import { getExaApiKey } from "./config.ts";

const EXA_SEARCH_URL = "https://api.exa.ai/search";
const REQUEST_TIMEOUT_MS = 60_000;

export interface ExaSearchOptions {
	numResults?: number;
	recencyFilter?: "day" | "week" | "month" | "year";
	domainFilter?: string[];
	signal?: AbortSignal;
}

export interface ExaResult {
	title: string;
	url: string;
	text: string;
	publishedDate?: string;
}

export interface ExaResponse {
	query: string;
	results: ExaResult[];
}

interface ExaApiResponse {
	results?: Array<{
		title?: string;
		url?: string;
		text?: string;
		publishedDate?: string;
		highlights?: unknown;
	}>;
}

function recencyToStartDate(filter: NonNullable<ExaSearchOptions["recencyFilter"]>): string {
	const days = { day: 1, week: 7, month: 30, year: 365 }[filter];
	return new Date(Date.now() - days * 86_400_000).toISOString();
}

function mapDomainFilter(domainFilter?: string[]): {
	includeDomains?: string[];
	excludeDomains?: string[];
} {
	if (!domainFilter?.length) return {};
	const include = domainFilter.filter((d) => !d.startsWith("-") && d.trim()).map((d) => d.trim());
	const exclude = domainFilter
		.filter((d) => d.startsWith("-"))
		.map((d) => d.slice(1).trim())
		.filter(Boolean);
	return {
		...(include.length ? { includeDomains: include } : {}),
		...(exclude.length ? { excludeDomains: exclude } : {}),
	};
}

function normalizeHighlights(value: unknown): string {
	if (!Array.isArray(value)) return "";
	return value.filter((h): h is string => typeof h === "string" && h.trim().length > 0).join(" … ");
}

function requestSignal(signal?: AbortSignal): AbortSignal {
	const timeout = AbortSignal.timeout(REQUEST_TIMEOUT_MS);
	return signal ? AbortSignal.any([signal, timeout]) : timeout;
}

export async function searchWithExa(
	query: string,
	options: ExaSearchOptions = {},
): Promise<ExaResponse> {
	const apiKey = getExaApiKey();
	if (!apiKey) {
		throw new Error(
			"No Exa API key. Set EXA_API_KEY or add \"exaApiKey\" to ~/.pi/web-tools.json (get one at https://exa.ai).",
		);
	}

	const startDate = options.recencyFilter ? recencyToStartDate(options.recencyFilter) : null;
	const response = await fetch(EXA_SEARCH_URL, {
		method: "POST",
		headers: { "x-api-key": apiKey, "Content-Type": "application/json" },
		body: JSON.stringify({
			query,
			type: "auto",
			numResults: options.numResults ?? 5,
			...mapDomainFilter(options.domainFilter),
			...(startDate ? { startPublishedDate: startDate } : {}),
			contents: {
				text: { maxCharacters: 2000 },
				highlights: true,
			},
		}),
		signal: requestSignal(options.signal),
	});

	if (!response.ok) {
		const body = await response.text();
		throw new Error(`Exa API error ${response.status}: ${body.slice(0, 300)}`);
	}

	const data = (await response.json()) as ExaApiResponse;
	const results: ExaResult[] = (data.results ?? [])
		.filter((r): r is typeof r & { url: string } => typeof r?.url === "string")
		.map((r, i) => ({
			title: r.title || `Source ${i + 1}`,
			url: r.url,
			text: normalizeHighlights(r.highlights) || (typeof r.text === "string" ? r.text.trim() : ""),
			publishedDate: r.publishedDate,
		}));

	return { query, results };
}

/** Format one or more Exa responses as markdown for the tool output. */
export function formatExaResults(responses: ExaResponse[]): string {
	const blocks = responses.map(({ query, results }) => {
		const header = `## Results for "${query}"`;
		if (results.length === 0) return `${header}\n\n_No results._`;
		const items = results.map((r, i) => {
			const date = r.publishedDate ? ` — ${r.publishedDate.slice(0, 10)}` : "";
			const snippet = r.text ? `\n${r.text}` : "";
			return `### ${i + 1}. ${r.title}${date}\n${r.url}${snippet}`;
		});
		return `${header}\n\n${items.join("\n\n")}`;
	});
	return blocks.join("\n\n---\n\n");
}