import pytest
from calculate.utils.files import Process
from subprocess import run, PIPE


@pytest.mark.files_utils
class TestUtils():
    def test_if_single_correct_command_executed_using_Process_object__it_successfully_executes(self):
        try:
            ls_process = Process('ls', '-a', cwd='/')
            ls_result = run('ls -a', shell=True, stdout=PIPE, cwd='/')
        except Exception as error:
            print('error:', str(error))
            assert False

        output = ls_process.read().strip()
        result = ls_result.stdout.decode().strip()
        assert output == result

    def test_if_pipe_is_executed_using_Process_object__it_has_successfully_executed(self):
        try:
            pipe = Process('grep', 'VGA',
                           stdin=Process('/usr/sbin/lspci')
                           )
            pipe_result = run('/usr/sbin/lspci | grep "VGA"', shell=True, stdout=PIPE)
        except Exception as error:
            print('error:', str(error))
            assert False

        output = pipe.read().strip()
        result = pipe_result.stdout.decode().strip()
        assert output == result

    def test_if_a_pipe_Process_object_uses_for_several_writes_without_readings__it_successfully_executes(self):
        input_lines = ['KEY: important line.\n',
                       'NONE: not important line.\n',
                       'NONE: nothing interesting.\n',
                       'KEY: another line.\n']

        output_text = 'KEY: important line.\nKEY: another line.\n'

        try:
            pipe = Process('grep', 'KEY',
                           stdin=Process('cat', stdin=PIPE)
                           )
        except Exception as error:
            print('error:', str(error))
            assert False

        for line in input_lines:
            pipe.write(line)
        output = pipe.read()
        assert output == output_text

    def test_if_a_pipe_Process_object_uses_for_several_writes__it_successfully_executes_even_after_read(self):
        input_lines = ['KEY: important line.\n',
                       'NONE: not important line.\n',
                       'NONE: nothing interesting.\n',
                       'KEY: another line.\n']

        output_lines = ['KEY: important line.\n',
                        'KEY: another line.\n']

        try:
            pipe = Process('grep', 'KEY',
                           stdin=Process('cat', stdin=PIPE)
                           )
        except Exception as error:
            print('error:', str(error))
            assert False

        output = []
        for line in input_lines:
            pipe.write(line)
            output_line = pipe.read()

            if output_line:
                output.append(output_line)
        assert output == output_lines