import { describe, it, expect, vi, beforeEach } from "vitest";

vi.mock("~/database/context", () => ({
  database: vi.fn(),
}));

import { runBackfill } from "../backfill-canonical-layer";
import { database } from "~/database/context";
import * as schema from "~/database/schema";

/**
 * Fixture rows used across multiple tests.
 */
const SPORT_ID = "sport-golf";
const SEASON_ID = "season-golf-2026";

const GOLF_SEASON = {
  id: SEASON_ID,
  sportId: SPORT_ID,
  scoringPattern: "qualifying_points",
} as const;

function makeEvent(overrides: Partial<Record<string, unknown>> = {}) {
  return {
    id: "event-1",
    sportsSeasonId: SEASON_ID,
    tournamentId: null,
    name: "Masters Tournament",
    eventDate: "2026-04-09",
    eventType: "tournament",
    ...overrides,
  };
}

function makeSeasonParticipant(
  overrides: Partial<Record<string, unknown>> = {},
) {
  return {
    id: "sp-1",
    sportsSeasonId: SEASON_ID,
    participantId: null,
    name: "Scottie Scheffler",
    ...overrides,
  };
}

/**
 * Builds a fake drizzle db that routes select/insert/update calls based
 * on the target table. The caller supplies per-table select-result
 * arrays (one per call to that table's select()). Inserts return the
 * value they were given, extended with a stub id. Updates are recorded
 * but otherwise no-op.
 */
interface TableState {
  /** Queue of results to return for successive select() calls on this table. */
  selects?: unknown[][];
  /** Rows that insert().values().returning() should yield. */
  insertReturns?: unknown[];
  /** Incremented on each update() call. */
  updates?: { count: number };
}

interface FakeDbOptions {
  tables: Map<unknown, TableState>;
  /** Records every insert call: tableRef → rows seen. */
  inserts?: Map<unknown, unknown[]>;
  /** Records every update call: tableRef → count. */
  updateCounts?: Map<unknown, number>;
}

function makeFakeDb(opts: FakeDbOptions) {
  const { tables, inserts, updateCounts } = opts;

  // Each select() starts a new chain that ultimately resolves to the
  // next queued selects[] entry for the passed table. The chain is a
  // thenable via .limit/.where resolution.
  const db = {
    select: vi.fn().mockImplementation(() => {
      let boundTable: unknown;
      const chain: Record<string, unknown> = {
        from: vi.fn().mockImplementation((table: unknown) => {
          boundTable = table;
          return chain;
        }),
        where: vi.fn().mockImplementation(() => chain),
        limit: vi.fn().mockImplementation(() => chain),
        // Terminal: make chain thenable so `await chain` yields the queued result.
        then: (resolve: (v: unknown) => unknown) => {
          const state = tables.get(boundTable);
          const queue = state?.selects ?? [];
          const next = queue.shift() ?? [];
          return Promise.resolve(next).then(resolve);
        },
      };
      return chain;
    }),

    insert: vi.fn().mockImplementation((table: unknown) => {
      return {
        values: vi.fn().mockImplementation((row: unknown) => {
          if (inserts) {
            const seen = inserts.get(table) ?? [];
            seen.push(row);
            inserts.set(table, seen);
          }
          const state = tables.get(table);
          const returnRows = state?.insertReturns ?? [
            { ...(row as object), id: `generated-${Math.random()}` },
          ];
          const afterValues = {
            returning: vi.fn().mockResolvedValue(returnRows),
            // If the caller doesn't chain .returning(), make it awaitable anyway.
            then: (resolve: (v: unknown) => unknown) =>
              Promise.resolve(returnRows).then(resolve),
          };
          return afterValues;
        }),
      };
    }),

    update: vi.fn().mockImplementation((table: unknown) => {
      if (updateCounts) {
        updateCounts.set(table, (updateCounts.get(table) ?? 0) + 1);
      }
      return {
        set: vi.fn().mockReturnValue({
          where: vi.fn().mockResolvedValue(undefined),
        }),
      };
    }),
  };

  return db;
}

beforeEach(() => {
  vi.clearAllMocks();
});

// ─── 1. empty DB no-op ─────────────────────────────────────────────────────

describe("runBackfill - empty DB", () => {
  it("returns zero counts when no qualifying-points seasons exist", async () => {
    const tables = new Map<unknown, TableState>([
      [schema.sportsSeasons, { selects: [[]] }],
    ]);
    vi.mocked(database).mockReturnValue(makeFakeDb({ tables }) as never);

    const report = await runBackfill({ dryRun: false });

    expect(report).toMatchObject({
      tournamentsCreated: 0,
      tournamentsLinked: 0,
      participantsCreated: 0,
      participantsLinked: 0,
      tournamentResultsCreated: 0,
      surfaceElosCreated: 0,
      errors: [],
    });
  });
});

// ─── 2. golf window with 4 events creates 4 tournaments ───────────────────

describe("runBackfill - golf tournaments", () => {
  it("creates 4 canonical tournaments for a golf season with 4 events", async () => {
    const events = [
      makeEvent({ id: "ev-1", name: "Masters Tournament", eventDate: "2026-04-09" }),
      makeEvent({ id: "ev-2", name: "PGA Championship", eventDate: "2026-05-14" }),
      makeEvent({ id: "ev-3", name: "U.S. Open", eventDate: "2026-06-18" }),
      makeEvent({ id: "ev-4", name: "The Open Championship", eventDate: "2026-07-16" }),
    ];

    const inserts = new Map<unknown, unknown[]>();

    // Build per-event insertReturns so each new tournament gets its id.
    const tables = new Map<unknown, TableState>([
      [schema.sportsSeasons, { selects: [[GOLF_SEASON]] }],
      [
        schema.scoringEvents,
        {
          // 1st select: unlinked events; 2nd: refetch for results loop.
          selects: [events, events.map((e, i) => ({ ...e, tournamentId: `t-${i + 1}` }))],
        },
      ],
      [
        schema.tournaments,
        {
          // One select-miss per event, all return [] (no existing row).
          selects: [[], [], [], []],
          // One insert per event; return sequential ids.
          insertReturns: [{ id: "t-1" }],
        },
      ],
      [schema.seasonParticipants, { selects: [[]] }],
      [schema.eventResults, { selects: [[], [], [], []] }],
      [schema.seasonParticipantSurfaceElos, { selects: [[]] }],
    ]);

    // Because our insertReturns is consumed once per test, re-queue per event
    // by overriding insert behaviour via the fake db options.
    const tournamentIds = ["t-1", "t-2", "t-3", "t-4"];
    let insertIdx = 0;
    const db: ReturnType<typeof makeFakeDb> = makeFakeDb({ tables, inserts });
    // Override insert for tournaments specifically to return sequential ids.
    db.insert.mockImplementation((table: unknown) => ({
      values: vi.fn().mockImplementation((row: unknown) => {
        const seen = inserts.get(table) ?? [];
        seen.push(row);
        inserts.set(table, seen);
        let returnRows: unknown[];
        if (table === schema.tournaments) {
          returnRows = [{ ...(row as object), id: tournamentIds[insertIdx++] }];
        } else {
          returnRows = [{ ...(row as object), id: "x" }];
        }
        return {
          returning: vi.fn().mockResolvedValue(returnRows),
          then: (resolve: (v: unknown) => unknown) =>
            Promise.resolve(returnRows).then(resolve),
        };
      }),
    }));

    vi.mocked(database).mockReturnValue(db as never);

    const report = await runBackfill({ dryRun: false });

    expect(report.tournamentsCreated).toBe(4);
    expect(report.tournamentsLinked).toBe(4);
    expect(inserts.get(schema.tournaments)).toHaveLength(4);
    expect(report.errors).toEqual([]);
  });
});

// ─── 3. re-running doesn't duplicate ──────────────────────────────────────

describe("runBackfill - idempotence", () => {
  it("does not create new tournaments when they already exist", async () => {
    const events = [
      makeEvent({ id: "ev-1", name: "Masters Tournament", eventDate: "2026-04-09" }),
    ];
    const existingTournament = {
      id: "t-existing",
      sportId: SPORT_ID,
      name: "Masters Tournament",
      year: 2026,
    };

    const inserts = new Map<unknown, unknown[]>();
    const updateCounts = new Map<unknown, number>();
    const tables = new Map<unknown, TableState>([
      [schema.sportsSeasons, { selects: [[GOLF_SEASON]] }],
      [
        schema.scoringEvents,
        {
          selects: [events, [{ ...events[0], tournamentId: "t-existing" }]],
        },
      ],
      [schema.tournaments, { selects: [[existingTournament]] }],
      [schema.seasonParticipants, { selects: [[]] }],
      [schema.eventResults, { selects: [[]] }],
      [schema.seasonParticipantSurfaceElos, { selects: [[]] }],
    ]);

    vi.mocked(database).mockReturnValue(
      makeFakeDb({ tables, inserts, updateCounts }) as never,
    );

    const report = await runBackfill({ dryRun: false });

    expect(report.tournamentsCreated).toBe(0);
    expect(report.tournamentsLinked).toBe(1);
    expect(inserts.get(schema.tournaments)).toBeUndefined();
  });
});

// ─── 4. participant backfill ───────────────────────────────────────────────

describe("runBackfill - participants", () => {
  it("creates canonical participants and links season_participants", async () => {
    const sps = [
      makeSeasonParticipant({ id: "sp-1", name: "Scottie Scheffler" }),
      makeSeasonParticipant({ id: "sp-2", name: "Rory McIlroy" }),
    ];

    const inserts = new Map<unknown, unknown[]>();
    const updateCounts = new Map<unknown, number>();
    const pIds = ["p-1", "p-2"];
    let pIdx = 0;

    const tables = new Map<unknown, TableState>([
      [schema.sportsSeasons, { selects: [[GOLF_SEASON]] }],
      [schema.scoringEvents, { selects: [[], []] }],
      [schema.seasonParticipants, { selects: [sps] }],
      [schema.participants, { selects: [[], []] }],
      [schema.eventResults, { selects: [] }],
      [schema.seasonParticipantSurfaceElos, { selects: [[]] }],
    ]);

    const db = makeFakeDb({ tables, inserts, updateCounts });
    db.insert.mockImplementation((table: unknown) => ({
      values: vi.fn().mockImplementation((row: unknown) => {
        const seen = inserts.get(table) ?? [];
        seen.push(row);
        inserts.set(table, seen);
        let returnRows: unknown[];
        if (table === schema.participants) {
          returnRows = [{ ...(row as object), id: pIds[pIdx++] }];
        } else {
          returnRows = [{ ...(row as object), id: "x" }];
        }
        return {
          returning: vi.fn().mockResolvedValue(returnRows),
          then: (resolve: (v: unknown) => unknown) =>
            Promise.resolve(returnRows).then(resolve),
        };
      }),
    }));

    vi.mocked(database).mockReturnValue(db as never);

    const report = await runBackfill({ dryRun: false });

    expect(report.participantsCreated).toBe(2);
    expect(report.participantsLinked).toBe(2);
    expect(inserts.get(schema.participants)).toHaveLength(2);
    expect(updateCounts.get(schema.seasonParticipants)).toBe(2);
  });
});

// ─── 5. Masters 2026 round-trip ───────────────────────────────────────────

describe("runBackfill - tournament_results from event_results", () => {
  it("copies placement and rawScore but NOT qualifying_points_awarded", async () => {
    const events = [
      makeEvent({
        id: "ev-masters",
        tournamentId: "t-masters",
        name: "Masters Tournament",
        eventDate: "2026-04-09",
      }),
    ];
    const seasonParticipant = {
      id: "sp-1",
      sportsSeasonId: SEASON_ID,
      participantId: "p-scottie",
      name: "Scottie Scheffler",
    };
    const eventResult = {
      id: "er-1",
      scoringEventId: "ev-masters",
      seasonParticipantId: "sp-1",
      placement: 1,
      rawScore: "-12.00",
      qualifyingPointsAwarded: "100.00",
    };

    const inserts = new Map<unknown, unknown[]>();

    const tables = new Map<unknown, TableState>([
      [schema.sportsSeasons, { selects: [[GOLF_SEASON]] }],
      [
        schema.scoringEvents,
        {
          // 1st: no unlinked events (tournamentId already set)
          // 2nd: refetch — events linked to tournament
          selects: [[], events],
        },
      ],
      [schema.tournaments, { selects: [] }],
      [schema.seasonParticipants, { selects: [[], [seasonParticipant]] }],
      [schema.participants, { selects: [] }],
      [schema.eventResults, { selects: [[eventResult]] }],
      [schema.tournamentResults, { selects: [[]] }],
      [schema.seasonParticipantSurfaceElos, { selects: [[]] }],
    ]);

    vi.mocked(database).mockReturnValue(
      makeFakeDb({ tables, inserts }) as never,
    );

    const report = await runBackfill({ dryRun: false });

    expect(report.tournamentResultsCreated).toBe(1);
    const trInserts = inserts.get(schema.tournamentResults) ?? [];
    expect(trInserts).toHaveLength(1);
    const inserted = trInserts[0] as Record<string, unknown>;
    expect(inserted.tournamentId).toBe("t-masters");
    expect(inserted.participantId).toBe("p-scottie");
    expect(inserted.placement).toBe(1);
    expect(inserted.rawScore).toBe("-12.00");
    // CRITICAL: qualifying_points_awarded must NOT be copied.
    expect(inserted).not.toHaveProperty("qualifyingPointsAwarded");
  });
});

// ─── 6. Surface elo conflict detection ────────────────────────────────────

describe("runBackfill - surface elo conflicts", () => {
  it("records a conflict error when two windows disagree on eloHard", async () => {
    const sp = {
      id: "sp-1",
      sportsSeasonId: SEASON_ID,
      participantId: "p-tennis-1",
      name: "Carlos Alcaraz",
    };
    const windowElo = {
      id: "se-1",
      participantId: "sp-1",
      sportsSeasonId: SEASON_ID,
      eloHard: 2050,
      eloClay: 2100,
      eloGrass: 2000,
      worldRanking: 2,
    };
    const existingCanonicalElo = {
      id: "cpe-1",
      participantId: "p-tennis-1",
      eloHard: 2000, // differs!
      eloClay: 2100,
      eloGrass: 2000,
      worldRanking: 2,
    };

    const inserts = new Map<unknown, unknown[]>();
    const tables = new Map<unknown, TableState>([
      [schema.sportsSeasons, { selects: [[GOLF_SEASON]] }],
      [schema.scoringEvents, { selects: [[], []] }],
      [schema.seasonParticipants, { selects: [[], [sp]] }],
      [schema.participants, { selects: [] }],
      [schema.eventResults, { selects: [] }],
      [schema.seasonParticipantSurfaceElos, { selects: [[windowElo]] }],
      [schema.participantSurfaceElos, { selects: [[existingCanonicalElo]] }],
    ]);

    vi.mocked(database).mockReturnValue(
      makeFakeDb({ tables, inserts }) as never,
    );

    const report = await runBackfill({ dryRun: false });

    expect(report.surfaceElosCreated).toBe(0);
    expect(report.errors).toHaveLength(1);
    expect(report.errors[0]).toMatch(/conflict for participant p-tennis-1/);
    expect(report.errors[0]).toMatch(/eloHard/);
    // Must not have inserted a conflicting row.
    expect(inserts.get(schema.participantSurfaceElos)).toBeUndefined();
  });
});