"use client";

import { useMemo, useState } from "react";
import Link from "next/link";
import {
  flexRender,
  getCoreRowModel,
  getFilteredRowModel,
  getSortedRowModel,
  useReactTable,
  type ColumnDef,
  type Row,
  type SortingState,
} from "@tanstack/react-table";
import {
  Table, TableBody, TableCell, TableHead, TableHeader, TableRow,
} from "@/components/ui/table";
import { Input } from "@/components/ui/input";
import { Skeleton } from "@/components/ui/skeleton";
import { Badge } from "@/components/ui/badge";
import {
  Select, SelectContent, SelectItem, SelectTrigger, SelectValue,
} from "@/components/ui/select";
import { StatusBadge } from "@/components/cases/status-badge";
import { isBlamSubtype } from "@/lib/practice-area";
import type { Case } from "@/lib/api/cases";

function formatDate(iso?: string) {
  if (!iso) return "—";
  try {
    return new Date(iso).toLocaleDateString("he-IL", {
      day: "2-digit",
      month: "2-digit",
      year: "numeric",
    });
  } catch {
    return iso;
  }
}

/** Midnight today, in ms — the pivot between an upcoming and a past hearing. */
function startOfToday() {
  const d = new Date();
  d.setHours(0, 0, 0, 0);
  return d.getTime();
}

/** Day-precision ms for a hearing date, or null when absent/unparseable. */
function hearingMs(iso?: string | null): number | null {
  if (!iso) return null;
  const t = new Date(iso).setHours(0, 0, 0, 0);
  return Number.isNaN(t) ? null : t;
}

type HearingClass = "soon" | "upcoming" | "past" | "none";

/** Classify a hearing date for the cell's colour cue (within ~7 days = "soon"). */
function classifyHearing(iso?: string | null): HearingClass {
  const t = hearingMs(iso);
  if (t === null) return "none";
  const today = startOfToday();
  if (t < today) return "past";
  return t - today <= 7 * 86_400_000 ? "soon" : "upcoming";
}

const HEARING_CLASS_STYLE: Record<HearingClass, string> = {
  soon: "text-gold-deep font-semibold",
  upcoming: "text-navy font-semibold",
  past: "text-ink-light",
  none: "text-ink-light",
};

/** Relative-time label beside the hearing date (mockup 04b `.hd-rel`). */
function relativeHearing(iso?: string | null): string | null {
  const t = hearingMs(iso);
  if (t === null) return null;
  const days = Math.round((t - startOfToday()) / 86_400_000);
  if (days === 0) return "היום";
  if (days === 1) return "מחר";
  if (days === -1) return "אתמול";
  return days > 0 ? `בעוד ${days} ימים` : `לפני ${Math.abs(days)} ימים`;
}

/**
 * Default ordering for the case list: the nearest upcoming hearing on top,
 * past hearings sinking below it (most-recently-passed first), and cases with
 * no hearing date last. Authored as a non-inverting comparator, so the column's
 * initial (ascending) sort yields exactly this sequence.
 */
function hearingDateSort(a: Row<Case>, b: Row<Case>): number {
  const today = startOfToday();
  // group: 0 = upcoming (incl. today), 1 = past, 2 = no date
  const rank = (iso?: string | null): { g: number; t: number } => {
    const t = hearingMs(iso);
    if (t === null) return { g: 2, t: 0 };
    return t >= today ? { g: 0, t } : { g: 1, t };
  };
  const ra = rank(a.original.hearing_date);
  const rb = rank(b.original.hearing_date);
  if (ra.g !== rb.g) return ra.g - rb.g;
  if (ra.g === 0) return ra.t - rb.t; // upcoming: ascending (nearest first)
  if (ra.g === 1) return rb.t - ra.t; // past: descending (most recent first)
  return 0; // both undated — keep stable order
}

const columns: ColumnDef<Case>[] = [
  {
    accessorKey: "case_number",
    header: "מס׳ ערר",
    cell: ({ row }) => (
      <Link
        href={`/cases/${row.original.case_number}`}
        className="text-navy font-semibold hover:text-gold-deep tabular-nums"
      >
        {row.original.case_number}
      </Link>
    ),
  },
  {
    accessorKey: "title",
    header: "כותרת",
    cell: ({ row }) => (
      <div className="text-ink max-w-[420px] min-w-0 truncate flex items-center gap-2" title={row.original.title}>
        {(row.original.proceeding_type === 'בל"מ' || isBlamSubtype(row.original.appeal_subtype)) && (
          <Badge
            variant="outline"
            className="rounded-full px-1.5 py-0 text-[0.65rem] font-bold bg-warn/10 text-warn-deep border-warn/40 shrink-0"
            title="בקשה להארכת מועד להגשת ערר"
          >
            בל&quot;מ
          </Badge>
        )}
        <span className="truncate">{row.original.title}</span>
      </div>
    ),
  },
  {
    accessorKey: "status",
    header: "סטטוס",
    cell: ({ row }) => <StatusBadge status={row.original.status} />,
  },
  {
    accessorKey: "document_count",
    header: "מסמכים",
    cell: ({ row }) => (
      <span className="tabular-nums text-ink-soft">
        {row.original.document_count ?? "—"}
      </span>
    ),
  },
  {
    accessorKey: "hearing_date",
    header: "מועד דיון",
    sortingFn: hearingDateSort,
    cell: ({ row }) => {
      const klass = classifyHearing(row.original.hearing_date);
      const rel = relativeHearing(row.original.hearing_date);
      return (
        <div className="leading-tight">
          <span className={`tabular-nums text-sm ${HEARING_CLASS_STYLE[klass]}`}>
            {formatDate(row.original.hearing_date ?? undefined)}
          </span>
          {rel ? (
            <span className="block text-[0.7rem] text-ink-muted">{rel}</span>
          ) : null}
        </div>
      );
    },
  },
  {
    accessorKey: "updated_at",
    header: "עודכן",
    cell: ({ row }) => (
      <span className="text-ink-muted text-sm">{formatDate(row.original.updated_at)}</span>
    ),
  },
];

export function CasesTable({
  cases,
  loading,
  error,
  emptyText = "עדיין אין תיקי ערר",
  searchPlaceholder = "חיפוש לפי מס׳ ערר או כותרת…",
}: {
  cases?: Case[];
  loading?: boolean;
  error?: Error | null;
  emptyText?: string;
  searchPlaceholder?: string;
}) {
  // Default: nearest upcoming hearing on top; past hearings sink below
  // (most-recently-passed first); undated cases last. desc:false keeps the
  // hearingDateSort comparator's intended (non-inverted) sequence.
  const [sorting, setSorting] = useState<SortingState>([
    { id: "hearing_date", desc: false },
  ]);
  const [globalFilter, setGlobalFilter] = useState("");
  /* "all" = all cases; "blam" = only בל"מ; "regular" = exclude בל"מ */
  const [blamFilter, setBlamFilter] = useState<"all" | "blam" | "regular">("all");

  const data = useMemo(() => {
    const all = cases ?? [];
    const isBlam = (c: Case) =>
      c.proceeding_type === 'בל"מ' || isBlamSubtype(c.appeal_subtype);
    if (blamFilter === "blam") return all.filter(isBlam);
    if (blamFilter === "regular") return all.filter((c) => !isBlam(c));
    return all;
  }, [cases, blamFilter]);

  const table = useReactTable({
    data,
    columns,
    state: { sorting, globalFilter },
    onSortingChange: setSorting,
    onGlobalFilterChange: setGlobalFilter,
    getCoreRowModel: getCoreRowModel(),
    getSortedRowModel: getSortedRowModel(),
    getFilteredRowModel: getFilteredRowModel(),
    globalFilterFn: (row, _colId, filterValue: string) => {
      if (!filterValue) return true;
      const needle = filterValue.toLowerCase();
      return (
        row.original.case_number.toLowerCase().includes(needle) ||
        row.original.title.toLowerCase().includes(needle)
      );
    },
  });

  return (
    <div className="space-y-3">
      <div className="flex items-center gap-3">
        <Input
          value={globalFilter}
          onChange={(e) => setGlobalFilter(e.target.value)}
          placeholder={searchPlaceholder}
          className="max-w-sm bg-surface"
          dir="rtl"
        />
        <Select
          value={blamFilter}
          onValueChange={(v) => setBlamFilter(v as "all" | "blam" | "regular")}
          dir="rtl"
        >
          <SelectTrigger className="w-40 bg-surface">
            <SelectValue />
          </SelectTrigger>
          <SelectContent>
            <SelectItem value="all">כל התיקים</SelectItem>
            <SelectItem value="blam">בל&quot;מ בלבד</SelectItem>
            <SelectItem value="regular">ערר רגיל בלבד</SelectItem>
          </SelectContent>
        </Select>
        <span className="text-sm text-ink-muted me-auto">
          {table.getFilteredRowModel().rows.length} תיקים
        </span>
      </div>

      <div className="rounded-lg border border-rule bg-surface shadow-sm overflow-hidden">
        <Table>
          <TableHeader className="bg-rule-soft/60">
            {table.getHeaderGroups().map((hg) => (
              <TableRow key={hg.id} className="border-rule">
                {hg.headers.map((header) => (
                  <TableHead
                    key={header.id}
                    onClick={header.column.getToggleSortingHandler()}
                    className="text-navy font-semibold cursor-pointer select-none text-right"
                  >
                    {flexRender(header.column.columnDef.header, header.getContext())}
                    {{ asc: " ▲", desc: " ▼" }[header.column.getIsSorted() as string] ?? ""}
                  </TableHead>
                ))}
              </TableRow>
            ))}
          </TableHeader>
          <TableBody>
            {loading ? (
              Array.from({ length: 4 }).map((_, i) => (
                <TableRow key={i} className="border-rule">
                  {columns.map((_c, j) => (
                    <TableCell key={j}>
                      <Skeleton className="h-4 w-24" />
                    </TableCell>
                  ))}
                </TableRow>
              ))
            ) : error ? (
              <TableRow>
                <TableCell colSpan={columns.length} className="text-center text-danger py-8">
                  שגיאה בטעינת תיקים: {error.message}
                </TableCell>
              </TableRow>
            ) : table.getRowModel().rows.length === 0 ? (
              <TableRow>
                <TableCell colSpan={columns.length} className="text-center text-ink-muted py-12">
                  <div className="text-gold text-2xl mb-2" aria-hidden>❦</div>
                  {globalFilter ? "אין תיקים תואמים לחיפוש" : emptyText}
                </TableCell>
              </TableRow>
            ) : (
              table.getRowModel().rows.map((row) => (
                <TableRow
                  key={row.id}
                  className="border-rule hover:bg-gold-wash/40 transition-colors"
                >
                  {row.getVisibleCells().map((cell) => (
                    <TableCell key={cell.id} className="py-3">
                      {flexRender(cell.column.columnDef.cell, cell.getContext())}
                    </TableCell>
                  ))}
                </TableRow>
              ))
            )}
          </TableBody>
        </Table>
      </div>
    </div>
  );
}