import "server-only";
import { and, eq, gte, inArray } from "drizzle-orm";
import { drizzle } from "drizzle-orm/postgres-js";
import { integer, numeric, pgTable, text } from "drizzle-orm/pg-core";
import postgres from "postgres";
import {
  buildVoiceLeaderboard,
  buildXpLeaderboard,
  type VoiceSourceRow,
} from "@/lib/leaderboard/ranking";

const userLevels = pgTable("user_levels", {
  userId: text("user_id").notNull(),
  username: text("username").notNull(),
  displayName: text("display_name"),
  xp: numeric("xp", { precision: 40, scale: 0 }).notNull(),
  level: integer("level").notNull(),
});

const voiceTime = pgTable("voice_time", {
  userId: text("user_id").notNull(),
  channelId: text("channel_id").notNull(),
  totalSeconds: numeric("total_seconds", { precision: 40, scale: 0 }).notNull(),
});

type LeaderboardClient = ReturnType<typeof postgres>;

const globalForLeaderboard = globalThis as typeof globalThis & {
  erikaLeaderboardReadOnlyClient?: LeaderboardClient;
};

function getLeaderboardDatabase() {
  const connectionString = process.env.LEADERBOARD_DATABASE_URL;
  if (!connectionString) {
    throw new Error("LEADERBOARD_DATABASE_URL is not configured.");
  }

  if (!globalForLeaderboard.erikaLeaderboardReadOnlyClient) {
    globalForLeaderboard.erikaLeaderboardReadOnlyClient = postgres(connectionString, {
      max: 3,
      idle_timeout: 20,
      connect_timeout: 5,
      connection: {
        application_name: "erika-leaderboard",
        default_transaction_read_only: true,
        statement_timeout: 15_000,
      },
    });
  }

  return drizzle(globalForLeaderboard.erikaLeaderboardReadOnlyClient);
}

export async function getXpLeaderboardPage(
  requestedPage: number,
  searchQuery?: string,
) {
  const rows = await getLeaderboardDatabase()
    .select({
      userId: userLevels.userId,
      username: userLevels.username,
      displayName: userLevels.displayName,
      level: userLevels.level,
      totalXp: userLevels.xp,
    })
    .from(userLevels)
    .where(gte(userLevels.level, 1));

  return buildXpLeaderboard(rows, requestedPage, searchQuery);
}

export async function getMemberXpStats(userId: string) {
  const database = getLeaderboardDatabase();
  const [sourceRows, leaderboard] = await Promise.all([
    database
      .select({
        level: userLevels.level,
        totalXp: userLevels.xp,
      })
      .from(userLevels)
      .where(eq(userLevels.userId, userId))
      .limit(1),
    getXpLeaderboardPage(1, userId),
  ]);
  const rankedRow = leaderboard.rows.find((row) => row.userId === userId);
  const sourceRow = sourceRows[0];

  return {
    level: sourceRow?.level ?? 0,
    totalXp: sourceRow?.totalXp ?? "0",
    rank: rankedRow?.rank ?? null,
  };
}

export async function getVoiceLeaderboardPage(
  currentChannelIds: string[],
  requestedPage: number,
  selectedChannelId?: string,
  searchQuery?: string,
) {
  const scopedChannelIds = selectedChannelId
    ? [selectedChannelId]
    : currentChannelIds;

  if (scopedChannelIds.length === 0) {
    return buildVoiceLeaderboard([], currentChannelIds, requestedPage, selectedChannelId, searchQuery);
  }

  const rows: VoiceSourceRow[] = await getLeaderboardDatabase()
    .select({
      userId: voiceTime.userId,
      channelId: voiceTime.channelId,
      totalSeconds: voiceTime.totalSeconds,
      username: userLevels.username,
      displayName: userLevels.displayName,
    })
    .from(voiceTime)
    .leftJoin(userLevels, eq(voiceTime.userId, userLevels.userId))
    .where(
      and(
        inArray(voiceTime.channelId, scopedChannelIds),
        gte(voiceTime.totalSeconds, "0"),
      ),
    );

  return buildVoiceLeaderboard(
    rows,
    currentChannelIds,
    requestedPage,
    selectedChannelId,
    searchQuery,
  );
}

export async function getMemberVoiceStats(
  userId: string,
  currentChannelIds: string[],
) {
  const leaderboard = await getVoiceLeaderboardPage(
    currentChannelIds,
    1,
    undefined,
    userId,
  );
  const rankedRow = leaderboard.rows.find((row) => row.userId === userId);

  return {
    totalSeconds: rankedRow?.totalSeconds ?? "0",
    rank: rankedRow?.rank ?? null,
  };
}