const { ButtonMachine } = require('../../src/node_modules/buttons');

const run_code = (expecting, code, debug=false) => {
  let machine = new ButtonMachine(code);

  machine.run(debug);

  expect(machine.stack_top).toBe(expecting);

  return machine;
}

it('Can do addition', () => {
  run_code(3, [
    ['PUSH', 1],
    ['PUSH', 2],
    ['ADD'],
  ])
});

it('Can do subtraction', () => {
  run_code(1, [
    ['PUSH', 2],
    ['PUSH', 1],
    ['SUB'],
  ])
})

it('Can do multiplication', () => {
  run_code(20, [
    ['PUSH', 10],
    ['PUSH', 2],
    ['MUL'],
  ])
})

it('Can do division', () => {
  run_code(5, [
    ['PUSH', 10],
    ['PUSH', 2],
    ['DIV'],
  ])
})

it('Can do modulus', () => {
  run_code(0, [
    ['PUSH', 10],
    ['PUSH', 2],
    ['MOD'],
  ])
})

it('Can loop until the end of ticks', () => {
  run_code(43, [
    ['PUSH', 1],
    ['PUSH', 1],
    ['ADD'],
    ['JUMP', 1]
  ]);
});


it('Can do zero test for jump', () => {
  run_code(0, [
    ['PUSH', 20], // start at 20
    ['PUSH', 1],  // decrement by 1
    ['SUB'],      
    ['JZ', 5],    // if we're at 0 jumps to the end
    ['JUMP', 1]   // the previous test fails so it jumps to loop again
  ]);
});


it('Can do NOT zero test for jump', () => {
  run_code(-19, [
    ['PUSH', -20], // start at 20
    ['PUSH', 1],  // decrement by 1
    ['ADD'],      
    ['JNZ', 5],    // if we're at 0 jumps to the end
    ['JUMP', 1]    // the previous test fails so it jumps to loop again
  ]);
});

it('Can store and restor', () => {
  run_code(150, [
    ['PUSH', 100],    // start with 100
    ['STOR', 'AX'], // put it in the regA register
    ['PUSH', 50],     // push 50 on too
    ['ADD'],          // add those for 150
    ['RSTOR', 'AX'],// recover the original 100
    ['SUB']           // sub and should be 150
  ]);
});

it('Halts on bad registers', () => {
  run_code(0, [
    ['PUSH', 0],
    ['STOR', 'AX'],
    ['RSTOR', 'BAD NAME'], // should cause a halt here
    ['PUSH', 100],
    ['ADD']
  ]);
});

it('Can halt on purpose', () => {
  let machine = run_code(0, [
   ['PUSH', 0],
   ['HALT', 'Done on purpose.']
  ]);

  expect(machine.halted).toBe(true);
  expect(machine.error).toBe('Done on purpose.');
});