import { useLoaderData, Link } from "react-router";
import { getAuth } from "@clerk/react-router/server";
import { database } from "~/database/context";
import { eq, and } from "drizzle-orm";
import * as schema from "~/database/schema";
import { Button } from "~/components/ui/button";
import { Card, CardContent, CardHeader, CardTitle } from "~/components/ui/card";
import { StandingsTable } from "~/components/standings/StandingsTable";
import { logger } from "~/lib/logger";
import { getSevenDayStandingsChange, getSeasonPointProgression } from "~/models/standings";
import { isSeasonComplete, getSeasonCompletionPercentage } from "~/lib/season-helpers.server";
import { PointProgressionChart } from "~/components/standings/PointProgressionChart";
import { findUsersByClerkIds, getUserDisplayName } from "~/models/user";
import type { Route } from "./+types/$leagueId.standings.$seasonId";

export function meta({ data }: Route.MetaArgs): Route.MetaDescriptors {
  return [{ title: `Standings — ${data?.league?.name ?? "League"} - Brackt` }];
}

export async function loader(args: Route.LoaderArgs) {
  try {
    const { userId } = await getAuth(args);
    const { params } = args;
    const { leagueId, seasonId } = params;

    const db = database();

  // Fetch league
  const league = await db.query.leagues.findFirst({
    where: eq(schema.leagues.id, leagueId),
  });

  if (!league) {
    throw new Response("League not found", { status: 404 });
  }

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

  if (!season || season.leagueId !== leagueId) {
    throw new Response("Season not found", { status: 404 });
  }

  // Check access
  if (!userId) {
    throw new Response("You must be logged in to view standings", {
      status: 401,
    });
  }

  // Check if user is a commissioner
  const isUserCommissioner = await db.query.commissioners.findFirst({
    where: and(
      eq(schema.commissioners.leagueId, leagueId),
      eq(schema.commissioners.userId, userId)
    ),
  });

  // Check if user has a team in this season
  const hasTeam = await db.query.teams.findFirst({
    where: and(
      eq(schema.teams.seasonId, seasonId),
      eq(schema.teams.ownerId, userId)
    ),
  });

  if (!isUserCommissioner && !hasTeam) {
    throw new Response("You do not have access to this league", {
      status: 403,
    });
  }

  // Fetch standings, teams (for owner lookup), and independent data in parallel
  const [standingsWithComparison, teams, progressionData, seasonComplete, completionPercentage] =
    await Promise.all([
      getSevenDayStandingsChange(seasonId, db),
      db.query.teams.findMany({
        where: eq(schema.teams.seasonId, seasonId),
        columns: { id: true, ownerId: true },
      }),
      getSeasonPointProgression(seasonId, db),
      isSeasonComplete(seasonId, db),
      getSeasonCompletionPercentage(seasonId, db),
    ]);

  // Build teamId -> ownerName map
  const ownerIds = [...new Set(teams.map((t) => t.ownerId).filter((id): id is string => id !== null))];
  const userRows = await findUsersByClerkIds(ownerIds);
  const userByClerkId = new Map(userRows.map((u) => [u.clerkId, u]));
  const ownerNameByTeamId = new Map(
    teams
      .filter((t): t is typeof t & { ownerId: string } => t.ownerId !== null)
      .map((t) => {
        const user = userByClerkId.get(t.ownerId);
        return [t.id, user ? getUserDisplayName(user) : null] as const;
      })
  );

  // Map to format expected by component (use sevenDayRankChange instead of previousRank)
  const formattedStandings = standingsWithComparison.map((standing) => ({
    ...standing,
    rankChange: standing.sevenDayRankChange,
    ownerName: ownerNameByTeamId.get(standing.teamId) ?? null,
  }));

    return {
      league,
      season,
      standings: formattedStandings,
      progressionData,
      seasonComplete,
      completionPercentage,
    };
  } catch (error) {
    logger.error("Error loading standings:", error);
    logger.error("Error details:", {
      message: error instanceof Error ? error.message : String(error),
      stack: error instanceof Error ? error.stack : undefined,
    });
    throw error;
  }
}

export default function LeagueStandings() {
  const { league, season, standings, progressionData, seasonComplete, completionPercentage } = useLoaderData<typeof loader>();

  return (
    <div className="container mx-auto py-8 px-4">
      {/* Header */}
      <div className="mb-8">
        <Button variant="ghost" className="mb-4" asChild>
          <Link to={`/leagues/${league.id}`}>
            ← Back to League
          </Link>
        </Button>

        <div className="flex items-center justify-between">
          <div>
            <h1 className="text-4xl font-bold mb-2">{league.name}</h1>
            <p className="text-muted-foreground text-lg">
              {season.year} Season Standings
            </p>
          </div>
          <div className="text-right">
            {seasonComplete ? (
              <div className="inline-flex items-center px-3 py-1 rounded-full bg-green-100 text-green-800 dark:bg-green-900 dark:text-green-100 text-sm font-medium">
                ✓ Season Complete
              </div>
            ) : (
              <div className="text-sm text-muted-foreground">
                {completionPercentage}% Complete
              </div>
            )}
          </div>
        </div>
      </div>

      {/* Point Progression Chart */}
      {progressionData.chartData.length > 0 && (
        <div className="mb-6">
          <PointProgressionChart
            chartData={progressionData.chartData}
            teams={progressionData.teams}
          />
        </div>
      )}

      {/* Standings Card */}
      <Card>
        <CardHeader>
          <CardTitle>
            {seasonComplete ? "Final Standings" : "Current Standings"}
          </CardTitle>
        </CardHeader>
        <CardContent>
          {standings.length === 0 ? (
            <div className="text-center py-12 text-muted-foreground">
              <p className="text-lg">No standings data yet.</p>
              <p className="text-sm mt-2">
                Standings will appear once participants have results.
              </p>
            </div>
          ) : (
            <StandingsTable
              standings={standings}
              leagueId={league.id}
              seasonId={season.id}
              showPlacementBreakdown={true}
            />
          )}
        </CardContent>
      </Card>

      {/* Info Card */}
      <Card className="mt-6">
        <CardContent className="pt-6">
          <div className="text-sm text-muted-foreground space-y-2">
            <p>
              <strong>Projected Points:</strong> Shows actual points from finished
              participants plus expected value (EV) from remaining participants based
              on their probability distributions. The "+X.X EV" indicates how many
              additional points are expected from unfinished participants.
            </p>
            <p>
              <strong>Tiebreaker Rules:</strong> Teams are ranked by total
              points. If tied, the team with more 1st place finishes ranks
              higher. If still tied, 2nd place finishes are compared, then 3rd,
              and so on through 8th place.
            </p>
            <p>
              <strong>Movement Indicators:</strong> Arrows show rank changes
              compared to 7 days ago. Green arrows (↑) indicate improvement in rank,
              red arrows (↓) indicate decline.
            </p>
            <p>
              <strong>Placement Breakdown:</strong> Shows how many times each
              team's participants finished in each position (1st×2 means 2 first-place finishes).
            </p>
            {progressionData.chartData.length > 0 && (
              <p>
                <strong>Point Progression Chart:</strong> Visualizes how each team's
                total points evolved over time based on {progressionData.chartData.length} day{progressionData.chartData.length !== 1 ? 's' : ''} of snapshot data.
                {seasonComplete && " Use this to see how the final standings developed throughout the season."}
              </p>
            )}
          </div>
        </CardContent>
      </Card>
    </div>
  );
}