-- Eventloop behavior tests for the CraftOS-PC harness.
-- Invoked via `craftos --headless --script tests/eventloop.lua` from `just test`.
local createEventLoop = require('/apis/eventloop');

local args = { ... };
local verbose = false;
local tests = {};

for _, arg in ipairs(args) do
  if arg == '--verbose' then
    verbose = true;
  end
end

local function test(name, fn)
  tests[#tests + 1] = { name = name, fn = fn };
end

local function fail(message)
  error(message, 2);
end

local function assertEquals(actual, expected, message)
  if actual ~= expected then
    fail((message or 'assertEquals failed') .. ': expected ' .. tostring(expected) .. ', got ' .. tostring(actual));
  end
end

local function assertTrue(value, message)
  if not value then
    fail(message or 'assertTrue failed');
  end
end

local function assertErrors(fn, expected)
  local ok, err = pcall(fn);
  if ok then
    fail('expected error');
  end
  if expected and not string.find(tostring(err), expected, 1, true) then
    fail('expected error containing ' .. expected .. ', got ' .. tostring(err));
  end
end

test('register dispatches queued event args', function()
  local events = createEventLoop();
  local called = 0;

  events.register('eventloop_test_basic', function(a, b)
    called = called + 1;
    assertEquals(a, 'first');
    assertEquals(b, 42);
    events.stopLoop();
  end);

  os.queueEvent('eventloop_test_basic', 'first', 42);
  events.runLoop();

  assertEquals(called, 1);
  assertTrue(not events.isRunningLoop());
end);

test('STOP unregisters handler after first call', function()
  local events = createEventLoop();
  local stoppedHandlerCalls = 0;
  local observerCalls = 0;

  events.register('eventloop_test_stop', function()
    stoppedHandlerCalls = stoppedHandlerCalls + 1;
    return events.STOP;
  end);

  events.register('eventloop_test_stop', function()
    observerCalls = observerCalls + 1;
    if observerCalls == 1 then
      os.queueEvent('eventloop_test_stop');
    else
      events.stopLoop();
    end
  end);

  os.queueEvent('eventloop_test_stop');
  events.runLoop();

  assertEquals(stoppedHandlerCalls, 1);
  assertEquals(observerCalls, 2);
end);

test('manual unregister prevents dispatch', function()
  local events = createEventLoop();
  local called = 0;
  local dispose = events.register('eventloop_test_unregister', function()
    called = called + 1;
  end);

  events.setTimeout(function()
    events.stopLoop();
  end, 0);
  dispose();

  os.queueEvent('eventloop_test_unregister');
  events.runLoop();

  assertEquals(called, 0);
end);

test('setTimeout before runLoop fires once', function()
  local events = createEventLoop();
  local called = 0;

  events.setTimeout(function()
    called = called + 1;
    events.stopLoop();
  end, 0);

  events.runLoop();

  assertEquals(called, 1);
end);

test('setTimeout during runLoop fires after event handler', function()
  local events = createEventLoop();
  local order = '';

  events.register('eventloop_test_runtime_timeout', function()
    order = order .. 'event>';
    events.setTimeout(function()
      order = order .. 'timeout';
      events.stopLoop();
    end, 0);
    return events.STOP;
  end);

  os.queueEvent('eventloop_test_runtime_timeout');
  events.runLoop();

  assertEquals(order, 'event>timeout');
end);

test('cleared timeout before runLoop does not fire', function()
  local events = createEventLoop();
  local called = 0;

  local clear = events.setTimeout(function()
    called = called + 1;
  end, 0);
  clear();

  events.setTimeout(function()
    events.stopLoop();
  end, 0);
  events.runLoop();

  assertEquals(called, 0);
end);

test('onStart and onStop run around loop', function()
  local events = createEventLoop();
  local order = '';

  events.onStart(function()
    order = order .. 'start>';
  end);

  events.onStop(function()
    order = order .. 'stop';
  end);

  events.setTimeout(function()
    order = order .. 'timeout>';
    events.stopLoop();
  end, 0);

  events.runLoop();

  assertEquals(order, 'start>timeout>stop');
end);

test('empty loop returns and runs onStop', function()
  local events = createEventLoop();
  local stopped = false;

  events.onStop(function()
    stopped = true;
  end);

  events.runLoop();

  assertTrue(stopped);
  assertTrue(not events.isRunningLoop());
end);

test('error contracts are enforced', function()
  local events = createEventLoop();
  local function handler()
  end

  events.register('eventloop_test_errors', handler);

  assertErrors(function()
    events.register('eventloop_test_errors', handler);
  end, 'handler already registered');

  assertErrors(function()
    events.stopLoop();
  end, 'loop is already stopped');

  assertErrors(function()
    events.register(1, handler);
  end, 'string expected');

  assertErrors(function()
    events.register('eventloop_test_errors_2', 'not a function');
  end, 'function expected');
end);

for _, t in ipairs(tests) do
  if verbose then
    print('RUN ' .. t.name);
  end
  local ok, err = pcall(t.fn);
  if not ok then
    print('FAIL ' .. t.name .. ': ' .. tostring(err));
    os.shutdown();
  end
end

print('__READY__');
os.shutdown();