import type { Route } from "./+types/admin.sports-seasons.$id.events.$eventId.bracket";
import { redirect } from "react-router";
import { findSportsSeasonById } from "~/models/sports-season";
import { findParticipantsBySportsSeasonId } from "~/models/participant";
import { getScoringEventById } from "~/models/scoring-event";
import {
  findPlayoffMatchesByEventId,
  generateSingleEliminationBracket,
  setMatchWinner,
  advanceWinner,
  findPlayoffMatchById,
} from "~/models/playoff-match";
import { processPlayoffEvent } from "~/models/scoring-calculator";
import { database } from "~/database/context";
import * as schema from "~/database/schema";
import { eq } from "drizzle-orm";

export async function loader({ params }: Route.LoaderArgs) {
  const sportsSeason = await findSportsSeasonById(params.id);

  if (!sportsSeason) {
    throw new Response("Sports season not found", { status: 404 });
  }

  const event = await getScoringEventById(params.eventId);

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

  if (event.eventType !== "playoff_game") {
    throw new Response("This event is not a playoff event", { status: 400 });
  }

  const participants = await findParticipantsBySportsSeasonId(params.id);
  const matches = await findPlayoffMatchesByEventId(params.eventId);

  // The matches already include participant relations from the model query
  return {
    sportsSeason: sportsSeason as typeof sportsSeason & {
      sport: { id: string; name: string; type: string; slug: string };
    },
    event,
    participants,
    matches: matches as Array<typeof matches[0] & {
      participant1: { id: string; name: string } | null;
      participant2: { id: string; name: string } | null;
      winner: { id: string; name: string } | null;
      loser: { id: string; name: string } | null;
    }>,
  };
}

export async function action({ request, params }: Route.ActionArgs) {
  const formData = await request.formData();
  const intent = formData.get("intent");

  if (intent === "generate-bracket") {
    const bracketSize = formData.get("bracketSize");

    if (bracketSize !== "4" && bracketSize !== "8") {
      return { error: "Invalid bracket size" };
    }

    const size = parseInt(bracketSize, 10);
    const participantIds: string[] = [];

    for (let i = 0; i < size; i++) {
      const participantId = formData.get(`participant${i}`);
      if (typeof participantId !== "string" || !participantId) {
        return { error: `Participant ${i + 1} is required` };
      }
      participantIds.push(participantId);
    }

    // Check for duplicates
    const uniqueParticipants = new Set(participantIds);
    if (uniqueParticipants.size !== participantIds.length) {
      return { error: "Each participant can only be selected once" };
    }

    try {
      await generateSingleEliminationBracket(params.eventId, participantIds);
      return { success: "Bracket generated successfully" };
    } catch (error) {
      console.error("Error generating bracket:", error);
      return {
        error:
          error instanceof Error
            ? error.message
            : "Failed to generate bracket",
      };
    }
  }

  if (intent === "set-winner") {
    const matchId = formData.get("matchId");
    const winnerId = formData.get("winnerId");

    if (typeof matchId !== "string" || !matchId) {
      return { error: "Match ID is required" };
    }

    if (typeof winnerId !== "string" || !winnerId) {
      return { error: "Winner ID is required" };
    }

    try {
      const match = await findPlayoffMatchById(matchId);
      if (!match) {
        return { error: "Match not found" };
      }

      // Determine loser
      const loserId =
        match.participant1Id === winnerId
          ? match.participant2Id
          : match.participant1Id;

      if (!loserId) {
        return { error: "Could not determine loser" };
      }

      // Set the winner
      await setMatchWinner(matchId, winnerId, loserId);

      // Try to advance the winner to the next round (if not Finals)
      if (match.round !== "Finals") {
        try {
          await advanceWinner(matchId, winnerId);
        } catch (error) {
          // Only ignore "already filled" errors, re-throw unexpected errors
          if (
            error instanceof Error &&
            error.message.includes("already filled")
          ) {
            console.warn("Match already filled, skipping advancement");
          } else {
            throw error; // Re-throw unexpected errors
          }
        }
      }

      return { success: "Winner set successfully" };
    } catch (error) {
      console.error("Error setting winner:", error);
      return {
        error:
          error instanceof Error ? error.message : "Failed to set winner",
      };
    }
  }

  if (intent === "complete-round") {
    const round = formData.get("round");

    if (
      round !== "Quarterfinals" &&
      round !== "Semifinals" &&
      round !== "Finals"
    ) {
      return { error: "Invalid round" };
    }

    try {
      // Get the event and update playoffRound to the completed round
      const event = await getScoringEventById(params.eventId);
      if (!event) {
        return { error: "Event not found" };
      }

      // Verify all matches in this round are complete
      const matches = await findPlayoffMatchesByEventId(params.eventId);
      const roundMatches = matches.filter((m) => m.round === round);

      const allComplete = roundMatches.every((m) => m.isComplete);
      if (!allComplete) {
        return { error: `Not all matches in ${round} are complete` };
      }

      // Validate round order: ensure previous rounds are complete
      const { findParticipantResultsBySportsSeasonId } = await import(
        "~/models/participant-result"
      );
      const existingResults = await findParticipantResultsBySportsSeasonId(
        params.id
      );

      if (round === "Finals") {
        // Finals requires Semifinals to be complete (3rd/4th place results exist)
        const hasSemifinalResults = existingResults.some(
          (r) => r.finalPosition === 3 || r.finalPosition === 4
        );
        if (!hasSemifinalResults) {
          return {
            error:
              "Semifinals must be completed before Finals (no 3rd/4th place results found)",
          };
        }
      } else if (round === "Semifinals") {
        // Semifinals requires Quarterfinals to be complete if QF matches exist
        const hasQuarterfinals = matches.some((m) => m.round === "Quarterfinals");
        if (hasQuarterfinals) {
          const hasQuarterfinalsResults = existingResults.some(
            (r) =>
              r.finalPosition === 5 ||
              r.finalPosition === 6 ||
              r.finalPosition === 7 ||
              r.finalPosition === 8
          );
          if (!hasQuarterfinalsResults) {
            return {
              error:
                "Quarterfinals must be completed before Semifinals (no 5th-8th place results found)",
            };
          }
        }
      }

      // Get the sports season to find a fantasy season for scoring rules
      const sportsSeason = await findSportsSeasonById(params.id);
      if (!sportsSeason) {
        return { error: "Sports season not found" };
      }

      // Process the playoff event to calculate placements
      // TODO Phase 2.7: Refactor processPlayoffEvent to use template system
      // For now, we still need to set playoffRound for the old scoring logic
      // even though we removed it from the create event UI
      const db = database();
      await db
        .update(schema.scoringEvents)
        .set({ playoffRound: round, updatedAt: new Date() })
        .where(eq(schema.scoringEvents.id, params.eventId));

      // Get a fantasy season ID for scoring calculation
      const { findSeasonSportsBySportsSeasonId } = await import(
        "~/models/season-sport"
      );
      const seasonSports = await findSeasonSportsBySportsSeasonId(params.id);
      if (seasonSports.length === 0) {
        return {
          error: "No fantasy seasons found for this sports season",
        };
      }

      // Process playoff event to update participant results
      await processPlayoffEvent(params.eventId);

      return {
        success: `${round} completed and placements calculated successfully`,
      };
    } catch (error) {
      console.error("Error completing round:", error);
      return {
        error:
          error instanceof Error ? error.message : "Failed to complete round",
      };
    }
  }

  return { error: "Invalid action" };
}