import { useEffect, useState } from 'react';
import { Link, useSearchParams } from 'react-router';
import { useAuth } from '../../auth/AuthContext';
import { Alert, EmptyState, LoadingBlock, errorMessage } from '../../components/Feedback';
import { Icon } from '../../components/Icon';
import { getAssetLineage } from '../../lib/api';
import type { AssetLineageItem, AssetType } from '../../lib/api';
import {
  listInventoryCompanies,
  listInventoryDepartments,
  listInventoryChildren,
} from '../../lib/inventoryBrowserApi';
import type {
  InventoryBrowserCompany,
  InventoryBrowserDepartment,
  InventoryBrowserItem,
  InventoryQuery,
} from '../../lib/inventoryBrowserApi';
import { assetOperationalStatusLabel, assetStatusClass, assetStatusLabel } from './assetPresentation';

const structuredInventorySections = [
  {
    code: 'empresa',
    label: 'Empresas',
    description: 'Maestro de empresas operadoras. Se vinculan a una o más Áreas sin formar parte del árbol territorial.',
    icon: 'users' as const,
  },
  {
    code: 'departamento',
    label: 'Departamentos',
    description: 'Primer nivel territorial. Desde cada Departamento se accede a sus Áreas.',
    icon: 'map' as const,
  },
  {
    code: 'area',
    label: 'Áreas',
    description: 'Cada Área pertenece a un Departamento y puede tener una o más Empresas operadoras vinculadas.',
    icon: 'map' as const,
  },
  {
    code: 'yacimiento',
    label: 'Yacimientos',
    description: 'Nivel operativo dentro de un Área. Organiza las Instalaciones que pertenecen a ese Yacimiento.',
    icon: 'map' as const,
  },
  {
    code: 'instalacion',
    label: 'Instalaciones',
    description: 'Elementos técnicos ubicados dentro de un Yacimiento y clasificados por su familia de Inventario.',
    icon: 'layers' as const,
  },
  {
    code: 'subinstalacion',
    label: 'Subinstalaciones',
    description: 'Último nivel estructural. Dependen de una Instalación y conservan su clasificación técnica.',
    icon: 'layers' as const,
  },
] as const;

function navigationHref(base: URLSearchParams, parentId?: string) {
  const params = new URLSearchParams(base);
  params.delete('view');
  params.delete('page');
  params.delete('section');
  params.delete('companyId');
  params.delete('typeId');
  parentId ? params.set('parentId', parentId) : params.delete('parentId');
  return `/inventarios${params.size ? `?${params}` : ''}`;
}

function inventoryTypeForSection(types: AssetType[], code: string) {
  if (code === 'empresa') return types.find((type) => type.operationalRole === 'COMPANY') ?? null;
  return types.find((type) => type.code.toLowerCase() === code) ?? null;
}

function DepartmentCard({ department, href }: { department: InventoryBrowserDepartment; href: string }) {
  return <Link className="asset-browser-item" to={href}>
    <span className="asset-browser-item-icon"><Icon name="map" size={17} /></span>
    <span className="asset-browser-item-main">
      <strong>{department.name}</strong>
      <small>{department.code} · {department.areaCount} Área{department.areaCount === 1 ? '' : 's'}</small>
    </span>
    <span className="asset-browser-item-status"><span className={`status-badge ${assetStatusClass(department.informationStatus)}`}>{assetStatusLabel(department.informationStatus)}</span></span>
    <Icon name="chevron" size={16} />
  </Link>;
}

function CompanyCard({ company }: { company: InventoryBrowserCompany }) {
  return <Link className="asset-browser-item" to={`/inventarios/${company.id}`}>
    <span className="asset-browser-item-icon"><Icon name="users" size={17} /></span>
    <span className="asset-browser-item-main"><strong>{company.name}</strong><small>{company.code} · {company.areaCount} Área{company.areaCount === 1 ? '' : 's'} operada{company.areaCount === 1 ? '' : 's'}</small></span>
    <span className="asset-browser-item-status"><span className={`status-badge ${assetStatusClass(company.informationStatus)}`}>{assetStatusLabel(company.informationStatus)}</span></span>
    <Icon name="chevron" size={16} />
  </Link>;
}

function InventoryCard({ item, href }: { item: InventoryBrowserItem; href: string }) {
  return <Link className="asset-browser-item" to={href}>
    <span className="asset-browser-item-icon"><Icon name={['departamento','area','yacimiento'].includes(item.type.code.toLowerCase()) ? 'map' : 'layers'} size={17} /></span>
    <span className="asset-browser-item-main">
      <strong>{item.name}</strong>
      <small>
        {item.code} · {item.type.name}
        {item.inventoryFamily ? ` · ${item.inventoryFamily.name}` : ''}
        {item.commonName ? ` · ${item.commonName}` : ''}
      </small>
    </span>
    <span className="asset-browser-item-status">
      <span className={`status-badge ${assetStatusClass(item.informationStatus)}`}>{assetStatusLabel(item.informationStatus)}</span>
      {item.inventoryFamily
        ? <small>{item.findingCount} Hallazgo{item.findingCount === 1 ? '' : 's'} asociado{item.findingCount === 1 ? '' : 's'}</small>
        : <small>{item.childrenCount} registro{item.childrenCount === 1 ? '' : 's'} inferior{item.childrenCount === 1 ? '' : 'es'}</small>}
    </span>
    <Icon name="chevron" size={16} />
  </Link>;
}

function nextLevelLabel(typeCode: string | undefined) {
  switch (typeCode?.toLowerCase()) {
    case 'departamento': return 'Áreas';
    case 'area': return 'Yacimientos';
    case 'yacimiento': return 'Instalaciones';
    case 'instalacion': return 'Subinstalaciones';
    default: return 'Niveles inferiores';
  }
}

export function AssetHierarchyView({ filters, types }: { filters: InventoryQuery; types: AssetType[] }) {
  const { hasPermission } = useAuth();
  const canCreate = hasPermission('assets.create');
  const [searchParams] = useSearchParams();
  const parentId = searchParams.get('parentId') ?? '';
  const [departments, setDepartments] = useState<InventoryBrowserDepartment[]>([]);
  const [companies, setCompanies] = useState<InventoryBrowserCompany[]>([]);
  const [children, setChildren] = useState<InventoryBrowserItem[]>([]);
  const [lineage, setLineage] = useState<AssetLineageItem[]>([]);
  const [hasMore, setHasMore] = useState(false);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');

  useEffect(() => {
    let active = true;
    setLoading(true); setError(''); setDepartments([]); setCompanies([]); setChildren([]); setLineage([]); setHasMore(false);
    const run = async () => {
      if (!parentId) {
        const [loadedDepartments, loadedCompanies] = await Promise.all([
          listInventoryDepartments({ search: filters.search, operatorCompanyId: filters.operatorCompanyId }),
          listInventoryCompanies({ search: filters.search }),
        ]);
        if (active) { setDepartments(loadedDepartments.data); setCompanies(loadedCompanies.data); }
        return;
      }
      const [loadedLineage, response] = await Promise.all([
        getAssetLineage(parentId),
        listInventoryChildren(parentId, { search: filters.search }),
      ]);
      if (!active) return;
      setLineage(loadedLineage.filter((item) => ['departamento','area','yacimiento','instalacion','subinstalacion'].includes(item.type.code.toLowerCase())));
      setChildren(response.data); setHasMore(response.meta.hasMore);
    };
    run().catch((requestError) => active && setError(errorMessage(requestError))).finally(() => active && setLoading(false));
    return () => { active = false; };
  }, [parentId, filters.search, filters.operatorCompanyId]);

  if (loading) return <LoadingBlock label="Cargando Inventarios…" />;

  if (!parentId) {
    return <div className="asset-browser-panel">
      {error && <Alert>{error}</Alert>}
      <div className="asset-browser-section-heading">
        <div>
          <span className="eyebrow">INVENTARIOS ESTRUCTURADOS</span>
          <h2>Elegí qué querés administrar</h2>
          <p>La estructura queda fija y fácil de leer: Empresas como maestro de operadoras y, por separado, Departamento → Área → Yacimiento → Instalación → Subinstalación.</p>
        </div>
        <div className="asset-browser-current-actions"><span className="count-pill">{departments.length} Departamentos</span><span className="count-pill">{companies.length} Empresas</span></div>
      </div>

      <div className="asset-browser-list" aria-label="Secciones estructuradas de Inventarios">
        {structuredInventorySections.map((section, index) => {
          const assetType = inventoryTypeForSection(types, section.code);
          const content = <>
            <span className="asset-browser-item-icon"><Icon name={section.icon} size={17} /></span>
            <span className="asset-browser-item-main">
              <strong>{section.label}</strong>
              <small>{section.description}</small>
            </span>
            <span className="asset-browser-item-status"><small>{section.code === 'empresa' ? 'Maestro independiente' : `Nivel ${index}`}</small></span>
            {assetType && <Icon name="chevron" size={16} />}
          </>;
          return assetType
            ? <Link key={section.code} className="asset-browser-item" to={`/inventarios?view=list&typeId=${assetType.id}`}>{content}</Link>
            : <div key={section.code} className="asset-browser-item" aria-disabled="true">{content}</div>;
        })}
      </div>

      <div className="asset-browser-levels" aria-label="Jerarquía territorial de Inventarios">
        <div><span>1</span><strong>Departamento</strong><small>raíz territorial</small></div><i>›</i>
        <div><span>2</span><strong>Área</strong><small>operadoras vinculadas</small></div><i>›</i>
        <div><span>3</span><strong>Yacimiento</strong><small>dentro del Área</small></div><i>›</i>
        <div><span>4</span><strong>Instalación</strong><small>clasificación técnica</small></div><i>›</i>
        <div><span>5</span><strong>Subinstalación</strong><small>clasificación técnica</small></div>
      </div>

      <section className="asset-browser-group" style={{ marginTop: 20 }}>
        <div className="asset-browser-group-heading">
          <div><h3>Recorrido por territorio</h3><p>También podés navegar como árbol: entrá por un Departamento y descendé hasta la Instalación o Subinstalación concreta.</p></div>
          <span>{departments.length}</span>
        </div>
        {departments.length === 0
          ? <EmptyState title="Todavía no hay Departamentos" text="Creá el primer registro para comenzar a construir el Inventario manualmente." />
          : <div className="asset-browser-list">{departments.map((department) => <DepartmentCard key={department.id} department={department} href={navigationHref(searchParams, department.id)} />)}</div>}
      </section>
    </div>;
  }

  const current = lineage.at(-1) ?? null;
  const breadcrumb = <nav className="asset-browser-breadcrumb" aria-label="Ruta del Inventario">
    <Link to="/inventarios">Inventarios</Link>
    {lineage.map((item,index) => {
      const isLast=index===lineage.length-1;
      return <span className="asset-browser-crumb-part" key={item.id}><span>›</span>{isLast ? <strong>{item.name}</strong> : <Link to={navigationHref(searchParams,item.id)}>{item.name}</Link>}</span>;
    })}
  </nav>;

  return <div className="asset-browser-panel">
    {breadcrumb}
    {error && <Alert>{error}</Alert>}
    {hasMore && <Alert type="info">Este nivel tiene más de 200 registros. Usá la búsqueda para acotar el resultado.</Alert>}
    <div className="asset-browser-current-heading">
      <div><span className="eyebrow">{current?.type.name ?? 'INVENTARIO'}</span><h2>{current?.name ?? 'Nivel de Inventario'}</h2><p>{current?.code ?? ''}</p></div>
      <div className="asset-browser-current-actions">
        {current && <Link className="button secondary" to={`/inventarios/${current.id}`}>Ver ficha{['instalacion','subinstalacion'].includes(current.type.code.toLowerCase()) ? ' y Hallazgos' : ''}</Link>}
        {canCreate && current?.type.code.toLowerCase() !== 'subinstalacion' && <Link className="button primary" to={`/inventarios/nuevo?parentId=${parentId}`}><Icon name="plus" />Agregar aquí</Link>}
      </div>
    </div>

    <section className="asset-browser-group">
      <div className="asset-browser-group-heading"><div><h3>{nextLevelLabel(current?.type.code)}</h3><p>Jerarquía: Departamento → Área → Yacimiento → Instalación → Subinstalación.</p></div><span>{children.length}</span></div>
      {children.length === 0
        ? <EmptyState title={current?.type.code.toLowerCase() === 'subinstalacion' ? 'Fin de la jerarquía' : 'No hay registros en este nivel'} text={current?.type.code.toLowerCase() === 'subinstalacion' ? 'Abrí la ficha para ver su clasificación y Hallazgos asociados.' : 'Agregá el primer registro de este nivel o revisá la búsqueda actual.'} />
        : <div className="asset-browser-list">{children.map((item) => <InventoryCard key={item.id} item={item} href={navigationHref(searchParams,item.id)} />)}</div>}
    </section>
  </div>;
}