import { useEffect, useMemo, useState } from 'react';
import type { FormEvent } from 'react';
import { Link, useNavigate, useSearchParams } from 'react-router';
import { Alert, LoadingBlock, errorMessage } from '../components/Feedback';
import { Icon } from '../components/Icon';
import { getAsset } from '../lib/api';
import {
  createInventoryStructure,
  getInventoryFamilyFindings,
  getInventoryStructureOptions,
  listInventoryStructureParents,
} from '../lib/inventoryStructureApi';
import type {
  InventoryFamily,
  InventoryFamilyFindings,
  InventoryStructureKind,
  InventoryStructureOptions,
  InventoryStructureParent,
} from '../lib/inventoryStructureApi';

const KINDS: Array<{ kind: InventoryStructureKind; label: string; help: string; step: number }> = [
  { kind: 'AREA', label: 'Área', help: 'Nivel territorial raíz.', step: 1 },
  { kind: 'YACIMIENTO', label: 'Yacimiento', help: 'Debe pertenecer a un Área.', step: 2 },
  { kind: 'INSTALACION', label: 'Instalación', help: 'Debe pertenecer a un Yacimiento.', step: 3 },
  { kind: 'SUBINSTALACION', label: 'Subinstalación', help: 'Debe pertenecer a una Instalación.', step: 4 },
];

const childKindByParentType: Record<string, InventoryStructureKind | undefined> = {
  area: 'YACIMIENTO',
  yacimiento: 'INSTALACION',
  instalacion: 'SUBINSTALACION',
};

function kindLabel(kind: InventoryStructureKind): string {
  return KINDS.find((item) => item.kind === kind)?.label ?? kind;
}

export function InventoryCreatePage() {
  const navigate = useNavigate();
  const [searchParams] = useSearchParams();
  const contextParentId = searchParams.get('parentId');
  const [options, setOptions] = useState<InventoryStructureOptions | null>(null);
  const [kind, setKind] = useState<InventoryStructureKind>('AREA');
  const [parents, setParents] = useState<InventoryStructureParent[]>([]);
  const [parentSearch, setParentSearch] = useState('');
  const [parentId, setParentId] = useState('');
  const [familyId, setFamilyId] = useState('');
  const [familyFindings, setFamilyFindings] = useState<InventoryFamilyFindings | null>(null);
  const [code, setCode] = useState('');
  const [name, setName] = useState('');
  const [commonName, setCommonName] = useState('');
  const [description, setDescription] = useState('');
  const [loading, setLoading] = useState(true);
  const [saving, setSaving] = useState(false);
  const [error, setError] = useState('');

  useEffect(() => {
    getInventoryStructureOptions()
      .then(async (loaded) => {
        setOptions(loaded);
        if (contextParentId) {
          const parent = await getAsset(contextParentId);
          const inferred = childKindByParentType[parent.type.code.toLowerCase()];
          if (inferred) {
            setKind(inferred);
            setParentId(parent.id);
          }
        }
      })
      .catch((requestError) => setError(errorMessage(requestError)))
      .finally(() => setLoading(false));
  }, [contextParentId]);

  useEffect(() => {
    if (kind === 'AREA') {
      setParents([]);
      setParentId('');
      return;
    }
    const timer = window.setTimeout(() => {
      listInventoryStructureParents(kind, parentSearch)
        .then((loaded) => {
          setParents(loaded);
          if (contextParentId && loaded.some((item) => item.id === contextParentId)) {
            setParentId(contextParentId);
          }
        })
        .catch((requestError) => setError(errorMessage(requestError)));
    }, 180);
    return () => window.clearTimeout(timer);
  }, [kind, parentSearch, contextParentId]);

  const selectedParent = parents.find((item) => item.id === parentId) ?? null;
  const families = useMemo(() => {
    if (!options) return [] as InventoryFamily[];
    if (kind === 'INSTALACION') return options.installationFamilies;
    if (kind === 'SUBINSTALACION') {
      const parentFamilyId = selectedParent?.inventoryFamily?.id;
      return parentFamilyId
        ? options.subinstallationFamilies.filter((item) => item.parentFamilyId === parentFamilyId)
        : [];
    }
    return [];
  }, [options, kind, selectedParent]);
  const selectedFamily = families.find((item) => item.id === familyId) ?? null;

  useEffect(() => {
    if (!familyId) {
      setFamilyFindings(null);
      return;
    }
    getInventoryFamilyFindings(familyId)
      .then(setFamilyFindings)
      .catch((requestError) => setError(errorMessage(requestError)));
  }, [familyId]);

  useEffect(() => {
    if (kind !== 'INSTALACION' && kind !== 'SUBINSTALACION') setFamilyId('');
    if (kind === 'SUBINSTALACION' && familyId && !families.some((item) => item.id === familyId)) setFamilyId('');
  }, [kind, familyId, families]);

  const chooseKind = (next: InventoryStructureKind) => {
    setKind(next);
    setParentId('');
    setParentSearch('');
    setFamilyId('');
    setFamilyFindings(null);
    setError('');
  };

  const save = async (event: FormEvent) => {
    event.preventDefault();
    const requiresParent = kind !== 'AREA';
    const requiresFamily = kind === 'INSTALACION' || kind === 'SUBINSTALACION';
    if (requiresParent && !parentId) {
      setError(`Seleccioná el ${kind === 'YACIMIENTO' ? 'Área' : kind === 'INSTALACION' ? 'Yacimiento' : 'Instalación'} padre.`);
      return;
    }
    if (requiresFamily && !familyId) {
      setError(`Seleccioná la familia de ${kindLabel(kind).toLowerCase()}.`);
      return;
    }
    setSaving(true);
    setError('');
    try {
      const created = await createInventoryStructure({
        kind,
        code: code.trim() || null,
        name: name.trim(),
        commonName: commonName.trim() || null,
        parentId: parentId || null,
        familyId: familyId || null,
        description: description.trim() || null,
      });
      navigate(`/inventarios/${created.id}`, { replace: true });
    } catch (requestError) {
      setError(errorMessage(requestError));
    } finally {
      setSaving(false);
    }
  };

  if (loading) return <LoadingBlock label="Preparando alta de Inventario…" />;

  const parentLabel = kind === 'YACIMIENTO' ? 'Área' : kind === 'INSTALACION' ? 'Yacimiento' : 'Instalación';
  const currentStep = KINDS.find((item) => item.kind === kind)?.step ?? 1;

  return <section className="narrow-section asset-detail-page">
    <nav className="breadcrumb asset-detail-breadcrumb" aria-label="Ruta del inventario">
      <Link to="/inventarios">Inventarios</Link><span>›</span><strong>Nuevo registro</strong>
    </nav>

    <div className="page-heading asset-editor-heading">
      <div>
        <span className="eyebrow">INVENTARIO</span>
        <h1>Agregar a la estructura</h1>
        <p>La estructura oficial es Área → Yacimiento → Instalación → Subinstalación. Elegí el nivel y el sistema te guía con los vínculos válidos.</p>
      </div>
    </div>

    {error && <Alert>{error}</Alert>}

    <div className="panel" style={{ marginBottom: 18 }}>
      <div className="form-section">
        <div><h2>1. ¿Qué querés crear?</h2><p className="section-copy">Sólo se pueden crear los cuatro niveles estructurales definidos para DH.</p></div>
        <div style={{ display: 'grid', gridTemplateColumns: 'repeat(4, minmax(0, 1fr))', gap: 10 }}>
          {KINDS.map((item) => <button
            key={item.kind}
            type="button"
            className={`button ${kind === item.kind ? 'primary' : 'secondary'}`}
            onClick={() => chooseKind(item.kind)}
            style={{ minHeight: 76, display: 'flex', flexDirection: 'column', alignItems: 'flex-start', justifyContent: 'center', gap: 3 }}
          >
            <strong>{item.step}. {item.label}</strong>
            <small>{item.help}</small>
          </button>)}
        </div>
        <div className="temporal-notice" style={{ marginTop: 12 }}>
          <Icon name="layers" />
          <p><strong>Ruta:</strong> {KINDS.slice(0, currentStep).map((item) => item.label).join(' → ')}</p>
        </div>
      </div>
    </div>

    <form className="panel form-panel" onSubmit={save}>
      {kind !== 'AREA' && <div className="form-section">
        <div><h2>2. Ubicación en la estructura</h2><p className="section-copy">Primero elegí el {parentLabel} al que pertenece este registro.</p></div>
        <label className="field">
          <span>Buscar {parentLabel.toLowerCase()}</span>
          <input value={parentSearch} onChange={(event) => setParentSearch(event.target.value)} placeholder={`Buscar por nombre o código de ${parentLabel.toLowerCase()}…`} />
        </label>
        <label className="field">
          <span>{parentLabel} padre <em>obligatorio</em></span>
          <select value={parentId} onChange={(event) => { setParentId(event.target.value); setFamilyId(''); }} required>
            <option value="">Seleccionar {parentLabel.toLowerCase()}…</option>
            {parents.map((parent) => <option key={parent.id} value={parent.id}>{parent.name} · {parent.code}{parent.inventoryFamily ? ` · ${parent.inventoryFamily.name}` : ''}</option>)}
          </select>
          <small>No se permiten saltos de nivel ni padres incompatibles.</small>
        </label>
      </div>}

      {(kind === 'INSTALACION' || kind === 'SUBINSTALACION') && <div className="form-section">
        <div><h2>3. Familia técnica</h2><p className="section-copy">La familia no crea otro nivel. Sirve para aplicar exactamente los Hallazgos del Excel que corresponden.</p></div>
        {kind === 'SUBINSTALACION' && !selectedParent?.inventoryFamily ? <Alert>La Instalación seleccionada todavía no tiene una familia técnica F3.1. Revisala antes de crear una Subinstalación.</Alert> : <label className="field">
          <span>Familia de {kindLabel(kind).toLowerCase()} <em>obligatorio</em></span>
          <select value={familyId} onChange={(event) => setFamilyId(event.target.value)} required>
            <option value="">Seleccionar familia…</option>
            {families.map((family) => <option key={family.id} value={family.id}>{family.name}</option>)}
          </select>
          {kind === 'SUBINSTALACION' && selectedParent?.inventoryFamily && <small>Se muestran sólo las subinstalaciones válidas para {selectedParent.inventoryFamily.name}.</small>}
        </label>}

        {selectedFamily && <div className="context-create-banner" style={{ alignItems: 'flex-start' }}>
          <Icon name="alert" />
          <div style={{ flex: 1 }}>
            <strong>Hallazgos asociados automáticamente</strong>
            <span>{familyFindings ? `${familyFindings.count} controles del Excel para ${selectedFamily.name}` : 'Cargando catálogo asociado…'}</span>
            {familyFindings && familyFindings.items.length > 0 && <ul style={{ margin: '8px 0 0', paddingLeft: 18 }}>
              {familyFindings.items.slice(0, 7).map((item) => <li key={item.id}>{item.title}</li>)}
              {familyFindings.items.length > 7 && <li><strong>+ {familyFindings.items.length - 7} hallazgos más</strong></li>}
            </ul>}
          </div>
        </div>}

        {selectedFamily && selectedFamily.informationLabels.length > 0 && <div className="temporal-notice">
          <Icon name="clipboard" />
          <p><strong>Información técnica esperada:</strong> {selectedFamily.informationLabels.join(' · ')}</p>
        </div>}
      </div>}

      <div className="form-section">
        <div><h2>{kind === 'AREA' ? '2' : kind === 'YACIMIENTO' ? '3' : '4'}. Identificación</h2><p className="section-copy">Usá el nombre real de campo. El código DH puede generarse automáticamente.</p></div>
        <div className="form-grid">
          <label className="field"><span>Nombre <em>obligatorio</em></span><input value={name} onChange={(event) => setName(event.target.value)} required maxLength={200} placeholder={`Nombre de ${kindLabel(kind).toLowerCase()}`} /></label>
          <label className="field"><span>Código DH <em>opcional</em></span><input value={code} onChange={(event) => setCode(event.target.value.toUpperCase())} maxLength={120} pattern="[A-Z0-9][A-Z0-9._/-]*" placeholder="Dejar vacío para generar automáticamente" /><small>Si no lo informás, DH genera un código único.</small></label>
          <label className="field"><span>Nombre habitual / sobrenombre <em>opcional</em></span><input value={commonName} onChange={(event) => setCommonName(event.target.value)} maxLength={200} placeholder="Nombre usado por los inspectores en campo" /></label>
        </div>
        <label className="field"><span>Descripción <em>opcional</em></span><textarea value={description} onChange={(event) => setDescription(event.target.value)} rows={2} maxLength={4000} /></label>
      </div>

      <div className="form-actions">
        <Link className="button secondary" to="/inventarios">Cancelar</Link>
        <button className="button primary" disabled={saving || !name.trim() || (kind !== 'AREA' && !parentId) || ((kind === 'INSTALACION' || kind === 'SUBINSTALACION') && !familyId)}>
          <Icon name="check" />{saving ? 'Creando…' : `Crear ${kindLabel(kind)}`}
        </button>
      </div>
    </form>
  </section>;
}