const db = require('../../database/database');

function toTwo(value) {
  return Number(Number(value || 0).toFixed(2));
}

function toFour(value) {
  return Number(Number(value || 0).toFixed(4));
}

class PoolInflowService {
  async analyzePaidInvoice({ invoiceId, paidAt }) {
    const normalizedInvoiceId = Number(invoiceId);
    if (!Number.isFinite(normalizedInvoiceId) || normalizedInvoiceId <= 0) {
      return { ok: false, reason: 'invalid_invoice_id' };
    }

    const [invoiceRows] = await db.query(
      `SELECT id, source_type, source_id, currency, status, context
       FROM invoices
       WHERE id = ?
       LIMIT 1`,
      [normalizedInvoiceId]
    );
    const invoice = invoiceRows?.[0];
    if (!invoice) return { ok: false, reason: 'invoice_not_found' };
    if (String(invoice.status) !== 'paid') return { ok: false, reason: 'invoice_not_paid', invoice };
    if (String(invoice.source_type) !== 'subscription') return { ok: false, reason: 'unsupported_source_type', invoice };

    const abonementId = Number(invoice.source_id);
    if (!Number.isFinite(abonementId) || abonementId <= 0) {
      return { ok: false, reason: 'missing_abonement_relation', invoice };
    }

    const paidAtCandidate = paidAt ? new Date(paidAt) : new Date();
    const paidAtDate = Number.isFinite(paidAtCandidate.getTime()) ? paidAtCandidate : new Date();

    let context = {};
    try {
      context = invoice.context && typeof invoice.context === 'string' ? JSON.parse(invoice.context) : (invoice.context || {});
    } catch (_) {
      context = {};
    }
    const periodStart = context?.period_start ? new Date(context.period_start) : null;
    if (periodStart && Number.isFinite(periodStart.getTime()) && paidAtDate < periodStart) {
      return { ok: false, reason: 'paid_before_period_start', invoice, abonementId, paidAtDate, periodStart };
    }

    const [abonRows] = await db.query(
      `SELECT id, pack_breakdown, currency
       FROM coffee_abonements
       WHERE id = ?
       LIMIT 1`,
      [abonementId]
    );
    const abonement = abonRows?.[0];
    if (!abonement) return { ok: false, reason: 'abonement_not_found', invoice, abonementId };

    const breakdownRaw = abonement.pack_breakdown;
    let breakdown = [];
    try {
      breakdown = breakdownRaw
        ? (typeof breakdownRaw === 'string' ? JSON.parse(breakdownRaw) : breakdownRaw)
        : [];
    } catch (_) {
      breakdown = [];
    }

    const normalizedLines = Array.isArray(breakdown)
      ? breakdown
          .map((line) => ({
            coffeeId: Number(line?.coffee_table_id),
            capsulesCount: Number(line?.packs || 0) * 10,
          }))
          .filter((line) => Number.isFinite(line.coffeeId) && line.coffeeId > 0 && Number.isFinite(line.capsulesCount) && line.capsulesCount > 0)
      : [];

    if (!normalizedLines.length) return { ok: false, reason: 'no_breakdown_lines', invoice, abonementId };

    const byCoffee = new Map();
    for (const line of normalizedLines) {
      byCoffee.set(line.coffeeId, (byCoffee.get(line.coffeeId) || 0) + line.capsulesCount);
    }

    const coffeeIds = Array.from(byCoffee.keys());
    const placeholders = coffeeIds.map(() => '?').join(',');
    const [pools] = await db.query(
      `SELECT id, pool_name, subscription_coffee_id, price
       FROM pools
       WHERE is_active = 1 AND subscription_coffee_id IN (${placeholders})`,
      coffeeIds
    );

    if (!Array.isArray(pools) || pools.length === 0) {
      return { ok: false, reason: 'no_linked_pools', invoice, abonementId, normalizedLines };
    }

    return {
      ok: true,
      reason: 'ok',
      invoice,
      abonementId,
      paidAtDate,
      byCoffee,
      pools,
      normalizedLines,
      currency: invoice.currency || abonement.currency || 'EUR',
    };
  }

  async bookForPaidInvoice({ invoiceId, paidAt, actorUserId = null }) {
    const analysis = await this.analyzePaidInvoice({ invoiceId, paidAt });
    if (!analysis.ok) {
      return { inserted: 0, skipped: 0, reason: analysis.reason };
    }

    const normalizedInvoiceId = Number(analysis.invoice.id);
    const abonementId = Number(analysis.abonementId);
    const paidAtDate = analysis.paidAtDate;
    const byCoffee = analysis.byCoffee;
    const pools = analysis.pools;
    const currency = analysis.currency;
    const conn = await db.getConnection();
    let inserted = 0;
    try {
    let alreadyExists = 0;
      await conn.beginTransaction();
      for (const pool of pools) {
        const coffeeId = Number(pool.subscription_coffee_id);
        const capsulesCount = Number(byCoffee.get(coffeeId) || 0);
        if (!capsulesCount) continue;

        const pricePerCapsuleNet = toFour(pool.price);
        const amountNet = toTwo(capsulesCount * pricePerCapsuleNet);
        const details = {
          source: 'invoice_paid',
          formula: 'capsules_count * price_per_capsule_net',
          paid_at: paidAtDate,
        };

        const [res] = await conn.query(
          `INSERT INTO pool_inflows
             (pool_id, invoice_id, abonement_id, coffee_table_id, event_type, capsules_count, price_per_capsule_net, amount_net, currency, details, created_by_user_id, created_at)
           VALUES (?, ?, ?, ?, 'invoice_paid', ?, ?, ?, ?, ?, ?, NOW())
           ON DUPLICATE KEY UPDATE id = id`,
          [
            Number(pool.id),
            normalizedInvoiceId,
            abonementId,
            coffeeId,
            capsulesCount,
            pricePerCapsuleNet,
            amountNet,
            currency,
            JSON.stringify(details),
            actorUserId || null,
          ]
        );

        if (res && Number(res.affectedRows) === 1) inserted += 1;
        else alreadyExists += 1;
      }

      await conn.commit();
      return { inserted, alreadyExists, skipped: Math.max(0, pools.length - inserted), reason: 'ok' };
    } catch (err) {
      await conn.rollback();
      throw err;
    } finally {
      conn.release();
    }
  }

  async getInvoiceInflowDiagnostics({ invoiceId, paidAt }) {
    const analysis = await this.analyzePaidInvoice({ invoiceId, paidAt });
    if (!analysis.ok) {
      return {
        ok: false,
        reason: analysis.reason,
        invoiceId: Number(invoiceId),
      };
    }

    const invoiceIdNum = Number(analysis.invoice.id);
    const poolEntries = [];

    for (const pool of analysis.pools) {
      const coffeeId = Number(pool.subscription_coffee_id);
      const capsulesCount = Number(analysis.byCoffee.get(coffeeId) || 0);
      const pricePerCapsuleNet = toFour(pool.price);
      const amountNet = toTwo(capsulesCount * pricePerCapsuleNet);
      const [existingRows] = await db.query(
        `SELECT id, created_at
         FROM pool_inflows
         WHERE pool_id = ? AND invoice_id = ? AND coffee_table_id = ? AND event_type = 'invoice_paid'
         LIMIT 1`,
        [Number(pool.id), invoiceIdNum, coffeeId]
      );

      poolEntries.push({
        pool_id: Number(pool.id),
        pool_name: pool.pool_name,
        coffee_table_id: coffeeId,
        capsules_count: capsulesCount,
        price_per_capsule_net: pricePerCapsuleNet,
        amount_net: amountNet,
        already_booked: !!existingRows?.length,
        existing_inflow_id: existingRows?.[0]?.id || null,
      });
    }

    return {
      ok: true,
      reason: 'ok',
      invoice_id: invoiceIdNum,
      abonement_id: Number(analysis.abonementId),
      paid_at: analysis.paidAtDate,
      currency: analysis.currency,
      candidates: poolEntries,
      will_book_count: poolEntries.filter((x) => !x.already_booked).length,
      already_booked_count: poolEntries.filter((x) => x.already_booked).length,
    };
  }
}

module.exports = new PoolInflowService();