"use client";

import { useState, useEffect, useRef } from "react";
import { Input } from "@/components/ui/input";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";
import { Checkbox } from "@/components/ui/checkbox";
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from "@/components/ui/table";
import {
  Search,
  ChevronLeft,
  ChevronRight,
  Loader2,
  Inbox,
  ChevronRight as ChevronRightIcon,
} from "lucide-react";

interface Column<T = unknown> {
  key: string;
  label: string;
  render?: (item: T) => React.ReactNode;
  sortable?: boolean;
  className?: string;
}

/**
 * Optional expandable-row config. When set, the table adds a small
 * chevron column at the start of each row; clicking it toggles a
 * spanned row beneath with the rendered content. Clicking the chevron
 * does NOT trigger `onRowClick` — the row stays put so the user can
 * read details without navigating away.
 */
interface ExpandableConfig<T> {
  isExpanded: (item: T) => boolean;
  onToggle: (item: T) => void;
  renderExpanded: (item: T) => React.ReactNode;
  /** Optional label for the chevron's `aria-label`. */
  ariaLabel?: (item: T) => string;
}

interface SelectionConfig<T> {
  /** Whether this item is currently selected. */
  isSelected: (item: T) => boolean;
  /** Toggle selection for this item. */
  onToggle: (item: T) => void;
  /**
   * Whether selection is disabled for this item (checkbox renders greyed
   * + the row's click handlers ignore it). Use for items that can't be
   * acted on in bulk (e.g. terminal-state rows the bulk action would
   * reject).
   */
  isDisabled?: (item: T) => boolean;
}

/**
 * Optional row-selection config. When provided, the table prepends a
 * checkbox column on desktop + adds a checkbox to each mobile card. The
 * page owns the selection state (typically a `Set<id>`) and passes the
 * `isSelected` / `onToggle` callbacks in; DataTable is purely
 * presentational here. The page can then drive a page-wide bulk action
 * (e.g. "Combine N selected") from the `actions` prop.
 *
 * Click semantics: clicking the checkbox toggles selection without
 * triggering `onRowClick` (otherwise clicking the checkbox would also
 * navigate to the detail page). This matters when the row is also
 * clickable.
 */
interface DataTableProps<T = unknown> {
  columns: Column<T>[];
  data: T[];
  loading?: boolean;
  error?: string;
  searchPlaceholder?: string;
  onSearch?: (query: string) => void;
  page?: number;
  totalPages?: number;
  onPageChange?: (page: number) => void;
  onRowClick?: (item: T) => void;
  actions?: React.ReactNode;
  mobileCardRender?: (item: T) => React.ReactNode;
  /**
   * Optional slot rendered next to the search input. Used by pages
   * like `/quotes` to expose an "Include older" toggle that flips
   * the search-route's recent-window cutoff (Path A scoping). The
   * DataTable keeps this blind to the host page's behaviour — it
   * just lays it out.
   */
  searchExtras?: React.ReactNode;
  /**
   * Debounce window between the last keystroke and the `onSearch`
   * callback firing. Default 300 ms — long enough to coalesce a
   * fast typist into one fetch, short enough to feel responsive.
   * The `/quotes` page passes 0 because it debounces at the page
   * level (its `searchInput → search` debounce has extra
   * side-effects like `setPage(1)` that DataTable can't replicate);
   * without this knob the quotes page double-debounces to 550 ms.
   * Mirrors the DataTable-internal 300 ms at the time of writing —
   * pages that don't pre-debounce can still rely on this default.
   */
  searchDebounceMs?: number;
  /**
   * Custom empty-state node rendered when `data.length === 0` and
   * the table isn't loading. Default is the generic "No records
   * found / Create your first record" panel. Pages with search pass
   * a search-specific empty state ("No matches for 'X' — try a
   * shorter query") so the operator gets a clear next-action hint
   * instead of a "create your first" prompt that doesn't apply.
   */
  emptyState?: React.ReactNode;
  /**
   * Per-row extra class names for the desktop table row. Use for row-
   * level highlights (e.g. background tint for claimed quotes).
   */
  rowClassName?: (item: T) => string | undefined;
  /**
   * Per-row inline style for the desktop table row. Use to set custom
   * CSS variables or border colours without forcing every consumer to
   * know the table's internal structure.
   */
  rowStyle?: (item: T) => React.CSSProperties | undefined;
  /**
   * Per-row extra class names for the mobile card wrapper.
   */
  mobileCardClassName?: (item: T) => string | undefined;
  /**
   * Per-row inline style for the mobile card wrapper.
   */
  mobileCardStyle?: (item: T) => React.CSSProperties | undefined;
  /**
   * Expandable-row config. When provided, a chevron column is added on
   * desktop and a "Show items" toggle is added to the mobile card.
   */
  expandable?: ExpandableConfig<T>;
  /**
   * Row-selection config. When provided, a leading checkbox column is
   * added on desktop + checkboxes are added to each mobile card. See
   * `SelectionConfig` above for the callback contract.
   */
  selection?: SelectionConfig<T>;
}

export function DataTable<T>({
  columns,
  data,
  loading = false,
  error,
  searchPlaceholder = "Search...",
  onSearch,
  page = 1,
  totalPages = 1,
  onPageChange,
  onRowClick,
  actions,
  mobileCardRender,
  rowClassName,
  rowStyle,
  mobileCardClassName,
  mobileCardStyle,
  expandable,
  selection,
  searchExtras,
  searchDebounceMs = 300,
  emptyState,
}: DataTableProps<T>) {
  const [searchQuery, setSearchQuery] = useState("");
  const [debouncedQuery, setDebouncedQuery] = useState("");
  const onSearchRef = useRef(onSearch);

  useEffect(() => {
    onSearchRef.current = onSearch;
  }, [onSearch]);

  useEffect(() => {
    // 0 ms → call onSearch synchronously (the caller pre-debounces).
    // Positive values → coalesce a fast typist into one fetch. The
    // default 300 ms mirrors the pre-existing behaviour so other
    // pages that don't pre-debounce still feel responsive without
    // firing a fetch per keystroke.
    if (searchDebounceMs <= 0) {
      /* eslint-disable react-hooks/set-state-in-effect */
      setDebouncedQuery(searchQuery);
      /* eslint-enable react-hooks/set-state-in-effect */
      return;
    }
    const timer = setTimeout(
      () => setDebouncedQuery(searchQuery),
      searchDebounceMs,
    );
    return () => clearTimeout(timer);
  }, [searchQuery, searchDebounceMs]);

  useEffect(() => {
    onSearchRef.current?.(debouncedQuery);
  }, [debouncedQuery]);

  if (error) {
    return (
      <div className="flex flex-col items-center justify-center py-12 text-muted-foreground">
        <Inbox className="h-12 w-12 mb-4" />
        <p className="text-lg font-medium">Error loading data</p>
        <p className="text-sm">{error}</p>
      </div>
    );
  }

  const desktopColCount =
    columns.length + (expandable ? 1 : 0) + (selection ? 1 : 0);

  return (
    <div className="space-y-4">
      <div className="flex flex-col sm:flex-row gap-3 items-start sm:items-center justify-between">
        {onSearch && (
          <div className="flex flex-col sm:flex-row gap-3 items-start sm:items-center w-full sm:max-w-2xl">
            <div className="relative w-full sm:max-w-sm">
              <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
              <Input
                placeholder={searchPlaceholder}
                value={searchQuery}
                onChange={(e) => setSearchQuery(e.target.value)}
                className="pl-9"
              />
            </div>
            {searchExtras}
          </div>
        )}
        {actions && <div className="flex gap-2">{actions}</div>}
      </div>

      {loading ? (
        <div className="flex items-center justify-center py-12">
          <Loader2 className="h-8 w-8 animate-spin text-muted-foreground" />
        </div>
      ) : data.length === 0 ? (
        emptyState ?? (
          <div className="flex flex-col items-center justify-center py-12 text-muted-foreground">
            <Inbox className="h-12 w-12 mb-4" />
            <p className="text-lg font-medium">No records found</p>
            <p className="text-sm">Create your first record to get started</p>
          </div>
        )
      ) : (
        <>
          {/* Desktop table */}
          {/*
           * `overflow-x-auto` on the wrapper so the table can scroll
           * horizontally when the viewport is narrower than the table's
           * natural width (e.g. 768–960 px iPad-landscape, where the
           * chevron + 7 columns exceed the viewport). Without this the
           * Actions column is clipped and unreachable on those widths.
           * The wrapper itself is `hidden md:block` so phones still see
           * the stacked card layout below.
           */}
          <div className="hidden md:block rounded-md border overflow-x-auto">
            <Table>
              <TableHeader>
                <TableRow>
                  {expandable && <TableHead className="w-8 p-0" />}
                  {selection && (
                    <TableHead className="w-8 px-2 py-1">
                      <span className="sr-only">Select</span>
                    </TableHead>
                  )}
                  {columns.map((col) => (
                    <TableHead key={col.key} className={col.className}>
                      {col.label}
                    </TableHead>
                  ))}
                </TableRow>
              </TableHeader>
              <TableBody>
                {data.map((item, i) => {
                  const expanded = expandable?.isExpanded(item) ?? false;
                  const rowKey =
                    ((item as unknown as Record<string, unknown>).id as string) || String(i);
                  return (
                    <ExpandableRow
                      key={rowKey}
                      item={item}
                      columns={columns}
                      onRowClick={onRowClick}
                      rowClassName={rowClassName}
                      rowStyle={rowStyle}
                      expandable={expandable}
                      expanded={expanded}
                      colSpan={desktopColCount}
                      selection={selection}
                    />
                  );
                })}
              </TableBody>
            </Table>
          </div>

          {/* Mobile cards — <md (768px). Desktop table switches to
              `hidden md:block`, mobile cards take over. Always rendered
              so every list page is mobile-usable even without a custom
              `mobileCardRender` — the default below reads the first
              two columns as a title + subtitle.
              The wrapping div handles the row click when `onRowClick`
              is set, so a custom `mobileCardRender` doesn't have to
              wire its own click target. Inner interactive elements
              (selection checkbox, "Show items" toggle) already
              stopPropagation. */}
          <div className="md:hidden space-y-3">
            {data.map((item, i) => {
              const expanded = expandable?.isExpanded(item) ?? false;
              const rowKey =
                ((item as unknown as Record<string, unknown>).id as string) || String(i);
              const selDisabled =
                selection?.isDisabled?.(item) ?? false;
              const selected = selection?.isSelected(item) ?? false;
              return (
                <div
                  key={rowKey}
                  role={onRowClick ? "button" : undefined}
                  tabIndex={onRowClick ? 0 : undefined}
                  onClick={onRowClick ? () => onRowClick(item) : undefined}
                  onKeyDown={
                    onRowClick
                      ? (e) => {
                          if (e.key === "Enter" || e.key === " ") {
                            e.preventDefault();
                            onRowClick(item);
                          }
                        }
                      : undefined
                  }
                  className={cn(
                    "rounded-2xl bg-card text-card-foreground shadow-sm shadow-foreground/5 ring-1 ring-foreground/5 overflow-hidden",
                    onRowClick && "cursor-pointer active:scale-[0.99] transition-transform",
                    mobileCardClassName?.(item),
                    selected && "ring-2 ring-info/40",
                  )}
                  style={mobileCardStyle?.(item)}
                >
                  {selection && (
                    <div className="flex items-center gap-2 px-3 pt-3 pb-1">
                      <Checkbox
                        checked={selected}
                        disabled={selDisabled}
                        onCheckedChange={() => selection.onToggle(item)}
                        aria-label={
                          selected ? "Deselect row" : "Select row"
                        }
                      />
                      <span className="text-[11px] text-muted-foreground">
                        {selected ? "Selected" : "Tap to select"}
                      </span>
                    </div>
                  )}
                  {mobileCardRender ? (
                    mobileCardRender(item)
                  ) : (
                    <DefaultMobileCard
                      item={item}
                      columns={columns}
                      onRowClick={onRowClick}
                    />
                  )}
                  {expandable && (
                    <div className="px-4 pb-3 pt-1">
                      <Button
                        variant="ghost"
                        size="sm"
                        className="h-7 px-2 text-xs w-full justify-start"
                        onClick={(e) => {
                          e.stopPropagation();
                          expandable.onToggle(item);
                        }}
                        aria-expanded={expanded}
                      >
                        <ChevronRightIcon
                          className={cn(
                            "h-3.5 w-3.5 mr-1 transition-transform",
                            expanded && "rotate-90"
                          )}
                        />
                        {expanded ? "Hide items" : "Show items"}
                      </Button>
                      {expanded && (
                        <div className="mt-2 border-t pt-2">
                          {expandable.renderExpanded(item)}
                        </div>
                      )}
                    </div>
                  )}
                </div>
              );
            })}
          </div>

          {/* Pagination */}
          {totalPages > 1 && (
            <div className="flex items-center justify-between">
              <p className="text-sm text-muted-foreground">
                Page {page} of {totalPages}
              </p>
              <div className="flex gap-2">
                <Button
                  variant="outline"
                  size="sm"
                  onClick={() => onPageChange?.(page - 1)}
                  disabled={page <= 1}
                >
                  <ChevronLeft className="h-4 w-4" />
                </Button>
                <Button
                  variant="outline"
                  size="sm"
                  onClick={() => onPageChange?.(page + 1)}
                  disabled={page >= totalPages}
                >
                  <ChevronRight className="h-4 w-4" />
                </Button>
              </div>
            </div>
          )}
        </>
      )}
    </div>
  );
}

/**
 * Internal: a single data row plus its optional expanded panel below.
 * Pulled out of the map so we don't have to write the colSpan/expand
 * logic inline twice.
 */
function ExpandableRow<T>({
  item,
  columns,
  onRowClick,
  rowClassName,
  rowStyle,
  expandable,
  expanded,
  colSpan,
  selection,
}: {
  item: T;
  columns: Column<T>[];
  onRowClick?: (item: T) => void;
  rowClassName?: (item: T) => string | undefined;
  rowStyle?: (item: T) => React.CSSProperties | undefined;
  expandable?: ExpandableConfig<T>;
  expanded: boolean;
  colSpan: number;
  selection?: SelectionConfig<T>;
}) {
  const selected = selection?.isSelected(item) ?? false;
  const selDisabled = selection?.isDisabled?.(item) ?? false;
  return (
    <>
      <TableRow
        className={cn(
          onRowClick && "cursor-pointer",
          rowClassName?.(item),
          selected && "bg-info/5",
        )}
        style={rowStyle?.(item)}
        onClick={() => onRowClick?.(item)}
        data-expanded={expanded || undefined}
        data-selected={selected || undefined}
      >
        {expandable && (
          <TableCell className="w-8 p-0 text-center">
            <button
              type="button"
              onClick={(e) => {
                e.stopPropagation();
                expandable.onToggle(item);
              }}
              aria-expanded={expanded}
              aria-label={
                expandable.ariaLabel
                  ? expandable.ariaLabel(item)
                  : expanded
                  ? "Hide details"
                  : "Show details"
              }
              className="inline-flex items-center justify-center h-8 w-8 rounded hover:bg-accent/60 text-muted-foreground"
            >
              <ChevronRightIcon
                className={cn(
                  "h-4 w-4 transition-transform duration-150",
                  expanded && "rotate-90"
                )}
              />
            </button>
          </TableCell>
        )}
        {selection && (
          <TableCell
            className="w-8 px-2 py-1"
            onClick={(e) => e.stopPropagation()}
          >
            <Checkbox
              checked={selected}
              disabled={selDisabled}
              onCheckedChange={() => selection.onToggle(item)}
              aria-label={selected ? "Deselect row" : "Select row"}
            />
          </TableCell>
        )}
        {columns.map((col) => (
          <TableCell key={col.key} className={col.className}>
            {col.render
              ? col.render(item)
              : String(((item as unknown as Record<string, unknown>)[col.key]) ?? "")}
          </TableCell>
        ))}
      </TableRow>
      {expandable && expanded && (
        <TableRow
          // The expanded panel is not clickable — we stop propagation so
          // clicking inside the panel (e.g. on a link or button) doesn't
          // bubble up and trigger the row's onClick handler.
          onClick={(e) => e.stopPropagation()}
          // `border-t` + slightly darker bg gives the panel a hard top
          // edge so the eye can anchor which expanded panel belongs to
          // which row when multiple rows in a row are expanded.
          className="bg-muted/40 hover:bg-muted/40 border-t border-border/60"
        >
          <TableCell colSpan={colSpan} className="p-0">
            {expandable.renderExpanded(item)}
          </TableCell>
        </TableRow>
      )}
    </>
  );
}

/**
 * Default fallback mobile card — used when a list page didn't pass a
 * custom `mobileCardRender`. Renders the first column as the title
 * (the row's "name"-equivalent) and the second column as a single
 * supporting line; further columns are stacked underneath in muted
 * text. The whole card is tappable when `onRowClick` was provided.
 *
 * Touch targets: 56px+ on the title row when tappable, so phones get
 * a comfortable thumb-zone hit area. Description wraps naturally
 * (no fixed-width truncation).
 *
 * Pages with bespoke mobile layouts (e.g. `/sprint`) still pass
 * `mobileCardRender` and skip this; this card exists so the other 9+
 * list pages are usable on mobile with zero per-page wiring.
 */
function DefaultMobileCard<T>({
  item,
  columns,
  onRowClick,
}: {
  item: T;
  columns: Column<T>[];
  onRowClick?: (item: T) => void;
}) {
  const titleCol = columns[0];
  const subtitleCol = columns[1];
  const tail = columns.slice(2);
  const titleNode = titleCol
    ? titleCol.render
      ? titleCol.render(item)
      : String(
          (item as unknown as Record<string, unknown>)[titleCol.key] ?? "",
        )
    : null;
  const subtitleNode = subtitleCol
    ? subtitleCol.render
      ? subtitleCol.render(item)
      : String(
          (item as unknown as Record<string, unknown>)[subtitleCol.key] ?? "",
        )
    : null;

  const CardInner = (
    <div
      className={cn(
        "rounded-md border bg-card text-card-foreground p-3 space-y-1.5",
        onRowClick && "cursor-pointer transition-colors hover:bg-muted/30",
      )}
    >
      <div className="font-medium text-sm leading-tight truncate">
        {titleNode}
      </div>
      {subtitleNode && (
        <div className="text-xs text-muted-foreground leading-snug line-clamp-2">
          {subtitleNode}
        </div>
      )}
      {tail.length > 0 && (
        <div className="flex flex-wrap gap-x-3 gap-y-1 pt-1 border-t border-border/50 text-[11px] text-muted-foreground">
          {tail.map((c) => {
            const v = c.render
              ? c.render(item)
              : String(
                  (item as unknown as Record<string, unknown>)[c.key] ?? "",
                );
            return (
              <span key={c.key}>
                <span className="text-foreground/60">{c.label}:</span>{" "}
                <span className="text-foreground/90">{v}</span>
              </span>
            );
          })}
        </div>
      )}
    </div>
  );

  if (onRowClick) {
    return (
      <button
        type="button"
        onClick={() => onRowClick(item)}
        className="block w-full text-left min-h-[56px]"
      >
        {CardInner}
      </button>
    );
  }
  return CardInner;
}