import { eq, and, inArray } from "drizzle-orm";
import { database } from "~/database/context";
import * as schema from "~/database/schema";
import {
  processQualifyingEvent,
  recalculateAffectedLeagues,
  buildTieCountByPlacement,
} from "~/models/scoring-calculator";
import { completeScoringEvent, getScoringEventById } from "~/models/scoring-event";
import { getEventResults } from "~/models/event-result";
import { upsertTournamentResult } from "~/models/tournament-result";
import { logger } from "~/lib/logger";

export interface SyncReport {
  tournamentId: string;
  windowsSynced: number;
  windowsFailed: number;
  failures: Array<{
    scoringEventId: string;
    sportsSeasonId: string;
    error: string;
  }>;
}

export interface SyncOptions {
  /**
   * Mark each synced window's scoring_event as complete (is_complete +
   * completed_at). Use for final results (golf batch entry, finalize-bracket).
   * Leave false for mid-tournament fan-out (e.g. live bracket rounds) so a major
   * isn't marked complete before it actually finishes.
   * @default true
   */
  markComplete?: boolean;
  /**
   * Skip the primary window when fanning out from a bracket/stage major — the
   * primary is already scored in place, so re-running it would be wasted work.
   */
  skipEventId?: string;
  /**
   * Suppress ALL Discord notifications for this fan-out (both the per-window QP
   * update from processQualifyingEvent and the league standings recalc). Used by
   * one-off backfills that re-score historical events — the QP values change
   * (e.g. a mis-split 2 → correct 1.5), which would otherwise re-ping every league.
   */
  skipNotifications?: boolean;
}

/**
 * Fan out canonical tournament_results to every scoring_event window that
 * points at this tournament. For each linked window:
 *   1. Upsert event_results rows mirroring canonical placement / rawScore for
 *      every roster participant that appears in the canonical results.
 *   2. Write 0-QP filler rows for roster participants who have no result.
 *   3. Delegate to processQualifyingEvent to compute QP.
 *
 * Each window runs in its own transaction so partial failures isolate.
 * Errors in one window never interrupt sync of the remaining windows.
 *
 * This service NEVER writes qualifying_points_awarded directly (except the
 * "0" filler for participants with no placement) — QP calculation for real
 * results is owned by processQualifyingEvent.
 */
export async function syncTournamentResults(
  tournamentId: string,
  options: SyncOptions = {}
): Promise<SyncReport> {
  const db = database();
  const { markComplete = true, skipEventId, skipNotifications = false } = options;

  const report: SyncReport = {
    tournamentId,
    windowsSynced: 0,
    windowsFailed: 0,
    failures: [],
  };

  // 1. Load canonical results for this tournament.
  const canonicalResults = await db
    .select()
    .from(schema.tournamentResults)
    .where(eq(schema.tournamentResults.tournamentId, tournamentId));

  // The full-field tie span (placement → count) is a property of the whole
  // tournament, so compute it once here and hand it to every window's
  // processQualifyingEvent instead of re-querying canonical results per window.
  const canonicalTieCountByPlacement = buildTieCountByPlacement(canonicalResults);

  // 2. Load every scoring_event that points at this tournament.
  const allLinkedEvents = await db
    .select()
    .from(schema.scoringEvents)
    .where(eq(schema.scoringEvents.tournamentId, tournamentId));
  // The primary window (when fanning out from a bracket/stage major) is already
  // scored in place — skip it so we don't redo its work.
  const linkedEvents = skipEventId
    ? allLinkedEvents.filter((ev) => ev.id !== skipEventId)
    : allLinkedEvents;

  // Windows that synced cleanly — used to propagate to leagues after the loop
  // (kept out of the per-window transaction so a recalc failure can't roll back
  // the result write).
  const syncedWindows: Array<{
    sportsSeasonId: string;
    eventId: string;
    eventName: string | null;
  }> = [];

  // 3. Fan out — each event gets its own transaction.
  for (const ev of linkedEvents) {
    try {
      await db.transaction(async (tx: typeof db) => {
        // 3a. Window roster = season_participants for this event's sports_season.
        const rosters = await tx
          .select()
          .from(schema.seasonParticipants)
          .where(eq(schema.seasonParticipants.sportsSeasonId, ev.sportsSeasonId));

        // 3b. For each canonical result whose participant is on the roster,
        // upsert the matching event_results row. Only placement / rawScore
        // are copied; qualifying_points_awarded is left for
        // processQualifyingEvent to recompute.
        const canonicalSpIds = new Set<string>();
        for (const cr of canonicalResults) {
          const sp = rosters.find((r) => r.participantId === cr.participantId);
          if (!sp) continue;
          canonicalSpIds.add(sp.id);

          const [existing] = await tx
            .select()
            .from(schema.eventResults)
            .where(
              and(
                eq(schema.eventResults.scoringEventId, ev.id),
                eq(schema.eventResults.seasonParticipantId, sp.id)
              )
            );

          if (existing) {
            await tx
              .update(schema.eventResults)
              .set({
                placement: cr.placement,
                rawScore: cr.rawScore,
                updatedAt: new Date(),
              })
              .where(eq(schema.eventResults.id, existing.id));
          } else {
            await tx.insert(schema.eventResults).values({
              scoringEventId: ev.id,
              seasonParticipantId: sp.id,
              placement: cr.placement,
              rawScore: cr.rawScore,
            });
          }
        }

        // 3c. Reconcile every roster member NOT in the canonical results to a
        // 0-QP filler row (placement=null, QP=0). This both creates missing rows
        // AND resets rows for participants whose canonical placement was removed
        // (a correction) — without this, a stale placement/rawScore would persist
        // and keep fanning out. notParticipating markers are left untouched.
        const afterRows = await tx
          .select()
          .from(schema.eventResults)
          .where(eq(schema.eventResults.scoringEventId, ev.id));
        const existingBySp = new Map(afterRows.map((r) => [r.seasonParticipantId, r]));
        for (const sp of rosters) {
          if (canonicalSpIds.has(sp.id)) continue;
          const existing = existingBySp.get(sp.id);
          if (!existing) {
            await tx.insert(schema.eventResults).values({
              scoringEventId: ev.id,
              seasonParticipantId: sp.id,
              placement: null,
              qualifyingPointsAwarded: "0",
            });
          } else if (!existing.notParticipating && existing.placement !== null) {
            // Stale placement from a prior sync — reset to filler.
            await tx
              .update(schema.eventResults)
              .set({
                placement: null,
                rawScore: null,
                qualifyingPointsAwarded: "0",
                updatedAt: new Date(),
              })
              .where(eq(schema.eventResults.id, existing.id));
          }
        }

        // 3d. Delegate to scoring engine inside the same transaction.
        await processQualifyingEvent(ev.id, tx, {
          skipNotifications,
          canonicalTieCountByPlacement,
        });

        // 3e. Mark the window event complete (final-results sync only). This is
        // what makes "score once" actually complete every window — without it,
        // each sibling stayed "In Progress" and had to be completed by hand.
        // Skip windows already complete so a re-run (e.g. a backfill) doesn't
        // needlessly re-stamp completedAt.
        if (markComplete && !ev.isComplete) {
          await completeScoringEvent(ev.id, tx);
        }
      });
      report.windowsSynced += 1;
      syncedWindows.push({
        sportsSeasonId: ev.sportsSeasonId,
        eventId: ev.id,
        eventName: ev.name,
      });
    } catch (e: unknown) {
      report.windowsFailed += 1;
      const msg =
        e instanceof Error ? e.message : typeof e === "string" ? e : String(e);
      report.failures.push({
        scoringEventId: ev.id,
        sportsSeasonId: ev.sportsSeasonId,
        error: msg,
      });
    }
  }

  // 4. Propagate to leagues for every cleanly-synced window. Done outside the
  // per-window transactions: recalculateAffectedLeagues touches many fantasy
  // seasons and must not roll back a committed result write if it fails.
  for (const w of syncedWindows) {
    try {
      await recalculateAffectedLeagues(w.sportsSeasonId, undefined, {
        eventId: w.eventId,
        eventName: w.eventName ?? undefined,
        // Mid-tournament fan-out (markComplete=false) updates standings silently;
        // the primary window already announced the round. Only the final sync
        // (completion) announces to each window's leagues. A backfill
        // (skipNotifications) is always silent.
        skipDiscord: skipNotifications || !markComplete,
      });
    } catch (e: unknown) {
      const msg =
        e instanceof Error ? e.message : typeof e === "string" ? e : String(e);
      // Count this as a failed window so the caller's status derivation
      // (windowsFailed === 0 ? "completed") doesn't mask stale standings behind
      // a green badge — the result write committed, but the league is not current.
      report.windowsFailed += 1;
      report.failures.push({
        scoringEventId: w.eventId,
        sportsSeasonId: w.sportsSeasonId,
        error: `League recalc failed: ${msg}`,
      });
    }
  }

  return report;
}

/**
 * Fan out a bracket/stage major (tennis, CS2) from its primary window.
 *
 * The admin builds and scores the bracket/Swiss stages on ONE window (the
 * primary). Those derive per-participant placements into the primary's
 * event_results. This reads them back, translates each window-scoped
 * season_participant to its canonical participant, and persists them as the
 * tournament's canonical tournament_results — the exact same shape golf produces
 * by hand. It then runs the normal fan-out to every sibling window (skipping the
 * primary, which is already scored).
 *
 * markComplete: pass false while a tournament is still in progress (live rounds)
 * so siblings stay in sync without being marked finished; pass true on finalize.
 */
export async function syncMajorFromPrimaryEvent(
  primaryEventId: string,
  options: { markComplete?: boolean; skipNotifications?: boolean } = {}
): Promise<SyncReport> {
  const { markComplete = false, skipNotifications = false } = options;

  const primaryEvent = await getScoringEventById(primaryEventId);
  if (!primaryEvent) {
    throw new Error(`Primary event ${primaryEventId} not found`);
  }
  if (!primaryEvent.tournamentId) {
    throw new Error(
      `Event ${primaryEventId} is not linked to a tournament; cannot fan out`
    );
  }

  const tournamentId = primaryEvent.tournamentId;

  // Read the primary window's derived results and persist them as canonical
  // tournament_results, keyed by canonical participant. Only real placements are
  // promoted — unplaced/filler rows are reconstructed per-window by the fan-out.
  const primaryResults = await getEventResults(primaryEventId);
  const promotedCanonicalIds = new Set<string>();
  for (const r of primaryResults) {
    if (r.placement === null || r.notParticipating) continue;
    const canonicalParticipantId = r.seasonParticipant?.participantId;
    if (!canonicalParticipantId) {
      logger.warn(
        `[syncMajorFromPrimaryEvent] season_participant ${r.seasonParticipantId} has no canonical participant link; skipping`
      );
      continue;
    }
    await upsertTournamentResult({
      tournamentId,
      participantId: canonicalParticipantId,
      placement: r.placement,
      rawScore: r.rawScore,
    });
    promotedCanonicalIds.add(canonicalParticipantId);
  }

  // Remove canonical rows for participants no longer placed on the primary (a
  // correction that dropped someone) so the stale placement stops fanning out.
  const db = database();
  const existingCanonical = await db
    .select({ participantId: schema.tournamentResults.participantId })
    .from(schema.tournamentResults)
    .where(eq(schema.tournamentResults.tournamentId, tournamentId));
  const staleIds = existingCanonical
    .map((r) => r.participantId)
    .filter((id) => !promotedCanonicalIds.has(id));
  if (staleIds.length > 0) {
    await db
      .delete(schema.tournamentResults)
      .where(
        and(
          eq(schema.tournamentResults.tournamentId, tournamentId),
          inArray(schema.tournamentResults.participantId, staleIds)
        )
      );
  }

  logger.log(
    `[syncMajorFromPrimaryEvent] promoted ${promotedCanonicalIds.size} result(s) from primary ${primaryEventId} to tournament ${tournamentId}; removed ${staleIds.length} stale`
  );

  return syncTournamentResults(tournamentId, {
    markComplete,
    skipEventId: primaryEventId,
    skipNotifications,
  });
}

/**
 * Convenience guard for route handlers: fan out a just-scored bracket/stage event
 * to its sibling windows ONLY when it's the designated primary of a shared
 * tournament. No-ops for standalone events (no tournament_id) or non-primary
 * windows (which are read-only and never scored directly). Failures are logged
 * but never thrown — fan-out must not break the admin's local scoring action.
 */
export async function fanOutMajorIfPrimary(
  event: { id: string; isPrimary: boolean; tournamentId: string | null },
  options: { markComplete?: boolean } = {}
): Promise<void> {
  if (!event.isPrimary || !event.tournamentId) return;
  try {
    await syncMajorFromPrimaryEvent(event.id, options);
  } catch (e: unknown) {
    const msg = e instanceof Error ? e.message : String(e);
    logger.error(
      `[fanOutMajorIfPrimary] fan-out failed for primary event ${event.id}: ${msg}`
    );
  }
}