import { useEffect, useMemo, useRef, useState } from 'react';

import { useKeydown } from '../../hooks/use-keydown';
import { useOutsideClick } from '../../hooks/use-outside-click';
import { markdownToHtml } from '../../lib/markdown';
import { Ban, Contact, FileText, X, ArrowRight } from 'lucide-react';
import { Spinner } from '../ReactIcons/Spinner';
import type { RoadmapNodeDetails } from './GenerateRoadmap';
import { isLoggedIn, removeAuthToken } from '../../lib/jwt';
import { cn } from '../../lib/classname';
import { showLoginPopup } from '../../lib/popup';
import { readAIRoadmapContentStream } from '../../lib/ai';

type RoadmapTopicDetailProps = RoadmapNodeDetails & {
  onClose?: () => void;
  roadmapId: string;
  topicLimitUsed: number;
  topicLimit: number;
  onTopicContentGenerateComplete?: () => void;
  onConfigureOpenAI?: () => void;
};

export function RoadmapTopicDetail(props: RoadmapTopicDetailProps) {
  const {
    onClose,
    roadmapId,
    nodeTitle,
    parentTitle,
    topicLimit,
    topicLimitUsed,
    onTopicContentGenerateComplete,
    onConfigureOpenAI,
  } = props;

  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState('');
  const [topicHtml, setTopicHtml] = useState('');
  const [isStreaming, setIsStreaming] = useState(false);

  const topicRef = useRef<HTMLDivElement>(null);

  const abortController = useMemo(() => new AbortController(), []);
  const generateAiRoadmapTopicContent = async () => {
    setIsLoading(true);
    setError('');

    if (!isLoggedIn()) {
      return;
    }

    if (!roadmapId || !nodeTitle) {
      setIsLoading(false);
      setError('Invalid roadmap id or node title');
      return;
    }

    const response = await fetch(
      `${import.meta.env.PUBLIC_API_URL}/v1-generate-ai-roadmap-content/${roadmapId}`,
      {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        credentials: 'include',
        body: JSON.stringify({
          nodeTitle,
          parentTitle,
        }),
        signal: abortController.signal,
      },
    );

    if (!response.ok) {
      const data = await response.json();

      setError(data?.message || 'Something went wrong');
      setIsLoading(false);

      // Logout user if token is invalid
      if (data.status === 401) {
        removeAuthToken();
        window.location.reload();
      }
    }
    const reader = response.body?.getReader();

    if (!reader) {
      setIsLoading(false);
      setError('Something went wrong');
      return;
    }

    setIsLoading(false);
    setIsStreaming(true);
    await readAIRoadmapContentStream(reader, {
      onStream: async (result) => {
        setTopicHtml(markdownToHtml(result, false));
      },
      onStreamEnd(roadmap) {
        setIsStreaming(false);
      },
    });
    onTopicContentGenerateComplete?.();
  };

  // Close the topic detail when user clicks outside the topic detail
  useOutsideClick(topicRef, () => {
    onClose?.();
  });

  useKeydown('Escape', () => {
    onClose?.();
  });

  useEffect(() => {
    if (!topicRef?.current) {
      return;
    }

    topicRef?.current?.focus();
    generateAiRoadmapTopicContent().finally(() => {});

    return () => {
      abortController.abort();
    };
  }, []);

  const hasContent = topicHtml?.length > 0;

  return (
    <div className={'relative z-92'}>
      <div
        ref={topicRef}
        tabIndex={0}
        className="fixed right-0 top-0 z-40 h-screen w-full overflow-y-auto bg-white p-4 focus:outline-0 sm:max-w-[600px] sm:p-6"
      >
        {isLoggedIn() && (
          <div className="flex flex-col items-start gap-2 sm:flex-row">
            <span>
              <span
                className={cn(
                  'mr-0.5 inline-block rounded-xl border px-1.5 text-center text-sm tabular-nums text-gray-800',
                  {
                    'animate-pulse border-zinc-300 bg-zinc-300 text-zinc-300':
                      !topicLimit,
                  },
                )}
              >
                {topicLimitUsed} of {topicLimit}
              </span>{' '}
              topics generated
            </span>
            <button
              className="rounded-xl border border-current px-1.5 py-0.5 text-left text-sm font-medium text-blue-500 sm:text-center"
              onClick={onConfigureOpenAI}
            >
              Need more? <span className="font-semibold">Click here.</span>
            </button>
          </div>
        )}

        {isLoggedIn() && isLoading && (
          <div className="mt-6 flex w-full justify-center">
            <Spinner
              outerFill="#d1d5db"
              className="h-6 w-6 sm:h-12 sm:w-12"
              innerFill="#2563eb"
            />
          </div>
        )}

        {!isLoggedIn() && (
          <div className="flex h-full flex-col items-center justify-center">
            <Contact className="mb-3.5 h-14 w-14 text-gray-200" />
            <h2 className="text-xl font-medium">You must be logged in</h2>
            <p className="text-base text-gray-400">
              Sign up or login to generate topic content.
            </p>
            <button
              className="mt-3.5 w-full max-w-[300px] rounded-md bg-black px-3 py-2 text-base font-medium text-white"
              onClick={showLoginPopup}
            >
              Sign up / Login
            </button>
          </div>
        )}

        {!isLoading && !error && (
          <>
            <div className="mb-2">
              <button
                type="button"
                id="close-topic"
                className="absolute right-2.5 top-2.5 inline-flex items-center rounded-lg bg-transparent p-1.5 text-sm text-gray-400 hover:bg-gray-200 hover:text-gray-900"
                onClick={onClose}
              >
                <X className="h-5 w-5" />
              </button>
            </div>

            {hasContent ? (
              <div className="prose prose-quoteless prose-h1:mb-2.5 prose-h1:mt-7 prose-h2:mb-3 prose-h2:mt-0 prose-h3:mb-[5px] prose-h3:mt-[10px] prose-p:mb-2 prose-p:mt-0 prose-blockquote:font-normal prose-blockquote:not-italic prose-blockquote:text-gray-700 prose-li:m-0 prose-li:mb-0.5">
                <div
                  id="topic-content"
                  dangerouslySetInnerHTML={{ __html: topicHtml }}
                />

                {!isStreaming && (
                  <div className="mt-4">
                    <a
                      href="/ai"
                      className="mb-1 mt-2 inline-flex items-center rounded-md bg-yellow-400 px-3 py-2 text-sm font-medium text-gray-800 no-underline hover:bg-yellow-500"
                    >
                      Dive deeper using AI Tutor
                      <ArrowRight className="ml-2 h-4 w-4" />
                    </a>
                  </div>
                )}
              </div>
            ) : (
              <div className="flex h-[calc(100%-38px)] flex-col items-center justify-center">
                <FileText className="h-16 w-16 text-gray-300" />
                <p className="mt-2 text-lg font-medium text-gray-500">
                  Empty Content
                </p>
              </div>
            )}
          </>
        )}

        {/* Error */}
        {!isLoading && error && (
          <>
            <button
              type="button"
              id="close-topic"
              className="absolute right-2.5 top-2.5 inline-flex items-center rounded-lg bg-transparent p-1.5 text-sm text-gray-400 hover:bg-gray-200 hover:text-gray-900"
              onClick={onClose}
            >
              <X className="h-5 w-5" />
            </button>
            <div className="flex h-full flex-col items-center justify-center">
              <Ban className="h-16 w-16 text-red-500" />
              <p className="mt-2 text-lg font-medium text-red-500">{error}</p>
            </div>
          </>
        )}
      </div>
      <div className="fixed inset-0 z-30 bg-gray-900/50"></div>
    </div>
  );
}
