import type { Loader } from "astro/loaders";
import { marked } from "marked";
import TurndownService from "turndown";

interface PleromaFeedConfig {
	instanceUrl: string;
	username: string;
	maxPosts?: number;
	accountId?: string; // Optional: if provided, skips account lookup
	allowedTags?: string[]; // Optional: if provided, only posts with these tags are included
}

interface PleromaAccount {
	id: string;
	username: string;
	acct: string;
	display_name: string;
	url: string;
}

interface PleromaMediaAttachment {
	id: string;
	type: "image" | "video" | "gifv" | "audio" | "unknown";
	url: string;
	preview_url: string;
	description?: string;
}

interface PleromaStatus {
	id: string;
	created_at: string;
	content: string;
	url: string;
	reblog: PleromaStatus | null;
	in_reply_to_id: string | null;
	sensitive: boolean;
	media_attachments: PleromaMediaAttachment[];
	visibility: string;
}

/**
 * Parse the Link header to extract the max_id for the next page
 * Link header format: <url?max_id=123>; rel="next", <url?since_id=456>; rel="prev"
 */
function parseNextPageMaxId(linkHeader: string | null): string | null {
	if (!linkHeader) {
		return null;
	}

	// Split by comma to get individual links
	const links = linkHeader.split(",");

	for (const link of links) {
		// Check if this is the "next" rel link
		if (link.includes('rel="next"')) {
			// Extract URL from angle brackets
			const urlMatch = link.match(/<([^>]+)>/);
			if (urlMatch?.[1]) {
				// Parse the URL to extract max_id parameter
				try {
					const url = new URL(urlMatch[1]);
					const maxId = url.searchParams.get("max_id");
					return maxId;
				} catch {}
			}
		}
	}

	return null;
}

async function getAccountId(
	instanceUrl: string,
	username: string,
	logger: any,
): Promise<string | null> {
	try {
		const searchUrl = `${instanceUrl}/api/v1/accounts/search?q=${encodeURIComponent(username)}&limit=1`;
		logger.info(`Looking up account ID for username: ${username}`);

		const controller = new AbortController();
		const timeoutId = setTimeout(() => controller.abort(), 10000);

		const response = await fetch(searchUrl, {
			headers: {
				"User-Agent": "Astro Blog (pleroma-loader)",
			},
			signal: controller.signal,
		});

		clearTimeout(timeoutId);

		if (!response.ok) {
			logger.warn(`Failed to search for account: HTTP ${response.status}`);
			return null;
		}

		const accounts: PleromaAccount[] = await response.json();

		if (accounts.length === 0 || !accounts[0]) {
			logger.warn(`No account found for username: ${username}`);
			return null;
		}

		const account = accounts[0];
		logger.info(`Found account ID: ${account.id} for @${account.acct}`);
		return account.id;
	} catch (error) {
		logger.warn(`Failed to lookup account ID: ${error}`);
		return null;
	}
}

async function fetchAccountStatuses(
	instanceUrl: string,
	accountId: string,
	maxPosts: number,
	logger: any,
): Promise<PleromaStatus[]> {
	const allStatuses: PleromaStatus[] = [];
	let maxId: string | null = null;
	let pageCount = 0;
	const pageLimit = 40; // Mastodon/Pleroma API max per page
	const fetchAll = maxPosts === -1;

	// Fetch pages until we have enough posts or no more pages available
	while (fetchAll || allStatuses.length < maxPosts) {
		pageCount++;
		let response: Response | undefined;
		let lastError: unknown;

		// Build URL with pagination parameters
		// If fetching all, always use pageLimit; otherwise calculate remaining
		const requestLimit = fetchAll ? pageLimit : Math.min(pageLimit, maxPosts - allStatuses.length);
		const params = new URLSearchParams({
			limit: String(requestLimit),
			exclude_replies: "true",
			exclude_reblogs: "true",
		});

		if (maxId) {
			params.set("max_id", maxId);
		}

		const statusesUrl = `${instanceUrl}/api/v1/accounts/${accountId}/statuses?${params.toString()}`;

		// Add retry logic for network issues
		for (let attempt = 1; attempt <= 3; attempt++) {
			try {
				const modeMsg = fetchAll ? " [fetching all posts]" : ` [target: ${maxPosts}]`;
				logger.info(
					`Attempt ${attempt} to fetch statuses page ${pageCount}${maxId ? ` (max_id: ${maxId})` : ""}${modeMsg}...`,
				);

				// Create timeout controller
				const controller = new AbortController();
				const timeoutId = setTimeout(() => controller.abort(), 10000);

				response = await fetch(statusesUrl, {
					headers: {
						"User-Agent": "Astro Blog (pleroma-loader)",
					},
					signal: controller.signal,
				});

				clearTimeout(timeoutId);

				if (response.ok) {
					break; // Success, exit retry loop
				}
				throw new Error(`HTTP ${response.status}: ${response.statusText}`);
			} catch (error) {
				lastError = error;
				logger.warn(`Attempt ${attempt} failed: ${error}`);

				if (attempt < 3) {
					logger.info("Retrying in 2 seconds...");
					await new Promise((resolve) => setTimeout(resolve, 2000));
				}
			}
		}

		if (!response || !response.ok) {
			throw new Error(`Failed to fetch statuses after 3 attempts. Last error: ${lastError}`);
		}

		const statuses: PleromaStatus[] = await response.json();
		logger.info(`Fetched ${statuses.length} statuses from page ${pageCount}`);

		// If no statuses returned, we've reached the end
		if (statuses.length === 0) {
			logger.info("No more statuses available");
			break;
		}

		// Add statuses to our accumulated list
		allStatuses.push(...statuses);

		// Parse Link header to get next page max_id
		const linkHeader = response.headers.get("link");
		const nextMaxId = parseNextPageMaxId(linkHeader);

		if (!nextMaxId) {
			logger.info("No more pages available (no next link in header)");
			break;
		}

		// If the max_id hasn't changed, we're stuck in a loop - break
		if (nextMaxId === maxId) {
			logger.warn("Pagination returned same max_id, stopping to prevent infinite loop");
			break;
		}

		maxId = nextMaxId;
	}

	const summaryMsg = fetchAll
		? `Total fetched: ${allStatuses.length} statuses (all available) across ${pageCount} page(s)`
		: `Total fetched: ${allStatuses.length} statuses (target: ${maxPosts}) across ${pageCount} page(s)`;
	logger.info(summaryMsg);
	return allStatuses;
}

function isFilteredStatus(status: PleromaStatus): boolean {
	// Filter out boosts/reblogs (already handled by API parameter, but double-check)
	if (status.reblog) {
		return true;
	}

	// Filter out replies (already handled by API parameter, but double-check)
	if (status.in_reply_to_id) {
		return true;
	}

	// Filter out NSFW/sensitive content
	if (status.sensitive) {
		return true;
	}

	return false;
}

function extractHashtags(htmlContent: string): string[] {
	// Extract hashtags from HTML spans and plain text
	const hashtagPattern = /#(\w+)/gi;
	const matches = htmlContent.match(hashtagPattern);
	return matches ? [...new Set(matches.map((tag) => tag.toLowerCase()))] : [];
}

function hasAllowedTag(status: PleromaStatus, allowedTags: string[]): boolean {
	if (!allowedTags || allowedTags.length === 0) {
		return true; // No filtering if no tags specified
	}

	const content = status.content || "";
	const hashtags = extractHashtags(content);
	const normalizedAllowedTags = allowedTags.map((tag) => tag.toLowerCase().replace(/^#/, ""));
	const normalizedHashtags = hashtags.map((tag) => tag.toLowerCase().replace(/^#/, ""));

	return normalizedHashtags.some((tag) => normalizedAllowedTags.includes(tag));
}

function cleanContent(htmlContent: string): string {
	const turndownService = new TurndownService({
		headingStyle: "atx",
		codeBlockStyle: "fenced",
	});

	// Remove or replace common Pleroma/Mastodon elements
	const cleanedContent = htmlContent
		.replace(/<span class="[^"]*mention[^"]*"[^>]*>/gi, "") // Remove mention spans but keep content
		.replace(/<\/span>/gi, "")
		.replace(/<span class="[^"]*hashtag[^"]*"[^>]*>/gi, "") // Remove hashtag spans but keep content
		.replace(/<span class="[^"]*ellipsis[^"]*"[^>]*>.*?<\/span>/gi, "") // Remove ellipsis
		.replace(/<span class="[^"]*invisible[^"]*"[^>]*>.*?<\/span>/gi, ""); // Remove invisible text

	// Convert to markdown
	const markdown = turndownService.turndown(cleanedContent);

	// Clean up extra whitespace
	return markdown.trim().replace(/\n\s*\n\s*\n/g, "\n\n");
}

function markdownToHtml(markdown: string): string {
	// Configure marked options for safe rendering
	marked.setOptions({
		breaks: true, // Convert line breaks to <br>
		gfm: true, // GitHub flavored markdown
	});

	// Convert markdown to HTML
	const html = marked.parse(markdown);

	// Return as string (marked.parse can return string or Promise<string>)
	return typeof html === "string" ? html : "";
}

function extractTitle(content: string): string {
	// Extract first line or first sentence as title
	const firstLine = content.split("\n")[0];
	if (!firstLine) return "Micro post";

	const firstSentence = firstLine.split(/[.!?]/)[0];
	if (!firstSentence) return "Micro post";

	// Limit title length and clean it up
	const title = (firstSentence.length > 60 ? `${firstSentence.substring(0, 57)}...` : firstSentence)
		.replace(/[#*_`]/g, "") // Remove markdown formatting
		.trim();

	return title || "Micro post";
}

export function pleromaLoader(config: PleromaFeedConfig): Loader {
	return {
		name: "pleroma-loader",
		load: async ({ store, logger }) => {
			try {
				const { instanceUrl, username, maxPosts = 20, accountId: configAccountId } = config;

				logger.info(`Fetching Pleroma posts via API for user: ${username}`);

				// Get account ID (use provided one or lookup by username)
				let accountId: string | undefined = configAccountId;
				if (!accountId) {
					const lookedUpAccountId = await getAccountId(instanceUrl, username, logger);
					if (!lookedUpAccountId) {
						logger.warn("Failed to get account ID. Continuing without Pleroma posts...");
						store.clear();
						return;
					}
					accountId = lookedUpAccountId;
				}

				// Fetch statuses from API
				const statuses = await fetchAccountStatuses(instanceUrl, accountId, maxPosts, logger);
				logger.info(`Fetched ${statuses.length} statuses from API`);

				// Filter statuses
				const validStatuses = statuses.filter((status) => {
					if (isFilteredStatus(status)) return false;
					if (config.allowedTags && !hasAllowedTag(status, config.allowedTags)) return false;
					return true;
				});
				logger.info(`After filtering: ${validStatuses.length} valid posts`);

				// Clear existing entries
				store.clear();

				// Process each status
				for (const status of validStatuses) {
					try {
						const content = status.content || "";
						const cleanedContent = cleanContent(content);
						const title = extractTitle(cleanedContent);

						// Extract post ID from status
						const postId = status.id;

						// Use status URL as source
						const sourceUrl = status.url;

						// Extract image attachments only
						const attachments = status.media_attachments
							.filter((attachment) => attachment.type === "image")
							.map((attachment) => ({
								url: attachment.url,
								type: `image/${attachment.url.split(".").pop() || "jpeg"}`,
							}));

						// Create note entry
						store.set({
							id: `pleroma-${postId}`,
							data: {
								title,
								description:
									cleanedContent.substring(0, 160) + (cleanedContent.length > 160 ? "..." : ""),
								publishDate: new Date(status.created_at),
								sourceUrl,
								attachments,
							},
							body: cleanedContent,
							rendered: {
								html: markdownToHtml(cleanedContent),
							},
						});

						logger.info(`Processed post: ${title.substring(0, 50)}...`);
					} catch (error) {
						logger.warn(`Failed to process status ${status.id}: ${error}`);
					}
				}

				logger.info(`Successfully loaded ${validStatuses.length} Pleroma posts`);
			} catch (error) {
				logger.warn(`Pleroma loader failed: ${error}`);
				logger.info("Continuing build without Pleroma posts...");
				// Don't throw error to prevent build failure
				store.clear();
			}
		},
	};
}