"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 { COST_KINDS, COST_KIND_LABELS } from "@/lib/running-costs";
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])}`
  );
}

/** The four cost kinds. These ARE a vehicle's running cost — there is no fifth source —
 *  so the parts always add up to the vehicle's spend and the vehicles add up to the
 *  Overview. Showing them is what makes that checkable rather than a claim. */
const KINDS = COST_KINDS;

export function RunningView({
  rows,
  palette,
  monthTotals,
  monthTotalsExcl,
  byKind,
  visibleMonths,
  monthIndex,
}: {
  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;
  /**
   * The LIVE month, 0-based, decided on the server (lib/income-month.ts). It is the
   * month that is still filling up, so its figure grows as repairs and purchases are
   * entered against a vehicle.
   */
  monthIndex?: 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} monthIndex={monthIndex} />
      ) : (
        <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, monthIndex,
}: {
  rows: RunningRow[];
  visibleMonths?: number;
  expanded: string | null;
  setExpanded: (id: string | null) => void;
  palette: { income: string; profit: string; loss: string };
  monthIndex?: number;
}) {
  const monthLabel = monthIndex != null && monthIndex >= 0 ? MONTH_NAMES[monthIndex] : null;
  return (
    <div className="space-y-2">
      {rows.map((r) => {
        const isOpen = expanded === r.id;
        const hasData = r.ytd > 0;
        const monthValue = monthIndex != null ? r.months[monthIndex] ?? 0 : 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" />
                  {/* On a phone the name wraps onto its own line rather than being
                      cut short — the same rule the income cards follow. */}
                  <span className="sm:truncate">{r.name}</span>
                </div>
              </div>
              {/* The sparkline yields its width to the month figure below xl: the
                  content column is only ~670px wide between md and xl (the sidebar eats
                  the rest), and the vehicle NAME must not be truncated to pay for a
                  decorative trend. The same 12 months are on the strip in the expanded
                  panel, one click away. */}
              <div className="hidden xl:block shrink-0">
                <Sparkline data={r.months} color={palette.income} />
              </div>
              {/* The money: the year figure and the live month, side by side — the same
                  shape the income cards use. */}
              <div className="hidden md:flex shrink-0 items-start gap-4">
                <div className="text-right w-28">
                  <div className="text-xs 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>
                {monthLabel && (
                  <div className="text-right w-28">
                    <div className="text-xs text-gray-400 uppercase tracking-wider whitespace-nowrap">{monthLabel} so far</div>
                    <div className="text-sm font-semibold tabular-nums text-[#00798C] dark:text-[#EDAE49]">
                      {monthValue > 0 ? ZAR2(monthValue) : "—"}
                    </div>
                  </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>

            {/* Below md the money row above is hidden, so the year and the live month
                get their own line — the same shape the income cards use on a phone. */}
            <div className="flex md:hidden items-end justify-between gap-3 px-4 pb-2 pt-1 text-xs">
              <div>
                <div className="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>
              {monthLabel && (
                <div className="text-right">
                  <div className="text-gray-400 uppercase tracking-wider whitespace-nowrap">{monthLabel} so far</div>
                  <div className="text-sm font-semibold tabular-nums text-[#00798C] dark:text-[#EDAE49]">
                    {monthValue > 0 ? ZAR2(monthValue) : "—"}
                  </div>
                </div>
              )}
            </div>

            {/* What the vehicle's spend is MADE of, on the card itself. These four parts
                are the whole of it, so they add up to the YTD figure above — and the
                vehicles add up to the Overview. A vehicle with no spend shows nothing
                here: "nothing recorded" is already on the card. */}
            {hasData && (
              <div className="px-4 pb-3 -mt-1 flex flex-wrap items-center gap-x-3 gap-y-1 text-xs">
                {KINDS.map((k, index) => (
                  <span key={k} className="whitespace-nowrap">
                    <span className={r.byKindYtd[k] > 0 ? "text-gray-400 dark:text-text-soft" : "text-gray-300 dark:text-gray-600"}>{COST_KIND_LABELS[k]}</span>{" "}
                    <span className={r.byKindYtd[k] > 0 ? "font-medium tabular-nums text-gray-600 dark:text-gray-300" : "tabular-nums text-gray-300 dark:text-gray-600"}>{ZAR2(r.byKindYtd[k])}</span>
                    {index < KINDS.length - 1 && <span className="ml-3 text-gray-300 dark:text-gray-600">·</span>}
                  </span>
                ))}
              </div>
            )}

            {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-xs">
                  {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-xs 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>
                {/* The four kinds, and the total they add up to. This is the check: the
                    parts ARE the spend, so the parts and the total can never disagree. */}
                <div className="mt-4 grid grid-cols-2 gap-x-4 gap-y-3 border-t border-gray-100 pt-3 text-xs dark:border-border sm:grid-cols-5">
                  {KINDS.map((k) => (
                    <div key={k}>
                      <div className="text-gray-400 uppercase tracking-wider text-xs">{COST_KIND_LABELS[k]}</div>
                      <div className="font-semibold tabular-nums text-[#003D5B] dark:text-white">{ZAR2(r.byKindYtd[k])}</div>
                    </div>
                  ))}
                  <div>
                    <div className="text-gray-400 uppercase tracking-wider text-xs">YTD total</div>
                    <div className="font-semibold tabular-nums text-[#EDAE49]">{ZAR(r.ytd)}</div>
                  </div>
                </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>
            ))}
            {/* The four kinds, then the total they add up to. The fleet's parts are
                visible above its total, so "do the costs add up?" is answered on the
                screen instead of taken on trust. */}
            {byKind && KINDS.map((k) => {
              const cells = byKind[k].slice(0, visibleMonths ?? 12);
              const kindTotal = cells.reduce((s, v) => s + v, 0);
              return (
                <tr key={k} className="border-t border-gray-50 dark:border-border">
                  <td colSpan={2} className="py-2 px-6 text-right text-xs text-gray-500 dark:text-gray-400">
                    {COST_KIND_LABELS[k]}
                  </td>
                  {cells.map((v, i) => (
                    <td key={i} className="py-2 px-2 text-right tabular-nums whitespace-nowrap text-gray-500 dark:text-gray-400">
                      {v > 0 ? ZAR(v) : "—"}
                    </td>
                  ))}
                  <td className="py-2 px-6 text-right tabular-nums whitespace-nowrap text-gray-500 dark:text-gray-400">
                    {kindTotal > 0 ? ZAR(kindTotal) : "—"}
                  </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>
  );
}