'use server';

import { db } from '@/db';
import { transactions, assets, exchangeRates } from '@/db/schema';
import Big from 'big.js';
import { desc, eq } from 'drizzle-orm';

interface Position {
  assetId: string;
  symbol: string;
  type: string;
  quantity: string;
  baseCurrency: string;
  cnyValue: string;
  totalCostCny: string;
  pnlCny: string;
  totalCostNative: string;
  pnlNative: string;
}

interface RawRate {
  fromCurrency: string;
  toCurrency: string;
  rate: string;
}

function buildRateMap(rates: RawRate[]): Map<string, string> {
  const map = new Map<string, string>();
  for (const r of rates) {
    map.set(`${r.fromCurrency}_${r.toCurrency}`, r.rate);
  }
  return map;
}

function getRate(
  rateMap: Map<string, string>,
  from: string,
  to: string
): string | null {
  const direct = rateMap.get(`${from}_${to}`);
  if (direct) return direct;
  return null;
}

function calculateCnyValueFromPrice(
  quantity: Big,
  latestPrice: string,
  baseCurrency: string,
  rateMap: Map<string, string>
): Big {
  const price = new Big(latestPrice || '0');

  if (baseCurrency === 'CNY') {
    return quantity.times(price);
  }

  const directRate = getRate(rateMap, baseCurrency, 'CNY');
  if (directRate) {
    return quantity.times(price).times(new Big(directRate));
  }

  const usdToCny = getRate(rateMap, 'USD', 'CNY');
  if (!usdToCny) {
    return new Big('0');
  }

  const usdRate = getRate(rateMap, baseCurrency, 'USD');
  if (usdRate) {
    return quantity.times(price).times(new Big(usdRate)).times(new Big(usdToCny));
  }

  return new Big('0');
}

export async function getPortfolioPositions(): Promise<Position[]> {
 const allTransactions = await db
    .select({
      txType: transactions.txType,
      quantity: transactions.quantity,
      price: transactions.price,
      exchangeRate: transactions.exchangeRate,
      txCurrency: transactions.txCurrency,
      assetId: transactions.assetId,
      assetSymbol: assets.symbol,
      assetType: assets.type,
      assetBaseCurrency: assets.baseCurrency,
      assetLatestPrice: assets.latestPrice,
    })
    .from(transactions)
    .leftJoin(assets, eq(assets.id, transactions.assetId))
    .orderBy(desc(transactions.executedAt));

  const rates = await db.select({
    fromCurrency: exchangeRates.fromCurrency,
    toCurrency: exchangeRates.toCurrency,
    rate: exchangeRates.rate,
  }).from(exchangeRates);

  const rateMap = buildRateMap(rates);

  const holdings = new Map<string, {
    assetId: string;
    symbol: string;
    type: string;
    quantity: Big;
    baseCurrency: string;
    latestPrice: string;
    totalCostCny: Big;
    totalCostNative: Big;
  }>();

  for (const tx of allTransactions) {
    if (!tx.assetId) continue;

    const existing = holdings.get(tx.assetId);
    if (!existing) {
      holdings.set(tx.assetId, {
        assetId: tx.assetId,
        symbol: tx.assetSymbol || tx.assetId,
        type: tx.assetType || 'CASH',
        quantity: new Big('0'),
        baseCurrency: tx.assetBaseCurrency || '',
        latestPrice: tx.assetLatestPrice || '0',
        totalCostCny: new Big('0'),
        totalCostNative: new Big('0'),
      });
    }

    const holding = holdings.get(tx.assetId)!;

    if (tx.txType === 'BUY') {
      holding.quantity = holding.quantity.plus(new Big(tx.quantity));
      const costPerUnit = new Big(tx.quantity).times(new Big(tx.price));
      holding.totalCostNative = holding.totalCostNative.plus(costPerUnit);
      let appliedRate = tx.exchangeRate;
      if ((!appliedRate || appliedRate === '1' || appliedRate === '1.00000000') && tx.txCurrency !== 'CNY') {
        const fallbackRate = getRate(rateMap, tx.txCurrency, 'CNY');
        if (fallbackRate) {
          appliedRate = fallbackRate;
        }
      }
      const costCny = costPerUnit.times(new Big(appliedRate || '1'));
      holding.totalCostCny = holding.totalCostCny.plus(costCny);
    } else if (tx.txType === 'SELL') {
      holding.quantity = holding.quantity.minus(new Big(tx.quantity));
      const sellCostPerUnit = new Big(tx.quantity).times(new Big(tx.price));
      holding.totalCostNative = holding.totalCostNative.minus(sellCostPerUnit);
      let appliedRate = tx.exchangeRate;
      if ((!appliedRate || appliedRate === '1' || appliedRate === '1.00000000') && tx.txCurrency !== 'CNY') {
        const fallbackRate = getRate(rateMap, tx.txCurrency, 'CNY');
        if (fallbackRate) {
          appliedRate = fallbackRate;
        }
      }
      const sellCostCny = sellCostPerUnit.times(new Big(appliedRate || '1'));
      holding.totalCostCny = holding.totalCostCny.minus(sellCostCny);
    } else if (tx.txType === 'AIRDROP') {
      holding.quantity = holding.quantity.plus(new Big(tx.quantity));
    } else if (tx.txType === 'DIVIDEND') {
      holding.quantity = holding.quantity.plus(new Big(tx.quantity));
    }

    if (tx.assetLatestPrice) {
      holding.latestPrice = tx.assetLatestPrice;
    }
  }

  const result: Position[] = [];
  let totalCnyValue = new Big('0');
  let totalPnlCny = new Big('0');

  for (const [_, holding] of holdings) {
    if (holding.quantity.lte(0)) continue;

    const cnyValue = calculateCnyValueFromPrice(
      holding.quantity,
      holding.latestPrice,
      holding.baseCurrency,
      rateMap
    );

    totalCnyValue = totalCnyValue.plus(cnyValue);

    const pnlCny = cnyValue.minus(holding.totalCostCny);
    totalPnlCny = totalPnlCny.plus(pnlCny);

    const currentNativeValue = new Big(holding.latestPrice).times(holding.quantity);
    const pnlNative = currentNativeValue.minus(holding.totalCostNative);

    result.push({
      assetId: holding.assetId,
      symbol: holding.symbol,
      type: holding.type,
      quantity: holding.quantity.toString(),
      baseCurrency: holding.baseCurrency,
      cnyValue: cnyValue.toString(),
      totalCostCny: holding.totalCostCny.toString(),
      pnlCny: pnlCny.toString(),
      totalCostNative: holding.totalCostNative.toString(),
      pnlNative: pnlNative.toString(),
    });
  }

  return result;
}

export async function getPortfolioSummary() {
  const positions = await getPortfolioPositions();

  const totalCnyValue = positions.reduce(
    (sum, pos) => sum.plus(new Big(pos.cnyValue)),
    new Big('0')
  );

  const totalPnlCny = positions.reduce(
    (sum, pos) => sum.plus(new Big(pos.pnlCny)),
    new Big('0')
  );

  const chartData = positions.map((pos, index) => ({
    name: pos.symbol,
    value: new Big(pos.cnyValue),
    fill: [
      '#3b82f6',
      '#8b5cf6',
      '#10b981',
      '#f59e0b',
      '#ef4444',
      '#06b6d4',
    ][index % 6],
  }));

  return {
    positions,
    totalCnyValue: totalCnyValue.toString(),
    totalPnlCny: totalPnlCny.toString(),
    chartData,
  };
}