"use client";

import { useState, useRef, useEffect, useCallback } from "react";
import { useRouter } from "next/navigation";
import {
  FileUp, Loader2, AlertTriangle, CheckCircle2, RotateCw, Inbox, Trash2, X,
} from "lucide-react";
import { ZAR2 } from "@/lib/utils";

// "Add Invoice" — drop a PDF and the app parses it itself. No agent, no AI: the
// figures are read by coordinate from a fixed report template and checked
// arithmetically before anything is written.
export function AddInvoiceButton() {
  const [open, setOpen] = useState(false);
  const [busy, setBusy] = useState(false);
  const [dragging, setDragging] = useState(false);
  const [result, setResult] = useState<null | { ok: boolean; title: string; body: string }>(null);
  const inputRef = useRef<HTMLInputElement>(null);
  const router = useRouter();

  const send = useCallback(
    async (file: File) => {
      setBusy(true);
      setResult(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) {
          const unassigned = (data.unassigned ?? []) as string[];
          setResult({
            ok: true,
            title: `${data.invoice_no} imported`,
            body:
              `${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 a plant item."
                  : "."),
          });
        } else {
          setResult({
            ok: false,
            title: data.status === "failed" ? "Saved to the problem inbox" : "Could not import",
            body: data.error ?? "Unknown error",
          });
        }
        router.refresh();
      } catch {
        setResult({ ok: false, title: "Could not reach the server", body: "Check the app is running." });
      } finally {
        setBusy(false);
      }
    },
    [router],
  );

  useEffect(() => {
    if (!open) return;
    const onKey = (e: KeyboardEvent) => e.key === "Escape" && setOpen(false);
    document.addEventListener("keydown", onKey);
    return () => document.removeEventListener("keydown", onKey);
  }, [open]);

  if (!open) {
    return (
      <button
        type="button"
        onClick={() => 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>
    );
  }

  return (
    <div className="mb-5 bg-white dark:bg-[#131a21] border border-gray-100 dark:border-white/5 rounded-2xl shadow-sm p-4">
      <div className="flex items-center justify-between mb-3">
        <h2 className="text-sm font-semibold text-[#003D5B] dark:text-white">Add invoice</h2>
        <button
          type="button"
          onClick={() => setOpen(false)}
          aria-label="Close"
          className="grid place-items-center w-11 h-11 -mr-2 -mt-1 rounded-lg text-gray-500 hover:bg-gray-100 dark:hover:bg-white/5"
        >
          <X className="w-4 h-4" />
        </button>
      </div>

      <div
        role="button"
        tabIndex={0}
        aria-label="Upload 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);
          const f = e.dataTransfer.files?.[0];
          if (f) send(f);
        }}
        className={`flex flex-col sm:flex-row sm:items-center gap-3 px-4 py-4 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" : ""}`}
      >
        {busy ? (
          <Loader2 className="w-5 h-5 animate-spin text-[#00798C] shrink-0" />
        ) : (
          <FileUp className="w-5 h-5 text-[#00798C] shrink-0" />
        )}
        <div className="min-w-0">
          <div className="text-sm font-medium text-[#003D5B] dark:text-white">
            {busy ? "Reading the invoice…" : "Drop the invoice PDF here, or tap to browse"}
          </div>
          <div className="text-xs text-gray-500 dark:text-gray-400 mt-0.5">
            PDF only · up to 20 MB · figures are read from the invoice and checked before saving
          </div>
        </div>
      </div>

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

      {result && (
        <div
          className={`mt-3 flex items-start gap-2.5 px-3 py-2.5 rounded-xl text-sm ${
            result.ok ? "bg-[#00798C]/10 text-[#00798C]" : "bg-[#D1495B]/10 text-[#D1495B]"
          }`}
        >
          {result.ok ? (
            <CheckCircle2 className="w-4 h-4 shrink-0 mt-0.5" />
          ) : (
            <AlertTriangle className="w-4 h-4 shrink-0 mt-0.5" />
          )}
          <div className="min-w-0">
            <div className="font-semibold">{result.title}</div>
            <div className="mt-0.5 break-words">{result.body}</div>
          </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-[#131a21] border border-gray-100 dark:border-white/5 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-white/5">
        <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-white/5">
          {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-gray-500 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>
  );
}