"use client";

import { useState, useRef, useTransition, useMemo } from "react";
import { useRouter } from "next/navigation";
import {
  Upload, FileText, ChevronDown, ChevronRight, Loader2, TriangleAlert,
  Check, ShoppingCart, X, Plus, Trash2, Search, Receipt, ChevronLeft, Pencil,
} from "lucide-react";
import { ZAR, ZAR2 } from "@/lib/utils";
import { invoiceStatusOf, STATUS_STYLE } from "@/lib/purchase-invoice-status";

const ACCENT = "#30638E";

export type PurchaseLineView = {
  id: string;
  line_no: number;
  material_code: string;
  cost_code: string;
  description: string;
  qty: number | null;
  rate: number | null;
  amount_excl: number;
  vat: number | null;
  total_incl: number | null;
  assetCode: string;
  assetName: string;
};

export type PurchaseView = {
  id: string;
  po_no: string;
  supplier: string;
  supplier_code: string;
  po_date: string;
  required_by: string;
  req_no: string;
  currency: string;
  subtotal: number;
  vat: number;
  total: number;
  source_file: string;
  invoices: PurchaseInvoiceView[];
  lines: PurchaseLineView[];
};

export type PurchaseInvoiceView = {
  id: string;
  invoice_no: string;
  invoice_date: string;
  amount_incl: number | null;
  note: string;
  hasPdf: boolean;
};

export function PurchaseIntake({ purchases: allPurchases }: { purchases: PurchaseView[] }) {
  const router = useRouter();
  const inputRef = useRef<HTMLInputElement>(null);
  const [pending, startTransition] = useTransition();
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [notice, setNotice] = useState<string | null>(null);
  const [open, setOpen] = useState<string | null>(null);
  const [invoiceModal, setInvoiceModal] = useState(false);
  const [range, setRange] = useState<"all" | "week" | "month">("all");
  // 0 = the current week/month, -1 = the one before, …
  const [offset, setOffset] = useState(0);
  const [groupBySupplier, setGroupBySupplier] = useState(true);
  const [dragging, setDragging] = useState(false);
  // Deleting and correcting are hidden until this is switched on, and it resets on reload.
  const [editMode, setEditMode] = useState(false);
  // Drop a PO anywhere on the page. Not while the invoice window is open: that has its own
  // drop area, and an invoice PDF must never be read as a purchase order.
  const dropProps = {
    onDragOver: (e: React.DragEvent) => {
      if (invoiceModal || busy || !e.dataTransfer.types.includes("Files")) return;
      e.preventDefault();
      setDragging(true);
    },
    onDragLeave: (e: React.DragEvent) => {
      if (!e.currentTarget.contains(e.relatedTarget as Node)) setDragging(false);
    },
    onDrop: (e: React.DragEvent) => {
      if (invoiceModal || busy) return;
      e.preventDefault();
      setDragging(false);
      upload(e.dataTransfer.files);
    },
  };

  const win = useMemo(() => (range === "all" ? null : rangeWindow(range, offset)), [range, offset]);
  // A PO with no readable date cannot be placed in a week or month, so a range hides it —
  // and says so, rather than letting it quietly vanish.
  const purchases = useMemo(
    () => (win ? allPurchases.filter((p) => /^\d{4}-\d{2}-\d{2}/.test(p.po_date) && p.po_date.slice(0, 10) >= win.from && p.po_date.slice(0, 10) <= win.to) : allPurchases),
    [allPurchases, win],
  );
  const undated = win ? allPurchases.filter((p) => !/^\d{4}-\d{2}-\d{2}/.test(p.po_date)).length : 0;
  const groups = useMemo(() => {
    if (!groupBySupplier) return [{ key: "", name: "", items: purchases }];
    const m = new Map<string, PurchaseView[]>();
    for (const p of purchases) m.set(p.supplier || "No supplier", [...(m.get(p.supplier || "No supplier") ?? []), p]);
    return [...m.entries()]
      .sort((a, b) => a[0].localeCompare(b[0]))
      .map(([name, items]) => ({ key: name, name, items }));
  }, [purchases, groupBySupplier]);

  async function upload(files: FileList | null) {
    if (!files || !files.length) return;
    setBusy(true);
    setError(null);
    setNotice(null);
    try {
      for (const f of Array.from(files)) {
        const fd = new FormData();
        fd.append("file", f);
        const res = await fetch("/api/purchases/intake", { method: "POST", body: fd });
        const body = await res.json();
        if (!body.ok) {
          setError(`${f.name}: ${body.error}`);
          break;
        }
        // A line that found no machine is money that exists but is not yet on one.
        // Named, not buried — that is the whole point of reading the cost code.
        setNotice(
          body.unallocated?.length
            ? `${body.purchase.po_no}: ${body.lines} line(s) imported, but no machine matched ${body.unallocated.join(", ")} — left unallocated.`
            : `${body.purchase.po_no}: ${body.lines} line(s) imported and allocated.`,
        );
      }
      startTransition(() => router.refresh());
    } catch {
      setError("Upload failed — check your connection");
    } finally {
      setBusy(false);
      if (inputRef.current) inputRef.current.value = "";
    }
  }

  const totalSpend = purchases.reduce((s, p) => s + p.total, 0);
  const unallocatedLines = purchases.reduce(
    (s, p) => s + p.lines.filter((l) => !l.assetCode).length,
    0,
  );

  return (
    <div {...dropProps} className={`relative rounded-2xl transition ${dragging ? "ring-2 ring-dashed ring-[#30638E] ring-offset-4 bg-[#30638E]/5" : ""}`}>
      {dragging && (
        <div className="pointer-events-none absolute inset-0 z-10 grid place-items-center">
          <div className="rounded-xl bg-[#30638E] text-white text-sm font-medium px-5 py-3 shadow-lg inline-flex items-center gap-2">
            <Upload className="w-4 h-4" /> Drop purchase order PDFs to upload
          </div>
        </div>
      )}
      <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3 mb-5">
        <div className="flex items-center gap-2 text-xs text-gray-500 dark:text-gray-400 flex-wrap">
          <span className="px-2.5 py-1 rounded-md font-medium" style={{ background: `${ACCENT}1a`, color: ACCENT }}>
            {purchases.length} purchase order{purchases.length !== 1 && "s"}
          </span>
          <span className="px-2.5 py-1 rounded-md bg-gray-100 text-gray-500 dark:bg-white/5 dark:text-gray-400 font-medium">
            {ZAR(totalSpend)} total
          </span>
          {unallocatedLines > 0 && (
            <span className="px-2.5 py-1 rounded-md bg-[#EDAE49]/10 text-[#EDAE49] font-medium">
              {unallocatedLines} line{unallocatedLines !== 1 && "s"} with no machine
            </span>
          )}
        </div>

        <div className="flex flex-wrap gap-2">
          <button
            type="button"
            onClick={() => setInvoiceModal(true)}
            className="min-h-[44px] px-4 rounded-lg text-xs font-medium inline-flex items-center gap-2 text-white"
            style={{ background: BRAND_ORANGE }}
          >
            <Receipt className="w-4 h-4" /> Upload invoice
          </button>
          <input
            ref={inputRef}
            type="file"
            accept="application/pdf,.pdf"
            multiple
            // The input stays sr-only and the LABEL is the 44px control. It is still
            // focusable, so `peer-focus-visible` puts the focus ring on the label —
            // otherwise a keyboard user tabs onto an invisible 1px target.
            className="sr-only peer"
            id="po-upload"
            onChange={(e) => upload(e.target.files)}
          />
          <label
            htmlFor="po-upload"
            className="min-h-[44px] px-4 rounded-lg text-xs font-medium inline-flex items-center gap-2 text-white cursor-pointer peer-focus-visible:ring-2 peer-focus-visible:ring-[#30638E] peer-focus-visible:ring-offset-2"
            style={{ background: ACCENT }}
          >
            {busy ? <Loader2 className="w-4 h-4 animate-spin" /> : <Upload className="w-4 h-4" />}
            {busy ? "Reading…" : "Upload purchase orders"}
          </label>
        </div>
        {invoiceModal && <InvoiceUploadModal purchases={allPurchases} onClose={() => setInvoiceModal(false)} />}
      </div>

      {error && (
        <div className="mb-4 flex items-start gap-2 rounded-2xl border border-[#D1495B]/30 bg-[#D1495B]/[0.06] p-4">
          <TriangleAlert className="w-4 h-4 mt-0.5 shrink-0 text-[#D1495B] dark:text-[#D94F60]" />
          <div className="text-xs text-gray-600 dark:text-gray-400">
            <span className="font-semibold text-[#003D5B] dark:text-white">Could not import</span>
            <div className="mt-1">{error}</div>
          </div>
          <button onClick={() => setError(null)} aria-label="Dismiss"
            className="ml-auto min-h-[44px] min-w-[44px] grid place-items-center rounded-lg hover:bg-white dark:hover:bg-white/5">
            <X className="w-4 h-4" />
          </button>
        </div>
      )}
      {notice && (
        <div className="mb-4 flex items-start gap-2 rounded-2xl border border-[#00798C]/30 bg-[#00798C]/[0.06] p-4 text-xs text-gray-600 dark:text-gray-400">
          <Check className="w-4 h-4 mt-0.5 shrink-0 text-[#00798C]" />
          <span>{notice}</span>
        </div>
      )}

      <div className="flex flex-col sm:flex-row sm:flex-wrap sm:items-center gap-3 mb-4">
        <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 self-start">
          {([["all", "All"], ["week", "Week"], ["month", "Month"]] as const).map(([id, label]) => (
            <button key={id} onClick={() => { setRange(id); setOffset(0); }} aria-pressed={range === id}
              className={`min-h-[44px] px-3 rounded-md text-xs font-medium transition ${
                range === id ? "bg-[#003D5B] text-white dark:bg-[#00798C]" : "text-gray-500 dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-white/5"
              }`}>
              {label}
            </button>
          ))}
        </div>
        {win && (
          <div className="flex items-center gap-1">
            <button onClick={() => setOffset(offset - 1)} aria-label="Previous"
              className="min-h-[44px] min-w-[44px] grid place-items-center rounded-lg hover:bg-gray-100 dark:hover:bg-white/5"><ChevronLeft className="w-4 h-4" /></button>
            <span className="text-xs font-medium text-[#003D5B] dark:text-white min-w-[150px] text-center">{win.label}</span>
            <button onClick={() => setOffset(offset + 1)} aria-label="Next" disabled={offset >= 0}
              className="min-h-[44px] min-w-[44px] grid place-items-center rounded-lg hover:bg-gray-100 dark:hover:bg-white/5 disabled:opacity-30"><ChevronRight className="w-4 h-4" /></button>
          </div>
        )}
        <button
          onClick={() => setEditMode(!editMode)}
          aria-pressed={editMode}
          className={`min-h-[44px] px-3 rounded-lg text-xs font-medium inline-flex items-center gap-1.5 border transition sm:ml-auto ${
            editMode ? "bg-[#EDAE49] border-[#EDAE49] text-white" : "border-gray-200 dark:border-border text-gray-500 dark:text-gray-400 hover:bg-gray-50 dark:hover:bg-white/5"
          }`}
        >
          <Pencil className="w-4 h-4" /> {editMode ? "Editing — delete enabled" : "Edit mode"}
        </button>
        <label className="inline-flex items-center gap-2 min-h-[44px] text-xs text-gray-600 dark:text-gray-300 cursor-pointer">
          <input type="checkbox" checked={groupBySupplier} onChange={(e) => setGroupBySupplier(e.target.checked)} className="w-4 h-4" />
          Group by supplier
        </label>
      </div>
      {undated > 0 && (
        <div className="mb-3 text-xs text-[#8a6420] dark:text-[#EDAE49]">
          {undated} purchase order{undated !== 1 && "s"} with no readable date {undated !== 1 ? "are" : "is"} hidden while a range is chosen.
        </div>
      )}

      {allPurchases.length > 0 && purchases.length === 0 ? (
        <section className="bg-white dark:bg-surface rounded-2xl border border-gray-100 dark:border-border p-10 shadow-sm text-center text-sm text-gray-500 dark:text-gray-400">
          No purchase orders dated in this {range}.
        </section>
      ) : purchases.length === 0 ? (
        <section className="bg-white dark:bg-surface rounded-2xl border border-gray-100 dark:border-border p-12 shadow-sm text-center">
          <ShoppingCart className="w-8 h-8 mx-auto mb-3 text-gray-300" />
          <div className="text-sm text-gray-500 dark:text-gray-400">No purchase orders yet.</div>
          <div className="text-xs text-gray-400 dark:text-text-soft mt-1">
            Upload a PO PDF above, or drag it onto this page. Each line is allocated to a machine by its cost code.
          </div>
        </section>
      ) : (
        <div className="space-y-5">
          {groups.map((g) => (
          <div key={g.key || "all"}>
            {groupBySupplier && (
              <div className="flex items-baseline justify-between gap-3 mb-2 px-1">
                <h3 className="text-sm font-semibold text-[#003D5B] dark:text-white truncate">{g.name}</h3>
                <span className="text-xs text-gray-500 dark:text-gray-400 shrink-0 tabular-nums">
                  {g.items.length} PO{g.items.length !== 1 && "s"} · {ZAR2(g.items.reduce((t, x) => t + x.total, 0))}
                </span>
              </div>
            )}
          <div className="space-y-2">
          {g.items.map((p) => {
            const isOpen = open === p.id;
            const unalloc = p.lines.filter((l) => !l.assetCode).length;
            const inv = invoiceStatus(p);
            const sty = STATUS_STYLE[inv.status];
            return (
              <div key={p.id} className="relative bg-white dark:bg-surface border border-gray-100 dark:border-border rounded-xl overflow-hidden shadow-sm">
                <span
                  className="absolute left-0 inset-y-0 w-1.5"
                  style={{ background: sty.color }}
                  title={sty.label}
                  role="img"
                  aria-label={sty.label}
                />
                <button
                  onClick={() => setOpen(isOpen ? null : p.id)}
                  aria-expanded={isOpen}
                  className="w-full flex items-center gap-3 sm:gap-4 p-4 text-left min-h-[44px]"
                >
                  <FileText className="w-4 h-4 shrink-0" style={{ color: ACCENT }} />
                  <div className="flex-1 min-w-0">
                    <div className="flex items-center gap-2 flex-wrap">
                      <span className="font-mono text-xs px-2 py-1 rounded-md bg-[#00798C]/10 text-[#00798C] font-semibold">
                        {p.po_no}
                      </span>
                      <span className="text-sm font-medium text-[#003D5B] dark:text-white truncate">{p.supplier}</span>
                      {unalloc > 0 && (
                        <TriangleAlert className="w-3.5 h-3.5 text-[#EDAE49]" aria-label="Some lines have no machine" />
                      )}
                    </div>
                    <div className="text-xs text-gray-500 dark:text-gray-400 mt-1">
                      {p.po_date || "no date"} · {p.lines.length} line{p.lines.length !== 1 && "s"} ·{" "}
                      {p.lines.filter((l) => l.assetCode).length} allocated ·{" "}
                      <span style={{ color: sty.color }} className="font-medium">
                        {inv.status === "over" ? `invoiced ${ZAR2(inv.invoiced - p.total)} OVER the PO — check the amount` : inv.status === "complete" ? "fully invoiced — can be closed" : inv.status === "partial" ? `${ZAR2(inv.invoiced)} of ${ZAR2(p.total)} invoiced` : "no invoice yet"}
                      </span>
                    </div>
                  </div>
                  <div className="text-right shrink-0">
                    <div className="text-[12px] text-gray-400 uppercase tracking-wider">Total</div>
                    <div className="text-sm font-semibold tabular-nums text-[#003D5B] dark:text-white">
                      {ZAR(p.total)}
                    </div>
                  </div>
                  {isOpen ? <ChevronDown className="w-4 h-4 text-gray-400 shrink-0" /> : <ChevronRight className="w-4 h-4 text-gray-400 shrink-0" />}
                </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]">
                    <dl className="grid grid-cols-2 sm:grid-cols-4 gap-x-4 gap-y-2 text-xs mb-4">
                      <Meta label="Supplier" value={p.supplier} />
                      <Meta label="Supplier code" value={p.supplier_code || "—"} />
                      <Meta label="PO date" value={p.po_date || "—"} />
                      <Meta label="Required by" value={p.required_by || "—"} />
                      <Meta label="Requisition" value={p.req_no || "—"} />
                      <Meta label="Currency" value={p.currency || "—"} />
                      <Meta label="Sub-total" value={ZAR2(p.subtotal)} />
                      <Meta label="VAT" value={ZAR2(p.vat)} />
                    </dl>

                    <SupplierInvoices purchase={p} editMode={editMode} />

                    <div className="overflow-x-auto rounded-lg border border-gray-100 dark:border-border bg-white dark:bg-surface">
                      <table className="w-full text-xs">
                        <thead>
                          <tr className="text-gray-500 dark:text-gray-400 uppercase tracking-wider bg-gray-50 dark:bg-surface-muted">
                            <th className="text-left py-2 px-3 font-medium">#</th>
                            <th className="text-left py-2 px-3 font-medium">Description</th>
                            <th className="text-left py-2 px-3 font-medium">Cost code</th>
                            <th className="text-left py-2 px-3 font-medium">Machine</th>
                            <th className="text-right py-2 px-3 font-medium">Amount</th>
                            <th className="text-right py-2 px-3 font-medium">Incl VAT</th>
                          </tr>
                        </thead>
                        <tbody>
                          {p.lines.map((l) => (
                            <tr key={l.id} className="border-t border-gray-100 dark:border-border">
                              <td className="py-2 px-3 text-gray-400">{l.line_no}</td>
                              <td className="py-2 px-3 text-[#003D5B] dark:text-gray-300">
                                {l.description || <span className="italic text-gray-400">no description</span>}
                              </td>
                              <td className="py-2 px-3 font-mono text-gray-500 dark:text-gray-400">{l.cost_code || "—"}</td>
                              <td className="py-2 px-3">
                                {l.assetCode ? (
                                  <span className="inline-flex items-center gap-1.5 text-gray-700 dark:text-gray-300">
                                    <span className="font-mono text-[12px] px-1.5 py-0.5 rounded bg-[#00798C]/10 text-[#00798C]">
                                      {l.assetCode}
                                    </span>
                                    <span className="truncate">{l.assetName}</span>
                                  </span>
                                ) : (
                                  <span className="text-[12px] text-[#EDAE49] italic">no matching machine</span>
                                )}
                              </td>
                              <td className="py-2 px-3 text-right tabular-nums text-gray-600 dark:text-gray-400">
                                {ZAR2(l.amount_excl)}
                              </td>
                              <td className="py-2 px-3 text-right tabular-nums font-semibold text-[#003D5B] dark:text-white">
                                {l.total_incl == null ? "—" : ZAR2(l.total_incl)}
                              </td>
                            </tr>
                          ))}
                        </tbody>
                      </table>
                    </div>
                  </div>
                )}
              </div>
            );
          })}
          </div>
          </div>
          ))}
        </div>
      )}
    </div>
  );
}

function Meta({ label, value }: { label: string; value: string }) {
  return (
    <div>
      <dt className="text-gray-400 uppercase tracking-wider text-[12px]">{label}</dt>
      <dd className="text-gray-700 dark:text-gray-300 mt-0.5 break-words">{value}</dd>
    </div>
  );
}

const inputCls =
  "min-h-[44px] w-full rounded-lg border border-gray-200 dark:border-border bg-white dark:bg-surface px-3 text-sm text-[#003D5B] dark:text-white";

/**
 * Supplier invoices received against one PO. A PO can have several. Typed in by a person
 * with the PDF attached; the "invoiced" figure sums only the amounts actually entered, and
 * an invoice with no amount is listed but never counted as R0.
 */
function SupplierInvoices({ purchase: p, editMode }: { purchase: PurchaseView; editMode: boolean }) {
  const router = useRouter();
  const [adding, setAdding] = useState(false);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [amt, setAmt] = useState("");
  const [editId, setEditId] = useState<string | null>(null);
  const [editAmt, setEditAmt] = useState("");
  const [editReason, setEditReason] = useState("");

  const invoiced = p.invoices.reduce((s, i) => s + (i.amount_incl ?? 0), 0);
  const unpriced = p.invoices.filter((i) => i.amount_incl == null).length;
  const outstanding = p.total - invoiced;

  async function add(e: React.FormEvent<HTMLFormElement>) {
    e.preventDefault();
    const form = e.currentTarget;
    setBusy(true);
    setError(null);
    try {
      const res = await fetch(`/api/purchases/${p.id}/invoices`, { method: "POST", body: new FormData(form) });
      const body = await res.json();
      if (!body.ok) {
        setError(body.error);
        return;
      }
      if (body.over > 0) setError(`Saved — but this takes the invoices ${ZAR2(body.over)} OVER the PO total. Check the amount.`);
      else if (body.warning) setError(body.warning);
      form.reset();
      setAmt("");
      setAdding(false);
      router.refresh();
    } catch {
      setError("Could not save — check your connection");
    } finally {
      setBusy(false);
    }
  }

  function startEdit(i: PurchaseInvoiceView) {
    setEditId(i.id);
    setEditAmt(i.amount_incl == null ? "" : String(i.amount_incl));
    setEditReason("");
    setError(null);
  }

  async function saveEdit(i: PurchaseInvoiceView) {
    setBusy(true);
    setError(null);
    try {
      const res = await fetch(`/api/purchases/${p.id}/invoices/${i.id}`, {
        method: "PATCH",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ amount_incl: editAmt, reason: editReason }),
      });
      const body = await res.json();
      if (!body.ok) { setError(body.error); return; }
      setEditId(null);
      router.refresh();
    } catch {
      setError("Could not save — check your connection");
    } finally {
      setBusy(false);
    }
  }

  async function remove(i: PurchaseInvoiceView) {
    if (!confirm(`Remove invoice ${i.invoice_no} from ${p.po_no}?`)) return;
    const res = await fetch(`/api/purchases/${p.id}/invoices/${i.id}`, { method: "DELETE" });
    const body = await res.json().catch(() => ({ ok: false, error: "Could not remove" }));
    if (!body.ok) setError(body.error);
    else router.refresh();
  }

  return (
    <div className="mb-4 rounded-lg border border-gray-100 dark:border-border bg-white dark:bg-surface p-3">
      <div className="flex flex-wrap items-center justify-between gap-2 mb-2">
        <div className="text-xs font-semibold text-[#003D5B] dark:text-white">
          Supplier invoices
          {p.invoices.length > 0 && (
            <span className="ml-2 font-normal text-gray-500 dark:text-gray-400">
              {ZAR2(invoiced)} invoiced · {ZAR2(Math.abs(outstanding))} of PO {outstanding < 0 ? "over" : "not yet invoiced"}
              {unpriced > 0 && ` · ${unpriced} with no amount`}
            </span>
          )}
        </div>
        {!adding && (
          <button
            onClick={() => setAdding(true)}
            className="min-h-[44px] px-3 rounded-lg text-xs font-medium text-white inline-flex items-center gap-1.5"
            style={{ background: ACCENT }}
          >
            <Plus className="w-4 h-4" /> Add invoice
          </button>
        )}
      </div>

      {p.invoices.length === 0 && !adding && (
        <div className="text-xs text-gray-400">No invoices attached to this PO yet.</div>
      )}

      {p.invoices.length > 0 && (
        <ul className="divide-y divide-gray-100 dark:divide-border">
          {p.invoices.map((i) => editId === i.id ? (
            <li key={i.id} className="py-2 space-y-2">
              <div className="text-xs font-semibold text-[#003D5B] dark:text-white">Correct invoice {i.invoice_no}</div>
              <div className="grid grid-cols-1 sm:grid-cols-3 gap-2">
                <label className="text-[12px] text-gray-500 dark:text-gray-400">
                  Amount incl VAT (PO is {ZAR2(p.total)})
                  <input value={editAmt} onChange={(e) => setEditAmt(e.target.value)} inputMode="decimal" className={inputCls} autoFocus />
                </label>
                <label className="text-[12px] text-gray-500 dark:text-gray-400 sm:col-span-2">
                  Reason for the change (kept in the log)
                  <input value={editReason} onChange={(e) => setEditReason(e.target.value)} placeholder="e.g. decimal point missed when captured" className={inputCls} />
                </label>
              </div>
              <div className="flex gap-2">
                <button onClick={() => saveEdit(i)} disabled={busy || editReason.trim().length < 3}
                  className="min-h-[44px] px-4 rounded-lg text-xs font-medium text-white inline-flex items-center gap-2 disabled:opacity-50" style={{ background: ACCENT }}>
                  {busy && <Loader2 className="w-4 h-4 animate-spin" />} Save correction
                </button>
                <button onClick={() => setEditId(null)} className="min-h-[44px] px-4 rounded-lg text-xs font-medium text-gray-500 hover:bg-gray-50 dark:hover:bg-white/5">Cancel</button>
              </div>
            </li>
          ) : (
            <li key={i.id} className="flex items-center gap-3 py-1">
              <div className="flex-1 min-w-0 text-xs">
                <span className="font-mono font-semibold text-[#003D5B] dark:text-white">{i.invoice_no}</span>
                <span className="text-gray-500 dark:text-gray-400">
                  {" "}· {i.invoice_date || "no date"}
                  {i.note && ` · ${i.note}`}
                </span>
              </div>
              <div
                onDoubleClick={() => editMode && startEdit(i)}
                title={editMode ? "Double-click to correct this amount" : "Switch on Edit mode to correct this amount"}
                className="text-xs tabular-nums font-semibold text-[#003D5B] dark:text-white shrink-0 cursor-text select-none"
              >
                {i.amount_incl == null ? <span className="font-normal italic text-gray-400">no amount</span> : ZAR2(i.amount_incl)}
              </div>
              {editMode && (
              <button
                onClick={() => startEdit(i)}
                aria-label={`Correct the amount of ${i.invoice_no}`}
                className="min-h-[44px] min-w-[44px] grid place-items-center rounded-lg text-gray-400 hover:text-[#30638E] hover:bg-gray-50 dark:hover:bg-white/5"
              >
                <Pencil className="w-4 h-4" />
              </button>
              )}
              {i.hasPdf ? (
                <a
                  href={`/api/purchases/${p.id}/invoices/${i.id}/document`}
                  target="_blank"
                  rel="noreferrer"
                  aria-label={`Open PDF for ${i.invoice_no}`}
                  className="min-h-[44px] min-w-[44px] grid place-items-center rounded-lg text-[#30638E] hover:bg-gray-50 dark:hover:bg-white/5"
                >
                  <FileText className="w-4 h-4" />
                </a>
              ) : (
                <span className="min-w-[44px] text-center text-[12px] text-gray-400">no PDF</span>
              )}
              {editMode && (
              <button
                onClick={() => remove(i)}
                aria-label={`Remove invoice ${i.invoice_no}`}
                className="min-h-[44px] min-w-[44px] grid place-items-center rounded-lg text-gray-400 hover:text-[#D1495B] hover:bg-gray-50 dark:hover:bg-white/5"
              >
                <Trash2 className="w-4 h-4" />
              </button>
              )}
            </li>
          ))}
        </ul>
      )}

      {error && <div className="mt-2 text-xs text-[#D1495B] dark:text-[#D94F60]">{error}</div>}

      {adding && (
        <form onSubmit={add} className="mt-3 grid grid-cols-1 sm:grid-cols-2 gap-3">
          <label className="text-[12px] text-gray-500 dark:text-gray-400">
            Invoice number *
            <input name="invoice_no" required className={inputCls} />
          </label>
          <label className="text-[12px] text-gray-500 dark:text-gray-400">
            Invoice date
            <input name="invoice_date" type="date" className={inputCls} />
          </label>
          <label className="text-[12px] text-gray-500 dark:text-gray-400">
            Amount incl VAT
            <input name="amount_incl" value={amt} onChange={(e) => setAmt(e.target.value)} inputMode="decimal" placeholder="0.00" className={inputCls} />
            <OverWarning po={p} typed={amt} />
          </label>
          <label className="text-[12px] text-gray-500 dark:text-gray-400">
            Note
            <input name="note" placeholder="e.g. part delivery" className={inputCls} />
          </label>
          <label className="text-[12px] text-gray-500 dark:text-gray-400 sm:col-span-2">
            Invoice PDF
            <input name="file" type="file" accept="application/pdf,.pdf" className={`${inputCls} py-2`} />
          </label>
          <div className="sm:col-span-2 flex gap-2">
            <button
              type="submit"
              disabled={busy}
              className="min-h-[44px] px-4 rounded-lg text-xs font-medium text-white inline-flex items-center gap-2 disabled:opacity-60"
              style={{ background: ACCENT }}
            >
              {busy && <Loader2 className="w-4 h-4 animate-spin" />} Save invoice
            </button>
            <button
              type="button"
              onClick={() => { setAdding(false); setError(null); }}
              className="min-h-[44px] px-4 rounded-lg text-xs font-medium text-gray-500 hover:bg-gray-50 dark:hover:bg-white/5"
            >
              Cancel
            </button>
          </div>
        </form>
      )}
    </div>
  );
}


function invoiceStatus(p: PurchaseView) {
  return invoiceStatusOf(p.total, p.invoices.map((i) => i.amount_incl));
}

const BRAND_ORANGE = "#EDAE49";

/**
 * Global "Upload invoice": find the PO by number, supplier, amount or line description,
 * then give the invoice number, date, amount and PDF (drag and drop or browse).
 */
function InvoiceUploadModal({ purchases, onClose }: { purchases: PurchaseView[]; onClose: () => void }) {
  const router = useRouter();
  const fileRef = useRef<HTMLInputElement>(null);
  const [query, setQuery] = useState("");
  const [poId, setPoId] = useState("");
  const [file, setFile] = useState<File | null>(null);
  const [amt, setAmt] = useState("");
  const [drag, setDrag] = useState(false);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const q = query.trim().toLowerCase().replace(/[\s,]/g, "");
  const matches = purchases
    .filter((p) => {
      if (!q) return true;
      const hay = [
        p.po_no, p.supplier, p.supplier_code,
        p.total.toFixed(2), String(Math.round(p.total)),
        ...p.lines.map((l) => `${l.description} ${l.cost_code}`),
      ].join(" ").toLowerCase().replace(/[\s,]/g, "");
      return hay.includes(q);
    })
    .slice(0, 8);
  const po = purchases.find((p) => p.id === poId) || null;
  const st = po ? invoiceStatus(po) : null;

  function pick(f: File | undefined) {
    if (!f) return;
    if (!f.name.toLowerCase().endsWith(".pdf")) {
      setError("Invoices must be PDF files");
      return;
    }
    setError(null);
    setFile(f);
  }

  async function submit(e: React.FormEvent<HTMLFormElement>) {
    e.preventDefault();
    if (!po) {
      setError("Choose the purchase order first");
      return;
    }
    const fd = new FormData(e.currentTarget);
    if (file) fd.set("file", file);
    else fd.delete("file");
    setBusy(true);
    setError(null);
    try {
      const res = await fetch(`/api/purchases/${po.id}/invoices`, { method: "POST", body: fd });
      const body = await res.json();
      if (!body.ok) {
        setError(body.error);
        return;
      }
      router.refresh();
      onClose();
    } catch {
      setError("Could not save — check your connection");
    } finally {
      setBusy(false);
    }
  }

  return (
    <div className="fixed inset-0 z-50 bg-black/40 grid place-items-center p-4 overflow-y-auto" onClick={onClose}>
      <form
        onSubmit={submit}
        onClick={(e) => e.stopPropagation()}
        role="dialog"
        aria-label="Upload invoice"
        className="w-full max-w-lg bg-white dark:bg-surface rounded-2xl p-5 shadow-xl space-y-3"
      >
        <div className="flex items-center justify-between">
          <h2 className="text-base font-semibold text-[#003D5B] dark:text-white">Upload invoice</h2>
          <button type="button" onClick={onClose} aria-label="Close"
            className="min-h-[44px] min-w-[44px] grid place-items-center rounded-lg hover:bg-gray-50 dark:hover:bg-white/5">
            <X className="w-4 h-4" />
          </button>
        </div>

        <div>
          <label className="text-[12px] text-gray-500 dark:text-gray-400" htmlFor="inv-search">
            Find the purchase order — number, supplier, amount or description
          </label>
          <div className="relative">
            <Search className="w-4 h-4 absolute left-3 top-1/2 -translate-y-1/2 text-gray-400" />
            <input id="inv-search" value={query} onChange={(e) => { setQuery(e.target.value); setPoId(""); }}
              placeholder="e.g. MEGPPO49676, tyres, 12500" autoComplete="off"
              className={`${inputCls} pl-9`} />
          </div>
          {!po && (
            <ul className="mt-1 max-h-56 overflow-y-auto rounded-lg border border-gray-100 dark:border-border divide-y divide-gray-100 dark:divide-border">
              {matches.length === 0 && <li className="p-3 text-xs text-gray-400">No purchase order matches.</li>}
              {matches.map((p) => (
                <li key={p.id}>
                  <button type="button" onClick={() => setPoId(p.id)}
                    className="w-full min-h-[44px] flex items-center gap-2 px-3 py-2 text-left hover:bg-gray-50 dark:hover:bg-white/5">
                    <span className="w-1 self-stretch rounded" style={{ background: STATUS_STYLE[invoiceStatus(p).status].color }} />
                    <span className="flex-1 min-w-0 text-xs">
                      <span className="font-mono font-semibold text-[#003D5B] dark:text-white">{p.po_no}</span>
                      <span className="text-gray-500 dark:text-gray-400"> · {p.supplier}</span>
                      <span className="block truncate text-gray-400">{p.lines[0]?.description}</span>
                    </span>
                    <span className="text-xs tabular-nums font-semibold shrink-0">{ZAR2(p.total)}</span>
                  </button>
                </li>
              ))}
            </ul>
          )}
          {po && st && (
            <div className="mt-1 flex items-center gap-2 rounded-lg bg-gray-50 dark:bg-white/5 p-2 text-xs">
              <span className="w-1 self-stretch rounded" style={{ background: STATUS_STYLE[st.status].color }} />
              <span className="flex-1 min-w-0">
                <span className="font-mono font-semibold text-[#003D5B] dark:text-white">{po.po_no}</span>
                <span className="text-gray-500 dark:text-gray-400"> · {po.supplier}</span>
              </span>
              <button type="button" onClick={() => setPoId("")}
                className="min-h-[44px] px-2 text-[#30638E] font-medium">Change</button>
            </div>
          )}
        </div>

        <div className="grid grid-cols-1 sm:grid-cols-2 gap-3">
          <label className="text-[12px] text-gray-500 dark:text-gray-400">
            Invoice number *
            <input name="invoice_no" required className={inputCls} />
          </label>
          <label className="text-[12px] text-gray-500 dark:text-gray-400">
            Invoice date
            <input name="invoice_date" type="date" className={inputCls} />
          </label>
          <label className="text-[12px] text-gray-500 dark:text-gray-400 sm:col-span-2">
            Amount incl VAT
            <input name="amount_incl" value={amt} onChange={(e) => setAmt(e.target.value)} inputMode="decimal" placeholder="0.00" className={inputCls} />
            {po && <OverWarning po={po} typed={amt} />}
            {po && st && (
              <span className="block mt-1 text-xs text-gray-500 dark:text-gray-400">
                PO value <span className="font-semibold text-[#003D5B] dark:text-white tabular-nums">{ZAR2(po.total)}</span>
                {" · "}already invoiced {ZAR2(st.invoiced)}
                {" · "}left <span className="font-semibold tabular-nums">{ZAR2(Math.max(po.total - st.invoiced, 0))}</span>
              </span>
            )}
          </label>
        </div>

        <div
          onDragOver={(e) => { e.preventDefault(); setDrag(true); }}
          onDragLeave={() => setDrag(false)}
          onDrop={(e) => { e.preventDefault(); setDrag(false); pick(e.dataTransfer.files[0]); }}
          className={`rounded-xl border-2 border-dashed p-4 text-center text-xs transition-colors ${
            drag ? "border-[#EDAE49] bg-[#EDAE49]/10" : "border-gray-200 dark:border-border"
          }`}
        >
          <input ref={fileRef} type="file" accept="application/pdf,.pdf" className="sr-only"
            onChange={(e) => pick(e.target.files?.[0])} />
          {file ? (
            <div className="flex items-center justify-center gap-2 text-[#003D5B] dark:text-white">
              <FileText className="w-4 h-4" /> {file.name}
              <button type="button" onClick={() => setFile(null)} aria-label="Remove file"
                className="min-h-[44px] min-w-[44px] grid place-items-center"><X className="w-4 h-4" /></button>
            </div>
          ) : (
            <>
              <Upload className="w-5 h-5 mx-auto mb-1 text-gray-400" />
              <div className="text-gray-500 dark:text-gray-400">Drag the invoice PDF here, or</div>
              <button type="button" onClick={() => fileRef.current?.click()}
                className="mt-1 min-h-[44px] px-4 rounded-lg text-xs font-medium text-white"
                style={{ background: BRAND_ORANGE }}>
                Choose file
              </button>
            </>
          )}
        </div>

        {error && <div className="text-xs text-[#D1495B] dark:text-[#D94F60]">{error}</div>}

        <div className="flex gap-2 justify-end">
          <button type="button" onClick={onClose}
            className="min-h-[44px] px-4 rounded-lg text-xs font-medium text-gray-500 hover:bg-gray-50 dark:hover:bg-white/5">
            Cancel
          </button>
          <button type="submit" disabled={busy || !po}
            className="min-h-[44px] px-4 rounded-lg text-xs font-medium text-white inline-flex items-center gap-2 disabled:opacity-50"
            style={{ background: BRAND_ORANGE }}>
            {busy && <Loader2 className="w-4 h-4 animate-spin" />} Save invoice
          </button>
        </div>
      </form>
    </div>
  );
}


const isoDay = (d: Date) => `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, "0")}-${String(d.getDate()).padStart(2, "0")}`;
const fmtDay = (d: Date) => d.toLocaleDateString("en-ZA", { day: "numeric", month: "short" });

/** The week (Monday–Sunday) or calendar month `offset` periods from the current one. */
function rangeWindow(range: "week" | "month", offset: number): { from: string; to: string; label: string } {
  const now = new Date();
  if (range === "month") {
    const first = new Date(now.getFullYear(), now.getMonth() + offset, 1);
    const last = new Date(first.getFullYear(), first.getMonth() + 1, 0);
    return { from: isoDay(first), to: isoDay(last), label: first.toLocaleDateString("en-ZA", { month: "long", year: "numeric" }) };
  }
  const monday = new Date(now.getFullYear(), now.getMonth(), now.getDate() - ((now.getDay() + 6) % 7) + offset * 7);
  const sunday = new Date(monday.getFullYear(), monday.getMonth(), monday.getDate() + 6);
  return { from: isoDay(monday), to: isoDay(sunday), label: `${fmtDay(monday)} – ${fmtDay(sunday)}` };
}


/** Live check while typing an invoice amount: anything that takes the PO over its total is flagged before it is saved. */
function OverWarning({ po, typed }: { po: PurchaseView; typed: string }) {
  const n = Number(typed.trim().replace(/\s/g, "").replace(",", "."));
  if (!typed.trim() || !Number.isFinite(n)) return null;
  const over = po.invoices.reduce((t, i) => t + (i.amount_incl ?? 0), 0) + n - po.total;
  if (over <= 1) return null;
  return (
    <span className="mt-1 flex items-start gap-1.5 text-xs font-medium text-[#8B5CF6]">
      <TriangleAlert className="w-3.5 h-3.5 mt-0.5 shrink-0" />
      This is {ZAR2(over)} MORE than the PO ({ZAR2(po.total)}). Check for a typo before saving.
    </span>
  );
}