import { useRef, useState } from 'react'
import { useLocation } from 'react-router'
import { Info } from 'lucide-react'
import { PageError, PageHeader, PageLoading } from '@/components/page'
import { PeriodPicker } from '@/features/periods/period-picker'
import { SelectedPeriod } from '@/features/periods/selected-period'
import { Section } from '@/features/planning/plan-read'
import { useCategories, usePaymentMethods } from '@/lib/catalog'
import { useEntries } from '@/lib/entries'
import { toIsoDate } from '@/lib/format'
import { weekIndexFor } from '@/lib/ledger'
import { isWritable } from '@/lib/period-select'
import { useBudget } from '@/lib/periods'
import { t } from '@/lib/strings'
import type { Entry } from '@/types/Entry'
import type { Period } from '@/types/Period'
import { EntryForm } from './entry-form'
import { EntryList } from './entry-list'
import { WeekPicker } from './week-picker'
import { WeekSummary } from './week-summary'

export function LedgerPage() {
  return (
    <>
      <PageHeader
        title={t.pages.ledger.title}
        description={t.pages.ledger.description}
        actions={<PeriodPicker />}
      />
      <SelectedPeriod>{(p) => <LedgerView key={p.id} period={p} />}</SelectedPeriod>
    </>
  )
}

/**
 * Defter her açılışta **bugünün haftasıyla** başlar (dönem geçmişteyse son, gelecekteyse ilk
 * hafta); oklarla gezilen hafta yalnızca bu ekranda tutulur, adrese yazılmaz (kullanıcı kararı).
 * Düzen: hafta seçici → form → haftalık özet → girişler (masaüstünde form solda, diğerleri sağda).
 */
function LedgerView({ period }: { period: Period }) {
  const [today] = useState(() => toIsoDate(new Date()))
  const [editing, setEditing] = useState<Entry | null>(null)
  // Panel'deki "Harcama Ekle" → tutar alanına odaklan
  const focusAmount = (useLocation().state as { focus?: boolean } | null)?.focus === true
  const formRef = useRef<HTMLDivElement>(null)
  const inPeriod = today >= period.start_date && today <= period.last_date
  const todayIndex = inPeriod ? weekIndexFor(period.weeks, today) : null
  const [index, setIndex] = useState(() => weekIndexFor(period.weeks, today))
  // Dönem tarihleri değişip hafta sayısı azalırsa son haftaya düş
  const week = period.weeks[Math.min(index, period.weeks.length) - 1]
  const readOnly = !isWritable(period)

  const budget = useBudget(period.id)
  const categories = useCategories(true)
  const methods = usePaymentMethods(true)
  const entries = useEntries(period.id, { from: week.start_date, to: week.last_date })

  const goTo = (n: number) => {
    setEditing(null)
    setIndex(n)
  }

  function edit(e: Entry) {
    setEditing(e)
    formRef.current?.scrollIntoView({ behavior: 'smooth', block: 'start' })
  }

  const catalogFailed = [categories, methods].find((q) => q.isError)
  const catalog = categories.data && methods.data ? { c: categories.data, m: methods.data } : null

  return (
    <div className="space-y-4">
      <div className="mx-auto max-w-3xl lg:max-w-none">
        <WeekPicker
          weeks={period.weeks}
          index={week.index}
          todayIndex={todayIndex}
          budget={budget.data}
          onChange={goTo}
        />
      </div>
      {readOnly && (
        <p className="flex items-start gap-2 rounded-xl bg-muted px-3 py-2 text-sm text-muted-foreground">
          <Info className="mt-0.5 size-4 shrink-0" aria-hidden />
          {t.ledger.readOnly}
        </p>
      )}
      <div className="grid items-start gap-4 lg:grid-cols-2">
        {!readOnly && (
          <div ref={formRef} className="scroll-mt-4 lg:sticky lg:top-4">
            <Section title={editing ? t.ledger.editTitle : t.ledger.formTitle}>
              {catalogFailed?.error ? (
                <PageError message={catalogFailed.error.message} onRetry={catalogFailed.refetch} />
              ) : !catalog ? (
                <PageLoading />
              ) : (
                <EntryForm
                  key={editing?.id ?? 'new'}
                  period={period}
                  week={week}
                  today={today}
                  categories={catalog.c}
                  methods={catalog.m}
                  entry={editing ?? undefined}
                  autoFocus={focusAmount}
                  onSaved={(date) => goTo(weekIndexFor(period.weeks, date))}
                  onCancel={() => setEditing(null)}
                />
              )}
            </Section>
          </div>
        )}
        <div className={readOnly ? 'space-y-4 lg:col-span-2' : 'space-y-4'}>
          <Section title={t.ledger.summaryTitle}>
            {budget.isError ? (
              <PageError message={budget.error.message} onRetry={budget.refetch} />
            ) : budget.data ? (
              <WeekSummary budget={budget.data} index={week.index} />
            ) : (
              <PageLoading />
            )}
          </Section>
          <Section title={t.ledger.listTitle}>
            {entries.isError ? (
              <PageError message={entries.error.message} onRetry={entries.refetch} />
            ) : entries.data && catalog ? (
              <EntryList
                periodId={period.id}
                entries={entries.data}
                categories={catalog.c}
                methods={catalog.m}
                editingId={editing?.id}
                readOnly={readOnly}
                onEdit={edit}
                onDeleted={(id) => editing?.id === id && setEditing(null)}
              />
            ) : (
              <PageLoading />
            )}
          </Section>
        </div>
      </div>
    </div>
  )
}