import React, { useEffect, useMemo, useState } from 'react';
import { useInfiniteQuery } from '@tanstack/react-query';

import { MdCalendarMonth } from 'react-icons/md';

import { Card } from '@astryxdesign/core/Card';
import { HStack } from '@astryxdesign/core/HStack';
import { VStack } from '@astryxdesign/core/VStack';
import { EmptyState } from '@astryxdesign/core/EmptyState';
import { DateInput } from '@astryxdesign/core/DateInput';

import dayjs from 'dayjs';
import { parseDoormileTimestamp } from 'utils/doormileTimestamp';

import { fetchDeliveries } from 'pages/api/api';
import Loader from 'components/Loader';
import PageHeader from 'components/nearle_components/PageHeader';
import ProfitabilitySection, {
  BASE_REVENUE,
  BASE_KM_LIMIT,
  EXTRA_RATE_KM,
  VARIABLE_RATE_KM,
  FIXED_COST_PER_SLOT,
  BATCHES_DEFAULT
} from '../dispatch/ProfitabilitySection';
import { SKIPPED_STATUSES } from '../dispatch/dispatchShared';

// ============================================================================
// Standalone Profitability report — reference project (nearle_console_express)
// has this as its own page (reports/profitability.js); here it only existed
// embedded inside Dispatch.js's live map. Rather than rebuild the UI (the
// reference re-implements the profit math inline in raw MUI), this reuses
// the already-built, already-tested ProfitabilitySection.js component as-is
// and just supplies it with independently-fetched data — mirrors how the
// reference page ALSO re-fetches and re-groups independently rather than
// reusing its own Dispatch page's pipeline (which is entangled with
// Leaflet/GPS/zone-bucketing state not needed for a report).
//
// GET /admin/bookings has no server-side date/zone/status filter params (see
// src/pages/api/CLAUDE.md) — bulk-fetched and grouped entirely client-side,
// same pattern as reports/ordersDetails.js and deliveries.js.
// ============================================================================

const BRAND = '#000000';

// Profit formulas + batch windows imported from ProfitabilitySection.js
// (the single source of truth) rather than duplicated here — used to total
// across all riders for the daily KPI chip; per-rider numbers are computed
// by ProfitabilitySection itself from the same `riders` data, so this must
// match exactly or the chip and the table below it would disagree.
const orderRevenue = (km) => (km <= BASE_KM_LIMIT ? BASE_REVENUE : BASE_REVENUE + (km - BASE_KM_LIMIT) * EXTRA_RATE_KM);

// Buckets on `orderdate` (the booking's createdat) and parses with
// parseDoormileTimestamp — must match ProfitabilitySection.getRowBatch,
// Dispatch.js's BATCH_TIME_FIELD and deliveries.js's BATCH_TIME_KEYS.
//
// It used to read `assigntime`, which api.js maps to the backend's
// last-modified column, so it was re-stamped by any status change and a
// rider's slot count drifted through the day; and it parsed with a bare
// dayjs(), which mis-handles the false trailing Z some Doormile timestamps
// carry. Slot count feeds the FIXED cost, so both bugs moved money.
const getOrderBatch = (o) => {
  const t = o.orderdate;
  if (!t || /^\d{4}-\d{2}-\d{2}$/.test(String(t).trim())) return null;
  const d = parseDoormileTimestamp(t);
  if (!d.isValid()) return null;
  const hour = d.hour() + d.minute() / 60;
  const batch = BATCHES_DEFAULT.find((b) => hour >= b.startHour && hour < b.endHour);
  return batch?.id || null;
};

const Profitability = () => {
  const [selectedDate, setSelectedDate] = useState(dayjs().format('YYYY-MM-DD'));

  const {
    data: deliveriesData,
    isLoading,
    fetchNextPage,
    hasNextPage,
    isFetchingNextPage
  } = useInfiniteQuery({
    queryKey: ['fetchdeliveries-profitability', 0, 0, 'all', selectedDate, selectedDate, 500, '', 0, 0, 0],
    queryFn: fetchDeliveries,
    getNextPageParam: (lastPage) => lastPage.nextPage ?? undefined
  });

  const allRows = useMemo(() => (deliveriesData?.pages || []).flatMap((page) => page.rows || []), [deliveriesData]);

  useEffect(() => {
    if (hasNextPage && !isFetchingNextPage) fetchNextPage();
  }, [hasNextPage, isFetchingNextPage, fetchNextPage, allRows.length]);

  // Group into { id, riderName, orders } — flat, no zone/suburb bucketing
  // (that's a Dispatch-map-specific concern, not needed for a report).
  // riderkms is what ProfitabilitySection's revenue/cost math actually reads
  // (see orderRevenue/calcRiderMetrics there) but GET /admin/bookings has no
  // road-distance field — mapped from the same haversine straight-line `kms`
  // every other page in this app already uses as the distance proxy.
  const riders = useMemo(() => {
    const byRider = new Map();
    allRows.forEach((row) => {
      if (!row.userid) return;
      const key = String(row.userid);
      if (!byRider.has(key)) {
        byRider.set(key, { id: key, riderName: row.ridername || `Rider #${key}`, orders: [] });
      }
      byRider.get(key).orders.push({ ...row, riderkms: row.kms });
    });
    return Array.from(byRider.values());
  }, [allRows]);

  const totalDailyProfit = useMemo(() => {
    let profit = 0;
    riders.forEach((rider) => {
      let revenue = 0;
      let kms = 0;
      const batchesWorked = new Set();
      rider.orders.forEach((o) => {
        const status = String(o.orderstatus || '').toLowerCase();
        if (SKIPPED_STATUSES.has(status)) return;
        // parseDoormileTimestamp (not bare dayjs()) avoids the false-trailing-Z
        // parse bug (utils/doormileTimestamp.js) — see ProfitabilitySection.js.
        const dateStr = o.orderdate ? parseDoormileTimestamp(o.orderdate).format('YYYY-MM-DD') : null;
        if (dateStr !== selectedDate) return;
        const km = parseFloat(o.riderkms || 0);
        revenue += orderRevenue(km);
        kms += km;
        const batch = getOrderBatch(o);
        if (batch) batchesWorked.add(batch);
      });
      const variableCost = kms * VARIABLE_RATE_KM;
      const fixedCost = Math.min(batchesWorked.size, 3) * FIXED_COST_PER_SLOT;
      profit += revenue - variableCost - fixedCost;
    });
    return profit;
  }, [riders, selectedDate]);

  return (
    <>
      {isLoading && <Loader />}

      <PageHeader
        title="Profitability"
        subtitle={`Live · ${dayjs(selectedDate).format('DD MMM YYYY')}`}
        live
        action={
          <HStack gap={2} vAlign="center">
            <MdCalendarMonth size={16} color={BRAND} />
            <DateInput label="Report date" isLabelHidden size="sm" value={selectedDate} onChange={(v) => v && setSelectedDate(v)} />
          </HStack>
        }
      />

      <VStack gap={0} padding={0} style={{ marginTop: 16 }}>
        {!isLoading && riders.length === 0 ? (
          <Card padding={6}>
            <EmptyState title={`No deliveries for ${dayjs(selectedDate).format('DD MMM YYYY')}`} />
          </Card>
        ) : (
          <ProfitabilitySection riders={riders} totalDailyProfit={totalDailyProfit} selectedDate={selectedDate} />
        )}
      </VStack>
    </>
  );
};

export default Profitability;