import type { BobbinContext } from "#lib/api/client.ts";
import { INVALID_HANDLE } from "#lib/api/identity.ts";
import { listIssues } from "#lib/api/issue.ts";
import { listPulls } from "#lib/api/records.ts";
import { searchActorsTypeahead } from "#lib/api/search.ts";
import { didOf } from "#lib/api/syntax.ts";
import { rkeyFromUri } from "#lib/api/uri.ts";
import type { TicketState } from "#lib/components/repo/tickets/TicketStatePill.svelte";
import type { MentionPerson } from "#lib/components/ui/mentionPeople.ts";

export interface UserSuggestion {
	kind: "user";
	key: string;
	did: string;
	handle: string;
	insert: string;
}

export interface TicketSuggestion {
	kind: "ticket";
	key: string;
	isPull: boolean;
	state: TicketState;
	title: string;
	rkey: string;
	createdAt: string;
	insert: string;
}

export type Suggestion = UserSuggestion | TicketSuggestion;

export interface TicketRepo {
	did: string;
	url: string;
}

const SUGGESTION_LIMIT = 8;
const RECOMMENDATION_LIMIT = 5;
const TICKET_FETCH_LIMIT = 100;

export const suggestUsers = async (
	ctx: BobbinContext,
	query: string,
	signal: AbortSignal
): Promise<UserSuggestion[]> => {
	if (query === "") return [];
	const { actors } = await searchActorsTypeahead(
		ctx,
		{ q: query, limit: SUGGESTION_LIMIT },
		{ signal }
	);
	return actors.map((actor) => userSuggestion(actor.did, actor.handle));
};

const userSuggestion = (did: string, handle: string): UserSuggestion => ({
	kind: "user",
	key: did,
	did,
	handle,
	insert: `@${handle} `
});

export const recommendUsers = (
	people: MentionPerson[],
	exclude: string | undefined
): UserSuggestion[] => {
	const seen = new Set(exclude ? [exclude] : []);
	const picked: UserSuggestion[] = [];
	for (const { did, handle } of people) {
		if (!handle || handle === INVALID_HANDLE || seen.has(did)) continue;
		seen.add(did);
		picked.push(userSuggestion(did, handle));
		if (picked.length === RECOMMENDATION_LIMIT) break;
	}
	return picked;
};

export const recommendPeople = async (
	known: MentionPerson[],
	members: () => Promise<MentionPerson[]>,
	exclude: string | undefined
): Promise<UserSuggestion[]> => {
	const participants = recommendUsers(known, exclude);
	if (participants.length >= RECOMMENDATION_LIMIT) return participants;
	const others = await members().catch(() => []);
	return recommendUsers([...known, ...others], exclude);
};

const ticket = (
	repo: TicketRepo,
	isPull: boolean,
	item: { uri: string; state: TicketState; value: { title: { text: string }; createdAt: string } }
): TicketSuggestion => {
	const rkey = rkeyFromUri(item.uri);
	return {
		kind: "ticket",
		key: item.uri,
		isPull,
		state: item.state,
		title: item.value.title.text,
		rkey,
		createdAt: item.value.createdAt,
		insert: `[#${rkey}](${repo.url}/${isPull ? "pulls" : "issues"}/${rkey}) `
	};
};

export const loadTickets = async (
	ctx: BobbinContext,
	repo: TicketRepo
): Promise<TicketSuggestion[]> => {
	const [issues, pulls] = await Promise.all([
		listIssues(ctx, didOf(repo.did), { limit: TICKET_FETCH_LIMIT }),
		listPulls(ctx, repo.did, { limit: TICKET_FETCH_LIMIT })
	]);
	return [
		...issues.items.map((item) => ticket(repo, false, item)),
		...pulls.items.map((item) => ticket(repo, true, item))
	].sort((a, b) => b.createdAt.localeCompare(a.createdAt));
};

export const filterTickets = (tickets: TicketSuggestion[], query: string): TicketSuggestion[] => {
	const needle = query.toLowerCase();
	return tickets
		.filter(
			(ticket) =>
				ticket.rkey.startsWith(needle) || ticket.title.toLowerCase().includes(needle)
		)
		.slice(0, SUGGESTION_LIMIT);
};