/**
 * Hours section card (migration 129).
 *
 * Used in two places:
 *   1. CustomerDetailPage — rendered when the per-customer
 *      `feature_hours_logging` flag is on AND the master `hoursLogging`
 *      flag is on. Sits between the features card and account actions.
 *   2. The standalone /admin/clients/hours page — admin picks ANY
 *      customer with hours logging enabled, then sees this card.
 *
 * Wraps customerAdminService.{list,create,delete,billUnbilled}HourEntries.
 * All writes go through react-query invalidation so the entry list
 * refreshes after every action.
 */
import React, { useMemo, useState } from 'react';
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { useTranslation } from 'react-i18next';
import { Link, useNavigate } from 'react-router-dom';
import { toast } from 'react-toastify';
import { Clock, AlertTriangle } from 'lucide-react';
import { Button, Card, LocalizedDateInput, TimeField } from '../common';
import { DecimalInput } from '../common/DecimalInput';
import { parseLocaleDecimal, parseDuration } from '../../utils/parsers';
import { customerAdminService } from '../../services/customerAdmin.service';
import { businessProfileService } from '../../services/businessProfile.service';
import { useLocalizedDate } from '../../hooks/useLocalizedDate';
import { ProjectSelect } from './ProjectSelect';

export interface HoursSectionProps {
  customerId: number;
  customerHourlyRateMinor: number | null;
  billingCadence: 'per_event' | 'monthly' | 'quarterly';
  onHourlyRateChange?: (next: number | null) => void;
  /**
   * When true, render only the entry-history table + the per-event
   * "Bill these hours" action. Hides the inline log-entry form and
   * the default-rate input. Used on the customer detail page now
   * that logging itself lives on the standalone /admin/clients/hours
   * surface — the detail page becomes a read-only history view with
   * the on-demand bill action for per-event customers.
   */
  compact?: boolean;
}

export const HoursSection: React.FC<HoursSectionProps> = ({
  customerId, customerHourlyRateMinor, billingCadence, onHourlyRateChange, compact,
}) => {
  const { t } = useTranslation();
  const qc = useQueryClient();
  const navigate = useNavigate();
  const { format: fmtDate, formatTime: fmtTime } = useLocalizedDate();
  const [entryDate, setEntryDate] = useState(() => new Date().toISOString().slice(0, 10));
  const [startTime, setStartTime] = useState('09:00');
  const [endTime, setEndTime] = useState('10:00');
  const [duration, setDuration] = useState<string>('');
  const [rateOverride, setRateOverride] = useState<string>('');
  const [description, setDescription] = useState('');
  // Migration 118 — optional "book to project" link (gated component).
  const [projectId, setProjectId] = useState<number | null>(null);

  // Duration shortcut — admin types "1.5", "1,5", "1:30" or "1h" and
  // the end-time jumps to start + duration. Pure convenience; the End
  // input still works for explicit times. Empty / unparseable input is
  // a no-op so a typo doesn't overwrite a freshly-edited End.
  const applyDuration = (raw: string) => {
    const minutes = parseDuration(raw);
    if (minutes == null) return;
    const [hh, mm] = startTime.split(':').map(Number);
    if (!Number.isFinite(hh) || !Number.isFinite(mm)) return;
    const totalEnd = Math.min(hh * 60 + mm + minutes, 24 * 60 - 1);
    const eh = Math.floor(totalEnd / 60).toString().padStart(2, '0');
    const em = (totalEnd % 60).toString().padStart(2, '0');
    setEndTime(`${eh}:${em}`);
  };

  const { data: entries = [], isLoading } = useQuery({
    queryKey: ['admin-customer-hour-entries', customerId],
    queryFn: () => customerAdminService.listHourEntries(customerId),
    enabled: Number.isFinite(customerId) && customerId > 0,
  });

  // Pull the configured default currency so the hint can show
  // "{{currency}} 150" instead of the hardcoded "CHF 150". Same cache
  // key as CustomerDetailPage so a single round-trip serves both
  // mount points. 5-minute stale window — the value changes via
  // Settings → Business profile, not during a hours-logging session.
  const { data: profileSnapshot } = useQuery({
    queryKey: ['business-profile-snapshot'],
    queryFn: () => businessProfileService.get(),
    staleTime: 5 * 60 * 1000,
  });
  const profileDefaultCurrency = profileSnapshot?.profile?.defaultCurrency || 'CHF';
  // Install-wide fallback rate (migration 113). Last link in the rate
  // chain after the per-entry override and the per-customer default.
  const installDefaultRateMinor = profileSnapshot?.profile?.defaultHourlyRateMinor ?? null;
  // The rate that applies to a NEW entry when no per-entry override is
  // typed: customer rate, else the install default. null = neither set,
  // so a save would fail unless the admin enters an override.
  const effectiveDefaultRateMinor = customerHourlyRateMinor ?? installDefaultRateMinor;
  // True when there's genuinely no rate to bill at — drives the inline
  // CTA + disables the save button. An override typed in the form lifts
  // this (handled below where the button is rendered).
  const noRateConfigured = effectiveDefaultRateMinor == null;
  const overrideTyped = (() => {
    if (!rateOverride.trim()) return false;
    const n = parseLocaleDecimal(rateOverride);
    return Number.isFinite(n) && n >= 0;
  })();

  const createMutation = useMutation({
    mutationFn: () => customerAdminService.createHourEntry(customerId, {
      entryDate, startTime, endTime,
      // Locale-tolerant: "12,50" and "12.50" both yield 1250.
      hourlyRateMinorOverride: (() => {
        if (!rateOverride) return null;
        const n = parseLocaleDecimal(rateOverride);
        return Number.isFinite(n) && n >= 0 ? Math.round(n * 100) : null;
      })(),
      description: description || null,
      projectId: projectId ?? null,
    }),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ['admin-customer-hour-entries', customerId] });
      qc.invalidateQueries({ queryKey: ['admin-customer', customerId] });
      setStartTime('09:00');
      setEndTime('10:00');
      setDuration('');
      setRateOverride('');
      setDescription('');
      setProjectId(null);
      toast.success(t('customers.hours.toast.created', 'Entry logged'));
    },
    onError: (err: any) => {
      // The save-time "no rate" failure is translated here off the
      // backend error code (the raw message is English-only). The inline
      // guard below normally prevents this, but a race (rate cleared in
      // another tab) can still surface it.
      if (err?.response?.data?.code === 'HOURLY_RATE_REQUIRED') {
        toast.error(t('customers.hours.error.noRate',
          'No hourly rate set for this customer. Enter a rate override, set a rate on the customer, or configure an install-wide default in Settings.'));
        return;
      }
      if (err?.response?.data?.code === 'PROJECT_CUSTOMER_MISMATCH') {
        toast.error(t('projects.error.customerMismatch',
          "That project belongs to a different customer than this entry."));
        return;
      }
      const msg = err?.response?.data?.error || err?.message
        || t('customers.hours.error.createFailed', 'Failed to log entry');
      toast.error(msg);
    },
  });

  const deleteMutation = useMutation({
    mutationFn: (entryId: number) => customerAdminService.deleteHourEntry(customerId, entryId),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ['admin-customer-hour-entries', customerId] });
      qc.invalidateQueries({ queryKey: ['admin-customer', customerId] });
      toast.success(t('customers.hours.toast.deleted', 'Entry deleted'));
    },
    onError: (err: any) => {
      toast.error(err?.response?.data?.error || 'Failed to delete entry');
    },
  });

  const billMutation = useMutation({
    mutationFn: () => customerAdminService.billUnbilledHourEntries(customerId),
    onSuccess: ({ invoiceId }) => {
      qc.invalidateQueries({ queryKey: ['admin-customer-hour-entries', customerId] });
      qc.invalidateQueries({ queryKey: ['admin-customer', customerId] });
      toast.success(t('customers.hours.toast.billed', 'Hours billed'));
      // Open the new scheduled invoice so the admin can add other line
      // items in addition to the hours before it ships.
      if (invoiceId) navigate(`/admin/clients/bills/${invoiceId}/edit`);
    },
    onError: (err: any) => {
      toast.error(err?.response?.data?.error || 'Failed to bill hours');
    },
  });

  // Single pass — both the count and the money total live behind the
  // same filter. Memoised so a parent re-render (e.g. the
  // CustomerDetailPage form state changing) doesn't reshuffle the
  // entries array in JS on every keystroke.
  const { unbilledCount, unbilledTotalMajor } = useMemo(() => {
    let count = 0;
    let minor = 0;
    for (const e of entries) {
      if (e.status !== 'unbilled') continue;
      count += 1;
      const rateMinor = e.hourlyRateMinorOverride ?? effectiveDefaultRateMinor ?? 0;
      minor += rateMinor * e.durationMinutes / 60;
    }
    return { unbilledCount: count, unbilledTotalMajor: minor / 100 };
  }, [entries, effectiveDefaultRateMinor]);
  const isMonthly = billingCadence === 'monthly';

  // Local lockout check — mirrors customerHoursService.isEntryLocked
  // so the delete button can be disabled before the request is sent.
  const isLocked = (entry: typeof entries[number]) => {
    if (!entry.invoiceId) return false;
    if (entry.invoiceIsMonthlyDraft) return false;
    if (entry.invoiceStatus !== 'scheduled') return true;
    if (!entry.invoiceScheduledSendAt) return false;
    return new Date(entry.invoiceScheduledSendAt).getTime() <= Date.now();
  };

  return (
    <Card padding="lg">
      <h2 className="text-lg font-semibold text-theme mb-1 flex items-center gap-2">
        <Clock className="w-5 h-5" />
        {t('customers.hours.section', 'Hours')}
      </h2>
      <p className="text-xs text-muted-theme mb-4">
        {isMonthly
          ? t('customers.hours.monthlyHint',
            'Entries auto-append to the current monthly draft. Edit / delete remains possible until the scheduler arms the draft for send.')
          : t('customers.hours.perEventHint',
            'Logged entries stay unbilled until you click "Create draft invoice" — one scheduled invoice is generated with a line per entry and opened in the editor, so you can add other items before it ships.')}
      </p>

      {/* Rate summary — hidden in compact mode (history-only on the
          customer detail page). When a caller wires onHourlyRateChange
          the field is editable; otherwise (the standalone hours page)
          we show the RESOLVED rate read-only so a disabled input can't
          masquerade as an editable value, and surface a CTA when no rate
          is configured anywhere along the chain. */}
      {!compact && (
        <div className="mb-4">
          <label className="block text-sm font-medium text-theme mb-1">
            {t('customers.field.hourlyRate', 'Default hourly rate')}
          </label>
          {onHourlyRateChange ? (
            <>
              <DecimalInput
                value={customerHourlyRateMinor != null ? customerHourlyRateMinor / 100 : NaN}
                fractionDigits={2}
                onChange={(n) => {
                  if (!Number.isFinite(n)) { onHourlyRateChange(null); return; }
                  onHourlyRateChange(Math.max(0, Math.round(n * 100)));
                }}
                className="w-40 input"
                placeholder="150.00"
              />
              <p className="text-xs text-muted-theme mt-1">
                {t('customers.field.hourlyRateHint',
                  'Major units (e.g. 150.00 for {{currency}} 150). Leave blank to require a per-entry override on every block.',
                  { currency: profileDefaultCurrency })}
              </p>
            </>
          ) : noRateConfigured ? (
            <div className="rounded-md border border-amber-300 dark:border-amber-700 bg-amber-50 dark:bg-amber-900/20 p-3 text-sm">
              <div className="flex items-start gap-2 text-amber-800 dark:text-amber-200">
                <AlertTriangle className="w-4 h-4 mt-0.5 shrink-0" />
                <div>
                  <p className="font-medium">
                    {t('customers.hours.noRate.title', 'No hourly rate configured')}
                  </p>
                  <p className="mt-0.5 text-amber-700 dark:text-amber-300">
                    {t('customers.hours.noRate.body',
                      'Logging needs a rate. Set one for this customer, type a per-entry override below, or configure an install-wide default.')}
                  </p>
                  <div className="mt-2 flex flex-wrap gap-3">
                    <Link to={`/admin/clients/accounts/${customerId}`}
                      className="text-accent-dark hover:underline font-medium">
                      {t('customers.hours.noRate.setForCustomer', 'Set a rate for this customer')}
                    </Link>
                    <Link to="/admin/settings?tab=businessProfile" target="_blank" rel="noopener noreferrer"
                      className="text-accent-dark hover:underline font-medium">
                      {t('customers.hours.noRate.setInstallDefault', 'Set an install-wide default')}
                    </Link>
                  </div>
                </div>
              </div>
            </div>
          ) : (
            <p className="text-sm text-theme">
              <span className="tabular-nums font-medium">
                {profileDefaultCurrency} {((effectiveDefaultRateMinor as number) / 100).toFixed(2)}
              </span>
              <span className="text-xs text-muted-theme ml-2">
                {customerHourlyRateMinor != null
                  ? t('customers.hours.rateSource.customer', 'from this customer')
                  : t('customers.hours.rateSource.installDefault', 'install-wide default')}
              </span>
            </p>
          )}
        </div>
      )}

      {/* Inline log-new-entry form — hidden in compact mode. Logging
          lives on the standalone /admin/clients/hours surface. */}
      {!compact && (
      <div className="border-t border-neutral-200 dark:border-neutral-700 pt-4 mb-4">
        <h3 className="text-sm font-semibold mb-3">{t('customers.hours.form.title', 'Log new entry')}</h3>
        <div className="grid grid-cols-2 md:grid-cols-6 gap-3">
          <div>
            <label className="block text-xs text-muted-theme mb-1">
              {t('customers.hours.form.date', 'Date')}
            </label>
            <LocalizedDateInput value={entryDate} onChange={setEntryDate} />
          </div>
          <div>
            <label className="block text-xs text-muted-theme mb-1">
              {t('customers.hours.form.start', 'Start')}
            </label>
            <TimeField value={startTime} onChange={setStartTime} />
          </div>
          <div>
            <label className="block text-xs text-muted-theme mb-1">
              {t('customers.hours.form.end', 'End')}
            </label>
            <TimeField value={endTime} onChange={setEndTime} />
          </div>
          <div>
            <label className="block text-xs text-muted-theme mb-1">
              {t('customers.hours.form.duration', 'Duration')}
            </label>
            <input
              type="text"
              inputMode="decimal"
              value={duration}
              onChange={(e) => setDuration(e.target.value)}
              onBlur={(e) => applyDuration(e.target.value)}
              onKeyDown={(e) => {
                if (e.key === 'Enter') {
                  e.preventDefault();
                  applyDuration((e.target as HTMLInputElement).value);
                }
              }}
              placeholder={t('customers.hours.form.durationPlaceholder', '1h · 1.5 · 1:30') as string}
              title={t('customers.hours.form.durationHint',
                'Type a duration to auto-fill End: 1h, 1.5, 1,5 or 1:30') as string}
              className="input w-full" />
          </div>
          <div>
            <label className="block text-xs text-muted-theme mb-1">
              {t('customers.hours.form.rateOverride', 'Rate override')}
            </label>
            <input
              type="text"
              inputMode="decimal"
              value={rateOverride}
              onChange={(e) => setRateOverride(e.target.value)}
              placeholder={effectiveDefaultRateMinor != null
                ? (effectiveDefaultRateMinor / 100).toFixed(2)
                : '—'}
              className="input w-full" />
          </div>
        </div>
        <div className="mt-3">
          <label className="block text-xs text-muted-theme mb-1">
            {t('customers.hours.form.note', 'Note / description')}
          </label>
          <textarea rows={2} value={description}
            onChange={(e) => setDescription(e.target.value)}
            className="input w-full text-sm"
            placeholder={t('customers.hours.form.notePlaceholder',
              'What was worked on?') as string} />
        </div>
        {/* Book to project — renders only when the projects feature is on. */}
        <ProjectSelect
          className="mt-3"
          label={t('customers.hours.form.bookToProject', 'Book to project') as string}
          value={projectId}
          customerAccountId={customerId}
          onChange={setProjectId}
        />
        <div className="mt-3 flex items-center justify-end gap-3">
          {noRateConfigured && !overrideTyped && (
            <span className="text-xs text-amber-700 dark:text-amber-300">
              {t('customers.hours.form.needRate', 'Set a rate or enter an override to log time.')}
            </span>
          )}
          <Button
            variant="primary"
            disabled={createMutation.isPending || (noRateConfigured && !overrideTyped)}
            isLoading={createMutation.isPending}
            onClick={() => createMutation.mutate()}
          >
            {t('customers.hours.form.save', 'Add entry')}
          </Button>
        </div>
      </div>
      )}

      {/* Bill-these-hours button for per-event customers only. Stays
          visible in compact mode so the customer-detail page can
          still trigger the on-demand billing action. */}
      {!isMonthly && unbilledCount > 0 && (
        <div className="mb-4 flex items-center justify-between bg-blue-50 dark:bg-blue-900/20 rounded p-3">
          <span className="text-sm">
            {t('customers.hours.unbilledCount',
              '{{count}} unbilled entries totaling {{total}}',
              {
                count: unbilledCount,
                total: unbilledTotalMajor.toFixed(2),
              })}
          </span>
          <Button
            variant="primary"
            disabled={billMutation.isPending}
            isLoading={billMutation.isPending}
            onClick={() => billMutation.mutate()}
          >
            {t('customers.hours.billButton', 'Create draft invoice')}
          </Button>
        </div>
      )}

      {/* Entry list table. */}
      {isLoading ? (
        <p className="text-sm text-muted-theme">{t('common.loading', 'Loading…')}</p>
      ) : entries.length === 0 ? (
        <p className="text-sm text-muted-theme">
          {t('customers.hours.empty', 'No entries logged yet.')}
        </p>
      ) : (
        <div className="overflow-x-auto">
          <table className="w-full text-sm">
            <thead>
              <tr className="text-left text-xs uppercase text-muted-theme">
                <th className="py-2 pr-3">{t('customers.hours.col.date', 'Date')}</th>
                <th className="py-2 pr-3">{t('customers.hours.col.range', 'Time')}</th>
                <th className="py-2 pr-3 text-right">{t('customers.hours.col.hours', 'Hours')}</th>
                <th className="py-2 pr-3 text-right">{t('customers.hours.col.rate', 'Rate')}</th>
                <th className="py-2 pr-3 text-right">{t('customers.hours.col.total', 'Total')}</th>
                <th className="py-2 pr-3">{t('customers.hours.col.note', 'Note')}</th>
                <th className="py-2 pr-3">{t('customers.hours.col.status', 'Status')}</th>
                <th className="py-2 pr-3"></th>
              </tr>
            </thead>
            <tbody>
              {entries.map((e) => {
                const rate = e.hourlyRateMinorOverride ?? effectiveDefaultRateMinor ?? 0;
                const hours = e.durationMinutes / 60;
                const total = (hours * rate) / 100;
                const locked = isLocked(e);
                return (
                  <tr key={e.id} className="border-t border-neutral-200 dark:border-neutral-700">
                    <td className="py-1.5 pr-3 tabular-nums">{fmtDate(e.entryDate)}</td>
                    <td className="py-1.5 pr-3 tabular-nums">{fmtTime(e.startTime)}–{fmtTime(e.endTime)}</td>
                    <td className="py-1.5 pr-3 text-right tabular-nums">{hours.toFixed(2)}</td>
                    <td className="py-1.5 pr-3 text-right tabular-nums">{(rate / 100).toFixed(2)}</td>
                    <td className="py-1.5 pr-3 text-right tabular-nums font-medium">{total.toFixed(2)}</td>
                    <td className="py-1.5 pr-3 max-w-xs truncate" title={e.description || ''}>
                      {e.description || '—'}
                    </td>
                    <td className="py-1.5 pr-3">
                      {e.status === 'billed' ? (
                        <span className="text-xs text-green-700 dark:text-green-300">
                          {e.invoiceNumber
                            ? t('customers.hours.status.billedOn',
                              'Billed: {{number}}', { number: e.invoiceNumber })
                            : t('customers.hours.status.billed', 'Billed')}
                        </span>
                      ) : (
                        <span className="text-xs text-amber-700 dark:text-amber-300">
                          {t('customers.hours.status.unbilled', 'Unbilled')}
                        </span>
                      )}
                    </td>
                    <td className="py-1.5 pr-3 text-right">
                      <button
                        type="button"
                        disabled={locked || deleteMutation.isPending}
                        onClick={() => {
                          if (window.confirm(t('customers.hours.confirmDelete',
                            'Delete this entry? If it has been billed onto a draft, the matching invoice line will also be removed.') as string)) {
                            deleteMutation.mutate(e.id);
                          }
                        }}
                        className="text-xs text-red-600 hover:underline disabled:text-neutral-400 disabled:cursor-not-allowed"
                        title={locked ? t('customers.hours.locked',
                          'Locked: invoice already armed for send') as string : undefined}
                      >
                        {t('common.delete', 'Delete')}
                      </button>
                    </td>
                  </tr>
                );
              })}
            </tbody>
          </table>
        </div>
      )}
    </Card>
  );
};

export default HoursSection;