import { useState } from 'react'
import { useNavigate } from 'react-router-dom'
import { formatINR } from '@sims/domain'
import { DataTable, EmptyState, ErrorState, Field, FilterChips, Skeleton, PageHeader } from '@sims/ui'
import { getDuesAging, getModuleRevenue, getProfitability, getAwsRanking } from '../api'
import { useData } from './Clients'

const inr = (p: number) => formatINR(p, { symbol: false })
const prevMonth = (): string => {
  const d = new Date()
  return new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth() - 1, 1)).toISOString().slice(0, 7)
}

/** Reports — dues aging, module revenue, client profitability, and the AWS cost chart (spec §5–§6). */
export function Reports() {
  const nav = useNavigate()
  const [month, setMonth] = useState(prevMonth())
  const [report, setReport] = useState<'dues' | 'revenue' | 'profit' | 'aws'>('dues')
  const dues = useData(getDuesAging, [])
  const revenue = useData(() => getModuleRevenue(), [])
  const profit = useData(() => getProfitability(), [])
  const ranking = useData(() => getAwsRanking(month), [month])

  return (
    <div className="wf-page">
      <PageHeader title="Reports" desc="Dues aging, module revenue, client profitability, and the AWS cost chart." />

      <FilterChips
        active={report}
        onChange={(k) => setReport(k as typeof report)}
        chips={[
          { key: 'dues', label: 'Dues aging' },
          { key: 'revenue', label: 'Module revenue' },
          { key: 'profit', label: 'Profitability' },
          { key: 'aws', label: 'AWS costs' },
        ]}
      />

      {report === 'dues' && (
        dues.error !== undefined ? <ErrorState message={dues.error} onRetry={dues.reload} />
          : dues.data === undefined ? <Skeleton rows={5} />
          : dues.data.length === 0 ? <EmptyState>No outstanding dues.</EmptyState>
          : (
            <DataTable
              columns={[
                { key: 'client', label: 'Client' }, { key: 'b1', label: '0–30', numeric: true },
                { key: 'b2', label: '31–60', numeric: true }, { key: 'b3', label: '61–90', numeric: true },
                { key: 'b4', label: '90+', numeric: true }, { key: 'total', label: 'Total', numeric: true },
              ]}
              onRowClick={(_r, i) => nav(`/clients/${dues.data![i]!.clientId}`)}
              rowTone={(i) => ((dues.data![i]!.b90p > 0) ? 'err' : dues.data![i]!.b61_90 > 0 ? 'warn' : undefined)}
              rows={dues.data.map((d) => ({
                client: d.clientName, b1: inr(d.b0_30), b2: inr(d.b31_60), b3: inr(d.b61_90), b4: inr(d.b90p), total: inr(d.totalPaise),
              }))}
            />
          )
      )}

      {report === 'revenue' && (
        revenue.error !== undefined ? <ErrorState message={revenue.error} onRetry={revenue.reload} />
          : revenue.data === undefined ? <Skeleton rows={5} />
          : revenue.data.length === 0 ? <EmptyState>No invoiced revenue yet.</EmptyState>
          : (
            <DataTable
              columns={[
                { key: 'module', label: 'Module' }, { key: 'billed', label: 'Billed', numeric: true },
                { key: 'settled', label: 'Settled', numeric: true },
              ]}
              rows={revenue.data.map((m) => ({ module: `${m.moduleName} (${m.moduleCode})`, billed: inr(m.billedPaise), settled: inr(m.settledPaise) }))}
            />
          )
      )}

      {report === 'profit' && (
        profit.error !== undefined ? <ErrorState message={profit.error} onRetry={profit.reload} />
          : profit.data === undefined ? <Skeleton rows={5} />
          : profit.data.length === 0 ? <EmptyState>No client activity yet.</EmptyState>
          : (
            <DataTable
              columns={[
                { key: 'client', label: 'Client' }, { key: 'billed', label: 'Billed', numeric: true },
                { key: 'settled', label: 'Settled', numeric: true }, { key: 'aws', label: 'AWS cost', numeric: true },
                { key: 'margin', label: 'Margin', numeric: true },
              ]}
              onRowClick={(_r, i) => nav(`/clients/${profit.data![i]!.clientId}`)}
              rows={profit.data.map((p) => ({
                client: p.clientName, billed: inr(p.billedPaise), settled: inr(p.settledPaise),
                aws: inr(p.awsCostPaise), margin: inr(p.marginPaise),
              }))}
            />
          )
      )}

      {report === 'aws' && (
        <>
          <Field label="Month"><input type="month" className="wf" value={month} onChange={(e) => setMonth(e.target.value)} /></Field>
          {ranking.error !== undefined ? <ErrorState message={ranking.error} onRetry={ranking.reload} />
            : ranking.data === undefined ? <Skeleton rows={5} />
            : ranking.data.rows.length === 0 ? <EmptyState>No AWS cost recorded for {month}.</EmptyState>
            : (
              <div style={{ margin: '10px 0' }}>
                {ranking.data.rows.map((row) => (
                  <div key={row.clientId} style={{ display: 'flex', alignItems: 'center', gap: 10, margin: '4px 0' }}>
                    <div style={{ width: 160, cursor: 'pointer' }} onClick={() => nav(`/clients/${row.clientId}`)}>{row.clientName}</div>
                    <div style={{ flex: 1, background: 'var(--border)', borderRadius: 4, height: 16 }}>
                      <div style={{ width: `${row.sharePctBp / 100}%`, background: 'var(--accent, #4a7)', height: '100%', borderRadius: 4 }} />
                    </div>
                    <div style={{ width: 120, textAlign: 'right' }}>{inr(row.costPaise)}</div>
                    <div style={{ width: 56, textAlign: 'right', color: 'var(--muted, #888)' }}>{(row.sharePctBp / 100).toFixed(1)}%</div>
                  </div>
                ))}
              </div>
            )}
        </>
      )}
    </div>
  )
}