xs text-gray-600 mb-1">{f.label}{f.isRequired ? ' *' : ''}</label>
                        {f.type === 'yes_no' ? (
                          <select className="border rounded px-2 py-1 text-sm" value={formsData[idx]?.[f.id] || ''} onChange={e => setFormsData(prev => ({ ...prev, [idx]: { ...(prev[idx]||{}), [f.id]: e.target.value } }))}>
                            <option value="">Select</option>
                            <option value="yes">Yes</option>
                            <option value="no">No</option>
                          </select>
                        ) : f.type === 'date' ? (
                          <input type="date" className="border rounded px-2 py-1 text-sm" value={formsData[idx]?.[f.id] || ''} onChange={e => setFormsData(prev => ({ ...prev, [idx]: { ...(prev[idx]||{}), [f.id]: e.target.value } }))} />
                        ) : f.type === 'numeric' ? (
                          <input type="number" className="border rounded px-2 py-1 text-sm" value={formsData[idx]?.[f.id] || ''} onChange={e => setFormsData(prev => ({ ...prev, [idx]: { ...(prev[idx]||{}), [f.id]: e.target.value } }))} />
                        ) : (
                          <input type="text" className="border rounded px-2 py-1 text-sm w-full" value={formsData[idx]?.[f.id] || ''} onChange={e => setFormsData(prev => ({ ...prev, [idx]: { ...(prev[idx]||{}), [f.id]: e.target.value } }))} />
                        )}
                        {f.helpText && <div className="text-xs text-gray-500 mt-1">{f.helpText}</div>}
                      </>
                    )}
                  </div>
                ))}
              </div>
            ))}
          </div>
          <div className="mt-3 flex gap-2">
            <button className="px-3 py-1.5 text-sm rounded bg-brand-600 text-white hover:bg-brand-700 disabled:opacity-50" disabled={!canSubmit} onClick={submit}>Submit</button>
            <button className="px-3 py-1.5 text-sm rounded bg-gray-100 hover:bg-gray-200" onClick={saveDraft}>Save for later</button>
          </div>
        </div>
      )}

      {eventForm && remaining === 0 && (
        <div className="text-sm text-emerald-700">All required attendee forms are completed for this registration.</div>
      )}
      </main>
      <Footer />
    </div>
  );
}

export default function FormsPage() {
  return (
    <Suspense fallback={<div className="p-6">Loading…</div>}>
      <FormsContent />
    </Suspense>
  );
}