import { desc, eq, asc, and, isNotNull, ne, gte, inArray, or } from "drizzle-orm";
import type { BunRequest } from "bun";

import _logger from "@/utils/logging";
import config, { isProd } from "@/config";
import { db, tickets, ticketMessages, moderators, sessions, attachments } from "@/database";
import { getUser, getUsers, hydrateTickets } from "./discord";
import { intoApiAttachment } from "./api";

import type {
	TicketResponse,
	TicketsResponse,
	MeResponse,
	ModeratorsResponse,
	OverallStatsResponse,
	LeaderboardResponse,
	Message,
	User,
	Statistic,
} from "@stealth-developers/api";

const logger = _logger.child({ name: "server" });

const CLIENT_ID = config.discord.app_id;
const CLIENT_SECRET = config.discord.client_secret;

const HOST = isProd ? "https://tickets.vt3e.cat" : "http://127.0.0.1:3000";
const REDIRECT_URI = `${HOST}/auth/callback`;
const FRONTEND_URL = isProd ? HOST : "http://127.0.0.1:5173";

async function authenticate(req: BunRequest) {
	const cookieHeader = req.headers.get("Cookie");
	if (!cookieHeader) return { user: null, isMod: false };

	const sessionCookie = cookieHeader.split("; ").find((c) => c.startsWith("session="));
	if (!sessionCookie) return { user: null, isMod: false };

	const sessionId = sessionCookie.split("=")[1];
	const sessionList = await db.select().from(sessions).where(eq(sessions.id, sessionId)).limit(1);
	if (sessionList.length === 0) return { user: null, isMod: false };

	const userId = sessionList[0].userId;
	const modCheck = await db
		.select()
		.from(moderators)
		.where(eq(moderators.user_id, userId))
		.limit(1);

	return {
		user: { id: userId, username: sessionList[0].username },
		isMod: modCheck.length > 0,
	};
}

function calculateStats(durations: number[]): { mean: number; median: number; count: number } {
	if (durations.length === 0) return { mean: 0, median: 0, count: 0 };
	const sum = durations.reduce((a, b) => a + b, 0);
	const sorted = [...durations].sort((a, b) => a - b);
	const mid = Math.floor(sorted.length / 2);

	return {
		mean: sum / durations.length,
		median: sorted.length % 2 !== 0 ? sorted[mid] : (sorted[mid - 1] + sorted[mid]) / 2,
		count: durations.length,
	};
}

const server = Bun.serve({
	hostname: "127.0.0.1",
	port: process.env.PORT || 3000,

	routes: {
		"/api/login": () => {
			const redirectUri = `https://discord.com/oauth2/authorize?client_id=${CLIENT_ID}&response_type=code&redirect_uri=${encodeURIComponent(REDIRECT_URI)}&scope=identify+guilds`;
			return Response.redirect(redirectUri, 302);
		},

		"/auth/callback": {
			GET: async (req: BunRequest) => {
				const url = new URL(req.url);
				const code = url.searchParams.get("code");
				if (!code) return new Response("No code provided", { status: 400 });

				const params = new URLSearchParams({
					client_id: CLIENT_ID,
					client_secret: CLIENT_SECRET,
					grant_type: "authorization_code",
					code,
					redirect_uri: REDIRECT_URI,
				});

				const tokenResponse = await fetch("https://discord.com/api/oauth2/token", {
					method: "POST",
					body: params,
					headers: { "Content-Type": "application/x-www-form-urlencoded" },
				});

				const data = await tokenResponse.json();
				if (data.error) return new Response(data.error_description, { status: 400 });

				const userResponse = await fetch("https://discord.com/api/users/@me", {
					headers: { Authorization: `Bearer ${data.access_token}` },
				});

				const userData = await userResponse.json();
				const sessionId = crypto.randomUUID();

				await db.insert(sessions).values({
					id: sessionId,
					userId: userData.id,
					username: userData.username,
				});

				return new Response(null, {
					status: 302,
					headers: {
						Location: `${FRONTEND_URL}/tickets`,
						"Set-Cookie": `session=${sessionId}; Path=/; HttpOnly; SameSite=Lax`,
					},
				});
			},
		},

		"/api/me": {
			GET: async (req: BunRequest) => {
				const { user, isMod } = await authenticate(req);
				if (!user) return new Response("Unauthorized", { status: 401 });

				const profile = await getUser(user.id);
				if (!profile) return new Response("Profile not found", { status: 404 });

				// Ensures the return strictly conforms to `MeResponse` (alias for User)
				const response: MeResponse = { ...profile, isModerator: isMod };
				return Response.json(response);
			},
		},

		"/api/tickets": {
			GET: async (req: BunRequest) => {
				const { user, isMod } = await authenticate(req);
				if (!user) return Response.redirect("/login", 302);

				const url = new URL(req.url);
				const limit = Number.parseInt(url.searchParams.get("limit") || "20", 10);

				const query = db.select().from(tickets).limit(limit).orderBy(desc(tickets.createdAt));
				const allTickets = isMod ? await query : await query.where(eq(tickets.authorId, user.id));

				const hydratedTickets = await hydrateTickets(allTickets);

				const response: TicketsResponse = { tickets: hydratedTickets };
				return Response.json(response);
			},
		},

		"/api/tickets/:id": {
			GET: async (req: BunRequest) => {
				const { user, isMod } = await authenticate(req);
				if (!user) return Response.redirect("/login", 302);

				const ticketId = Number.parseInt(req.params.id, 10);
				if (isNaN(ticketId)) return new Response("Invalid ID", { status: 400 });

				const ticketList = await db.select().from(tickets).where(eq(tickets.id, ticketId)).limit(1);
				const _ticket = ticketList[0];
				if (!_ticket) return new Response("Ticket not found", { status: 404 });

				if (!isMod && _ticket.authorId !== user.id) {
					return new Response("Forbidden", { status: 403 });
				}

				const messages = await db
					.select()
					.from(ticketMessages)
					.where(eq(ticketMessages.ticketId, ticketId))
					.orderBy(asc(ticketMessages.createdAt));

				const mentionRegex = /<@!?(\d+)>/g;
				const mentionedIds = messages.flatMap((m) =>
					[...m.content.matchAll(mentionRegex)].map((match) => match[1]),
				);

				const idsToFetch = [
					_ticket.authorId,
					_ticket.openedBy,
					_ticket.claimedBy,
					...messages.map((m) => m.authorId),
					...mentionedIds,
				];

				await getUsers(idsToFetch);

				const [hydratedTicket] = await hydrateTickets([_ticket]);
				const messageIds = messages.map((m) => m.id);

				const ticketAttachments = await db
					.select()
					.from(attachments)
					.where(
						or(
							and(eq(attachments.ownerType, "ticket"), eq(attachments.ownerId, ticketId)),
							messageIds.length > 0
								? and(
										eq(attachments.ownerType, "ticket_message"),
										inArray(attachments.ownerId, messageIds),
									)
								: undefined,
						),
					);

				const newMessages: Message[] = await Promise.all(
					messages.map(async (message) => {
						const author = await getUser(message.authorId);
						const _attachments = ticketAttachments.filter(
							(a) => a.ownerType === "ticket_message" && a.ownerId === message.id,
						);

						const mentions: Record<string, User> = {};
						for (const match of message.content.matchAll(mentionRegex)) {
							const id = match[1];
							if (!mentions[id]) {
								const matchedUser = await getUser(id);
								if (matchedUser) mentions[id] = matchedUser;
							}
						}

						return {
							id: message.id,
							messageId: message.messageId,
							createdAt: message.createdAt.toUTCString(),
							updatedAt: message.editedAt ? message.editedAt?.toUTCString() : null,
							deletedAt: message.deletedAt ? message.deletedAt?.toUTCString() : null,
							author: author as User,
							authorType: message.authorType as "user" | "staff" | "system",
							content: message.content,
							attachments: await Promise.all(_attachments.map(intoApiAttachment)),
							mentions: Object.values(mentions),
						};
					}),
				);

				const response: TicketResponse = {
					ticket: hydratedTicket,
					messages: newMessages,
				};

				return Response.json(response);
			},

			DELETE: async (req: BunRequest) => {
				const { user, isMod } = await authenticate(req);
				if (!user) return new Response("Unauthorized", { status: 401 });
				if (!isMod) return new Response("Forbidden", { status: 403 });

				const ticketId = Number.parseInt(req.params.id, 10);
				if (isNaN(ticketId)) return new Response("Invalid ID", { status: 400 });

				const deleted = await db.delete(tickets).where(eq(tickets.id, ticketId)).returning();
				if (deleted.length === 0) return new Response("Ticket not found", { status: 404 });

				return Response.json({ success: true });
			},
		},

		"/api/moderators": {
			GET: async (req: BunRequest) => {
				const { user, isMod } = await authenticate(req);
				if (!user) return new Response("Unauthorized", { status: 401 });
				if (!isMod) return new Response("Forbidden", { status: 403 });

				const mods = await db.select().from(moderators);
				await getUsers(mods.map((mod) => mod.user_id));

				const response: ModeratorsResponse = await Promise.all(
					mods.map(async (mod) => (await getUser(mod.user_id)) as User),
				);

				return Response.json(response);
			},
		},

		"/api/stats/overall": {
			GET: async (req: BunRequest) => {
				const url = new URL(req.url);
				const days = Number.parseInt(url.searchParams.get("days") || "0", 10);
				const guildId = url.searchParams.get("guildId");
				const cutoffDate = days ? new Date(Date.now() - days * 86400000) : null;

				const closedTickets = await db
					.select()
					.from(tickets)
					.where(
						and(
							isNotNull(tickets.closedAt),
							isNotNull(tickets.closedBy),
							ne(tickets.closedBy, "reporter"),
							ne(tickets.closedBy, "system"),
							guildId ? eq(tickets.guildId, guildId) : undefined,
							cutoffDate ? gte(tickets.closedAt, cutoffDate) : undefined,
						),
					);

				const allDurations = closedTickets.map(
					(t) => t.closedAt!.getTime() - t.createdAt.getTime(),
				);
				const hourlyDurations = new Map<number, number[]>();

				for (const t of closedTickets) {
					const hour = t.closedAt!.getHours();
					if (!hourlyDurations.has(hour)) hourlyDurations.set(hour, []);
					hourlyDurations.get(hour)!.push(t.closedAt!.getTime() - t.createdAt.getTime());
				}

				const response: OverallStatsResponse = {
					global: calculateStats(allDurations),
					hourly: Array.from(
						{ length: 24 },
						(_, hour) =>
							({
								hour,
								...calculateStats(hourlyDurations.get(hour) || []),
							}) as Statistic & { hour: number },
					).filter((h) => h.count > 0),
				};

				return Response.json(response);
			},
		},

		"/api/stats/leaderboard": {
			GET: async (req: BunRequest) => {
				const url = new URL(req.url);
				const days = Number.parseInt(url.searchParams.get("days") || "0", 10);
				const guildId = url.searchParams.get("guildId");
				const orderBy = url.searchParams.get("order_by") || "median";
				const cutoffDate = days ? new Date(Date.now() - days * 86400000) : null;

				const closedTickets = await db
					.select()
					.from(tickets)
					.where(
						and(
							isNotNull(tickets.closedAt),
							isNotNull(tickets.closedBy),
							ne(tickets.closedBy, "reporter"),
							ne(tickets.closedBy, "system"),
							guildId ? eq(tickets.guildId, guildId) : undefined,
							cutoffDate ? gte(tickets.closedAt, cutoffDate) : undefined,
						),
					);

				const modDurations = new Map<string, number[]>();
				for (const t of closedTickets) {
					const modId = t.closedBy!;
					if (!modDurations.has(modId)) modDurations.set(modId, []);
					modDurations.get(modId)!.push(t.closedAt!.getTime() - t.createdAt.getTime());
				}

				const modStats = Array.from(modDurations.entries()).map(([modId, durations]) => ({
					modId,
					...calculateStats(durations),
				}));

				if (orderBy === "mean") modStats.sort((a, b) => a.mean - b.mean);
				else if (orderBy === "count") modStats.sort((a, b) => b.count - a.count);
				else modStats.sort((a, b) => a.median - b.median);

				await getUsers(modStats.map((m) => m.modId));

				const response: LeaderboardResponse = await Promise.all(
					modStats.map(async (mod, i) => ({
						rank: i + 1,
						user: (await getUser(mod.modId)) as User,
						mean: mod.mean,
						median: mod.median,
						count: mod.count,
					})),
				);

				return Response.json(response);
			},
		},

		"/api/*": () => new Response(null, { status: 404 }),

		"/*": async (request: BunRequest) => {
			const { pathname } = new URL(request.url);

			const file = Bun.file(`../frontend/dist/${pathname}`);
			if (await file.exists()) return new Response(file);

			return new Response(Bun.file(`../frontend/dist/index.html`));
		},
	},
});

logger.info(`server is running at ${server.hostname}:${server.port}`);