import { database } from "~/database/context";
import * as schema from "~/database/schema";
import { eq, and, inArray } from "drizzle-orm";
import { getScoringRules, calculateFantasyPoints, calculateAveragedPoints } from "./scoring-rules";
import { getSeasonResults } from "./participant-season-result";

/**
 * Core scoring calculation engine
 * This file contains the logic for calculating fantasy points based on participant results
 */

export type ScoringPattern =
  | "single_elimination_playoff"
  | "page_playoff"
  | "season_standings"
  | "qualifying_points";

/**
 * Process a playoff event completion and assign final placements
 *
 * Q19: Admin enters the same placement for all tied participants,
 * system automatically shares positions
 *
 * Q20: Participants eliminated before Elite Eight get 0 points
 *
 * Phase 2.7: Updated to support template-based brackets with non-scoring rounds
 */
export async function processPlayoffEvent(
  eventId: string,
  providedDb?: ReturnType<typeof database>
): Promise<void> {
  const db = providedDb || database();

  // Get the event
  const event = await db.query.scoringEvents.findFirst({
    where: eq(schema.scoringEvents.id, eventId),
    with: {
      sportsSeason: {
        with: {
          seasonSports: {
            with: {
              season: true,
            },
          },
        },
      },
    },
  });

  if (!event) {
    throw new Error(`Event ${eventId} not found`);
  }

  if (!event.playoffRound) {
    throw new Error(`Event ${eventId} is not a playoff event`);
  }

  // Get all matches for this event in the specified round
  const matches = await db.query.playoffMatches.findMany({
    where: and(
      eq(schema.playoffMatches.scoringEventId, eventId),
      eq(schema.playoffMatches.round, event.playoffRound)
    ),
    orderBy: (matches, { asc }) => [asc(matches.matchNumber)],
  });

  // Process based on round
  const round = event.playoffRound;

  // Check if this is a scoring round
  // First try to get isScoring from the match (template-based)
  const isScoring = matches[0]?.isScoring ?? true; // Default to true for legacy brackets

  // Get season scoring rules for the first affected season
  // (all seasons should have their own rules, but we use the event's sports season to find one)
  const seasonSport = event.sportsSeason.seasonSports[0];
  if (!seasonSport) {
    throw new Error(`No fantasy seasons found for sports season ${event.sportsSeasonId}`);
  }

  const scoringRules = await getScoringRules(seasonSport.seasonId, db);
  if (!scoringRules) {
    throw new Error(`Scoring rules not found for season ${seasonSport.seasonId}`);
  }

  // If this is a non-scoring round, award 0 points (Q20)
  if (!isScoring) {
    for (const match of matches) {
      if (match.loserId) {
        await upsertParticipantResult(
          match.loserId,
          event.sportsSeasonId,
          0, // 0 placement = 0 points for early elimination
          db
        );
      }
    }
  }
  // Otherwise, process scoring rounds based on standard playoff logic
  else if (round === "Finals" || round === "Championship" || round === "Super Bowl" || round === "NBA Finals") {
    // Winner gets 1st, loser gets 2nd
    const finalMatch = matches[0];
    if (!finalMatch || !finalMatch.winnerId || !finalMatch.loserId) {
      throw new Error("Finals match is not complete");
    }

    // Update or create participant results for winner
    await upsertParticipantResult(
      finalMatch.winnerId,
      event.sportsSeasonId,
      1,
      db
    );

    // Update or create participant results for loser
    await upsertParticipantResult(
      finalMatch.loserId,
      event.sportsSeasonId,
      2,
      db
    );
  } else if (round === "Semifinals" || round === "Final Four" || round === "Conference Finals" || round === "Conference Championship") {
    // Losers share 3rd/4th
    for (const match of matches) {
      if (match.loserId) {
        await upsertParticipantResult(
          match.loserId,
          event.sportsSeasonId,
          3, // Store as placement 3 (the first shared placement)
          db
        );
      }
    }
  } else if (round === "Quarterfinals" || round === "Elite Eight" || round === "Divisional" || round === "Conference Semifinals") {
    // Losers share 5th-8th
    for (const match of matches) {
      if (match.loserId) {
        await upsertParticipantResult(
          match.loserId,
          event.sportsSeasonId,
          5, // Store as placement 5 (the first shared placement)
          db
        );
      }
    }
  }

  // Recalculate standings for all affected leagues
  await recalculateAffectedLeagues(event.sportsSeasonId, db);
}

/**
 * Helper to upsert participant result
 */
async function upsertParticipantResult(
  participantId: string,
  sportsSeasonId: string,
  finalPosition: number,
  db: ReturnType<typeof database>
): Promise<void> {
  const existing = await db.query.participantResults.findFirst({
    where: and(
      eq(schema.participantResults.participantId, participantId),
      eq(schema.participantResults.sportsSeasonId, sportsSeasonId)
    ),
  });

  if (existing) {
    await db
      .update(schema.participantResults)
      .set({
        finalPosition,
        updatedAt: new Date(),
      })
      .where(eq(schema.participantResults.id, existing.id));
  } else {
    await db.insert(schema.participantResults).values({
      participantId,
      sportsSeasonId,
      finalPosition,
    });
  }
}

/**
 * Process a qualifying event completion and update QP totals
 * Implementation will be added in Phase 3
 */
export async function processQualifyingEvent(
  eventId: string,
  providedDb?: ReturnType<typeof database>
): Promise<void> {
  const db = providedDb || database();

  // TODO: Implement in Phase 3
  // 1. Get event results
  // 2. Award qualifying points based on placement
  // 3. Update participant_qualifying_totals
  // 4. Check if all majors complete
  // 5. Update QP standings displays

  console.log(`[ScoringCalculator] processQualifyingEvent not yet implemented: ${eventId}`);
}

/**
 * Finalize qualifying points and convert to fantasy placements
 * Called manually by admin when all majors are complete
 * Implementation will be added in Phase 3
 */
export async function finalizeQualifyingPoints(
  sportsSeasonId: string,
  providedDb?: ReturnType<typeof database>
): Promise<void> {
  const db = providedDb || database();

  // TODO: Implement in Phase 3
  // 1. Get all participants ranked by total QP
  // 2. Handle ties in QP (share placements)
  // 3. Assign final placements (1-8) based on QP ranking
  // 4. Update participantResults with final placements
  // 5. Mark sports season as finalized
  // 6. Trigger recalculation for all affected leagues

  console.log(
    `[ScoringCalculator] finalizeQualifyingPoints not yet implemented: ${sportsSeasonId}`
  );
}

/**
 * Process season standings (F1) and assign final placements
 *
 * Q7: For F1, we show current F1 points during the season, then assign fantasy points at the end
 * Q8: Just final standings, not individual races
 * Q14: Store current running total, manual update with API future
 * Q13/Q19: Ties handled by admin entering same position, system auto-shares placements
 */
export async function processSeasonStandings(
  sportsSeasonId: string,
  providedDb?: ReturnType<typeof database>
): Promise<void> {
  const db = providedDb || database();

  // Get all season results for this sports season, sorted by standings
  const seasonResults = await getSeasonResults(sportsSeasonId, db);

  // Group participants by position to handle ties
  const positionGroups: Record<number, string[]> = {};

  for (const result of seasonResults) {
    const position = result.currentPosition;
    if (position === null) continue; // Skip participants without a position

    if (!positionGroups[position]) {
      positionGroups[position] = [];
    }
    positionGroups[position].push(result.participantId);
  }

  // Get sorted positions
  const positions = Object.keys(positionGroups)
    .map(Number)
    .sort((a, b) => a - b);

  // Assign fantasy placements (1-8) based on standings
  let currentPlacement = 1;

  for (const position of positions) {
    const participantIds = positionGroups[position];

    // Stop if we've gone beyond the top 8 fantasy placements
    if (currentPlacement > 8) break;

    // Calculate how many placements this group shares
    const participantsInGroup = participantIds.length;

    // If this group would exceed position 8, only some participants get points
    const maxPlacementForGroup = Math.min(8, currentPlacement + participantsInGroup - 1);
    const actualParticipantsScoring = maxPlacementForGroup - currentPlacement + 1;

    // Determine if we should assign placements to this group
    if (currentPlacement <= 8) {
      // All participants tied at this position get the first placement in the range
      // (e.g., if 4 people tie for 5th place, they all get placement 5)
      // The scoring system will handle averaging the points for positions 5, 6, 7, 8
      for (let i = 0; i < Math.min(participantIds.length, actualParticipantsScoring); i++) {
        const participantId = participantIds[i];
        await upsertParticipantResult(
          participantId,
          sportsSeasonId,
          currentPlacement,
          db
        );
      }

      // If there are more participants than scoring positions, assign 0 to the rest
      for (let i = actualParticipantsScoring; i < participantIds.length; i++) {
        const participantId = participantIds[i];
        await upsertParticipantResult(
          participantId,
          sportsSeasonId,
          0, // Beyond top 8
          db
        );
      }
    } else {
      // Position is beyond top 8, assign 0 points
      for (const participantId of participantIds) {
        await upsertParticipantResult(
          participantId,
          sportsSeasonId,
          0,
          db
        );
      }
    }

    // Move to next placement group
    currentPlacement += participantsInGroup;
  }

  // Trigger recalculation for all affected leagues
  await recalculateAffectedLeagues(sportsSeasonId, db);

  console.log(
    `[ScoringCalculator] Processed season standings for sports season ${sportsSeasonId}`
  );
}

/**
 * Calculate total fantasy points for a team in a specific season
 * Sums points from all drafted participants based on their final placements
 */
export async function calculateTeamScore(
  teamId: string,
  seasonId: string,
  providedDb?: ReturnType<typeof database>
): Promise<{
  totalPoints: number;
  placementCounts: Record<number, number>;
  participantsCompleted: number;
  participantsTotal: number;
}> {
  const db = providedDb || database();

  // Get season scoring rules
  const scoringRules = await getScoringRules(seasonId, db);
  if (!scoringRules) {
    throw new Error(`Season ${seasonId} not found`);
  }

  // Get all draft picks for this team
  const picks = await db.query.draftPicks.findMany({
    where: and(
      eq(schema.draftPicks.teamId, teamId),
      eq(schema.draftPicks.seasonId, seasonId)
    ),
    with: {
      participant: {
        with: {
          results: true,
        },
      },
    },
  });

  let totalPoints = 0;
  const placementCounts: Record<number, number> = {
    1: 0,
    2: 0,
    3: 0,
    4: 0,
    5: 0,
    6: 0,
    7: 0,
    8: 0,
  };
  let participantsCompleted = 0;

  for (const pick of picks) {
    const result = pick.participant.results[0]; // Should only be one result per participant

    if (result && result.finalPosition) {
      const points = calculateFantasyPoints(result.finalPosition, scoringRules);
      totalPoints += points;
      participantsCompleted++;

      // Track placement for tiebreakers
      if (result.finalPosition >= 1 && result.finalPosition <= 8) {
        placementCounts[result.finalPosition]++;
      }
    }
  }

  return {
    totalPoints,
    placementCounts,
    participantsCompleted,
    participantsTotal: picks.length,
  };
}

/**
 * Recalculate standings for all teams in a season
 * Called after any scoring event completes or participant results change
 * Implementation will be completed in Phase 4
 */
export async function recalculateStandings(
  seasonId: string,
  providedDb?: ReturnType<typeof database>
): Promise<void> {
  const db = providedDb || database();

  // TODO: Complete implementation in Phase 4
  // For now, calculate basic scores without rankings

  const teams = await db.query.teams.findMany({
    where: eq(schema.teams.seasonId, seasonId),
  });

  for (const team of teams) {
    const teamScore = await calculateTeamScore(team.id, seasonId, db);

    // Upsert team standings
    const existing = await db.query.teamStandings.findFirst({
      where: and(
        eq(schema.teamStandings.teamId, team.id),
        eq(schema.teamStandings.seasonId, seasonId)
      ),
    });

    if (existing) {
      await db
        .update(schema.teamStandings)
        .set({
          totalPoints: teamScore.totalPoints.toString(),
          firstPlaceCount: teamScore.placementCounts[1],
          secondPlaceCount: teamScore.placementCounts[2],
          thirdPlaceCount: teamScore.placementCounts[3],
          fourthPlaceCount: teamScore.placementCounts[4],
          fifthPlaceCount: teamScore.placementCounts[5],
          sixthPlaceCount: teamScore.placementCounts[6],
          seventhPlaceCount: teamScore.placementCounts[7],
          eighthPlaceCount: teamScore.placementCounts[8],
          participantsRemaining:
            teamScore.participantsTotal - teamScore.participantsCompleted,
          calculatedAt: new Date(),
        })
        .where(eq(schema.teamStandings.id, existing.id));
    } else {
      await db.insert(schema.teamStandings).values({
        teamId: team.id,
        seasonId,
        totalPoints: teamScore.totalPoints.toString(),
        currentRank: 1, // Will be updated when we add ranking logic
        firstPlaceCount: teamScore.placementCounts[1],
        secondPlaceCount: teamScore.placementCounts[2],
        thirdPlaceCount: teamScore.placementCounts[3],
        fourthPlaceCount: teamScore.placementCounts[4],
        fifthPlaceCount: teamScore.placementCounts[5],
        sixthPlaceCount: teamScore.placementCounts[6],
        seventhPlaceCount: teamScore.placementCounts[7],
        eighthPlaceCount: teamScore.placementCounts[8],
        participantsRemaining: teamScore.participantsTotal - teamScore.participantsCompleted,
      });
    }
  }

  console.log(`[ScoringCalculator] Recalculated standings for season ${seasonId}`);
}

/**
 * Recalculate standings for all leagues that include a specific sports season
 * Called after a sports season event completes
 */
export async function recalculateAffectedLeagues(
  sportsSeasonId: string,
  providedDb?: ReturnType<typeof database>
): Promise<void> {
  const db = providedDb || database();

  // Get all fantasy seasons that include this sports season
  const seasonSports = await db.query.seasonSports.findMany({
    where: eq(schema.seasonSports.sportsSeasonId, sportsSeasonId),
  });

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

  // Recalculate each affected season
  for (const seasonId of seasonIds) {
    await recalculateStandings(seasonId, db);
  }

  console.log(
    `[ScoringCalculator] Recalculated ${seasonIds.length} affected season(s) for sports season ${sportsSeasonId}`
  );
}