import { useEffect, useRef, useState } from "react";
import { useTranslation } from "react-i18next";
import { useQueryClient } from "@tanstack/react-query";
import { UploadCloud, File as FileIcon } from "lucide-react";
import Modal from "./Modal";
import { Button } from "./ui/Button";
import { api } from "../lib/api";
import { invalidateDownloads } from "../lib/downloads";
import { notify } from "../lib/notifications";
import { navigateTo } from "../lib/nav";
import { formatBytes } from "../lib/format";
import { inputCls } from "./ui/form";

// Local-file ingest (E7 S5c · D5-A). A general upload — ANY file type, no format list: media
// (video/audio) joins the library with the full function set, a generic file is download-only. The
// file is streamed to the server via XHR so this dialog can show real upload progress. On success it
// lands in the Library as an already-`done` job, so we invalidate + point the user there.
export default function UploadDialog({ onClose }: { onClose: () => void }) {
  const { t } = useTranslation();
  const qc = useQueryClient();
  const [file, setFile] = useState<File | null>(null);
  const [name, setName] = useState("");
  const [dragOver, setDragOver] = useState(false);
  const [pct, setPct] = useState<number | null>(null); // null = idle; 0–100 while uploading
  const inputRef = useRef<HTMLInputElement>(null);
  const abortRef = useRef<AbortController | null>(null);
  // dragenter/dragleave fire as the cursor crosses the drop zone's OWN children (icon/text), so a
  // plain boolean flickers. Count enter vs leave and only clear the highlight at depth 0.
  const dragDepth = useRef(0);
  const busy = pct !== null;

  // Closing the dialog mid-upload (X / ESC / backdrop / browser Back all unmount us) must abort the
  // in-flight XHR — otherwise it keeps streaming in the background and still toasts success. Only the
  // footer Cancel wired the abort; this covers every other dismissal.
  useEffect(() => () => abortRef.current?.abort(), []);

  const pick = () => inputRef.current?.click();

  const submit = async () => {
    if (!file || busy) return;
    const ac = new AbortController();
    abortRef.current = ac;
    setPct(0);
    try {
      await api.uploadDownload(file, {
        displayName: name.trim() || undefined,
        onProgress: setPct,
        signal: ac.signal,
      });
      invalidateDownloads(qc);
      notify({
        level: "success",
        message: t("downloads.upload.added"),
        action: { label: t("downloads.dialog.view"), onClick: () => navigateTo("downloads") },
      });
      onClose();
    } catch {
      // An aborted upload (Cancel) or a server rejection (cap/quota — already surfaced by the global
      // error modal, like every other req call). Re-arm the form so the user can retry or pick again.
      setPct(null);
      abortRef.current = null;
    }
  };

  return (
    <Modal title={t("downloads.upload.title")} onClose={onClose}>
      <p className="text-sm text-muted mb-4">{t("downloads.upload.hint")}</p>

      {/* Drop zone doubles as the picker trigger — a click anywhere opens the native file dialog. */}
      <button
        type="button"
        onClick={pick}
        onDragEnter={(e) => {
          e.preventDefault();
          dragDepth.current += 1;
          setDragOver(true);
        }}
        onDragOver={(e) => e.preventDefault()}
        onDragLeave={() => {
          dragDepth.current = Math.max(0, dragDepth.current - 1);
          if (dragDepth.current === 0) setDragOver(false);
        }}
        onDrop={(e) => {
          e.preventDefault();
          dragDepth.current = 0;
          setDragOver(false);
          const f = e.dataTransfer.files?.[0];
          if (f) {
            setFile(f);
            setName("");
          }
        }}
        disabled={busy}
        className={`w-full flex flex-col items-center justify-center gap-2 rounded-xl border-2 border-dashed px-4 py-8 text-center transition disabled:opacity-60 ${
          dragOver ? "border-accent bg-accent/5" : "border-border hover:border-fg/40"
        }`}
      >
        {file ? (
          <>
            <FileIcon className="w-6 h-6 text-muted" />
            <span className="text-sm font-medium break-all">{file.name}</span>
            <span className="text-xs text-muted">{formatBytes(file.size)}</span>
          </>
        ) : (
          <>
            <UploadCloud className="w-7 h-7 text-muted" />
            <span className="text-sm text-muted">
              {dragOver ? t("downloads.upload.dropActive") : t("downloads.upload.drop")}
            </span>
          </>
        )}
      </button>
      <input
        ref={inputRef}
        type="file"
        className="hidden"
        onChange={(e) => {
          const f = e.target.files?.[0];
          if (f) {
            setFile(f);
            setName("");
          }
          e.target.value = ""; // let re-picking the same file fire onChange again
        }}
      />

      <label className="block text-sm font-medium mt-4 mb-1">
        {t("downloads.upload.nameLabel")}
      </label>
      <input
        value={name}
        onChange={(e) => setName(e.target.value)}
        placeholder={t("downloads.upload.namePlaceholder")}
        disabled={busy}
        className={`${inputCls} mb-5`}
      />

      {busy && (
        <div className="mb-5" aria-live="polite">
          <div
            className="h-2 rounded-full bg-surface overflow-hidden"
            role="progressbar"
            aria-valuenow={pct ?? 0}
            aria-valuemin={0}
            aria-valuemax={100}
            // A STABLE descriptor as the name; the live percentage rides aria-valuenow (and the visible
            // <p> below re-announces it via the aria-live wrapper) — don't bake the value into the name.
            aria-label={t("downloads.upload.uploadProgress")}
          >
            <div
              className="h-full bg-accent transition-[width] duration-150"
              style={{ width: `${pct ?? 0}%` }}
            />
          </div>
          <p className="text-xs text-muted mt-1.5 text-center">
            {t("downloads.upload.uploading", { pct: pct ?? 0 })}
          </p>
        </div>
      )}

      <div className="flex justify-end gap-2">
        <Button
          variant="ghost"
          size="sm"
          onClick={() => (busy ? abortRef.current?.abort() : onClose())}
        >
          {t("downloads.actions.cancel")}
        </Button>
        <Button variant="primary" size="sm" onClick={submit} disabled={!file || busy}>
          {t("downloads.upload.submit")}
        </Button>
      </div>
    </Modal>
  );
}