import React, { useState, useEffect } from 'react';
import { Link } from 'react-router-dom';
import { Helmet } from 'react-helmet';
import localForage from 'localforage';
import { sourceLink, infoLine, logos } from './utils.js';

function Feed({ updateCache }) {
	const [stories, setStories] = useState(() => JSON.parse(localStorage.getItem('stories')) || false);
	const [error, setError] = useState('');

	useEffect(() => {
		fetch('/api')
			.then(res => {
				if (!res.ok) {
					throw new Error(`Server responded with ${res.status} ${res.statusText}`);
				}
				return res.json();
			})
			.then(
				async (result) => {
					const newApiStories = result.stories;

					const updated = !stories || !stories.length || stories[0].id !== newApiStories[0].id;
					console.log('New stories available:', updated);

					if (!updated) return;

					if (!stories || !stories.length) {
						setStories(newApiStories);
						localStorage.setItem('stories', JSON.stringify(newApiStories));
					}

					let currentStories = Array.isArray(stories) ? [...stories] : [];

					for (const newStory of [...newApiStories].reverse()) {
						try {
							const controller = new AbortController();
							const timeoutId = setTimeout(() => controller.abort(), 10000); // 10-second timeout
							const storyRes = await fetch('/api/' + newStory.id, { signal: controller.signal });
							clearTimeout(timeoutId);

							if (!storyRes.ok) throw new Error('Story fetch failed');
							const storyResult = await storyRes.json();
							const fullStory = storyResult.story;

							await localForage.setItem(fullStory.id, fullStory);
							console.log('Preloaded story:', fullStory.id, fullStory.title);
							updateCache(fullStory.id, fullStory);

							const existingStoryIndex = currentStories.findIndex(s => s.id === newStory.id);
							if (existingStoryIndex > -1) {
								currentStories.splice(existingStoryIndex, 1);
							}
							currentStories.unshift(newStory);
						} catch (error) {
							let errorMessage;
							if (error.name === 'AbortError') {
								errorMessage = `The request to fetch story '${newStory.title}' (${newStory.id}) timed out after 10 seconds. Your connection may be unstable.`;
								console.log('Fetch timed out for story:', newStory.id);
							} else {
								errorMessage = `An error occurred while fetching story '${newStory.title}' (${newStory.id}): ${error.toString()}`;
								console.log('Fetch failed for story:', newStory.id, error);
							}
							setError(errorMessage);
							break;
						}
					}

					const finalStories = currentStories.slice(0, newApiStories.length);
					const removedStories = currentStories.slice(newApiStories.length);
					for (const story of removedStories) {
						console.log('Removed story:', story.id, story.title);
						localForage.removeItem(story.id);
					}

					localStorage.setItem('stories', JSON.stringify(finalStories));
					setStories(finalStories);
				},
				(error) => {
					const errorMessage = `Failed to fetch the main story list from the API. Your connection may be down or the server might be experiencing issues. Error: ${error.toString()}`;
					setError(errorMessage);
				}
			);
	}, [updateCache]);

	return (
		<div className='container'>
			<Helmet>
				<title>QotNews</title>
				<meta name="robots" content="index" />
			</Helmet>
			{error &&
				<details>
					<summary>Connection error? Click to expand.</summary>
					<p>{error}</p>
				</details>
			}
			{stories ?
				<div>
					{stories.map(x =>
						<div className='item' key={x.id}>
							<div className='title'>
								<Link className='link' to={'/' + x.id}>
									<img className='source-logo' src={logos[x.source]} alt='source logo' /> {x.title}
								</Link>

								<span className='source'>
									({sourceLink(x)})
								</span>
							</div>

							{infoLine(x)}
						</div>
					)}
				</div>
			:
				<p>loading...</p>
			}
		</div>
	);
}

export default Feed;