import { describe, it, expect } from 'vitest';
import { createPointer, advance, enterSubPlan, exitSubPlan, currentPath, isDone } from './step-pointer.mjs';

describe('step-pointer (волны: линейный → дерево указателей, D6/OQ1)', () => {
  it('линейное продвижение даёт путь [n]', () => {
    let p = createPointer({ length: 3 });
    expect(currentPath(p)).toEqual([0]);
    p = advance(p); expect(currentPath(p)).toEqual([1]);
  });
  it('вход в под-план углубляет путь, выход возвращает', () => {
    let p = createPointer({ length: 2 });
    p = enterSubPlan(p, { length: 2 });
    expect(currentPath(p)).toEqual([0, 0]);
    p = advance(p); expect(currentPath(p)).toEqual([0, 1]);
    p = exitSubPlan(p);
    p = advance(p); expect(currentPath(p)).toEqual([1]);
  });
  it('isDone когда корень исчерпан', () => {
    let p = createPointer({ length: 1 });
    expect(isDone(p)).toBe(false);
    p = advance(p);
    expect(isDone(p)).toBe(true);
  });
  it('линейный режим обратно совместим (один уровень = число indexAtRoot)', () => {
    let p = createPointer({ length: 5 });
    p = advance(advance(p));
    expect(p.indexAtRoot).toBe(2);
  });
});

// ── R-08: сериализация + дерево-навигация ──
import { serializePointer, deserializePointer, nodeAt, isContainer, normalizeToLeaf, advanceOverTree, MAX_TREE_DEPTH } from './step-pointer.mjs';

const FLAT = [{ n: 1, op: 'Write', object: 'a' }, { n: 2, op: 'Bash', object: 'b' }];
const TREE = [
  { n: 1, op: 'Write', object: 'a' },
  { n: 2, substeps: [{ n: '2.1', op: 'Edit', object: 'x' }, { n: '2.2', op: 'Bash', object: 'y' }] },
  { n: 3, op: 'Write', object: 'c' },
];

describe('serialize/deserialize (§4.0: depth-1 = целое)', () => {
  it('depth-1 ↔ целое', () => {
    expect(serializePointer(createPointer({ length: 3 }))).toBe(0);
    expect(serializePointer(advance(createPointer({ length: 3 })))).toBe(1);
    expect(deserializePointer(1, FLAT).stack).toEqual([{ index: 1, length: 2 }]);
  });
  it('глубже ↔ массив индексов', () => {
    let p = enterSubPlan(advance(createPointer({ length: 3 })), { length: 2 });
    p = advance(p);
    expect(serializePointer(p)).toEqual([1, 1]);
    const d = deserializePointer([1, 1], TREE);
    expect(d.stack).toEqual([{ index: 1, length: 3 }, { index: 1, length: 2 }]);
  });
  it('строгий deserialize: мусор → null (SE-5)', () => {
    expect(deserializePointer('x', FLAT)).toBe(null);
    expect(deserializePointer([0, 'a'], TREE)).toBe(null);
    expect(deserializePointer(-1, FLAT)).toBe(null);
    expect(deserializePointer([1, 0], FLAT)).toBe(null);
  });
});

describe('nodeAt / isContainer', () => {
  it('nodeAt следует currentPath', () => {
    expect(nodeAt(TREE, deserializePointer(0, TREE)).n).toBe(1);
    expect(nodeAt(TREE, deserializePointer([1, 1], TREE)).n).toBe('2.2');
    expect(nodeAt(TREE, deserializePointer(9, TREE))).toBe(null);
  });
  it('isContainer', () => {
    expect(isContainer(TREE[1])).toBe(true);
    expect(isContainer(TREE[0])).toBe(false);
    expect(isContainer({ substeps: [] })).toBe(true);
  });
});

describe('normalizeToLeaf (спуск к листу, SE-2)', () => {
  it('лист → сам', () => {
    expect(nodeAt(TREE, normalizeToLeaf(TREE, deserializePointer(0, TREE))).n).toBe(1);
  });
  it('контейнер → спуск к первому листу', () => {
    const p = normalizeToLeaf(TREE, deserializePointer(1, TREE));
    expect(serializePointer(p)).toEqual([1, 0]);
    expect(nodeAt(TREE, p).n).toBe('2.1');
  });
  it('за концом → null', () => {
    expect(normalizeToLeaf(TREE, deserializePointer(9, TREE))).toBe(null);
  });
  it('плоский план: normalizeToLeaf — тождество', () => {
    expect(serializePointer(normalizeToLeaf(FLAT, deserializePointer(1, FLAT)))).toBe(1);
  });
});

describe('advanceOverTree (depth-first, SE-4/SE-6)', () => {
  it('плоский: +1 как целое', () => {
    const p = deserializePointer(0, FLAT);
    expect(serializePointer(advanceOverTree(FLAT, p))).toBe(1);
  });
  it('depth-first полный обход листьев TREE (snapshot, без пропусков/повторов)', () => {
    let p = normalizeToLeaf(TREE, deserializePointer(0, TREE));
    const seq = [];
    let guard = 0;
    while (p && nodeAt(TREE, p) && guard++ < 20) {
      seq.push(nodeAt(TREE, p).n);
      p = advanceOverTree(TREE, p);
    }
    expect(seq).toEqual([1, '2.1', '2.2', 3]);
  });
  it('предел глубины → throw (SE-4)', () => {
    const deep = (d) => d === 0 ? [{ n: 'leaf', op: 'Write', object: 'z' }] : [{ substeps: deep(d - 1) }];
    const bad = deep(MAX_TREE_DEPTH + 2);
    expect(() => normalizeToLeaf(bad, createPointer({ length: bad.length }))).toThrow();
  });
});