import { useState } from 'react'
import { Link } from 'react-router'
import { paths } from '@/components/layout/nav-items'
import { PageError } from '@/components/page'
import { Skeleton } from '@/components/skeleton'
import { Button } from '@/components/ui/button'
import { WeekSummary } from '@/features/ledger/week-summary'
import { PeriodHeading } from '@/features/planning/plan-read'
import { dailyAllowance } from '@/lib/dashboard'
import { formatDayMonth, formatMoney, toIsoDate } from '@/lib/format'
import { weekIndexFor } from '@/lib/ledger'
import { periodPath } from '@/lib/period-select'
import { useBudget, useStats, useSummary } from '@/lib/periods'
import { t } from '@/lib/strings'
import { cn } from '@/lib/utils'
import type { GroupBudget } from '@/types/GroupBudget'
import type { Period } from '@/types/Period'
import type { PeriodSummary } from '@/types/PeriodSummary'

const s = t.dashboard

/** Özet kartları: gelir, sabit gider, toplam birikim, devreden borç, anlık durum, gruplar */
export function Overview({ period, writable }: { period: Period; writable: boolean }) {
  const summary = useSummary(period.id)
  const budget = useBudget(period.id)
  const stats = useStats()
  const [today] = useState(() => toIsoDate(new Date()))

  const failed = [summary, budget].find((q) => q.isError)
  if (failed?.error) return <PageError message={failed.error.message} onRetry={failed.refetch} />
  if (!summary.data || !budget.data) return <DashboardSkeleton />
  const sum = summary.data

  return (
    <div className="space-y-4">
      <PeriodHeading period={period} />
      {/* Borç kartı yalnızca varsa: 3 kartta mobilde sonuncusu tam genişlik, masaüstünde 3 sütun */}
      <dl
        className={cn(
          'grid grid-cols-2 gap-3',
          sum.carryover_debt > 0
            ? 'lg:grid-cols-4'
            : 'lg:grid-cols-3 [&>*:last-child]:col-span-2 lg:[&>*:last-child]:col-span-1',
        )}
      >
        <Tile emoji="💰" label={s.income} amount={sum.income_total} tone="text-income" />
        <Tile emoji="📌" label={s.fixed} amount={sum.fixed_expense_total} />
        <Tile
          emoji="🐷"
          label={s.saved}
          amount={stats.data?.total_saved}
          hint={s.savedHint}
          tone="text-income"
        />
        {sum.carryover_debt > 0 && (
          <Tile
            emoji="⚠️"
            label={s.debt}
            amount={sum.carryover_debt}
            hint={s.debtHint}
            tone="text-expense"
          />
        )}
      </dl>
      {/* Anlık durum DOM'da önce (ekran okuyucu ve mobilde ilk), masaüstünde sağ sütunda */}
      <div className="grid items-start gap-4 lg:grid-cols-[3fr_2fr]">
        <StatusCard period={period} summary={sum} today={today} writable={writable} />
        <GroupsCard
          period={period}
          budget={budget.data}
          summary={sum}
          today={today}
          writable={writable}
        />
      </div>
    </div>
  )
}

function Tile({
  emoji,
  label,
  amount,
  hint,
  tone,
}: {
  emoji: string
  label: string
  /** `undefined` → yükleniyor */
  amount: number | undefined
  hint?: string
  tone?: string
}) {
  return (
    <div className="rounded-2xl border bg-card p-4">
      <dt className="text-sm text-muted-foreground">
        <span aria-hidden>{emoji}</span> {label}
      </dt>
      <dd className={cn('money mt-1 text-lg font-semibold sm:text-xl', tone)}>
        {amount === undefined ? <Skeleton className="h-7 w-28" /> : formatMoney(amount)}
      </dd>
      {hint && <dd className="mt-1 text-xs text-muted-foreground">{hint}</dd>}
    </div>
  )
}

/** En belirgin kart: kalan harcanabilir + günlük öneri */
function StatusCard({
  period,
  summary,
  today,
  writable,
}: {
  period: Period
  summary: PeriodSummary
  today: string
  writable: boolean
}) {
  const over = summary.remaining < 0
  const { daysLeft, perDay } = dailyAllowance(summary.remaining, period, today)
  return (
    <section
      aria-labelledby="status-title"
      className={cn(
        'rounded-2xl border-2 p-5 lg:col-start-2 lg:row-start-1',
        over ? 'border-expense/50 bg-expense/5' : 'border-primary/40 bg-primary/5',
      )}
    >
      <h2 id="status-title" className="text-sm font-medium text-muted-foreground">
        <span aria-hidden>📍</span> {s.statusTitle}
      </h2>
      <p className="mt-2 text-sm">{over ? s.overspent : s.remaining}</p>
      <p
        className={cn(
          'money text-4xl font-bold tracking-tight',
          over ? 'text-expense' : 'text-foreground',
        )}
      >
        {formatMoney(over ? -summary.remaining : summary.remaining)}
      </p>
      <p className="mt-2 text-sm text-muted-foreground">
        {s.statusDetail(formatMoney(summary.spendable), formatMoney(summary.spent_total))}
      </p>
      {writable &&
        (daysLeft === 0 ? (
          <div className="mt-3 space-y-2">
            <p className="text-sm">{s.ended}</p>
            <Button asChild variant="outline">
              <Link to={periodPath(paths.review, period)}>{s.toReview}</Link>
            </Button>
          </div>
        ) : (
          <p className="mt-3 text-sm font-medium">
            {perDay !== null ? s.perDay(daysLeft, formatMoney(perDay)) : s.daysLeft(daysLeft)}
          </p>
        ))}
    </section>
  )
}

/** 4 grup: planlanan / gerçekleşen; Haftalık (bugünün haftası) ↔ Aylık (tüm dönem) */
function GroupsCard({
  period,
  budget,
  summary,
  today,
  writable,
}: {
  period: Period
  budget: GroupBudget[]
  summary: PeriodSummary
  today: string
  writable: boolean
}) {
  const [mode, setMode] = useState<'week' | 'month'>('week')
  const index = weekIndexFor(period.weeks, today)
  const week = period.weeks[index - 1]
  const range = (a: string, b: string) => `${formatDayMonth(a)}–${formatDayMonth(b)}`

  return (
    <section
      aria-labelledby="groups-title"
      className="rounded-2xl border bg-card p-4 sm:p-5 lg:col-start-1 lg:row-start-1"
    >
      <div className="mb-1 flex flex-wrap items-center justify-between gap-2">
        <h2 id="groups-title" className="font-semibold">
          <span aria-hidden>🎯</span> {s.groupsTitle}
        </h2>
        <div role="group" aria-label={s.groupsTitle} className="flex rounded-lg border p-0.5">
          {(['week', 'month'] as const).map((m) => (
            <button
              key={m}
              type="button"
              aria-pressed={mode === m}
              onClick={() => setMode(m)}
              className={cn(
                'min-h-11 rounded-md px-4 text-sm font-medium',
                mode === m ? 'bg-primary text-primary-foreground' : 'hover:bg-muted',
              )}
            >
              {m === 'week' ? s.weekly : s.monthly}
            </button>
          ))}
        </div>
      </div>
      <p className="mb-3 text-sm text-muted-foreground">
        {mode === 'week' && week
          ? s.weekLabel(index, range(week.start_date, week.last_date))
          : s.monthLabel(range(period.start_date, period.last_date))}
      </p>

      {summary.budget_total === 0 ? (
        <Empty text={s.noBudget} to={periodPath(paths.planning, period)} action={s.toPlan} />
      ) : (
        <WeekSummary budget={budget} index={mode === 'week' ? index : 'month'} />
      )}
      {writable && summary.spent_total === 0 && summary.budget_total > 0 && (
        <p className="mt-3 text-sm text-muted-foreground">
          <Link to={paths.ledger} state={{ focus: true }} className="underline">
            {s.noEntries}
          </Link>
        </p>
      )}
    </section>
  )
}

function Empty({ text, to, action }: { text: string; to: string; action: string }) {
  return (
    <div className="flex flex-col items-start gap-3 rounded-xl bg-muted p-4">
      <p className="text-sm text-muted-foreground">{text}</p>
      <Button asChild variant="outline">
        <Link to={to}>{action}</Link>
      </Button>
    </div>
  )
}

/** Yükleniyor: kartların şeklinde yer tutucular */
export function DashboardSkeleton() {
  return (
    <div role="status" aria-label={t.common.loading} className="space-y-4">
      <Skeleton className="h-12 w-56" />
      <div className="grid grid-cols-2 gap-3 lg:grid-cols-4">
        {[0, 1, 2, 3].map((i) => (
          <Skeleton key={i} className="h-24" />
        ))}
      </div>
      <div className="grid gap-4 lg:grid-cols-[3fr_2fr]">
        <Skeleton className="h-72" />
        <Skeleton className="h-48" />
      </div>
    </div>
  )
}