import "server-only";

import {
	and,
	count,
	desc,
	eq,
	inArray,
	like,
	ne,
	or,
	type SQL,
} from "drizzle-orm";
import { alias } from "drizzle-orm/mysql-core";
import { calcPagination } from "@/lib/admin-helpers";
import { db, User, WebsiteHelpCenterTickets, WebsiteTicket } from "@/lib/db";
import { formatDate } from "@/lib/format-date";

export type TicketInboxKind = "cms" | "help";
export type TicketInboxTypeFilter = "all" | TicketInboxKind;

export interface TicketInboxRow {
	key: string;
	kind: TicketInboxKind;
	id: string;
	title: string;
	user: string;
	userId: number | null;
	status: string;
	open: boolean;
	sortAt: number;
	date: string;
	href: string;
}

export interface FetchTicketInboxOptions {
	page: number;
	perPage: number;
	search?: string;
	type?: TicketInboxTypeFilter;
	/** Default true: only non-closed CMS + open help-center. */
	openOnly?: boolean;
	base?: "admin" | "mod";
}

function toSortMs(value: Date | string | null | undefined): number {
	if (!value) return 0;
	const ms =
		value instanceof Date ? value.getTime() : Date.parse(String(value));
	return Number.isFinite(ms) ? ms : 0;
}

async function fetchCmsCandidates(
	limit: number,
	search: string,
	openOnly: boolean,
	base: "admin" | "mod",
): Promise<TicketInboxRow[]> {
	const Creator = alias(User, "inbox_ticket_creator");
	const conditions: SQL[] = [];

	if (openOnly) {
		conditions.push(ne(WebsiteTicket.status, "closed"));
	}

	if (search) {
		const asId = Number(search);
		const searchOr = [
			like(WebsiteTicket.subject, `%${search}%`),
			like(WebsiteTicket.category, `%${search}%`),
			like(Creator.username, `%${search}%`),
			...(Number.isFinite(asId) && asId > 0
				? [eq(WebsiteTicket.id, asId)]
				: []),
		];
		const searchFilter = or(...searchOr);
		if (searchFilter) conditions.push(searchFilter);
	}

	const where = conditions.length > 0 ? and(...conditions) : undefined;

	const rows = await db
		.select({
			id: WebsiteTicket.id,
			subject: WebsiteTicket.subject,
			status: WebsiteTicket.status,
			creatorId: WebsiteTicket.creatorId,
			updatedAt: WebsiteTicket.updatedAt,
			createdAt: WebsiteTicket.createdAt,
			creatorUsername: Creator.username,
		})
		.from(WebsiteTicket)
		.leftJoin(Creator, eq(WebsiteTicket.creatorId, Creator.id))
		.where(where)
		.orderBy(desc(WebsiteTicket.updatedAt), desc(WebsiteTicket.id))
		.limit(limit)
		.catch(() => []);

	const prefix = base === "mod" ? "/mod/tickets" : "/admin/tickets";

	return rows.map((row) => ({
		key: `cms-${row.id}`,
		kind: "cms" as const,
		id: String(row.id),
		title: row.subject,
		user: row.creatorUsername ?? "—",
		userId: row.creatorId,
		status: row.status,
		open: row.status !== "closed",
		sortAt: toSortMs(row.updatedAt ?? row.createdAt),
		date: formatDate(row.updatedAt ?? row.createdAt, "date"),
		href: `${prefix}/${row.id}`,
	}));
}

async function fetchHelpCandidates(
	limit: number,
	search: string,
	openOnly: boolean,
	base: "admin" | "mod",
): Promise<TicketInboxRow[]> {
	const conditions: SQL[] = [];

	if (openOnly) {
		conditions.push(eq(WebsiteHelpCenterTickets.open, true));
	}

	if (search) {
		const asId = /^\d+$/.test(search) ? BigInt(search) : null;
		const matchingUsers = await db
			.select({ id: User.id })
			.from(User)
			.where(like(User.username, `%${search}%`))
			.limit(50)
			.catch(() => []);

		const searchOr = [
			like(WebsiteHelpCenterTickets.title, `%${search}%`),
			like(WebsiteHelpCenterTickets.content, `%${search}%`),
			...(matchingUsers.length > 0
				? [
						inArray(
							WebsiteHelpCenterTickets.userId,
							matchingUsers.map((u) => u.id),
						),
					]
				: []),
			...(asId !== null ? [eq(WebsiteHelpCenterTickets.id, asId)] : []),
		];
		const searchFilter = or(...searchOr);
		if (searchFilter) conditions.push(searchFilter);
	}

	const where = conditions.length > 0 ? and(...conditions) : undefined;

	const rows = await db
		.select({
			id: WebsiteHelpCenterTickets.id,
			title: WebsiteHelpCenterTickets.title,
			open: WebsiteHelpCenterTickets.open,
			userId: WebsiteHelpCenterTickets.userId,
			updatedAt: WebsiteHelpCenterTickets.updatedAt,
			createdAt: WebsiteHelpCenterTickets.createdAt,
		})
		.from(WebsiteHelpCenterTickets)
		.where(where)
		.orderBy(
			desc(WebsiteHelpCenterTickets.updatedAt),
			desc(WebsiteHelpCenterTickets.id),
		)
		.limit(limit)
		.catch(() => []);

	const userIds = [
		...new Set(
			rows.map((row) => row.userId).filter((id): id is number => id != null),
		),
	];
	const users =
		userIds.length > 0
			? await db
					.select({ id: User.id, username: User.username })
					.from(User)
					.where(inArray(User.id, userIds))
					.catch(() => [])
			: [];
	const usernameById = new Map(users.map((u) => [u.id, u.username]));

	const prefix = base === "mod" ? "/mod/help-tickets" : "/admin/help-tickets";

	return rows.map((row) => ({
		key: `help-${row.id}`,
		kind: "help" as const,
		id: String(row.id),
		title: row.title,
		user:
			row.userId != null
				? (usernameById.get(row.userId) ?? `#${row.userId}`)
				: "—",
		userId: row.userId,
		status: row.open ? "open" : "closed",
		open: row.open,
		sortAt: toSortMs(row.updatedAt ?? row.createdAt),
		date: formatDate(row.updatedAt ?? row.createdAt, "date"),
		href: `${prefix}/${row.id}`,
	}));
}

async function countCms(search: string, openOnly: boolean): Promise<number> {
	const Creator = alias(User, "inbox_ticket_creator_count");
	const conditions: SQL[] = [];
	if (openOnly) conditions.push(ne(WebsiteTicket.status, "closed"));
	if (search) {
		const asId = Number(search);
		const searchFilter = or(
			like(WebsiteTicket.subject, `%${search}%`),
			like(WebsiteTicket.category, `%${search}%`),
			like(Creator.username, `%${search}%`),
			...(Number.isFinite(asId) && asId > 0
				? [eq(WebsiteTicket.id, asId)]
				: []),
		);
		if (searchFilter) conditions.push(searchFilter);
	}
	const where = conditions.length > 0 ? and(...conditions) : undefined;
	const rows = await db
		.select({ total: count() })
		.from(WebsiteTicket)
		.leftJoin(Creator, eq(WebsiteTicket.creatorId, Creator.id))
		.where(where)
		.catch(() => [{ total: 0 }]);
	return Number(rows[0]?.total ?? 0);
}

async function countHelp(search: string, openOnly: boolean): Promise<number> {
	const conditions: SQL[] = [];
	if (openOnly) conditions.push(eq(WebsiteHelpCenterTickets.open, true));
	if (search) {
		const asId = /^\d+$/.test(search) ? BigInt(search) : null;
		const matchingUsers = await db
			.select({ id: User.id })
			.from(User)
			.where(like(User.username, `%${search}%`))
			.limit(50)
			.catch(() => []);
		const searchFilter = or(
			like(WebsiteHelpCenterTickets.title, `%${search}%`),
			like(WebsiteHelpCenterTickets.content, `%${search}%`),
			...(matchingUsers.length > 0
				? [
						inArray(
							WebsiteHelpCenterTickets.userId,
							matchingUsers.map((u) => u.id),
						),
					]
				: []),
			...(asId !== null ? [eq(WebsiteHelpCenterTickets.id, asId)] : []),
		);
		if (searchFilter) conditions.push(searchFilter);
	}
	const where = conditions.length > 0 ? and(...conditions) : undefined;
	const rows = await db
		.select({ total: count() })
		.from(WebsiteHelpCenterTickets)
		.where(where)
		.catch(() => [{ total: 0 }]);
	return Number(rows[0]?.total ?? 0);
}

/** Merged read-model over CMS desk + help-center queues (no DB merge). */
export async function fetchUnifiedTicketInbox(
	options: FetchTicketInboxOptions,
): Promise<{
	rows: TicketInboxRow[];
	total: number;
	page: number;
	perPage: number;
	lastPage: number;
	cmsTotal: number;
	helpTotal: number;
}> {
	const type = options.type ?? "all";
	const openOnly = options.openOnly !== false;
	const search = options.search?.trim() ?? "";
	const base = options.base ?? "admin";

	const includeCms = type === "all" || type === "cms";
	const includeHelp = type === "all" || type === "help";

	const [cmsTotal, helpTotal] = await Promise.all([
		includeCms ? countCms(search, openOnly) : Promise.resolve(0),
		includeHelp ? countHelp(search, openOnly) : Promise.resolve(0),
	]);

	const total = cmsTotal + helpTotal;
	const pagination = calcPagination(total, options.page, options.perPage);
	const window = pagination.offset + pagination.perPage;

	const [cmsRows, helpRows] = await Promise.all([
		includeCms
			? fetchCmsCandidates(window, search, openOnly, base)
			: Promise.resolve([]),
		includeHelp
			? fetchHelpCandidates(window, search, openOnly, base)
			: Promise.resolve([]),
	]);

	const merged = [...cmsRows, ...helpRows].sort((a, b) => {
		if (b.sortAt !== a.sortAt) return b.sortAt - a.sortAt;
		return a.key < b.key ? 1 : -1;
	});

	const rows = merged.slice(
		pagination.offset,
		pagination.offset + pagination.perPage,
	);

	return {
		rows,
		total,
		page: pagination.page,
		perPage: pagination.perPage,
		lastPage: pagination.lastPage,
		cmsTotal,
		helpTotal,
	};
}