"use client";

import { useQuery, useMutation } from "@tanstack/react-query";
import { useParams } from "next/navigation";
import { api } from "@/lib/api";
import type { DocumentTemplate, Case, RenderResponse } from "@/lib/types";
import { Breadcrumb } from "@/components/layout/Breadcrumb";
import {
  Loader2,
  FileDown,
  Copy,
  Check,
} from "lucide-react";
import { useState } from "react";
import { toast } from "sonner";

export default function RenderTemplatePage() {
  const { id } = useParams<{ id: string }>();
  const [selectedCaseId, setSelectedCaseId] = useState("");
  const [rendered, setRendered] = useState<RenderResponse | null>(null);
  const [copied, setCopied] = useState(false);

  const { data: template, isLoading: templateLoading } = useQuery({
    queryKey: ["template", id],
    queryFn: () => api.get<DocumentTemplate>(`/templates/${id}`),
  });

  const { data: casesData, isLoading: casesLoading } = useQuery({
    queryKey: ["cases"],
    queryFn: () =>
      api.get<{ data: Case[]; total: number }>("/cases?limit=100"),
  });

  const cases = casesData?.data ?? [];

  const renderMutation = useMutation({
    mutationFn: () =>
      api.post<RenderResponse>(
        `/templates/${id}/render${selectedCaseId ? `?case_id=${selectedCaseId}` : ""}`,
      ),
    onSuccess: (data) => setRendered(data),
    onError: () => toast.error("Fehler beim Erstellen"),
  });

  const handleCopy = async () => {
    if (!rendered) return;
    await navigator.clipboard.writeText(rendered.content);
    setCopied(true);
    toast.success("In Zwischenablage kopiert");
    setTimeout(() => setCopied(false), 2000);
  };

  const handleDownload = () => {
    if (!rendered) return;
    const blob = new Blob([rendered.content], { type: "text/markdown" });
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = `${rendered.name.replace(/\s+/g, "_")}.md`;
    a.click();
    URL.revokeObjectURL(url);
    toast.success("Dokument heruntergeladen");
  };

  if (templateLoading) {
    return (
      <div className="flex items-center justify-center py-12">
        <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
      </div>
    );
  }

  if (!template) {
    return (
      <div className="py-12 text-center text-sm text-neutral-500">
        Vorlage nicht gefunden
      </div>
    );
  }

  return (
    <div className="animate-fade-in space-y-4">
      <Breadcrumb
        items={[
          { label: "Dashboard", href: "/dashboard" },
          { label: "Vorlagen", href: "/vorlagen" },
          { label: template.name, href: `/vorlagen/${id}` },
          { label: "Dokument erstellen" },
        ]}
      />

      <h1 className="text-lg font-semibold text-neutral-900">
        Dokument erstellen
      </h1>
      <p className="text-sm text-neutral-500">
        Vorlage &ldquo;{template.name}&rdquo; mit Falldaten befüllen
      </p>

      {/* Step 1: Select case */}
      <div className="rounded-lg border border-neutral-200 bg-white p-4">
        <h3 className="mb-3 text-sm font-medium text-neutral-700">
          1. Akte auswählen
        </h3>
        {casesLoading ? (
          <Loader2 className="h-4 w-4 animate-spin text-neutral-400" />
        ) : (
          <select
            value={selectedCaseId}
            onChange={(e) => {
              setSelectedCaseId(e.target.value);
              setRendered(null);
            }}
            className="w-full rounded-md border border-neutral-200 px-3 py-2 text-sm text-neutral-700 focus:border-neutral-400 focus:outline-none"
          >
            <option value="">Ohne Akte (nur Datumsvariablen)</option>
            {cases.map((c) => (
              <option key={c.id} value={c.id}>
                {c.case_number} — {c.title}
              </option>
            ))}
          </select>
        )}
      </div>

      {/* Step 2: Render */}
      <div className="rounded-lg border border-neutral-200 bg-white p-4">
        <div className="flex items-center justify-between">
          <h3 className="text-sm font-medium text-neutral-700">
            2. Vorschau erstellen
          </h3>
          <button
            onClick={() => renderMutation.mutate()}
            disabled={renderMutation.isPending}
            className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
          >
            {renderMutation.isPending ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <FileDown className="h-3.5 w-3.5" />
            )}
            Vorschau
          </button>
        </div>

        {rendered && (
          <div className="mt-4">
            <div className="mb-2 flex items-center justify-end gap-2">
              <button
                onClick={handleCopy}
                className="flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1 text-xs text-neutral-600 transition-colors hover:bg-neutral-50"
              >
                {copied ? (
                  <Check className="h-3 w-3" />
                ) : (
                  <Copy className="h-3 w-3" />
                )}
                {copied ? "Kopiert" : "Kopieren"}
              </button>
              <button
                onClick={handleDownload}
                className="flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1 text-xs text-neutral-600 transition-colors hover:bg-neutral-50"
              >
                <FileDown className="h-3 w-3" />
                Herunterladen
              </button>
            </div>
            <div className="rounded-lg border border-neutral-200 bg-neutral-50 p-6">
              <div className="whitespace-pre-wrap font-mono text-xs leading-relaxed text-neutral-700">
                {rendered.content}
              </div>
            </div>
          </div>
        )}
      </div>
    </div>
  );
}