import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { useLocation } from "react-router-dom";
import { Wand2, Tag, Receipt } from "lucide-react";
import { PageHelp } from "../components/shared/PageHelp";
import EmptyState from "../components/shared/EmptyState";
import OnboardingStepCard from "../components/onboarding/OnboardingStepCard";
import { useOnboarding } from "../contexts/OnboardingContext";
import {
  readOnboardingNavState,
  showsStepCard,
  transactionsCardModel,
} from "../utils/onboardingPath";
import {
  useTransactions,
  showsEmptyState,
  GUIDED_ENTRY_FILTERS,
} from "../hooks/useTransactions";
import TransactionFilterBar from "../components/transactions/TransactionFilterBar";
import TransactionSummaryBar from "../components/transactions/TransactionSummaryBar";
import TransactionTable from "../components/transactions/TransactionTable";
import TransactionPagination from "../components/transactions/TransactionPagination";
import ContextMenu from "../components/shared/ContextMenu";
import AddKeywordDialog from "../components/categories/AddKeywordDialog";
import {
  listAllLinkedTransfersForTooltip,
  type LinkedTransferTooltipRow,
} from "../services/balance.service";
import type { TransactionRow } from "../shared/types";

export default function TransactionsPage() {
  const { t } = useTranslation();
  const location = useLocation();
  // The link of the "categorize by hand" step opens the guided entry (#399),
  // read like any navigation state through `readOnboardingNavState` (CWE-476).
  // The hook takes its start filters at mount only: the card consuming the
  // navigation state afterwards changes nothing.
  const { state, setFilter, setSort, setPage, updateCategory, saveNotes, autoCategorize, addKeywordToCategory, loadSplitChildren, saveSplit, deleteSplit } =
    useTransactions(
      readOnboardingNavState(location.state).guided ? GUIDED_ENTRY_FILTERS : undefined
    );
  const onboarding = useOnboarding();
  const [resultMessage, setResultMessage] = useState<string | null>(null);
  const [menu, setMenu] = useState<{ x: number; y: number; row: TransactionRow } | null>(null);
  const [pending, setPending] = useState<TransactionRow | null>(null);
  // Issue #142 — single batch lookup for the inlined transfer icon. One
  // SELECT on mount gives us a Map<txId, links[]> the table consults via
  // `.has()` per row. Avoids an N+1 hit on the rendered page.
  const [linkedTransfersByTxId, setLinkedTransfersByTxId] = useState<
    Map<number, LinkedTransferTooltipRow[]>
  >(new Map());

  useEffect(() => {
    listAllLinkedTransfersForTooltip()
      .then(setLinkedTransfersByTxId)
      .catch(() => setLinkedTransfersByTxId(new Map()));
  }, []);

  const handleRowContextMenu = (e: React.MouseEvent, row: TransactionRow) => {
    e.preventDefault();
    setMenu({ x: e.clientX, y: e.clientY, row });
  };

  const handleAutoCategorize = async () => {
    setResultMessage(null);
    const count = await autoCategorize();
    if (count > 0) {
      setResultMessage(t("transactions.autoCategorizeResult", { count }));
    } else {
      setResultMessage(t("transactions.autoCategorizeNone"));
    }
    setTimeout(() => setResultMessage(null), 4000);
  };

  // #353 — a profile without any transaction gets the "import first" card in
  // place of the filter bar, table and pagination. `rows.length === 0` is not
  // the signal: the default filter is "since January 1st", so an empty page
  // can still sit on a populated profile.
  const isEmptyProfile = showsEmptyState(state);

  // The getting-started card follows the list's filter (#399). Its target is
  // highlighted only while the card is on screen: a ring needs the card that
  // explains it.
  const cardModel = transactionsCardModel(state.filters, onboarding.checklist);
  const target = showsStepCard(onboarding.mode, onboarding.cardPage, location.pathname)
    ? cardModel.target
    : null;

  return (
    <div>
      <OnboardingStepCard model={cardModel} />

      <div className="relative flex items-center gap-3 mb-6">
        <h1 className="text-2xl font-bold">{t("transactions.title")}</h1>
        <PageHelp helpKey="transactions" />
        <button
          onClick={handleAutoCategorize}
          disabled={state.isAutoCategorizing}
          className="flex items-center gap-1.5 px-3 py-1.5 text-sm rounded-lg bg-[var(--primary)] text-white hover:opacity-90 disabled:opacity-50 transition-opacity"
        >
          <Wand2 size={16} />
          {state.isAutoCategorizing
            ? t("common.loading")
            : t("transactions.autoCategorize")}
        </button>
        {resultMessage && (
          <span className="text-sm text-[var(--muted-foreground)]">
            {resultMessage}
          </span>
        )}
      </div>

      {state.error && (
        <div className="mb-4 p-3 rounded-lg bg-[color-mix(in_srgb,var(--negative)_10%,var(--card))] border border-[var(--negative)] text-[var(--negative)] text-sm">
          {state.error}
        </div>
      )}

      {isEmptyProfile ? (
        <EmptyState
          icon={<Receipt size={40} />}
          title={t("transactions.empty.title")}
          description={t("transactions.empty.description")}
          primaryAction={{ label: t("transactions.empty.cta"), to: "/import" }}
        />
      ) : (
        <>
          <TransactionFilterBar
            filters={state.filters}
            categories={state.categories}
            sources={state.sources}
            onFilterChange={setFilter}
          />

          <TransactionSummaryBar
            totalCount={state.totalCount}
            totalAmount={state.totalAmount}
            incomeTotal={state.incomeTotal}
            expenseTotal={state.expenseTotal}
          />

          {state.isLoading ? (
            <div className="text-center py-8 text-[var(--muted-foreground)]">
              {t("common.loading")}
            </div>
          ) : (
            <>
              <TransactionTable
                rows={state.rows}
                sort={state.sort}
                categories={state.categories}
                onSort={setSort}
                onCategoryChange={updateCategory}
                onNotesChange={saveNotes}
                onAddKeyword={addKeywordToCategory}
                onLoadSplitChildren={loadSplitChildren}
                onSaveSplit={saveSplit}
                onDeleteSplit={deleteSplit}
                onRowContextMenu={handleRowContextMenu}
                linkedTransfersByTxId={linkedTransfersByTxId}
                onboardingTarget={target === "firstRowCategory"}
              />

              <TransactionPagination
                page={state.page}
                pageSize={state.pageSize}
                totalCount={state.totalCount}
                onPageChange={setPage}
              />
            </>
          )}
        </>
      )}

      {menu && (
        <ContextMenu
          x={menu.x}
          y={menu.y}
          header={menu.row.description}
          onClose={() => setMenu(null)}
          items={[
            {
              icon: <Tag size={14} />,
              label: t("reports.keyword.addFromTransaction"),
              onClick: () => setPending(menu.row),
            },
          ]}
        />
      )}

      {pending && (
        <AddKeywordDialog
          initialKeyword={pending.description.split(/\s+/)[0] ?? ""}
          initialCategoryId={pending.category_id}
          onClose={() => setPending(null)}
          onApplied={() => setPending(null)}
        />
      )}
    </div>
  );
}