import { database } from "~/database/context";
import * as schema from "~/database/schema";
import { eq, inArray } from "drizzle-orm";
import { calculatePickInfo } from "~/models/draft-utils";
import { getUserDisplayName } from "~/models/user";

import type { LoaderFunctionArgs } from "react-router";

const UUID_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;

export async function loader({ params }: LoaderFunctionArgs) {
  const { seasonId } = params;

  // Fix #1: validate UUID format up front so malformed IDs return 400, not a DB error
  if (!seasonId || !UUID_RE.test(seasonId)) {
    return Response.json({ error: "Invalid season ID" }, { status: 400 });
  }

  const db = database();

  const season = await db.query.seasons.findFirst({
    where: eq(schema.seasons.id, seasonId),
  });

  if (!season) {
    return Response.json({ error: "Season not found" }, { status: 404 });
  }

  const draftSlots = await db.query.draftSlots.findMany({
    where: eq(schema.draftSlots.seasonId, seasonId),
    orderBy: schema.draftSlots.draftOrder,
    with: { team: true },
  });

  const totalTeams = draftSlots.length;
  const totalPicks = totalTeams * season.draftRounds;
  const currentPickNumber = season.currentPickNumber ?? 1;
  const isDraftComplete = season.status === "active" || season.status === "completed";

  // Fix #4: guard against totalTeams === 0 before calling calculatePickInfo
  let onTheClockSlot: (typeof draftSlots)[number] | null = null;
  if (season.status === "draft" && totalTeams > 0) {
    const { pickInRound } = calculatePickInfo(currentPickNumber, totalTeams);
    onTheClockSlot = draftSlots.find((slot) => slot.draftOrder === pickInRound) ?? null;
  }

  // All picks with participant + sport + team owner info
  const picksRaw = await db
    .select({
      pickNumber: schema.draftPicks.pickNumber,
      round: schema.draftPicks.round,
      teamName: schema.teams.name,
      teamOwnerId: schema.teams.ownerId,
      participantName: schema.participants.name,
      sport: schema.sports.name,
    })
    .from(schema.draftPicks)
    .innerJoin(schema.teams, eq(schema.draftPicks.teamId, schema.teams.id))
    .innerJoin(schema.participants, eq(schema.draftPicks.participantId, schema.participants.id))
    .innerJoin(schema.sportsSeasons, eq(schema.participants.sportsSeasonId, schema.sportsSeasons.id))
    .innerJoin(schema.sports, eq(schema.sportsSeasons.sportId, schema.sports.id))
    .where(eq(schema.draftPicks.seasonId, seasonId))
    .orderBy(schema.draftPicks.pickNumber);

  // Fix #2: include the on-the-clock owner in the batch so we never make a separate user query
  const picksOwnerIds = picksRaw.map((p) => p.teamOwnerId).filter(Boolean) as string[];
  const clockOwnerId = onTheClockSlot?.team.ownerId ?? null;
  const allOwnerIds = [...new Set([...picksOwnerIds, ...(clockOwnerId ? [clockOwnerId] : [])])];

  const usernameByUserId = new Map<string, string | null>();
  if (allOwnerIds.length > 0) {
    const owners = await db
      .select({
        id: schema.users.id,
        username: schema.users.username,
        displayName: schema.users.displayName,
      })
      .from(schema.users)
      .where(inArray(schema.users.id, allOwnerIds));
    for (const owner of owners) {
      usernameByUserId.set(owner.id, getUserDisplayName(owner));
    }
  }

  // Fix #3: single helper so onTheClock and picks use identical null-fallback logic
  const getUsername = (ownerId: string | null) =>
    ownerId ? (usernameByUserId.get(ownerId) ?? null) : null;

  const onTheClock = onTheClockSlot
    ? { teamName: onTheClockSlot.team.name, username: getUsername(onTheClockSlot.team.ownerId) }
    : null;

  const picks = picksRaw.map((p) => ({
    pickNumber: p.pickNumber,
    round: p.round,
    teamName: p.teamName,
    username: getUsername(p.teamOwnerId),
    participantName: p.participantName,
    sport: p.sport,
  }));

  return Response.json({
    seasonId,
    status: season.status,
    currentPickNumber,
    totalPicks,
    isDraftComplete,
    isPaused: season.draftPaused,
    onTheClock,
    picks,
  });
}