local CircularBuffer = require('circular-buffer')

describe('circular-buffer', function()
  it('reading an empty buffer throws a BufferEmptyException', function()
    local buffer = CircularBuffer:new(1)
    assert.has_error((function() buffer:read() end), 'buffer is empty')
  end)

  it('write and read back one item', function()
    local buffer = CircularBuffer:new(1)
    buffer:write('1')
    assert.are.equals('1', buffer:read())
    assert.has_error((function() buffer:read() end), 'buffer is empty')
  end)

  it('write and read back multiple items', function()
    local buffer = CircularBuffer:new(2)
    buffer:write('1')
    buffer:write('2')
    assert.are.equals('1', buffer:read())
    assert.are.equals('2', buffer:read())
    assert.has_error((function() buffer:read() end), 'buffer is empty')
  end)

  it('clearing a buffer', function()
    local buffer = CircularBuffer:new(2)
    buffer:write('1')
    buffer:write('2')
    buffer:clear()
    assert.has_error((function() buffer:read() end), 'buffer is empty')
    buffer:write('3')
    buffer:write('4')
    assert.are.equals('3', buffer:read())
    assert.are.equals('4', buffer:read())
  end)

  it('alternate write and read', function()
    local buffer = CircularBuffer:new(2)
    buffer:write('1')
    assert.are.equals('1', buffer:read())
    buffer:write('2')
    assert.are.equals('2', buffer:read())
  end)

  it('reads back oldest item', function()
    local buffer = CircularBuffer:new(3)
    buffer:write('1')
    buffer:write('2')
    buffer:read()
    buffer:write('3')
    assert.are.equals('2', buffer:read())
    assert.are.equals('3', buffer:read())
  end)

  it('writes of nil do not occupy buffer', function()
    local buffer = CircularBuffer:new(3)
    buffer:write(nil)
    for i = 1, 3 do
      buffer:write(tostring(i))
    end
    assert.are.equals('1', buffer:read())
  end)

  it('writing to a full buffer throws a BufferFullException', function()
    local buffer = CircularBuffer:new(2)
    buffer:write('1')
    buffer:write('2')
    assert.has_error((function() buffer:write('A') end), 'buffer is full')
  end)

  it('forced writes over write oldest item in a full buffer', function()
    local buffer = CircularBuffer:new(2)
    buffer:write('1')
    buffer:write('2')
    buffer:forceWrite('A')
    assert.are.equals('2', buffer:read())
    assert.are.equals('A', buffer:read())
    assert.has_error((function() buffer:read() end), 'buffer is empty')
  end)

  it('forced writes act like normal writes in a non-full buffer', function()
    local buffer = CircularBuffer:new(2)
    buffer:write('1')
    buffer:forceWrite('2')
    assert.are.equals('1', buffer:read())
    assert.are.equals('2', buffer:read())
    assert.has_error((function() buffer:read() end), 'buffer is empty')
  end)

  it('alternate force write and read into full buffer', function()
    local buffer = CircularBuffer:new(5)
    for i = 1, 3 do
      buffer:write(tostring(i))
    end
    buffer:read()
    buffer:read()
    buffer:write('4')
    buffer:read()
    for i = 5, 8 do
      buffer:write(tostring(i))
    end
    buffer:forceWrite('A')
    buffer:forceWrite('B')
    assert.are.equals('6', buffer:read())
    assert.are.equals('7', buffer:read())
    assert.are.equals('8', buffer:read())
    assert.are.equals('A', buffer:read())
    assert.are.equals('B', buffer:read())
    assert.has_error((function() buffer:read() end), 'buffer is empty')
  end)
end)