import { useEffect, useState } from "react";
import { FileText, AlertCircle } from "lucide-react";
import { api, ApiError } from "@/lib/api";
import { cn } from "@/lib/utils";

/**
 * Aperçu du fichier importé (PDF / image) — utilisé sur :
 *  - la review OCR (volet gauche, source = batch + draft)
 *  - la fiche facture (source = invoice id direct)
 *
 * Fetch via api.fetchBlob (Bearer auto-injecté) → object URL → <iframe>
 * pour les PDF (viewer Chrome/Safari natif), <img> pour les images.
 * Fallback "barres" si pdfAvailable=false.
 */
type PdfPreviewProps = {
  filename: string;
  /** Source 1 : draft d'un import en cours (batchId + draftId). */
  batchId?: string;
  draftId?: string;
  /** Source 2 : facture validée (invoiceId direct). Prioritaire. */
  invoiceId?: string;
  /** Indique si le backend a effectivement un fichier (sinon fallback). */
  pdfAvailable?: boolean;
  className?: string;
};

export function PdfPreview({
  filename,
  batchId,
  draftId,
  invoiceId,
  pdfAvailable = true,
  className,
}: PdfPreviewProps) {
  const [objectUrl, setObjectUrl] = useState<string | null>(null);
  const [contentType, setContentType] = useState<string>("application/pdf");
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!pdfAvailable) {
      setObjectUrl(null);
      return;
    }
    // Source : invoiceId prioritaire, sinon batch+draft.
    const path = invoiceId
      ? `/api/v1/invoices/${invoiceId}/pdf`
      : batchId && draftId
        ? `/api/v1/invoices/import-batch/${batchId}/drafts/${draftId}/pdf`
        : null;
    if (!path) {
      setObjectUrl(null);
      return;
    }
    const controller = new AbortController();
    let url: string | null = null;
    setError(null);

    api
      .fetchBlob(path, controller.signal)
      .then(({ blob, contentType: ct }) => {
        url = URL.createObjectURL(blob);
        setObjectUrl(url);
        setContentType(ct);
      })
      .catch((err) => {
        if (controller.signal.aborted) return;
        if (err instanceof ApiError && err.status === 404) {
          setError("Aperçu indisponible.");
        } else {
          setError("Impossible de charger l'aperçu.");
        }
      });

    return () => {
      controller.abort();
      if (url) URL.revokeObjectURL(url);
    };
  }, [batchId, draftId, invoiceId, pdfAvailable]);

  const isImage = contentType.startsWith("image/");

  return (
    <div
      className={cn(
        "flex flex-col rounded-card border border-line bg-white overflow-hidden",
        className,
      )}
    >
      <div className="flex items-center gap-2 border-b border-line bg-cream-2/60 px-4 py-2.5">
        <FileText size={14} className="text-ink-3" aria-hidden="true" />
        <span className="font-mono text-[12px] text-ink-2 truncate">
          {filename}
        </span>
      </div>

      <div className="flex-1 bg-cream/60 min-h-[420px] relative">
        {objectUrl ? (
          isImage ? (
            <img
              src={objectUrl}
              alt={`Aperçu ${filename}`}
              className="w-full h-full max-h-[680px] object-contain bg-white"
            />
          ) : (
            <iframe
              src={objectUrl}
              title={`Aperçu ${filename}`}
              className="w-full h-full min-h-[680px] border-0"
            />
          )
        ) : error ? (
          <div className="flex flex-col items-center justify-center gap-2 h-full p-7 text-ink-3">
            <AlertCircle size={20} className="text-rubis-deep" />
            <p className="text-[13px]">{error}</p>
            <p className="text-[11.5px] italic">Vous pouvez quand même valider à partir des champs OCR.</p>
          </div>
        ) : pdfAvailable && batchId && draftId ? (
          <div className="flex items-center justify-center h-full p-7">
            <div
              className="size-6 animate-spin rounded-full border-2 border-rubis-glow border-t-rubis"
              aria-label="Chargement de l'aperçu"
            />
          </div>
        ) : (
          <PdfPlaceholder />
        )}
      </div>
    </div>
  );
}

/**
 * Placeholder utilisé quand aucun PDF n'est dispo (mocks MSW, ou
 * import sans fichier réel). Garde l'identité visuelle.
 */
function PdfPlaceholder() {
  return (
    <div className="p-7">
      <div className="space-y-2.5">
        <div className="h-3 w-1/2 rounded-sharp bg-ink/15" />
        <div className="h-3 w-1/3 rounded-sharp bg-ink/8" />
      </div>
      <div className="mt-7 space-y-2">
        <div className="h-2.5 w-3/4 rounded-sharp bg-ink/10" />
        <div className="h-2.5 w-2/3 rounded-sharp bg-ink/10" />
        <div className="h-2.5 w-1/2 rounded-sharp bg-ink/10" />
      </div>
      <div className="mt-9 grid grid-cols-2 gap-3">
        <div className="h-7 rounded-sharp bg-rubis-glow/70" />
        <div className="h-7 rounded-sharp bg-rubis-glow/70" />
      </div>
      <div className="mt-3 grid grid-cols-2 gap-3">
        <div className="h-7 rounded-sharp bg-cream-2" />
        <div className="h-7 rounded-sharp bg-cream-2" />
      </div>
      <div className="mt-9 space-y-2">
        <div className="h-2.5 w-2/3 rounded-sharp bg-ink/10" />
        <div className="h-2.5 w-1/2 rounded-sharp bg-ink/10" />
      </div>
      <p className="mt-7 text-[11px] italic text-ink-3 text-center">
        Aperçu non disponible pour cette source.
      </p>
    </div>
  );
}