import { delivery as defaultDeliveryApi, ledger as defaultLedgerApi, stock as defaultStockApi } from '../api';
import artikelAutomat, { getArticle } from '../automats/artikelAutomat';
import articleIndexAutomat from '../automats/articleIndexAutomat';

/**
 * Determines whether a delivery line represents an article that tracks stock.
 *
 * @param {object} line Delivery line
 * @param {object|null} [article] Optional pre-resolved article
 * @returns {boolean}
 */
export function isLineStockTracked(line, article = null) {
  if (!line) return false;
  if (line.track_stock !== undefined) {
    return line.track_stock !== false && line.track_stock !== 0 && line.track_stock !== '0';
  }
  if (line.trackStock !== undefined) {
    return Boolean(line.trackStock);
  }
  if (line.article?.track_stock !== undefined) {
    return line.article.track_stock !== false && line.article.track_stock !== 0 && line.article.track_stock !== '0';
  }
  const sku = line.sku ? String(line.sku).trim() : null;
  if (!sku) return false;

  const art = article || getArticle(sku) || articleIndexAutomat.state.items?.find((item) => String(item.sku) === sku);
  if (art?.track_stock !== undefined) {
    return art.track_stock !== false && art.track_stock !== 0 && art.track_stock !== '0';
  }
  return false;
}

/**
 * @typedef {Object} DeliveryLineLedgerStatus
 * @property {number} id - Manifestarticle ID
 * @property {string} sku - Article SKU
 * @property {string} name - Article Name
 * @property {number} targetAmount - Expected delivery quantity
 * @property {number} bookedAmount - Quantity booked in ledger
 * @property {number} remainingAmount - Quantity remaining to be booked
 * @property {boolean} isBooked - Whether this position is fully booked
 * @property {boolean} trackStock - Whether this article tracks inventory
 * @property {boolean} isBookable - Whether this position can be booked into the warehouse
 * @property {Array<Object>} ledgerEntries - Ledger entries for this line
 */

/**
 * @typedef {Object} DeliveryLedgerSummary
 * @property {number} deliveryId
 * @property {Object} delivery - Full delivery object with lines
 * @property {'empty' | 'booked' | 'partial' | 'unbooked'} status
 * @property {number} totalPositions
 * @property {number} bookedPositions
 * @property {number} totalQuantity
 * @property {number} bookedQuantity
 * @property {boolean} hasTrackStock
 * @property {Array<DeliveryLineLedgerStatus>} lines
 */

/**
 * Fetches delivery lines and checks ledger entries for each line to compute the booking status.
 *
 * @param {number|string} deliveryId
 * @param {Object} [options]
 * @param {Object} [options.deliveryApi]
 * @param {Object} [options.ledgerApi]
 * @returns {Promise<DeliveryLedgerSummary>}
 */
export async function fetchDeliveryLedgerSummary(deliveryId, { deliveryApi = defaultDeliveryApi, ledgerApi = defaultLedgerApi } = {}) {
  const res = await deliveryApi.get(deliveryId);
  const delivery = res?.delivery ?? res;
  const rawLines = Array.isArray(delivery?.lines) ? delivery.lines : [];

  if (rawLines.length === 0) {
    return {
      deliveryId,
      delivery,
      status: 'empty',
      totalPositions: 0,
      bookedPositions: 0,
      totalQuantity: 0,
      bookedQuantity: 0,
      hasTrackStock: false,
      lines: [],
    };
  }

  // Fetch ledger entries for each line in parallel
  const linesWithLedger = await Promise.all(
    rawLines.map(async (line) => {
      let ledgerEntries = [];
      let article = null;

      const promises = [
        ledgerApi.listByManifestarticleId(line.id).catch((err) => {
          console.error(`[deliveryLedger] Failed to fetch ledger for line ${line.id}:`, err);
          return null;
        }),
      ];

      if (line.sku) {
        const cached = getArticle(line.sku);
        if (cached) {
          article = cached;
        } else {
          promises.push(
            artikelAutomat.actions.loadArticle(line.sku).catch(() => null)
          );
        }
      }

      const results = await Promise.all(promises);
      const ledgerRes = results[0];
      if (results[1]) {
        article = results[1];
      }
      ledgerEntries = Array.isArray(ledgerRes?.ledger) ? ledgerRes.ledger : [];

      const trackStock = isLineStockTracked(line, article);

      const deliveryEntries = ledgerEntries.filter((e) => {
        const t = String(e.transaction_type).toUpperCase();
        return t === 'ACCEPTANCE' || t === 'RETURN' || t === 'DELIVERY';
      });
      const bookedAmount = deliveryEntries.reduce((sum, e) => sum + Number(e.amount || 0), 0);
      const targetAmount = Number(line.amount || 0);
      const remainingAmount = Math.max(0, targetAmount - bookedAmount);
      const isBooked = targetAmount > 0 ? bookedAmount >= targetAmount : bookedAmount > 0;

      return {
        ...line,
        targetAmount,
        bookedAmount,
        remainingAmount,
        isBooked,
        trackStock,
        isBookable: true,
        ledgerEntries: deliveryEntries,
      };
    })
  );

  const totalPositions = linesWithLedger.length;
  const bookedPositions = linesWithLedger.filter((l) => l.isBooked).length;
  const totalQuantity = linesWithLedger.reduce((sum, l) => sum + l.targetAmount, 0);
  const bookedQuantity = linesWithLedger.reduce((sum, l) => sum + l.bookedAmount, 0);
  const hasTrackStock = linesWithLedger.some((l) => l.trackStock);

  let status;
  if (totalPositions === 0) {
    status = 'empty';
  } else if (bookedPositions === totalPositions && bookedQuantity >= totalQuantity) {
    status = 'booked';
  } else if (bookedPositions > 0 || bookedQuantity > 0) {
    status = 'partial';
  } else {
    status = 'unbooked';
  }

  return {
    deliveryId,
    delivery,
    status,
    totalPositions,
    bookedPositions,
    totalQuantity,
    bookedQuantity,
    hasTrackStock,
    lines: linesWithLedger,
  };
}

/**
 * Books specified delivery lines to the ledger as goods receipts via /stock/accept.
 *
 * @param {Object} params
 * @param {Object} params.delivery - The delivery object (used for transaction memo and fallback)
 * @param {Array<{ manifestarticleId?: number, id?: number, amount: number, sku?: string, trackStock?: boolean }>} params.linesToBook
 * @param {number|string} [params.warehouseId] - Warehouse ID (mandatory only when at least one line tracks stock)
 * @param {Object} [params.stockApi]
 * @param {string} [params.transactionText]
 * @returns {Promise<Array<Object>>}
 */
export async function bookDeliveryLines({
  delivery,
  linesToBook,
  warehouseId,
  stockApi = defaultStockApi,
  transactionText,
}) {
  if (!Array.isArray(linesToBook) || linesToBook.length === 0) {
    return [];
  }

  const numericWarehouseId = Number(warehouseId) || null;
  const hasTrackedLines = linesToBook.some((l) => l.trackStock);

  if (hasTrackedLines && (!numericWarehouseId || numericWarehouseId <= 0)) {
    throw new Error('Bitte wählen Sie ein Lager aus.');
  }

  const memo = String(
    transactionText != null && transactionText !== ''
      ? transactionText
      : `Lieferung ${delivery?.number || delivery?.id || ''}`
  ).trim();

  const items = linesToBook
    .map((item) => ({
      manifestarticleId: Number(item.manifestarticleId ?? item.id),
      warehouseId: numericWarehouseId,
      text: memo,
    }))
    .filter((item) => item.manifestarticleId && Number.isInteger(item.manifestarticleId) && item.manifestarticleId > 0);

  if (items.length === 0) {
    return [];
  }

  const res = await stockApi.accept({ items });

  for (const item of linesToBook) {
    if (item.sku) {
      void artikelAutomat.actions.reloadArticle(item.sku).catch(() => {});
    }
  }

  return Array.isArray(res?.accepted) ? res.accepted : (res ? [res] : []);
}