import { useMemo } from 'react';
import { Card, Title, Text, Group, Badge, SegmentedControl, Stack } from '@mantine/core';
import { useState } from 'react';
import {
  AreaChart, Area, XAxis, YAxis, CartesianGrid, Tooltip, Legend,
  ResponsiveContainer, ReferenceLine,
} from 'recharts';

const fmt = (v: number) => v.toLocaleString('en-US', { style: 'currency', currency: 'USD', maximumFractionDigits: 0 });

interface Datapoint {
  month: string;
  year: number;
  monthNum: number;
  is_forecast: boolean;
  operating_cash: number;
  operating_investments: number;
  reserve_cash: number;
  reserve_investments: number;
}

interface Props {
  datapoints: Datapoint[];
  title?: string;
  summary?: any;
}

export function ProjectionChart({ datapoints, title = 'Financial Projection', summary }: Props) {
  const [fundFilter, setFundFilter] = useState('all');

  const chartData = useMemo(() => {
    return datapoints.map((d) => ({
      ...d,
      label: `${d.month}`,
      total: d.operating_cash + d.operating_investments + d.reserve_cash + d.reserve_investments,
    }));
  }, [datapoints]);

  // Find first forecast month for reference line
  const forecastStart = chartData.findIndex((d) => d.is_forecast);

  const CustomTooltip = ({ active, payload, label }: any) => {
    if (!active || !payload?.length) return null;
    return (
      <Card shadow="sm" p="xs" withBorder style={{ background: 'var(--mantine-color-body)' }}>
        <Text fw={600} size="sm" mb={4}>{label}</Text>
        {payload.map((p: any) => (
          <Group key={p.name} justify="space-between" gap="xl">
            <Text size="xs" c={p.color}>{p.name}</Text>
            <Text size="xs" fw={600} ff="monospace">{fmt(p.value)}</Text>
          </Group>
        ))}
      </Card>
    );
  };

  const showOp = fundFilter === 'all' || fundFilter === 'operating';
  const showRes = fundFilter === 'all' || fundFilter === 'reserve';

  return (
    <Card withBorder p="lg">
      <Group justify="space-between" mb="md">
        <div>
          <Title order={4}>{title}</Title>
          {summary && (
            <Group gap="md" mt={4}>
              <Badge variant="light" color="teal">End Liquidity: {fmt(summary.end_liquidity || 0)}</Badge>
              <Badge variant="light" color="orange">Min Liquidity: {fmt(summary.min_liquidity || 0)}</Badge>
              {summary.reserve_coverage_months != null && (
                <Badge variant="light" color="violet">
                  Reserve Coverage: {summary.reserve_coverage_months.toFixed(1)} mo
                </Badge>
              )}
            </Group>
          )}
        </div>
        <SegmentedControl
          size="xs"
          value={fundFilter}
          onChange={setFundFilter}
          data={[
            { label: 'All', value: 'all' },
            { label: 'Operating', value: 'operating' },
            { label: 'Reserve', value: 'reserve' },
          ]}
        />
      </Group>
      <ResponsiveContainer width="100%" height={350}>
        <AreaChart data={chartData}>
          <defs>
            <linearGradient id="opCash" x1="0" y1="0" x2="0" y2="1">
              <stop offset="5%" stopColor="#228be6" stopOpacity={0.6} />
              <stop offset="95%" stopColor="#228be6" stopOpacity={0.15} />
            </linearGradient>
            <linearGradient id="opInv" x1="0" y1="0" x2="0" y2="1">
              <stop offset="5%" stopColor="#74c0fc" stopOpacity={0.6} />
              <stop offset="95%" stopColor="#74c0fc" stopOpacity={0.15} />
            </linearGradient>
            <linearGradient id="resCash" x1="0" y1="0" x2="0" y2="1">
              <stop offset="5%" stopColor="#7950f2" stopOpacity={0.6} />
              <stop offset="95%" stopColor="#7950f2" stopOpacity={0.15} />
            </linearGradient>
            <linearGradient id="resInv" x1="0" y1="0" x2="0" y2="1">
              <stop offset="5%" stopColor="#b197fc" stopOpacity={0.6} />
              <stop offset="95%" stopColor="#b197fc" stopOpacity={0.15} />
            </linearGradient>
          </defs>
          <CartesianGrid strokeDasharray="3 3" opacity={0.3} />
          <XAxis dataKey="month" tick={{ fontSize: 11 }} interval="preserveStartEnd" />
          <YAxis tick={{ fontSize: 11 }} tickFormatter={(v) => `$${(v / 1000).toFixed(0)}k`} />
          <Tooltip content={<CustomTooltip />} />
          <Legend />
          {forecastStart > 0 && (
            <ReferenceLine x={chartData[forecastStart]?.month} stroke="#aaa" strokeDasharray="5 5" label="Forecast" />
          )}
          {showOp && <Area type="monotone" dataKey="operating_cash" name="Operating Cash" stroke="#228be6" fill="url(#opCash)" stackId="1" />}
          {showOp && <Area type="monotone" dataKey="operating_investments" name="Operating Investments" stroke="#74c0fc" fill="url(#opInv)" stackId="1" />}
          {showRes && <Area type="monotone" dataKey="reserve_cash" name="Reserve Cash" stroke="#7950f2" fill="url(#resCash)" stackId="1" />}
          {showRes && <Area type="monotone" dataKey="reserve_investments" name="Reserve Investments" stroke="#b197fc" fill="url(#resInv)" stackId="1" />}
        </AreaChart>
      </ResponsiveContainer>
    </Card>
  );
}