const prisma = require('../config/db');
const { v4: uuidv4 } = require('uuid');
const { safeErrorMessage } = require('../utils/errorUtils');
const { ALL_METHODS, assertEventOpen, computeEventFinancials, computeAccountabilityByUser, computeEventCashActualFromPersonCounts, savePersonCashCount } = require('../utils/cashupUtils');

// @desc    Cashup preview for an event: live expected/actual numbers, costs, donations-to-profit, and history
// @route   GET /api/cashups/event/:eventId
// @access  Private/Supervisor
const getEventCashup = async (req, res) => {
  try {
    const financials = await computeEventFinancials(req.params.eventId);
    res.json(financials);
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

// @desc    Payments recorded for an event, broken down by staff member and method (cash/card/eft/
//          other) — cash also includes the live actual-vs-expected from per-person counts.
// @route   GET /api/cashups/event/:eventId/cash-by-user
// @access  Private/Supervisor
const getCashByRecordedUser = async (req, res) => {
  try {
    const [rows, cash] = await Promise.all([
      computeAccountabilityByUser(req.params.eventId),
      computeEventCashActualFromPersonCounts(req.params.eventId)
    ]);
    res.json({ rows, cashActualTotal: cash.actual, cashDenominations: cash.denominations });
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

// @desc    Enter (or update) one staff member's actual physical cash count for an event —
//          optional, can be done any time, purely for per-person accountability. Never blocks
//          or is required for closing the event.
// @route   PUT /api/cashups/event/:eventId/person-cash/:userId
// @access  Private/Supervisor
const savePersonCash = async (req, res) => {
  try {
    const { eventId, userId } = req.params;
    const { denominations, notes } = req.body;

    const targetUser = await prisma.user.findUnique({ where: { id: userId }, select: { id: true } });
    if (!targetUser) {
      res.status(404);
      throw new Error('User not found');
    }

    const record = await savePersonCashCount(eventId, userId, { denominations, notes, enteredById: req.user.id });
    res.json(record);
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

// @desc    Save in-progress reconciliation entries without closing the event
// @route   PUT /api/cashups/event/:eventId/draft
// @access  Private/Admin
const saveEventCashupDraft = async (req, res) => {
  try {
    const { eventId } = req.params;
    const { lines, notes } = req.body;

    await assertEventOpen(eventId, res);

    await prisma.event.update({
      where: { id: eventId },
      data: { cashupDraft: { lines: Array.isArray(lines) ? lines : [], notes: notes || null, savedAt: new Date().toISOString() } }
    });

    res.json({ message: 'Draft saved' });
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

// @desc    Close an event, optionally with a full per-method cashup
// @route   POST /api/cashups/event/:eventId/close
// @access  Private/Admin
const closeEvent = async (req, res) => {
  try {
    const { eventId } = req.params;
    const { lines, notes } = req.body;

    await assertEventOpen(eventId, res);

    const financials = await computeEventFinancials(eventId);
    const isFullCashup = Array.isArray(lines) && lines.length > 0;

    let cashupLines = [];
    if (isFullCashup) {
      const nonCashLines = lines
        .filter(l => l && ALL_METHODS.includes(l.method) && l.method !== 'cash')
        .map(l => {
          const expected = financials.expectedCashByMethod[l.method] || 0;
          const actual = l.actualAmount !== undefined && l.actualAmount !== null && l.actualAmount !== '' ? parseFloat(l.actualAmount) : null;
          return {
            id: uuidv4(),
            method: l.method,
            expectedAmount: expected,
            actualAmount: actual,
            variance: actual !== null ? actual - expected : null,
            notes: l.notes || null
          };
        });

      // Cash is never entered as a single event-wide figure — it's always the live sum of every
      // staff member's per-person count (see computeEventCashActualFromPersonCounts), so it's
      // always sourced here rather than from whatever (if anything) the frontend sent for it.
      const cashLineInput = lines.find(l => l && l.method === 'cash');
      const { actual: cashActual, denominations: cashDenominations } = await computeEventCashActualFromPersonCounts(eventId);
      const cashExpected = financials.expectedCashByMethod.cash || 0;
      const cashLine = {
        id: uuidv4(),
        method: 'cash',
        expectedAmount: cashExpected,
        actualAmount: cashActual,
        variance: cashActual !== null ? cashActual - cashExpected : null,
        notes: cashLineInput?.notes || null,
        denominations: cashDenominations.length > 0 ? { create: cashDenominations } : undefined
      };

      cashupLines = [cashLine, ...nonCashLines];
    }

    const totalActualRevenue = isFullCashup
      ? cashupLines.reduce((sum, l) => sum + (l.actualAmount !== null ? l.actualAmount : 0), 0)
      : null;
    const totalExpectedRevenue = ALL_METHODS.reduce((sum, m) => sum + financials.expectedCashByMethod[m], 0);

    const cashup = await prisma.eventCashup.create({
      data: {
        id: uuidv4(),
        eventId,
        action: isFullCashup ? 'closed' : 'quick_closed',
        unallocatedDonationsTotal: financials.unallocatedDonationsTotal,
        totalCosts: financials.totalCosts,
        totalExpectedRevenue,
        totalActualRevenue,
        notes: notes || null,
        performedById: req.user.id,
        lines: { create: cashupLines }
      },
      include: { lines: { include: { denominations: true } }, performedBy: { select: { id: true, name: true, email: true } } }
    });

    await prisma.event.update({
      where: { id: eventId },
      data: { cashupStatus: 'closed', cashupDraft: null, closedAt: new Date(), closedById: req.user.id }
    });

    res.status(201).json(cashup);
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

// @desc    Reopen a closed event (admin only)
// @route   POST /api/cashups/event/:eventId/reopen
// @access  Private/Admin
const reopenEvent = async (req, res) => {
  try {
    const { eventId } = req.params;
    const { notes } = req.body;

    const event = await prisma.event.findUnique({ where: { id: eventId } });
    if (!event) {
      res.status(404);
      throw new Error('Event not found');
    }
    if (event.cashupStatus !== 'closed') {
      res.status(400);
      throw new Error('Event is not closed');
    }

    const auditRow = await prisma.eventCashup.create({
      data: {
        id: uuidv4(),
        eventId,
        action: 'reopened',
        notes: notes || null,
        performedById: req.user.id
      },
      include: { performedBy: { select: { id: true, name: true, email: true } } }
    });

    await prisma.event.update({
      where: { id: eventId },
      data: { cashupStatus: 'open', reopenedAt: new Date(), reopenedById: req.user.id }
    });

    res.status(201).json(auditRow);
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

// @desc    Flat audit log of every close/quick-close/reopen, optionally filtered
// @route   GET /api/cashups/audit
// @access  Private/Supervisor
const getCashupAudit = async (req, res) => {
  try {
    const { eventId, from, to } = req.query;

    const where = {};
    if (eventId) where.eventId = eventId;
    if (from || to) {
      where.createdAt = {};
      if (from) where.createdAt.gte = new Date(from);
      if (to) where.createdAt.lte = new Date(to);
    }

    const rows = await prisma.eventCashup.findMany({
      where,
      include: {
        event: { select: { id: true, title: true } },
        performedBy: { select: { id: true, name: true, email: true } },
        lines: { include: { denominations: true } }
      },
      orderBy: { createdAt: 'desc' }
    });

    res.json(rows);
  } catch (error) {
    res.status(res.statusCode === 200 ? 400 : res.statusCode).json({ message: safeErrorMessage(error) });
  }
};

module.exports = {
  getEventCashup,
  getCashByRecordedUser,
  savePersonCash,
  saveEventCashupDraft,
  closeEvent,
  reopenEvent,
  getCashupAudit
};