import { inventoryTypeLabel, type InventoryFilters, type VehicleModalSelection } from '../../model';
import type { RegionalInventoryStats } from '../../types';
import { inventoryKey } from '../../../../shared/assets/inventory';

const BRAND_ORDER = ['现代', '帕力安', '宇通', '飞驰', '跃进'];
const normalizeBrand = (brand: string) => brand.trim().replace(/牌$/, '');

function compareInventoryBrand(left: string, right: string) {
  const rank = (brand: string) => {
    const normalized = normalizeBrand(brand);
    if (!normalized || normalized === '其他') return BRAND_ORDER.length + 1;
    const index = BRAND_ORDER.indexOf(normalized);
    return index < 0 ? BRAND_ORDER.length : index;
  };
  return rank(left) - rank(right);
}

export function inventoryTotal(rows: RegionalInventoryStats[]) {
  return rows.reduce((total, row) => total + row.quantity, 0);
}

/** Decompose display text only; never change the model used for drilldown. */
export function inventoryModelTags(row: Pick<RegionalInventoryStats, 'type' | 'model' | 'batch'> & Partial<Pick<RegionalInventoryStats, 'brand'>>) {
  const tags: { kind: 'type' | 'model' | 'detail' | 'batch'; label: string; value: string }[] = [];
  const type = inventoryTypeLabel(row.type.trim());
  const model = row.model.trim();
  const details = Array.from(model.matchAll(/[（(]([^（）()]+)[）)]/g), match => match[1].trim()).filter(Boolean);
  const base = model.replace(/[（(]([^（）()]+)[）)]/g, '').trim();
  // The type already has its own tag, so avoid repeating it in the model tag.
  let compactModel = (type ? base.replace(type, '') : base).trim();
  // Alias model names can say “现代” even when the separate brand is “帕力安牌”.
  // Strip only a leading brand, preserving body style, color and qualifiers.
  const brands = [...new Set([row.brand || '', normalizeBrand(row.brand || ''), ...BRAND_ORDER, '帕力安牌'])]
    .filter(brand => brand && brand !== '其他').sort((a, b) => b.length - a.length);
  const prefix = brands.find(brand => compactModel.startsWith(brand));
  if (prefix) compactModel = compactModel.slice(prefix.length).replace(/^[\s-]+/, '').trim();
  if (type) tags.push({ kind: 'type', label: '车型', value: type });
  if (compactModel) tags.push({ kind: 'model', label: '型号', value: compactModel });
  for (const value of new Set(details)) tags.push({ kind: 'detail', label: '型号说明', value });
  const batch = row.batch?.trim();
  // The current API aliases batch to model; only render genuinely distinct values.
  if (batch && batch !== model) tags.push({ kind: 'batch', label: '批次', value: batch });
  return tags;
}

/** Preserve the displayed scope when opening a filtered total or group. */
export function inventorySelection(filters: InventoryFilters, title: string, overrides: Partial<VehicleModalSelection> = {}): VehicleModalSelection {
  return {
    batch: 'All', model: filters.model || 'All',
    location: filters.city || filters.region || 'All',
    brand: filters.brand || undefined, vehicleType: inventoryTypeLabel(filters.type) === '其他' ? '库存其他' : filters.type || undefined,
    category: 'Inventory', source: 'asset', title, ...overrides,
  };
}

export function inventorySubtotalSelection(rows: RegionalInventoryStats[], label: string, category: 'Inventory' | 'Abnormal' = 'Inventory'): VehicleModalSelection {
  const common = (key: 'region' | 'city' | 'brand' | 'type') => rows.length && rows.every(row => row[key] === rows[0][key]) ? rows[0][key] : '';
  const scope = [...new Set([common('region'), common('city'), common('brand'), common('type'), label].filter(Boolean))].join(' · ');
  return {
    batch: 'All', model: 'All', location: 'All', source: 'asset', category,
    inventoryKeys: [...new Set(rows.map(inventoryKey))],
    title: `库存统计 · ${scope}`, scopeLabel: category === 'Abnormal'
      ? `${scope} · 异动 ${rows.reduce((sum, row) => sum + (row.abnormal ?? 0), 0)} 台`
      : `${scope} · 合计 ${inventoryTotal(rows)} 台`,
  };
}

export interface InventoryDisplayGroup {
  name: string;
  sections: [string, RegionalInventoryStats[]][];
  rows: RegionalInventoryStats[];
  quantity: number;
}

/** Keep each category's regions contiguous so only the first city renders its region cell. */
export function inventoryRegionRows(rows: RegionalInventoryStats[]) {
  const regions = new Map<string, RegionalInventoryStats[]>();
  for (const row of rows) {
    const records = regions.get(row.region) || [];
    records.push(row);
    regions.set(row.region, records);
  }
  return [...regions.values()].flatMap(records => records.map((row, index) => ({
    row, regionSpan: index === 0 ? records.length : 0,
  })));
}

/** Group presentation only: keep each original record for quantity and drilldown. */
export function inventoryBrandGroups(rows: RegionalInventoryStats[], groupBy: 'type' | 'model') {
  const brands = new Map<string, { brand: string; rows: RegionalInventoryStats[]; variants: Map<string, RegionalInventoryStats[]> }>();
  for (const row of rows) {
    const key = normalizeBrand(row.brand);
    let brand = brands.get(key);
    if (!brand) {
      brand = { brand: row.brand, rows: [], variants: new Map() };
      brands.set(key, brand);
    }
    brand.rows.push(row);
    const variantKey = groupBy === 'type' ? inventoryTypeLabel(row.type) : JSON.stringify([row.type, row.model, row.batch]);
    const variant = brand.variants.get(variantKey) || [];
    variant.push(row);
    brand.variants.set(variantKey, variant);
  }
  return [...brands.values()].sort((a, b) => compareInventoryBrand(a.brand, b.brand))
    .map(brand => ({ ...brand, variants: [...brand.variants.values()] }));
}

export function inventoryMobileRows(group: InventoryDisplayGroup, tab: 'region' | 'model') {
  const sections = tab === 'region' ? group.sections : [[group.name, group.rows] as const];
  return sections.flatMap(([, rows]) => inventoryBrandGroups(rows, tab === 'region' ? 'type' : 'model')
    .flatMap(brand => brand.variants.flatMap(variants => tab === 'model'
      ? inventoryRegionRows(variants).map(({ row }) => row) : variants)));
}

/** Each level is a subtotal within its parent, across all pages of the filtered list. */
export function inventoryHierarchy(row: RegionalInventoryStats, rows: RegionalInventoryStats[], tab: 'region' | 'model') {
  const cityRows = rows.filter(item => item.region === row.region && item.city === row.city);
  const brandRows = (tab === 'region' ? cityRows : rows).filter(item => normalizeBrand(item.brand) === normalizeBrand(row.brand));
  const variantRows = brandRows.filter(item => tab === 'region'
    ? inventoryTypeLabel(item.type) === inventoryTypeLabel(row.type)
    : item.type === row.type && item.model === row.model && item.batch === row.batch);
  const levels = tab === 'region'
    ? [{ label: row.city || '未分配', rows: cityRows }, { label: row.brand || '未分配品牌', rows: brandRows }, { label: inventoryTypeLabel(row.type) || '未分类', rows: variantRows }]
    : [{ label: row.brand || '未分配品牌', rows: brandRows }, { label: inventoryModelTags(row).filter(tag => tag.kind !== 'type').map(tag => tag.value).join(' · ') || '未分类', rows: variantRows }, { label: row.region || '未分配', rows: variantRows.filter(item => item.region === row.region) }];
  return levels.map(level => ({ ...level, quantity: inventoryTotal(level.rows) }));
}

export type InventoryMobileDimension = 'region' | 'city' | 'type' | 'variant';

/** One dimension per screen. Every child retains exact records from its parent. */
export function inventoryMobileGroups(rows: RegionalInventoryStats[], dimension: InventoryMobileDimension) {
  const groups = new Map<string, { key: string; label: string; rows: RegionalInventoryStats[] }>();
  for (const row of rows) {
    const key = dimension === 'variant'
      ? JSON.stringify([normalizeBrand(row.brand), row.type, row.model, row.batch])
      : dimension === 'type' ? inventoryTypeLabel(row.type) : row[dimension];
    const qualifiers = dimension === 'variant' ? inventoryModelTags(row).filter(tag => tag.kind !== 'type').map(tag => tag.value).join(' · ') : '';
    const label = dimension === 'variant'
      ? [row.brand || '未分配品牌', qualifiers || row.model || '未分配型号'].join(' · ')
      : key || (dimension === 'type' ? '未分类车型' : `未分配${dimension === 'city' ? '城市' : '区域'}`);
    const group = groups.get(key) || { key, label, rows: [] };
    group.rows.push(row);
    groups.set(key, group);
  }
  return [...groups.values()].map(group => ({ ...group, quantity: inventoryTotal(group.rows) }));
}

export function inventoryMobileDrilldown(rows: RegionalInventoryStats[], tab: 'region' | 'model', path: string[]) {
  const dimensions: InventoryMobileDimension[] = tab === 'region' ? ['city', 'type', 'variant'] : ['region', 'city', 'variant'];
  const parents: ReturnType<typeof inventoryMobileGroups> = [];
  let currentRows = rows;
  for (const key of path.slice(0, dimensions.length - 1)) {
    const parent = inventoryMobileGroups(currentRows, dimensions[parents.length]).find(group => group.key === key);
    if (!parent) break;
    parents.push(parent);
    currentRows = parent.rows;
  }
  const dimension = dimensions[parents.length];
  return { parents, rows: currentRows, dimension, groups: inventoryMobileGroups(currentRows, dimension) };
}

export function inventoryPage<T>(rows: T[], requestedPage: number) {
  const pageSize = 6;
  const pageCount = Math.max(1, Math.ceil(rows.length / pageSize));
  const page = Math.max(0, Math.min(requestedPage, pageCount - 1));
  return { page, pageCount, start: page * pageSize, rows: rows.slice(page * pageSize, (page + 1) * pageSize) };
}

export function inventoryGroups(source: Record<string, Record<string, RegionalInventoryStats[]>>, sort: 'default' | 'quantity', groupBy: 'region' | 'model' = 'region'): InventoryDisplayGroup[] {
  const groups = Object.entries(source).map(([name, children]) => {
    const sections: InventoryDisplayGroup['sections'] = Object.entries(children).map(([section, records]) => [
      section, [...records].sort((a, b) => compareInventoryBrand(a.brand, b.brand)),
    ]);
    // Keep city blocks intact; in the type view order whole model blocks by brand.
    if (groupBy === 'model') sections.sort(([, a], [, b]) => compareInventoryBrand(a[0]?.brand || '', b[0]?.brand || ''));
    const rows = sections.flatMap(([, records]) => records);
    return { name, sections, rows, quantity: inventoryTotal(rows) };
  });
  return sort === 'quantity' ? groups.sort((a, b) => b.quantity - a.quantity) : groups;
}