import type { FetchedStandingsRecord, StandingsSyncAdapter } from "./types";
import {
  flattenEspnStandings,
  parseConferenceRank,
  sortByWinLoss,
  statsMap,
  type EspnStandingsResponse,
} from "./espn";

const MLB_STANDINGS_URL =
  "https://site.api.espn.com/apis/v2/sports/baseball/mlb/standings";

// "American League" → "AL", "National League" → "NL"
function abbreviateLeague(name: string): string {
  if (name.startsWith("American")) return "AL";
  if (name.startsWith("National")) return "NL";
  return name;
}

// "American League East" → "AL East", "National League West" → "NL West"
function abbreviateDivision(name: string): string {
  return name
    .replace(/^American League /, "AL ")
    .replace(/^National League /, "NL ");
}

export class MlbStandingsAdapter implements StandingsSyncAdapter {
  async fetchStandings(): Promise<FetchedStandingsRecord[]> {
    const response = await fetch(MLB_STANDINGS_URL);
    if (!response.ok) {
      throw new Error(`MLB standings API returned ${response.status}: ${response.statusText}`);
    }

    const json = (await response.json()) as EspnStandingsResponse;
    const flattened = flattenEspnStandings(json);

    if (flattened.length === 0) {
      throw new Error("MLB standings API returned no entries — response shape may have changed");
    }

    // Pre-build statsMap once per entry so the sort doesn't rebuild it on every comparison.
    const withSm = flattened.map(({ entry, conference, division }) => ({
      entry,
      conference,
      division,
      sm: statsMap(entry.stats),
    }));

    // Compute divisionRank: rank each team within its own division by win/loss.
    const divisionRankMap = new Map<string, number>();
    const divisionGroups = new Map<string, typeof withSm>();
    for (const item of withSm) {
      const key = item.division;
      if (!divisionGroups.has(key)) divisionGroups.set(key, []);
      divisionGroups.get(key)?.push(item);
    }
    for (const divEntries of divisionGroups.values()) {
      // Use the ESPN entry order within each division — ESPN already applies correct tiebreakers.
      divEntries.forEach((e, i) => {
        divisionRankMap.set(e.entry.team.id, i + 1);
      });
    }

    const sorted = [...withSm].toSorted(sortByWinLoss);

    return sorted.map(({ entry, conference, division, sm }, leagueIdx): FetchedStandingsRecord => {
      const wins = sm.get("wins")?.value ?? 0;
      const losses = sm.get("losses")?.value ?? 0;

      // Fall back to computing win% from wins/losses if ESPN omits the stat.
      const winPctStat = sm.get("winPercent")?.value ?? sm.get("winPct")?.value;
      const winPct = winPctStat ?? (wins + losses > 0 ? wins / (wins + losses) : 0);

      const gamesBehind = sm.get("gamesBehind")?.value;
      const streak = sm.get("streak")?.displayValue ?? sm.get("streakSummary")?.displayValue;
      const lastTen =
        sm.get("Last Ten Games")?.displayValue ?? sm.get("L10")?.displayValue ?? undefined;
      const homeRecord = sm.get("Home")?.displayValue ?? undefined;
      const awayRecord = sm.get("Road")?.displayValue ?? undefined;

      const abbreviatedDiv = abbreviateDivision(division);

      return {
        teamName: entry.team.displayName,
        externalTeamId: entry.team.id,
        wins: Math.round(wins),
        losses: Math.round(losses),
        winPct,
        gamesPlayed: Math.round(wins) + Math.round(losses),
        gamesBack: gamesBehind,
        conference: abbreviateLeague(conference),
        division: abbreviatedDiv || undefined,
        conferenceRank: parseConferenceRank(sm),
        divisionRank: divisionRankMap.get(entry.team.id),
        leagueRank: leagueIdx + 1,
        streak,
        lastTen,
        homeRecord,
        awayRecord,
      };
    });
  }
}