import { describe, expect, it } from "vitest";
import {
  activeHypothesis,
  beginHypothesis,
  createGameplayHistory,
  createSavepoint,
  deleteSavepoint,
  describeGameplayChange,
  finishHypothesis,
  gameplayMoment,
  recordGameplayMoment,
  restoreSavepoint,
  sessionFromGameplayState,
} from "../../src/state/playHistory";
import {
  createAidMemoire,
  enterAidMemoireCell,
} from "../../src/state/aidMemoire";
import { createSession } from "../../src/state/session";

describe("gameplay history", () => {
  it("records immutable states with useful move labels", () => {
    const initial = createSession([0, 0, 0, 0]);
    const changed = { ...initial, values: [0, 3, 0, 0] };
    const label = describeGameplayChange(initial, changed, 2);
    const history = recordGameplayMoment(
      createGameplayHistory(initial),
      changed,
      label,
    );

    expect(label).toBe("Set r1c2 to 3");
    expect(history.moments.map((moment) => moment.label)).toEqual([
      "Puzzle opened",
      "Set r1c2 to 3",
    ]);
    changed.values[1] = 4;
    expect(history.moments[1]!.state.values[1]).toBe(3);
  });

  it("creates, restores and deletes full named savepoints", () => {
    const session = createSession([0, 0, 0, 0]);
    session.values[1] = 2;
    session.centerMarks[2] = 5;
    session.colors[3] = 4;
    session.elapsedSeconds = 75;
    let history = createSavepoint(
      createGameplayHistory(session),
      session,
      "Before chain",
    );

    session.values[1] = 4;
    session.centerMarks[2] = 0;
    const transition = restoreSavepoint(history, history.savepoints[0]!.id);
    const restored = sessionFromGameplayState(transition.state);
    expect(restored.values[1]).toBe(2);
    expect(restored.centerMarks[2]).toBe(5);
    expect(restored.colors[3]).toBe(4);
    expect(restored.elapsedSeconds).toBe(75);
    expect(transition.history.moments.at(-1)?.label).toBe(
      "Restored “Before chain”",
    );

    history = deleteSavepoint(
      transition.history,
      transition.history.savepoints[0]!.id,
    );
    expect(history.savepoints).toHaveLength(0);
  });

  it("captures aid-mémoire state in moments and savepoints", () => {
    const session = createSession([0, 0, 0, 0]);
    let aidMemoire = createAidMemoire(2, {
      enabled: true,
      cellCount: 2,
    });
    aidMemoire = enterAidMemoireCell(aidMemoire, 0, "value", 1, 2);
    const history = createSavepoint(
      createGameplayHistory(session, aidMemoire),
      session,
      "Scratch one",
      aidMemoire,
    );

    aidMemoire = enterAidMemoireCell(aidMemoire, 0, "value", 2, 2);
    const restored = restoreSavepoint(history, history.savepoints[0]!.id);
    expect(restored.state.aidMemoire?.cells[0]?.value).toBe(1);
    expect(history.moments[0]?.state.aidMemoire?.cells[0]?.value).toBe(1);
    expect(aidMemoire.cells[0]?.value).toBe(2);
  });

  it("keeps discarded hypotheses available while restoring their exact base", () => {
    const session = createSession([0, 0, 0, 0]);
    session.values[0] = 1;
    let transition = beginHypothesis(
      createGameplayHistory(session),
      session,
      "Try a 2",
    );
    expect(activeHypothesis(transition.history)?.name).toBe("Try a 2");

    const branchSession = sessionFromGameplayState(transition.state);
    branchSession.values[1] = 2;
    transition = {
      history: recordGameplayMoment(
        transition.history,
        branchSession,
        "Set r1c2 to 2",
      ),
      state: transition.state,
    };
    const result = finishHypothesis(
      transition.history,
      branchSession,
      "discard",
    );

    expect(result.state.values).toEqual([1, 0, 0, 0]);
    expect(result.history.branches[0]?.status).toBe("discarded");
    expect(
      result.history.moments.some(
        (moment) =>
          moment.branchId === result.history.branches[0]!.id &&
          moment.state.values[1] === 2,
      ),
    ).toBe(true);
    expect(result.history.moments.at(-1)?.label).toBe(
      "Discarded hypothesis “Try a 2”",
    );
  });

  it("can branch from a replayed moment and merge accepted changes", () => {
    const initial = createSession([0, 0, 0, 0]);
    const first = { ...initial, values: [1, 0, 0, 0] };
    const second = { ...initial, values: [1, 2, 0, 0] };
    let history = recordGameplayMoment(
      createGameplayHistory(initial),
      first,
      "First move",
    );
    const replayId = history.currentMomentId;
    history = recordGameplayMoment(history, second, "Second move");

    let transition = beginHypothesis(history, second, "Alternative", replayId);
    expect(transition.state.values).toEqual([1, 0, 0, 0]);
    const alternative = sessionFromGameplayState(transition.state);
    alternative.values[2] = 3;
    transition = {
      history: recordGameplayMoment(
        transition.history,
        alternative,
        "Alternative move",
      ),
      state: transition.state,
    };
    const kept = finishHypothesis(transition.history, alternative, "keep");

    expect(kept.state.values).toEqual([1, 0, 3, 0]);
    expect(kept.history.branches.at(-1)?.status).toBe("kept");
    expect(
      gameplayMoment(kept.history, kept.history.currentMomentId)?.label,
    ).toBe("Kept hypothesis “Alternative”");
  });

  it("rejects blank checkpoint and hypothesis names", () => {
    const session = createSession([0, 0, 0, 0]);
    const history = createGameplayHistory(session);
    expect(() => createSavepoint(history, session, "   ")).toThrow(
      "Savepoint name cannot be empty",
    );
    expect(() => beginHypothesis(history, session, "   ")).toThrow(
      "Hypothesis name cannot be empty",
    );
  });
});