"use client";

import { useState, useRef, useEffect, useCallback } from "react";
import { useRouter } from "next/navigation";
import {
  FileUp, Loader2, AlertTriangle, RotateCw, Inbox, Trash2, X, UploadCloud, FileText,
} from "lucide-react";
import { Toast } from "@/components/Toast";
import { ZAR2 } from "@/lib/utils";

// "Add Invoice" — opens a standalone dialog. The file is chosen or dropped into the
// modal and nothing is uploaded until OK is pressed, so a mis-drop can be cleared
// without leaving a stray record in the inbox.
export function AddInvoiceButton() {
  const [open, setOpen] = useState(false);
  const [file, setFile] = useState<File | null>(null);
  const [dragging, setDragging] = useState(false);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<null | { title: string; body: string }>(null);
  // The dialog closes on success, which would otherwise leave no feedback at all — so
  // a toast confirms it landed. Anything still needing attention is named in it AND
  // badged on the invoice row.
  const [toast, setToast] = useState<null | { message: string; detail: string; tone: "success" | "notice" }>(null);
  const inputRef = useRef<HTMLInputElement>(null);
  const router = useRouter();

  const reset = useCallback(() => {
    setFile(null);
    setError(null);
    setDragging(false);
  }, []);

  const close = useCallback(() => {
    if (busy) return;
    setOpen(false);
    reset();
  }, [busy, reset]);

  // Escape closes, and the page behind the dialog must not scroll under it.
  useEffect(() => {
    if (!open) return;
    const onKey = (e: KeyboardEvent) => {
      if (e.key === "Escape") close();
    };
    document.addEventListener("keydown", onKey);
    const prev = document.body.style.overflow;
    document.body.style.overflow = "hidden";
    return () => {
      document.removeEventListener("keydown", onKey);
      document.body.style.overflow = prev;
    };
  }, [open, close]);

  const accept = (f: File | undefined) => {
    if (!f) return;
    if (f.type !== "application/pdf" && !f.name.toLowerCase().endsWith(".pdf")) {
      setError({ title: "Not a PDF", body: `${f.name} — only PDF invoices are accepted.` });
      setFile(null);
      return;
    }
    if (f.size > 20 * 1024 * 1024) {
      setError({
        title: "Too large",
        body: `${(f.size / 1048576).toFixed(1)} MB — the limit is 20 MB.`,
      });
      setFile(null);
      return;
    }
    setError(null);
    setFile(f);
  };

  const upload = async () => {
    if (!file) return;
    setBusy(true);
    setError(null);
    const fd = new FormData();
    fd.append("file", file);
    try {
      const res = await fetch("/api/invoices/intake", { method: "POST", body: fd });
      const data = await res.json().catch(() => ({ ok: false, error: "Unexpected response" }));
      if (data.ok) {
        // Success closes the dialog and confirms with a toast, so the click is never
        // silent. A FAILURE stays open, because the reason is the whole point.
        const unassigned = (data.unassigned ?? []) as string[];
        setToast({
          tone: "success",
          message: `${data.invoice_no} imported`,
          detail:
            `${data.lines} line${data.lines > 1 ? "s" : ""} · ${ZAR2(data.total_incl)} · ` +
            `${data.booked} booked` +
            (unassigned.length
              ? ` — needs a plant item: ${unassigned.join(", ")}`
              : data.fullyBooked
                ? " · all lines matched"
                : ""),
        });
        reset();
        setOpen(false);
        router.refresh();
        return;
      } else if (data.status === "duplicate") {
        // Already in the register. Nothing was added and nothing is wrong, so this closes
        // the dialog and reports it — it is not a problem invoice and does not go to the
        // retry inbox. The detail names the copy you already have so it is obvious which
        // one this matched.
        const e = data.existing ?? {};
        setToast({
          tone: "notice",
          message: `${data.invoice_no} is already imported`,
          detail:
            `${e.site ?? "—"} · ${e.lines ?? 0} line${e.lines === 1 ? "" : "s"} · ` +
            `${ZAR2(e.total_incl ?? 0)} — nothing was added.`,
        });
        reset();
        setOpen(false);
        router.refresh();
        return;
      } else {
        setError({
          title: data.status === "failed" ? "Saved to the problem inbox" : "Could not import",
          body: data.error ?? "Unknown error",
        });
        router.refresh();
      }
    } catch {
      setError({ title: "Could not reach the server", body: "Check the app is running." });
    } finally {
      setBusy(false);
    }
  };

  return (
    <>
      <button
        type="button"
        onClick={() => {
          setToast(null);
          setOpen(true);
        }}
        className="inline-flex items-center gap-2 min-h-[44px] px-4 rounded-xl bg-gradient-to-br from-[#00798C] to-[#003D5B] text-white text-sm font-semibold shadow-lg shadow-teal-500/20 hover:opacity-90 transition"
      >
        <FileUp className="w-4 h-4" />
        Add Invoice
      </button>

      {toast && (
        <Toast
          message={toast.message}
          detail={toast.detail}
          tone={toast.tone}
          onDismiss={() => setToast(null)}
        />
      )}

      {open && (
        <div className="fixed inset-0 z-50 flex items-end sm:items-center justify-center p-0 sm:p-4">
          {/* Backdrop */}
          <div
            className="absolute inset-0 bg-black/50 backdrop-blur-sm"
            onClick={close}
            aria-hidden="true"
          />

          <div
            role="dialog"
            aria-modal="true"
            aria-label="Add invoice"
            className="relative w-full sm:max-w-lg bg-white dark:bg-surface rounded-t-2xl sm:rounded-2xl shadow-2xl border border-gray-100 dark:border-white/10 max-h-[90vh] overflow-y-auto"
          >
            <div className="flex items-center justify-between px-5 py-4 border-b border-gray-100 dark:border-border">
              <h2 className="text-base font-semibold text-[#003D5B] dark:text-white">Add invoice</h2>
              <button
                type="button"
                onClick={close}
                disabled={busy}
                aria-label="Close"
                className="grid place-items-center w-11 h-11 -mr-2 rounded-lg text-gray-500 hover:bg-gray-100 dark:hover:bg-white/5 transition disabled:opacity-50"
              >
                <X className="w-4 h-4" />
              </button>
            </div>

            <div className="p-5">
              <div
                role="button"
                tabIndex={0}
                aria-label="Choose or drop an invoice PDF"
                onClick={() => !busy && inputRef.current?.click()}
                onKeyDown={(e) => {
                  if ((e.key === "Enter" || e.key === " ") && !busy) {
                    e.preventDefault();
                    inputRef.current?.click();
                  }
                }}
                onDragOver={(e) => {
                  e.preventDefault();
                  setDragging(true);
                }}
                onDragLeave={() => setDragging(false)}
                onDrop={(e) => {
                  e.preventDefault();
                  setDragging(false);
                  accept(e.dataTransfer.files?.[0]);
                }}
                className={`flex flex-col items-center justify-center gap-2 text-center px-4 py-8 rounded-xl border-2 border-dashed cursor-pointer transition ${
                  dragging
                    ? "border-[#00798C] bg-[#00798C]/10"
                    : "border-gray-200 dark:border-white/10 hover:border-[#00798C]/50 hover:bg-gray-50 dark:hover:bg-white/[0.02]"
                } ${busy ? "opacity-60 pointer-events-none" : ""}`}
              >
                <UploadCloud className="w-7 h-7 text-[#00798C]" />
                <div className="text-sm font-medium text-[#003D5B] dark:text-white">
                  Drop the invoice PDF here
                </div>
                <div className="text-xs text-gray-500 dark:text-gray-400">
                  or tap to browse your files
                </div>
              </div>

              <input
                ref={inputRef}
                type="file"
                accept="application/pdf,.pdf"
                className="sr-only"
                onChange={(e) => {
                  accept(e.target.files?.[0]);
                  e.target.value = "";
                }}
              />

              {file && (
                <div className="mt-3 flex items-center gap-3 px-3 py-2.5 rounded-xl bg-[#00798C]/10">
                  <FileText className="w-4 h-4 text-[#00798C] shrink-0" />
                  <div className="min-w-0 flex-1">
                    <div className="text-sm font-medium text-[#003D5B] dark:text-white truncate">
                      {file.name}
                    </div>
                    <div className="text-xs text-gray-500 dark:text-gray-400">
                      {(file.size / 1024).toFixed(0)} KB · ready to upload
                    </div>
                  </div>
                  {!busy && (
                    <button
                      type="button"
                      onClick={reset}
                      aria-label="Remove the selected file"
                      className="grid place-items-center w-11 h-11 -mr-1 rounded-lg text-gray-500 hover:bg-white/60 dark:hover:bg-white/10 transition"
                    >
                      <X className="w-4 h-4" />
                    </button>
                  )}
                </div>
              )}

              {error && (
                <div className="mt-3 flex items-start gap-2.5 px-3 py-2.5 rounded-xl text-sm bg-[#D1495B]/10 text-[#D1495B]">
                  <AlertTriangle className="w-4 h-4 shrink-0 mt-0.5" />
                  <div className="min-w-0">
                    <div className="font-semibold">{error.title}</div>
                    <div className="mt-0.5 break-words">{error.body}</div>
                  </div>
                </div>
              )}

              <p className="mt-3 text-xs text-gray-500 dark:text-gray-400">
                Figures are read from the invoice and checked before anything is saved. If it
                does not reconcile it is kept in the problem inbox instead of imported.
              </p>
            </div>

            <div className="flex items-center justify-end gap-2 px-5 py-4 border-t border-gray-100 dark:border-border bg-gray-50/60 dark:bg-white/[0.04] rounded-b-2xl">
              <button
                type="button"
                onClick={close}
                disabled={busy}
                className="inline-flex items-center justify-center min-h-[44px] px-4 rounded-lg text-sm font-medium text-gray-600 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-white/5 transition disabled:opacity-50"
              >
                Cancel
              </button>
              <button
                type="button"
                onClick={upload}
                disabled={!file || busy}
                className="inline-flex items-center gap-2 min-h-[44px] px-4 rounded-lg text-sm font-semibold text-white bg-gradient-to-br from-[#00798C] to-[#003D5B] hover:opacity-90 transition disabled:opacity-40 disabled:pointer-events-none"
              >
                {busy ? <Loader2 className="w-4 h-4 animate-spin" /> : <FileUp className="w-4 h-4" />}
                {busy ? "Importing…" : "OK — Import"}
              </button>
            </div>
          </div>
        </div>
      )}
    </>
  );
}

type IntakeItem = {
  id: string;
  file_name: string;
  file_size: number;
  invoice_no: string;
  status: "imported" | "failed";
  error: string;
  created: string;
};

// The problem-invoice inbox. Anything that could not be parsed or imported lands here
// with the reason, so it can be inspected and retried instead of disappearing.
export function ProblemInbox() {
  const [items, setItems] = useState<IntakeItem[] | null>(null);
  const [retrying, setRetrying] = useState<string | null>(null);
  const [msg, setMsg] = useState<string | null>(null);
  const router = useRouter();

  const load = useCallback(async () => {
    try {
      const res = await fetch("/api/invoices/intake?status=failed", { cache: "no-store" });
      const data = await res.json().catch(() => ({ ok: false, items: [] }));
      setItems(data.ok ? data.items : []);
    } catch {
      setItems([]);
    }
  }, []);

  useEffect(() => {
    load();
  }, [load]);

  const retry = async (id: string) => {
    setRetrying(id);
    setMsg(null);
    try {
      const res = await fetch(`/api/invoices/intake/${id}/retry`, { method: "POST" });
      const data = await res.json().catch(() => ({ ok: false }));
      setMsg(
        data.ok
          ? `${data.invoice_no} imported on retry.`
          : `Still failing: ${data.error ?? "unknown reason"}`,
      );
      await load();
      router.refresh();
    } catch {
      setMsg("Could not reach the server");
    } finally {
      setRetrying(null);
    }
  };

  const discard = async (id: string) => {
    setRetrying(id);
    try {
      await fetch(`/api/invoices/intake/${id}`, { method: "DELETE" });
      await load();
    } catch {
      setMsg("Could not reach the server");
    } finally {
      setRetrying(null);
    }
  };

  return (
    <div className="bg-white dark:bg-surface border border-gray-100 dark:border-border rounded-2xl shadow-sm overflow-hidden mb-6">
      <div className="flex items-center gap-2.5 px-5 py-4 border-b border-gray-100 dark:border-border">
        <Inbox className="w-4 h-4 text-[#D1495B] shrink-0" />
        <h2 className="text-sm font-semibold text-[#003D5B] dark:text-white">Problem invoices</h2>
        <span className="text-xs px-2 py-0.5 rounded-md bg-[#D1495B]/10 text-[#D1495B] font-semibold">
          {items?.length ?? 0}
        </span>
      </div>

      {msg && (
        <div className="px-5 py-2.5 bg-[#EDAE49]/10 text-[#8a6420] dark:text-[#EDAE49] text-sm">{msg}</div>
      )}

      {items === null ? (
        <p className="px-5 py-6 text-sm text-gray-500 dark:text-gray-400">Checking…</p>
      ) : items.length === 0 ? (
        <p className="px-5 py-6 text-sm text-gray-500 dark:text-gray-400">
          Nothing in the inbox — every PDF offered so far imported cleanly.
        </p>
      ) : (
        <ul className="divide-y divide-gray-100 dark:border-border">
          {items.map((it) => (
            <li key={it.id} className="px-5 py-4">
              <div className="flex flex-wrap items-start justify-between gap-3">
                <div className="min-w-0 flex-1">
                  <div className="flex items-center gap-2 flex-wrap">
                    <span className="font-mono text-sm font-semibold text-[#003D5B] dark:text-white">
                      {it.file_name}
                    </span>
                    {it.invoice_no && (
                      <span className="text-xs px-2 py-0.5 rounded bg-gray-100 dark:bg-white/5 text-gray-600 dark:text-gray-300">
                        reads as {it.invoice_no}
                      </span>
                    )}
                  </div>
                  <p className="text-sm text-[#D1495B] mt-1.5 break-words">{it.error}</p>
                  <p className="text-xs text-gray-400 dark:text-text-soft mt-1">
                    {(it.file_size / 1024).toFixed(0)} KB
                    {it.created ? ` · ${new Date(it.created).toLocaleString("en-ZA")}` : ""}
                  </p>
                </div>
                <div className="flex items-center gap-2 shrink-0">
                  <button
                    type="button"
                    onClick={() => retry(it.id)}
                    disabled={retrying === it.id}
                    className="inline-flex items-center gap-1.5 min-h-[44px] px-3 rounded-lg text-sm font-medium text-[#003D5B] dark:text-white hover:bg-gray-100 dark:hover:bg-white/5 transition disabled:opacity-50"
                  >
                    {retrying === it.id ? (
                      <Loader2 className="w-4 h-4 animate-spin" />
                    ) : (
                      <RotateCw className="w-4 h-4" />
                    )}
                    Retry
                  </button>
                  <button
                    type="button"
                    onClick={() => discard(it.id)}
                    disabled={retrying === it.id}
                    aria-label={`Discard ${it.file_name}`}
                    className="inline-flex items-center justify-center w-11 h-11 rounded-lg text-gray-500 hover:bg-gray-100 dark:hover:bg-white/5 transition disabled:opacity-50"
                  >
                    <Trash2 className="w-4 h-4" />
                  </button>
                </div>
              </div>
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}