import { useCallback, useEffect, useRef, useState } from 'react';
import Link from 'next/link';
import { useRouter } from 'next/router';
import Layout from '../components/Layout';
import CardPreview from '../components/designer/CardFrame';
import { FRAMES, RARITIES } from '../components/designer/frames';
import { Button } from '../components/ui';
import { useAuth } from '../lib/use-auth';

const BLANK_DESIGN = {
  id: null,
  name: '',
  mana_cost: '',
  card_type: '',
  rarity: 'common',
  rules_text: '',
  actions: '',
  power: '',
  toughness: '',
  frame_id: 'classic',
  artwork_url: '',
};

export default function Designer() {
  const router = useRouter();
  const { user, loading: authLoading } = useAuth();

  const [design, setDesign] = useState(BLANK_DESIGN);
  const [saving, setSaving] = useState(false);
  const [exporting, setExporting] = useState(false);
  const [uploading, setUploading] = useState(false);
  const [message, setMessage] = useState(null);

  const cardRef = useRef(null);
  const fileInputRef = useRef(null);

  // Edit mode when ?id= is present
  useEffect(() => {
    if (!user || !router.query.id) return;

    const loadDesign = async () => {
      try {
        const token = localStorage.getItem('auth_token');
        const response = await fetch(`/api/custom-cards/${router.query.id}`, {
          headers: token ? { Authorization: `Bearer ${token}` } : {},
        });
        if (response.ok) {
          const data = await response.json();
          setDesign({ ...BLANK_DESIGN, ...data.design });
        } else {
          setMessage({ kind: 'error', text: 'Design not found.' });
        }
      } catch {
        setMessage({ kind: 'error', text: 'Failed to load design.' });
      }
    };

    loadDesign();
  }, [user, router.query.id]);

  const setField = useCallback((field, value) => {
    setDesign((prev) => ({ ...prev, [field]: value }));
  }, []);

  const handleUpload = async (file) => {
    if (!file) return;
    setUploading(true);
    setMessage(null);
    try {
      const body = new FormData();
      body.append('artwork', file);

      const token = localStorage.getItem('auth_token');
      const response = await fetch('/api/custom-cards/upload-artwork', {
        method: 'POST',
        headers: token ? { Authorization: `Bearer ${token}` } : undefined,
        body,
      });

      const data = await response.json();
      if (response.ok && data.artwork_url) {
        setField('artwork_url', data.artwork_url);
      } else {
        setMessage({ kind: 'error', text: data.error || 'Upload failed.' });
      }
    } catch {
      setMessage({ kind: 'error', text: 'Upload failed. Please try again.' });
    } finally {
      setUploading(false);
    }
  };

  const handleSave = async () => {
    if (!design.name.trim()) {
      setMessage({ kind: 'error', text: 'Give your card a title first.' });
      return;
    }
    setSaving(true);
    setMessage(null);
    try {
      const token = localStorage.getItem('auth_token');
      const isNew = !design.id;
      const response = await fetch(
        isNew ? '/api/custom-cards' : `/api/custom-cards/${design.id}`,
        {
          method: isNew ? 'POST' : 'PUT',
          headers: {
            'Content-Type': 'application/json',
            ...(token ? { Authorization: `Bearer ${token}` } : {}),
          },
          body: JSON.stringify(design),
        }
      );
      const data = await response.json();
      if (response.ok) {
        setDesign({ ...BLANK_DESIGN, ...data.design });
        setMessage({
          kind: 'success',
          text: isNew ? 'Card saved to your designs!' : 'Changes saved.',
        });
      } else {
        setMessage({ kind: 'error', text: data.error || 'Save failed.' });
      }
    } catch {
      setMessage({ kind: 'error', text: 'Save failed. Please try again.' });
    } finally {
      setSaving(false);
    }
  };

  const handleExportPng = async () => {
    if (!cardRef.current) return;
    setExporting(true);
    try {
      const { toPng } = await import('html-to-image');
      const dataUrl = await toPng(cardRef.current, {
        width: 420,
        height: 588,
        pixelRatio: 2,
        cacheBust: true,
      });
      const link = document.createElement('a');
      link.download = `${(design.name || 'card').replace(/[^a-z0-9-_ ]/gi, '').trim() || 'card'}.png`;
      link.href = dataUrl;
      link.click();
    } catch {
      setMessage({ kind: 'error', text: 'Export failed. Please try again.' });
    } finally {
      setExporting(false);
    }
  };

  const handleNew = () => {
    setDesign(BLANK_DESIGN);
    setMessage(null);
    router.replace('/designer', undefined, { shallow: true });
  };

  if (authLoading) {
    return (
      <Layout user={user}>
        <div className="flex items-center justify-center min-h-screen">
          <div className="animate-spin rounded-full h-32 w-32 border-b-2" style={{ borderColor: 'var(--accent-ember)' }} />
        </div>
      </Layout>
    );
  }

  return (
    <Layout user={user}>
      <div className="p-4 sm:p-6 max-w-[1500px] mx-auto space-y-6">
        {/* Header */}
        <div className="pt-2 flex flex-col sm:flex-row sm:items-center sm:justify-between gap-4">
          <div>
            <h1 className="text-2xl sm:text-3xl font-bold mb-1" style={{ color: 'var(--text-primary)' }}>
              Card Designer
            </h1>
            <p className="text-base" style={{ color: 'var(--text-secondary)' }}>
              Fill in the details and watch your card come to life.
            </p>
          </div>
          <div className="flex gap-2">
            <Button variant="secondary" onClick={handleNew}>New</Button>
            <Button variant="secondary" onClick={handleExportPng} disabled={exporting}>
              {exporting ? 'Exporting…' : 'Download PNG'}
            </Button>
            <Button variant="primary" onClick={handleSave} disabled={saving}>
              {saving ? 'Saving…' : design.id ? 'Save Changes' : 'Save Card'}
            </Button>
          </div>
        </div>

        {message && (
          <div
            className="glass-panel rounded-xl px-4 py-3 text-sm"
            style={{ color: message.kind === 'error' ? '#f87171' : '#4ade80' }}
            role="status"
          >
            {message.text}
          </div>
        )}

        <div className="grid grid-cols-1 lg:grid-cols-[minmax(0,1fr)_460px] gap-6">
          {/* ── Form column ─────────────────────────────── */}
          <div className="space-y-5 min-w-0">
            {/* Frame picker */}
            <section className="glass-panel rounded-2xl p-5">
              <h2 className="text-sm font-semibold uppercase tracking-wide mb-3" style={{ color: 'var(--text-secondary)' }}>
                Frame
              </h2>
              <div className="grid grid-cols-2 sm:grid-cols-4 gap-3">
                {FRAMES.map((frame) => (
                  <button
                    key={frame.id}
                    type="button"
                    onClick={() => setField('frame_id', frame.id)}
                    className={`rounded-xl p-3 text-left transition-all duration-200 border ${
                      design.frame_id === frame.id
                        ? 'shadow-lg scale-[1.02]'
                        : 'opacity-80 hover:opacity-100'
                    }`}
                    style={{
                      backgroundColor: frame.palette.outer,
                      borderColor: design.frame_id === frame.id ? frame.palette.border : 'transparent',
                      borderWidth: 2,
                    }}
                    aria-pressed={design.frame_id === frame.id}
                  >
                    <div
                      className="w-full h-8 rounded mb-2"
                      style={{
                        background: `linear-gradient(135deg, ${frame.palette.titleBar}, ${frame.palette.textBox})`,
                        border: `1px solid ${frame.palette.border}`,
                      }}
                    />
                    <span className="text-xs font-semibold block" style={{ color: frame.palette.titleText }}>
                      {frame.name}
                    </span>
                  </button>
                ))}
              </div>
            </section>

            {/* Artwork */}
            <section className="glass-panel rounded-2xl p-5">
              <h2 className="text-sm font-semibold uppercase tracking-wide mb-3" style={{ color: 'var(--text-secondary)' }}>
                Artwork
              </h2>
              <input
                ref={fileInputRef}
                type="file"
                accept="image/jpeg,image/png,image/webp"
                className="hidden"
                onChange={(e) => handleUpload(e.target.files?.[0])}
              />
              <div className="flex flex-wrap items-center gap-3">
                <Button variant="primary" onClick={() => fileInputRef.current?.click()} disabled={uploading}>
                  {uploading ? 'Uploading…' : design.artwork_url ? 'Replace Image' : 'Upload Image'}
                </Button>
                {design.artwork_url && (
                  <Button variant="secondary" onClick={() => setField('artwork_url', '')}>
                    Remove
                  </Button>
                )}
                <span className="text-xs" style={{ color: 'var(--text-secondary)' }}>
                  JPEG, PNG, or WebP · up to 5MB
                </span>
              </div>
            </section>

            {/* Details */}
            <section className="glass-panel rounded-2xl p-5 space-y-4">
              <h2 className="text-sm font-semibold uppercase tracking-wide" style={{ color: 'var(--text-secondary)' }}>
                Details
              </h2>

              <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
                <Field label="Title" required>
                  <input
                    className="input-field w-full"
                    value={design.name}
                    onChange={(e) => setField('name', e.target.value)}
                    placeholder="Emberwing Phoenix"
                    maxLength={60}
                  />
                </Field>
                <Field label="Cost" hint='e.g. "2RR" or "{2}{R}{R}"'>
                  <input
                    className="input-field w-full"
                    value={design.mana_cost}
                    onChange={(e) => setField('mana_cost', e.target.value)}
                    placeholder="2RR"
                    maxLength={24}
                  />
                </Field>
              </div>

              <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
                <Field label="Type">
                  <input
                    className="input-field w-full"
                    value={design.card_type}
                    onChange={(e) => setField('card_type', e.target.value)}
                    placeholder="Creature — Phoenix"
                    maxLength={80}
                  />
                </Field>
                <Field label="Rarity">
                  <div className="flex gap-2">
                    {RARITIES.map((rarity) => (
                      <button
                        key={rarity.id}
                        type="button"
                        onClick={() => setField('rarity', rarity.id)}
                        className={`flex-1 rounded-lg px-2 py-2 text-xs font-semibold transition-all duration-200 ${
                          design.rarity === rarity.id ? 'scale-105 shadow-md' : 'opacity-70 hover:opacity-100'
                        }`}
                        style={{
                          backgroundColor: 'var(--bg-tertiary)',
                          color: design.rarity === rarity.id ? rarity.color : 'var(--text-secondary)',
                          borderBottom: `3px solid ${rarity.color}`,
                        }}
                        aria-pressed={design.rarity === rarity.id}
                      >
                        {rarity.name}
                      </button>
                    ))}
                  </div>
                </Field>
              </div>

              <Field label="Description / Flavor">
                <textarea
                  className="input-field w-full resize-y"
                  rows={3}
                  value={design.rules_text}
                  onChange={(e) => setField('rules_text', e.target.value)}
                  placeholder="Flavor text or lore…"
                  maxLength={500}
                />
              </Field>

              <Field label="Actions / Abilities">
                <textarea
                  className="input-field w-full resize-y"
                  rows={3}
                  value={design.actions}
                  onChange={(e) => setField('actions', e.target.value)}
                  placeholder={'Flying, haste\nWhen Emberwing enters the battlefield, it deals 2 damage to any target.'}
                  maxLength={800}
                />
              </Field>

              <details className="text-sm" style={{ color: 'var(--text-secondary)' }}>
                <summary className="cursor-pointer select-none">Power / Toughness (optional)</summary>
                <div className="grid grid-cols-2 gap-4 mt-3">
                  <Field label="Power">
                    <input
                      className="input-field w-full"
                      value={design.power}
                      onChange={(e) => setField('power', e.target.value)}
                      placeholder="3"
                      maxLength={10}
                    />
                  </Field>
                  <Field label="Toughness">
                    <input
                      className="input-field w-full"
                      value={design.toughness}
                      onChange={(e) => setField('toughness', e.target.value)}
                      placeholder="4"
                      maxLength={10}
                    />
                  </Field>
                </div>
              </details>
            </section>
          </div>

          {/* ── Live preview column ─────────────────────── */}
          <div>
            <div className="sticky top-8 glass-panel rounded-2xl p-6">
              <h2 className="text-sm font-semibold uppercase tracking-wide mb-4" style={{ color: 'var(--text-secondary)' }}>
                Live Preview
              </h2>
              <CardPreview design={design} innerRef={cardRef} />
              <p className="text-xs mt-4 text-center" style={{ color: 'var(--text-secondary)' }}>
                Saved designs appear in{' '}
                <Link href="/my-designs" style={{ color: 'var(--accent-ember)' }}>My Designs</Link>{' '}
                and your collection.
              </p>
            </div>
          </div>
        </div>
      </div>
    </Layout>
  );
}

function Field({ label, hint, required, children }) {
  return (
    <label className="block">
      <span className="text-xs font-semibold mb-1.5 block" style={{ color: 'var(--text-primary)' }}>
        {label}
        {required && <span style={{ color: 'var(--accent-ember)' }}> *</span>}
        {hint && (
          <span className="font-normal ml-2" style={{ color: 'var(--text-secondary)' }}>
            ({hint})
          </span>
        )}
      </span>
      {children}
    </label>
  );
}