'use strict';

const test = require('node:test');
const assert = require('node:assert/strict');

const MovementExecutor = require('../../src/movement/movementExecutor');

function mkSchedule(commands, tStarS = 0, tickS = 1) {
    return { tStarS, tickS, commands };
}

const noopLogger = { debug() {}, info() {}, warn() {}, error() {} };

test('executor: throws if fireCommand callback missing', () => {
    assert.throws(() => new MovementExecutor({}), TypeError);
});

test('executor: fires commands whose fireAtTickN <= cursor', async () => {
    const fired = [];
    const ex = new MovementExecutor({
        fireCommand: (c) => fired.push(c),
        logger: noopLogger,
    });
    ex.replan(mkSchedule([
        { machineId: 'A', action: 'flowmovement', flow: 60, fireAtTickN: 0, eta: 0 },
        { machineId: 'B', action: 'flowmovement', flow: 40, fireAtTickN: 2, eta: 2 },
        { machineId: 'C', action: 'flowmovement', flow: 30, fireAtTickN: 5, eta: 5 },
    ]));
    let firedThisTick = await ex.tick();
    assert.equal(firedThisTick.length, 1);
    assert.equal(firedThisTick[0].machineId, 'A');
    firedThisTick = await ex.tick();
    assert.equal(firedThisTick.length, 0);
    firedThisTick = await ex.tick();
    assert.equal(firedThisTick.length, 1);
    assert.equal(firedThisTick[0].machineId, 'B');
    await ex.tick(); await ex.tick();
    firedThisTick = await ex.tick();
    assert.equal(firedThisTick.length, 1);
    assert.equal(firedThisTick[0].machineId, 'C');

    assert.deepEqual(fired.map((c) => c.machineId), ['A', 'B', 'C']);
    assert.equal(ex.pending(), 0);
});

test('executor: replan drops unfired commands and resets cursor', async () => {
    const fired = [];
    const ex = new MovementExecutor({ fireCommand: (c) => fired.push(c.machineId), logger: noopLogger });

    ex.replan(mkSchedule([
        { machineId: 'A', action: 'flowmovement', flow: 60, fireAtTickN: 0, eta: 0 },
        { machineId: 'B', action: 'flowmovement', flow: 40, fireAtTickN: 10, eta: 10 },
    ]));
    await ex.tick(); // A fires
    assert.deepEqual(fired, ['A']);
    assert.equal(ex.pending(), 1);

    ex.replan(mkSchedule([
        { machineId: 'X', action: 'flowmovement', flow: 80, fireAtTickN: 0, eta: 0 },
        { machineId: 'Y', action: 'flowmovement', flow: 20, fireAtTickN: 3, eta: 3 },
    ]));
    assert.equal(ex.cursor(), 0, 'cursor reset on replan');
    await ex.tick(); // X fires
    assert.deepEqual(fired, ['A', 'X']);
    await ex.tick(); await ex.tick(); await ex.tick();
    assert.ok(!fired.includes('B'), 'old B move was dropped by replan');
    assert.ok(fired.includes('Y'), 'new Y move fired after delay');
});

test('executor: fires only once per command even across many ticks', async () => {
    const fired = [];
    const ex = new MovementExecutor({ fireCommand: (c) => fired.push(c.machineId), logger: noopLogger });
    ex.replan(mkSchedule([
        { machineId: 'A', action: 'flowmovement', flow: 60, fireAtTickN: 0, eta: 0 },
    ]));
    for (let i = 0; i < 5; i++) await ex.tick();
    assert.deepEqual(fired, ['A']);
});

test('executor: catches fireCommand errors and continues', async () => {
    const fired = [];
    const ex = new MovementExecutor({
        fireCommand: (c) => {
            if (c.machineId === 'B') throw new Error('boom');
            fired.push(c.machineId);
        },
        logger: noopLogger,
    });
    ex.replan(mkSchedule([
        { machineId: 'A', action: 'flowmovement', flow: 60, fireAtTickN: 0, eta: 0 },
        { machineId: 'B', action: 'flowmovement', flow: 40, fireAtTickN: 0, eta: 0 },
        { machineId: 'C', action: 'flowmovement', flow: 30, fireAtTickN: 0, eta: 0 },
    ]));
    await ex.tick();
    // B's error must not block A or C.
    assert.deepEqual(fired, ['A', 'C']);
});

test('executor: empty / null schedule is safe to tick', async () => {
    const ex = new MovementExecutor({ fireCommand: () => {}, logger: noopLogger });
    assert.deepEqual(await ex.tick(), []);
    ex.replan({ commands: [] });
    assert.deepEqual(await ex.tick(), []);
});

test('executor: tick fires commands synchronously and does NOT await their promises', async () => {
    // Contract: tick() returns as soon as every due fireCommand has been
    // invoked. It does NOT wait for the returned promises to resolve.
    // This matters because a flowmovement-after-startup resolves only
    // after the pump's entire ramp completes — awaiting it would freeze
    // the executor's wall-clock progression and drag every delayed
    // command in the schedule forward by that duration.
    const order = [];
    let resolveFire;
    const firePromise = new Promise((r) => { resolveFire = r; });
    const ex = new MovementExecutor({
        fireCommand: (c) => {
            order.push(`fire-start-${c.machineId}`);
            return firePromise.then(() => { order.push(`fire-end-${c.machineId}`); });
        },
        logger: noopLogger,
    });
    ex.replan(mkSchedule([
        { machineId: 'A', action: 'flowmovement', flow: 60, fireAtTickN: 0, eta: 0 },
    ]));
    const tickPromise = ex.tick().then(() => order.push('tick-resolved'));
    // Wait one microtask cycle: tick should already have resolved even
    // though fire is still pending.
    await new Promise((r) => setTimeout(r, 10));
    assert.deepEqual(order, ['fire-start-A', 'tick-resolved'],
        'tick must resolve immediately after invoking fireCommand — not wait for its promise');
    resolveFire();
    await tickPromise;
    // The fire's tail runs in the background and lands after tick resolved.
    assert.deepEqual(order, ['fire-start-A', 'tick-resolved', 'fire-end-A']);
});