"use client";

import { useState } from "react";
import { useMutation } from "@tanstack/react-query";
import { api } from "@/lib/api";
import type { DocumentDraft, DraftDocumentRequest } from "@/lib/types";
import { FileText, Loader2, Copy, Check, Download } from "lucide-react";

const TEMPLATES = {
  klageschrift: "Klageschrift",
  klageerwiderung: "Klageerwiderung",
  abmahnung: "Abmahnung",
  schriftsatz: "Schriftsatz",
  berufung: "Berufungsschrift",
  antrag: "Antrag",
  stellungnahme: "Stellungnahme",
  gutachten: "Gutachten",
  vertrag: "Vertrag",
  vollmacht: "Vollmacht",
  upc_claim: "UPC Statement of Claim",
  upc_defence: "UPC Statement of Defence",
  upc_counterclaim: "UPC Counterclaim for Revocation",
  upc_injunction: "UPC Provisional Measures",
} as const;

const LANGUAGES = [
  { value: "de", label: "Deutsch" },
  { value: "en", label: "English" },
  { value: "fr", label: "Francais" },
] as const;

const inputClass =
  "w-full rounded-md border border-neutral-200 bg-white px-3 py-2 text-sm text-neutral-900 outline-none transition-colors focus:border-neutral-400 focus:ring-1 focus:ring-neutral-400";

interface DocumentDrafterProps {
  caseId: string;
}

export function DocumentDrafter({ caseId }: DocumentDrafterProps) {
  const [templateType, setTemplateType] = useState("");
  const [instructions, setInstructions] = useState("");
  const [language, setLanguage] = useState("de");
  const [copied, setCopied] = useState(false);

  const mutation = useMutation({
    mutationFn: (req: DraftDocumentRequest) =>
      api.post<DocumentDraft>("/ai/draft-document", req),
  });

  function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    if (!templateType) return;
    mutation.mutate({
      case_id: caseId,
      template_type: templateType,
      instructions,
      language,
    });
  }

  function handleCopy() {
    if (mutation.data?.content) {
      navigator.clipboard.writeText(mutation.data.content);
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    }
  }

  function handleDownload() {
    if (!mutation.data?.content) return;
    const blob = new Blob([mutation.data.content], { type: "text/plain;charset=utf-8" });
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = `${templateType}_entwurf.txt`;
    a.click();
    URL.revokeObjectURL(url);
  }

  return (
    <div className="space-y-4">
      <form onSubmit={handleSubmit} className="space-y-3">
        <div>
          <label className="mb-1 block text-xs font-medium text-neutral-500">
            Dokumenttyp
          </label>
          <select
            value={templateType}
            onChange={(e) => setTemplateType(e.target.value)}
            className={inputClass}
            disabled={mutation.isPending}
          >
            <option value="">Dokumenttyp waehlen...</option>
            {Object.entries(TEMPLATES).map(([key, label]) => (
              <option key={key} value={key}>
                {label}
              </option>
            ))}
          </select>
        </div>

        <div>
          <label className="mb-1 block text-xs font-medium text-neutral-500">
            Sprache
          </label>
          <select
            value={language}
            onChange={(e) => setLanguage(e.target.value)}
            className={inputClass}
            disabled={mutation.isPending}
          >
            {LANGUAGES.map((lang) => (
              <option key={lang.value} value={lang.value}>
                {lang.label}
              </option>
            ))}
          </select>
        </div>

        <div>
          <label className="mb-1 block text-xs font-medium text-neutral-500">
            Anweisungen (optional)
          </label>
          <textarea
            value={instructions}
            onChange={(e) => setInstructions(e.target.value)}
            placeholder="z.B. 'Fokus auf Patentanspruch 1, besonders die technischen Merkmale...'"
            rows={3}
            className={inputClass}
            disabled={mutation.isPending}
          />
        </div>

        <button
          type="submit"
          disabled={!templateType || mutation.isPending}
          className="inline-flex items-center gap-2 rounded-md bg-neutral-900 px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
        >
          {mutation.isPending ? (
            <>
              <Loader2 className="h-4 w-4 animate-spin" />
              Dokument wird erstellt...
            </>
          ) : (
            <>
              <FileText className="h-4 w-4" />
              KI-Entwurf erstellen
            </>
          )}
        </button>
      </form>

      {mutation.isError && (
        <div className="rounded-md border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
          Fehler beim Erstellen des Entwurfs. Bitte versuchen Sie es erneut.
        </div>
      )}

      {mutation.data && (
        <div className="space-y-3">
          <div className="flex items-center justify-between">
            <h4 className="text-sm font-medium text-neutral-900">
              {mutation.data.title}
            </h4>
            <div className="flex items-center gap-2">
              <button
                onClick={handleCopy}
                className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1.5 text-xs font-medium text-neutral-600 transition-colors hover:bg-neutral-50"
              >
                {copied ? (
                  <>
                    <Check className="h-3.5 w-3.5 text-emerald-500" />
                    Kopiert
                  </>
                ) : (
                  <>
                    <Copy className="h-3.5 w-3.5" />
                    Kopieren
                  </>
                )}
              </button>
              <button
                onClick={handleDownload}
                className="inline-flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1.5 text-xs font-medium text-neutral-600 transition-colors hover:bg-neutral-50"
              >
                <Download className="h-3.5 w-3.5" />
                Download
              </button>
            </div>
          </div>
          <pre className="max-h-[600px] overflow-auto whitespace-pre-wrap rounded-md border border-neutral-200 bg-neutral-50 p-4 text-sm text-neutral-800">
            {mutation.data.content}
          </pre>
        </div>
      )}
    </div>
  );
}