import type { database } from "~/database/context";
import * as schema from "~/database/schema";
import { eq, inArray } from "drizzle-orm";
import { findDiscordIdsByUserIds } from "~/models/account";
import { getUserDisplayName } from "~/models/user";
import {
  sendQualifyingPointsUpdateNotification,
  type QPEventEntry,
  type QPEliminatedEntry,
} from "~/services/discord";

export async function notifyQualifyingPointsUpdate(
  sportsSeasonId: string,
  scoringEventId: string,
  db: ReturnType<typeof database>,
  participantIdFilter?: Set<string>,
  /**
   * Participants knocked out this sync in a non-scoring round: they earn no QP,
   * so they never appear via qualifyingPointsAwarded, but a manager who drafted
   * them should still be told their player is out. Surfaced in a "Knocked Out"
   * section, deduped against QP earners.
   */
  eliminatedParticipantIds?: Set<string>
): Promise<void> {
  const event = await db.query.scoringEvents.findFirst({
    where: eq(schema.scoringEvents.id, scoringEventId),
    with: {
      sportsSeason: {
        with: { sport: true },
      },
    },
  });
  if (!event) return;

  const eventName = event.name;
  const sportName = event.sportsSeason?.sport?.name;

  const seasonSports = await db.query.seasonSports.findMany({
    where: eq(schema.seasonSports.sportsSeasonId, sportsSeasonId),
  });
  if (seasonSports.length === 0) return;

  // QP earned in this specific event (optionally scoped to participants new/changed in this call)
  const eventResultRows = await db.query.eventResults.findMany({
    where: eq(schema.eventResults.scoringEventId, scoringEventId),
  });
  const qpEarnedById = new Map<string, number>(
    eventResultRows
      .filter((r) => r.qualifyingPointsAwarded !== null)
      .filter((r) => !participantIdFilter || participantIdFilter.has(r.seasonParticipantId))
      .map((r) => [r.seasonParticipantId, parseFloat(r.qualifyingPointsAwarded as string)])
  );

  // Knocked-out players with no QP change. Exclude anyone who also earned QP this
  // sync (e.g. a Round-of-16 loser) so they aren't listed twice.
  const eliminatedIds = new Set(
    [...(eliminatedParticipantIds ?? [])].filter((id) => !qpEarnedById.has(id))
  );

  if (qpEarnedById.size === 0 && eliminatedIds.size === 0) return;

  const seasonIds = seasonSports.map((s) => s.seasonId);

  // Batch-fetch all draft picks for all leagues at once, grouped by season.
  // Fetched before the remaining lookups so we can short-circuit when nothing
  // that happened this sync was actually drafted: during a Grand Slam's early
  // rounds most eliminated players are undrafted, and the notifier now fires on
  // every sync that has any elimination — no point running the rest of the
  // queries just to send nothing.
  const allPicks = await db.query.draftPicks.findMany({
    where: inArray(schema.draftPicks.seasonId, seasonIds),
    with: { team: true },
  });
  const picksBySeasonId = new Map<string, (typeof allPicks)[number][]>();
  const draftedParticipantIds = new Set<string>();
  for (const pick of allPicks) {
    draftedParticipantIds.add(pick.participantId);
    const bucket = picksBySeasonId.get(pick.seasonId);
    if (bucket) {
      bucket.push(pick);
    } else {
      picksBySeasonId.set(pick.seasonId, [pick]);
    }
  }

  const hasDraftedQP = [...qpEarnedById.keys()].some((id) => draftedParticipantIds.has(id));
  const hasDraftedEliminated = [...eliminatedIds].some((id) => draftedParticipantIds.has(id));
  if (!hasDraftedQP && !hasDraftedEliminated) return;

  // Current running QP totals for the season
  const qpTotals = await db.query.seasonParticipantQualifyingTotals.findMany({
    where: eq(schema.seasonParticipantQualifyingTotals.sportsSeasonId, sportsSeasonId),
  });
  const qpTotalById = new Map<string, number>(
    qpTotals.map((t) => [t.participantId, parseFloat(t.totalQualifyingPoints)])
  );

  // Rank every participant across the FULL season field (not just this event's
  // scorers) so the notification's "QP Standings" block reads as a season-leaderboard
  // slice and matches the website's globalRank. Standard competition ranking: ties
  // share the lower rank (…, 9, 9, 11, …). Two R16 losers on 1.5 QP with 8 players
  // ahead therefore render as T9, not T1 among just the two of them.
  const rankedField = [...qpTotalById.entries()]
    .map(([id, total]) => ({ id, total }))
    .toSorted((a, b) => b.total - a.total);
  const globalRankById = new Map<string, number>();
  let prevTotal = Number.NaN;
  let prevRank = 0;
  rankedField.forEach((row, index) => {
    const rank =
      index > 0 && Math.abs(row.total - prevTotal) < 0.001 ? prevRank : index + 1;
    globalRankById.set(row.id, rank);
    prevTotal = row.total;
    prevRank = rank;
  });
  const countByRank = new Map<number, number>();
  for (const rank of globalRankById.values()) {
    countByRank.set(rank, (countByRank.get(rank) ?? 0) + 1);
  }

  // Batch-fetch all season + league metadata in one query
  const seasons = await db.query.seasons.findMany({
    where: inArray(schema.seasons.id, seasonIds),
    with: { league: true },
  });
  const seasonMap = new Map(seasons.map((s) => [s.id, s]));

  // Batch-fetch participant display names once (same participants across all leagues)
  const allParticipantIds = [...new Set([...qpEarnedById.keys(), ...eliminatedIds])];
  const participants = await db.query.seasonParticipants.findMany({
    where: inArray(schema.seasonParticipants.id, allParticipantIds),
  });
  const participantNameById = new Map(participants.map((p) => [p.id, p.name]));

  // Batch-fetch all team owners and their Discord IDs in two queries (not N per league)
  const allOwnerIds = new Set<string>();
  for (const pick of allPicks) {
    if (pick.team.ownerId) allOwnerIds.add(pick.team.ownerId);
  }
  const allUsers =
    allOwnerIds.size > 0
      ? await db.query.users.findMany({ where: inArray(schema.users.id, [...allOwnerIds]) })
      : [];
  const usernameByUserId = new Map(
    allUsers
      .map((u) => [u.id, getUserDisplayName(u)] as [string, string | null])
      .filter((entry): entry is [string, string] => entry[1] !== null)
  );
  const optedInUserIds = allUsers.filter((u) => u.discordPingEnabled).map((u) => u.id);
  const discordIdByUserId = await findDiscordIdsByUserIds(optedInUserIds);

  for (const { seasonId } of seasonSports) {
    const season = seasonMap.get(seasonId);
    const league = season?.league;
    const webhookUrl = league?.discordWebhookUrl;
    if (!webhookUrl || !season || !league) continue;

    const seasonName = `${league.name} ${season.year}`;

    // Link the embed title to this league's sport-season standings page. The
    // sportsSeasonId is exactly what the /leagues/:leagueId/sports-seasons/:sportsSeasonId
    // route expects (the page filters seasonSports by leagueId).
    const appUrl = process.env.APP_URL ?? "https://brackt.com";
    const standingsUrl = `${appUrl}/leagues/${league.id}/sports-seasons/${sportsSeasonId}`;

    const picks = picksBySeasonId.get(seasonId) ?? [];
    const teamByParticipantId = new Map<
      string,
      { teamName: string; ownerId: string | null }
    >();
    for (const pick of picks) {
      teamByParticipantId.set(pick.participantId, {
        teamName: pick.team.name,
        ownerId: pick.team.ownerId,
      });
    }

    // Only include participants that appear in both the event and this league's draft
    const relevantParticipantIds = [...qpEarnedById.keys()].filter((id) =>
      teamByParticipantId.has(id)
    );
    // Knocked-out players drafted in this league (0 QP, non-scoring-round exits)
    const eliminatedForLeague = [...eliminatedIds].filter((id) =>
      teamByParticipantId.has(id)
    );
    if (relevantParticipantIds.length === 0 && eliminatedForLeague.length === 0) continue;

    const entries: QPEventEntry[] = relevantParticipantIds.map((participantId) => {
      const ownerId = teamByParticipantId.get(participantId)?.ownerId ?? null;
      const globalRank = globalRankById.get(participantId) ?? 0;
      return {
        participantName: participantNameById.get(participantId) ?? participantId,
        qpEarned: qpEarnedById.get(participantId) ?? 0,
        qpTotal: qpTotalById.get(participantId) ?? 0,
        globalRank,
        globalRankTied: (countByRank.get(globalRank) ?? 0) > 1,
        ownerUsername: ownerId ? (usernameByUserId.get(ownerId) ?? undefined) : undefined,
        ownerDiscordUserId: ownerId ? discordIdByUserId.get(ownerId) : undefined,
      };
    });

    const eliminated: QPEliminatedEntry[] = eliminatedForLeague.map((participantId) => {
      const ownerId = teamByParticipantId.get(participantId)?.ownerId ?? null;
      return {
        participantName: participantNameById.get(participantId) ?? participantId,
        ownerUsername: ownerId ? (usernameByUserId.get(ownerId) ?? undefined) : undefined,
        ownerDiscordUserId: ownerId ? discordIdByUserId.get(ownerId) : undefined,
      };
    });

    await sendQualifyingPointsUpdateNotification({
      webhookUrl,
      seasonName,
      sportName,
      eventName,
      entries,
      eliminated,
      standingsUrl,
    });
  }
}