import { DynamicBorder, type ExtensionAPI, type ExtensionContext } from "@mariozechner/pi-coding-agent";
import { Container, Text } from "@mariozechner/pi-tui";

type PromptMatch = {
	kind: "pr" | "issue" | "forum";
	url: string;
	forumId?: string;
};

type GhMetadata = {
	title?: string;
	author?: {
		login?: string;
		name?: string | null;
	};
};

const URL_PATTERNS: { kind: PromptMatch["kind"]; pattern: RegExp }[] = [
	{ kind: "pr", pattern: /https?:\/\/github\.com\/[^\s/]+\/[^\s/]+\/pull\/\d+[^\s]*/gi },
	{ kind: "issue", pattern: /https?:\/\/github\.com\/[^\s/]+\/[^\s/]+\/issues\/\d+[^\s]*/gi },
	{ kind: "forum", pattern: /https?:\/\/(?:www\.)?esotericsoftware\.com\/forum\/d\/(\d+)[^\s]*/gi },
];

function extractPromptMatch(prompt: string): PromptMatch | undefined {
	let last: PromptMatch | undefined;

	for (const { kind, pattern } of URL_PATTERNS) {
		pattern.lastIndex = 0;
		let m;
		while ((m = pattern.exec(prompt)) !== null) {
			const url = m[0].trim();
			const forumId = kind === "forum" ? m[1] : undefined;
			last = { kind, url, forumId };
		}
	}

	return last;
}

async function fetchForumMetadata(forumId: string): Promise<{ title?: string } | undefined> {
	try {
		const res = await fetch(`https://esotericsoftware.com/forum/api/discussions/${forumId}`);
		if (!res.ok) return undefined;
		const data = (await res.json()) as { data?: { attributes?: { title?: string } } };
		return { title: data?.data?.attributes?.title };
	} catch {
		return undefined;
	}
}

async function fetchGhMetadata(
	pi: ExtensionAPI,
	kind: PromptMatch["kind"],
	url: string,
): Promise<GhMetadata | undefined> {
	const args =
		kind === "pr" ? ["pr", "view", url, "--json", "title,author"] : ["issue", "view", url, "--json", "title,author"];

	try {
		const result = await pi.exec("gh", args);
		if (result.code !== 0 || !result.stdout) return undefined;
		return JSON.parse(result.stdout) as GhMetadata;
	} catch {
		return undefined;
	}
}

function formatAuthor(author?: GhMetadata["author"]): string | undefined {
	if (!author) return undefined;
	const name = author.name?.trim();
	const login = author.login?.trim();
	if (name && login) return `${name} (@${login})`;
	if (login) return `@${login}`;
	if (name) return name;
	return undefined;
}

export default function promptUrlWidgetExtension(pi: ExtensionAPI) {
	const setWidget = (ctx: ExtensionContext, match: PromptMatch, title?: string, authorText?: string) => {
		ctx.ui.setWidget("prompt-url", (_tui, thm) => {
			const titleText = title ? thm.fg("accent", title) : thm.fg("accent", match.url);
			const authorLine = authorText ? thm.fg("muted", authorText) : undefined;
			const urlLine = thm.fg("dim", match.url);

			const lines = [titleText];
			if (authorLine) lines.push(authorLine);
			lines.push(urlLine);

			const container = new Container();
			container.addChild(new DynamicBorder((s: string) => thm.fg("muted", s)));
			container.addChild(new Text(lines.join("\n"), 1, 0));
			return container;
		});
	};

	const fetchMetadata = async (
		api: ExtensionAPI,
		match: PromptMatch,
	): Promise<{ title?: string; authorText?: string }> => {
		if (match.kind === "forum" && match.forumId) {
			const meta = await fetchForumMetadata(match.forumId);
			return { title: meta?.title?.trim() };
		}
		const meta = await fetchGhMetadata(api, match.kind as "pr" | "issue", match.url);
		return { title: meta?.title?.trim(), authorText: formatAuthor(meta?.author) };
	};

	const applySessionName = (ctx: ExtensionContext, match: PromptMatch, title?: string) => {
		const label = match.kind === "pr" ? "PR" : match.kind === "issue" ? "Issue" : "Forum";
		const trimmedTitle = title?.trim();
		const fallbackName = `${label}: ${match.url}`;
		const desiredName = trimmedTitle ? `${label}: ${trimmedTitle} (${match.url})` : fallbackName;
		const currentName = pi.getSessionName()?.trim();
		if (!currentName) {
			pi.setSessionName(desiredName);
			return;
		}
		if (currentName === match.url || currentName === fallbackName) {
			pi.setSessionName(desiredName);
		}
	};

	pi.on("before_agent_start", async (event, ctx) => {
		if (!ctx.hasUI) return;
		const match = extractPromptMatch(event.prompt);
		if (!match) {
			return;
		}

		setWidget(ctx, match);
		applySessionName(ctx, match);
		void fetchMetadata(pi, match).then(({ title, authorText }) => {
			setWidget(ctx, match, title, authorText);
			applySessionName(ctx, match, title);
		});
	});

	pi.on("session_switch", async (_event, ctx) => {
		rebuildFromSession(ctx);
	});

	const getUserText = (content: string | { type: string; text?: string }[] | undefined): string => {
		if (!content) return "";
		if (typeof content === "string") return content;
		return (
			content
				.filter((block): block is { type: "text"; text: string } => block.type === "text")
				.map((block) => block.text)
				.join("\n") ?? ""
		);
	};

	const rebuildFromSession = (ctx: ExtensionContext) => {
		if (!ctx.hasUI) return;

		const entries = ctx.sessionManager.getEntries();
		const lastMatch = [...entries].reverse().find((entry) => {
			if (entry.type !== "message" || entry.message.role !== "user") return false;
			const text = getUserText(entry.message.content);
			return !!extractPromptMatch(text);
		});

		const content =
			lastMatch?.type === "message" && lastMatch.message.role === "user" ? lastMatch.message.content : undefined;
		const text = getUserText(content);
		const match = text ? extractPromptMatch(text) : undefined;
		if (!match) {
			ctx.ui.setWidget("prompt-url", undefined);
			return;
		}

		setWidget(ctx, match);
		applySessionName(ctx, match);
		void fetchMetadata(pi, match).then(({ title, authorText }) => {
			setWidget(ctx, match, title, authorText);
			applySessionName(ctx, match, title);
		});
	};

	pi.on("session_start", async (_event, ctx) => {
		rebuildFromSession(ctx);
	});
}