"use client";

import { useState, useMemo, useRef, useEffect } from "react";
import { ScrollFade } from "@/components/ScrollFade";
import { Wrench, LayoutGrid, Sparkles, ChevronRight } from "lucide-react";
import { Sparkline } from "@/components/Sparkline";
import { MONTH_NAMES } from "@/lib/data";
import type { RunningRow } from "@/lib/rows";
import { ZAR, ZAR2 } from "@/lib/utils";

/** Month total split, for the cell tooltip. Rounded — raw float sums read as
 *  "41944.159999999996", which looks like a bug even though it is arithmetic. */
function kindTitle(byKind: { repairs: number[]; purchases: number[]; insurance: number[]; finance: number[] }, i: number) {
  const r2 = (n: number) => n.toFixed(2).replace(/\.00$/, "");
  return (
    `Repairs R${r2(byKind.repairs[i])} · Purchases R${r2(byKind.purchases[i])}` +
    ` · Insurance R${r2(byKind.insurance[i])} · Finance R${r2(byKind.finance[i])}`
  );
}

export function RunningView({
  rows,
  palette,
  monthTotals,
  monthTotalsExcl,
  byKind,
  visibleMonths,
}: {
  rows: RunningRow[];
  palette: { income: string; profit: string; loss: string };
  /** Per month, VAT-INCLUSIVE, all cost kinds combined. */
  monthTotals: number[];
  /** The same months net of VAT, shown UNDER each incl figure. */
  monthTotalsExcl?: number[];
  /** Per-month split behind the total, offered on hover rather than as columns. */
  byKind?: { repairs: number[]; purchases: number[]; insurance: number[]; finance: number[] };
  /**
   * How many months of the year to RENDER. A month ahead cannot be calculated, only
   * guessed at, so the columns for it are not shown at all rather than shown empty
   * (client ruling, 2026-10-09).
   */
  visibleMonths?: number;
}) {
  const [view, setView] = useState<"cards" | "grid">("cards");
  const [sort, setSort] = useState<"ytd" | "code">("ytd");
  const [expanded, setExpanded] = useState<string | null>(null);

  const sorted = useMemo(() => {
    return [...rows].sort((a, b) =>
      sort === "ytd" ? b.ytd - a.ytd : a.code.localeCompare(b.code)
    );
  }, [rows, sort]);

  const grandTotal = monthTotals.reduce((s, v) => s + v, 0);

  return (
    <>
      <div className="flex flex-col sm:flex-row sm:flex-wrap sm:items-center sm:justify-between gap-3 mb-5">
        <div className="flex items-center gap-2 text-xs text-gray-500 dark:text-gray-400 flex-wrap">
          <span className="px-2.5 py-1 rounded-md bg-[#EDAE49]/10 text-[#EDAE49] font-medium">
            {rows.filter((r) => r.ytd > 0).length} machines with costs
          </span>
          <span className="hidden md:inline">· sorted by {sort === "ytd" ? "total spend" : "code"}</span>
        </div>
        <div className="flex items-center gap-2 flex-wrap">
          <div className="flex items-center gap-1 p-0.5 rounded-lg bg-white dark:bg-white/5 border border-gray-200 dark:border-border">
            <button
              onClick={() => setView("cards")}
              aria-label="Cards view"
              className={`min-h-[44px] px-3 text-xs font-medium rounded-md transition flex items-center gap-1.5 ${
                view === "cards"
                  ? "bg-[#003D5B] text-white dark:bg-[#00798C]"
                  : "text-gray-500 dark:text-gray-400 hover:text-gray-900 dark:hover:text-white"
              }`}
            >
              <Sparkles className="w-3.5 h-3.5" /> Cards
            </button>
            <button
              onClick={() => setView("grid")}
              aria-label="Grid view"
              className={`min-h-[44px] px-3 text-xs font-medium rounded-md transition flex items-center gap-1.5 ${
                view === "grid"
                  ? "bg-[#003D5B] text-white dark:bg-[#00798C]"
                  : "text-gray-500 dark:text-gray-400 hover:text-gray-900 dark:hover:text-white"
              }`}
            >
              <LayoutGrid className="w-3.5 h-3.5" /> Grid
            </button>
          </div>
          <div className="hidden sm:flex items-center gap-1">
            <span className="text-xs text-gray-400 dark:text-text-soft mr-1">Sort:</span>
            {[
              { id: "ytd", label: "Total" },
              { id: "code", label: "Code" },
            ].map((s) => (
              <button
                key={s.id}
                onClick={() => setSort(s.id as typeof sort)}
                className={`min-h-[44px] px-2 text-xs font-medium rounded transition ${
                  sort === s.id ? "bg-[#EDAE49] text-white" : "text-gray-500 dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-white/5"
                }`}
              >
                {s.label}
              </button>
            ))}
          </div>
          <div className="sm:hidden">
            <label className="sr-only" htmlFor="running-sort">Sort by</label>
            <select
              id="running-sort"
              value={sort}
              onChange={(e) => setSort(e.target.value as typeof sort)}
              className="min-h-[44px] px-3 text-xs rounded-lg border border-gray-200 dark:border-white/10 bg-white dark:bg-white/5"
            >
              <option value="ytd">Sort by Total</option>
              <option value="code">Sort by Code</option>
            </select>
          </div>
        </div>
      </div>

      {view === "cards" ? (
        <CardsView rows={sorted} expanded={expanded} setExpanded={setExpanded} palette={palette} visibleMonths={visibleMonths} />
      ) : (
        <GridView rows={sorted} monthTotals={monthTotals} monthTotalsExcl={monthTotalsExcl} byKind={byKind} visibleMonths={visibleMonths} grandTotal={grandTotal} grandExcl={(monthTotalsExcl || []).reduce((s, v) => s + v, 0)} />
      )}
    </>
  );
}

function CardsView({
  rows, expanded, setExpanded, palette, visibleMonths,
}: {
  rows: RunningRow[];
  visibleMonths?: number;
  expanded: string | null;
  setExpanded: (id: string | null) => void;
  palette: { income: string; profit: string; loss: string };
}) {
  return (
    <div className="space-y-2">
      {rows.map((r) => {
        const isOpen = expanded === r.id;
        const hasData = r.ytd > 0;
        return (
          <div
            key={r.id}
            className="bg-white dark:bg-surface border border-gray-100 dark:border-border rounded-xl overflow-hidden shadow-sm hover:shadow-md transition"
          >
            <button
              onClick={() => setExpanded(isOpen ? null : r.id)}
              className="w-full flex items-center gap-4 p-4 text-left"
            >
              <span className="font-mono text-xs px-2 py-1 rounded-md bg-[#00798C]/10 text-[#00798C] font-semibold shrink-0">
                {r.code}
              </span>
              <div className="flex-1 min-w-0">
                <div className="flex items-center gap-2 text-sm font-medium text-[#003D5B] dark:text-white">
                  <Wrench className="w-3.5 h-3.5 text-[#EDAE49] shrink-0" />
                  <span className="truncate">{r.name}</span>
                </div>
              </div>
              <div className="hidden sm:block shrink-0">
                <Sparkline data={r.months} color={palette.income} />
              </div>
              <div className="text-right shrink-0 w-32 hidden md:block">
                <div className="text-[10px] text-gray-400 uppercase tracking-wider">YTD spend</div>
                <div className="text-sm font-semibold tabular-nums text-[#003D5B] dark:text-white">
                  {hasData ? ZAR2(r.ytd) : "—"}
                </div>
              </div>
              <div
                className={`shrink-0 px-2.5 py-1.5 rounded-lg text-xs font-semibold ${
                  hasData ? "bg-[#EDAE49]/10 text-[#EDAE49] dark:bg-[#EDAE49]/20" : "bg-gray-100 text-gray-400 dark:bg-white/5"
                }`}
              >
                {hasData ? `${r.months.filter((v) => v > 0).length} months` : "—"}
              </div>
              <ChevronRight
                className={`w-4 h-4 text-gray-400 shrink-0 transition-transform ${isOpen ? "rotate-90" : ""}`}
              />
            </button>

            {isOpen && (
              <div className="border-t border-gray-100 dark:border-border px-4 py-4 bg-gray-50/50 dark:bg-white/[0.04]">
                {/* Mobile: 3 cols (4 rows × 3 cols = 12 months). md+: 6 cols. lg+: 12 cols. */}
                <div className="grid grid-cols-3 md:grid-cols-6 lg:grid-cols-12 gap-2 text-[11px]">
                  {r.months.slice(0, visibleMonths ?? 12).map((v, i) => (
                    <div key={i} className="text-center">
                      <div className="text-gray-400 dark:text-text-soft text-[10px] mb-1">{MONTH_NAMES[i]}</div>
                      <div className={`py-1.5 rounded tabular-nums ${v > 0 ? "bg-[#EDAE49]/5 text-[#EDAE49] dark:bg-[#EDAE49]/15" : "text-gray-300 dark:text-text-soft"}`}>
                        {v > 0 ? ZAR2(v) : "—"}
                      </div>
                    </div>
                  ))}
                </div>
                <div className="mt-4 pt-3 border-t border-gray-100 dark:border-border text-xs">
                  <span className="text-gray-400 uppercase tracking-wider text-[10px]">YTD total</span>
                  <span className="ml-2 font-semibold tabular-nums text-[#EDAE49]">{ZAR(r.ytd)}</span>
                </div>
              </div>
            )}
          </div>
        );
      })}
    </div>
  );
}

function GridView({
  rows, monthTotals, monthTotalsExcl, byKind, visibleMonths, grandTotal, grandExcl,
}: {
  rows: RunningRow[];
  monthTotals: number[];
  monthTotalsExcl?: number[];
  byKind?: { repairs: number[]; purchases: number[]; insurance: number[]; finance: number[] };
  visibleMonths?: number;
  grandTotal: number;
  grandExcl: number;
}) {
  // Shown only when the table actually overflows — a permanent fade on a table that
  // cannot scroll tells the reader to drag a page with nowhere to go.
  const scroller = useRef<HTMLDivElement>(null);
  const [overflows, setOverflows] = useState(false);
  useEffect(() => {
    const el = scroller.current;
    if (!el) return;
    const check = () => setOverflows(el.scrollWidth > el.clientWidth + 1);
    check();
    const ro = new ResizeObserver(check);
    ro.observe(el);
    return () => ro.disconnect();
  }, [rows.length]);

  return (
    <div className="bg-white dark:bg-surface rounded-2xl border border-gray-100 dark:border-border shadow-sm overflow-hidden">
      {/* `relative` + the conditional fade give the right-edge affordance a wide table
          needs on a phone — but only when there is actually something to scroll to. */}
      <div className="relative">
      <div ref={scroller} className="overflow-x-auto" style={{ WebkitOverflowScrolling: "touch" }}>
        <table className="w-full text-sm">
          <thead>
            <tr className="text-xs text-gray-500 dark:text-gray-400 uppercase tracking-wider border-y border-gray-100 dark:border-border bg-gray-50/50 dark:bg-white/[0.04]">
              <th className="text-left py-3 px-6 font-medium sticky left-0 bg-gray-50/95 dark:bg-surface-muted/95 backdrop-blur z-10">Code</th>
              <th className="text-left py-3 px-3 font-medium">Machine</th>
              {MONTH_NAMES.slice(0, visibleMonths ?? 12).map((m) => (
                <th key={m} className="text-right py-3 px-2 font-medium min-w-[78px]">{m}</th>
              ))}
              <th className="text-right py-3 px-6 font-medium">YTD</th>
            </tr>
          </thead>
          <tbody>
            {rows.map((r) => (
              <tr key={r.id} className="border-b border-gray-50 dark:border-border hover:bg-gray-50/40 dark:hover:bg-white/[0.02]">
                <td className="py-2.5 px-6 sticky left-0 bg-white dark:bg-surface">
                  <span className="font-mono text-xs px-2 py-1 rounded-md bg-[#00798C]/10 text-[#00798C] font-semibold">
                    {r.code}
                  </span>
                </td>
                <td className="py-2.5 px-3 font-medium text-[#003D5B] dark:text-white whitespace-nowrap">
                  <div className="flex items-center gap-2">
                    <Wrench className="w-3 h-3 text-[#EDAE49]" />
                    {r.name}
                  </div>
                </td>
                {r.months.slice(0, visibleMonths ?? 12).map((v, i) => (
                  <td key={i} className={`py-2.5 px-2 text-right tabular-nums ${v > 0 ? "text-gray-700 dark:text-gray-300" : "text-gray-300 dark:text-text-soft"}`}>
                    {v > 0 ? ZAR2(v) : "—"}
                  </td>
                ))}
                <td className={`py-2.5 px-6 text-right tabular-nums font-semibold whitespace-nowrap ${r.ytd > 0 ? "text-[#EDAE49]" : "text-gray-300 dark:text-text-soft"}`}>
                  {r.ytd > 0 ? ZAR(r.ytd) : "—"}
                </td>
              </tr>
            ))}
            {/* Bottom row: the month's total on BOTH bases, incl ABOVE excl, so a
                reader never has to back the VAT out by hand. */}
            <tr className="bg-gradient-to-r from-[#EDAE49]/10 dark:from-[#EDAE49]/15 to-transparent border-t-2 border-[#EDAE49]/30">
              <td colSpan={2} className="py-3 px-6 font-semibold text-right align-bottom text-[#003D5B] dark:text-white">
                Total
                <span className="block text-[12px] font-normal text-gray-400 dark:text-text-soft">
                  incl / excl
                </span>
              </td>
              {monthTotals.slice(0, visibleMonths ?? 12).map((v, i) => (
                <td
                  key={i}
                  title={byKind ? kindTitle(byKind, i) : undefined}
                  className="py-3 px-2 text-right tabular-nums align-bottom"
                >
                  {v > 0 ? (
                    <>
                      <span className="block font-semibold text-[#003D5B] dark:text-white">{ZAR(v)}</span>
                      {monthTotalsExcl && (
                        <span className="block text-[12px] font-normal text-gray-400 dark:text-text-soft">
                          {ZAR(monthTotalsExcl[i] ?? 0)}
                        </span>
                      )}
                    </>
                  ) : (
                    <span className="text-[#003D5B] dark:text-white">—</span>
                  )}
                </td>
              ))}
              <td className="py-3 px-6 text-right tabular-nums align-bottom">
                <span className="block font-bold text-base text-[#EDAE49]">{ZAR(grandTotal)}</span>
                {grandExcl > 0 && (
                  <span className="block text-[12px] font-normal text-gray-400 dark:text-text-soft">
                    {ZAR(grandExcl)}
                  </span>
                )}
              </td>
            </tr>
          </tbody>
        </table>
      </div>
      {overflows && <ScrollFade />}
      </div>
    </div>
  );
}