"""
Test that build time memory limits are actually enforced.

We give the container image at least 128M of RAM (so base things like
apt and pip can run), and then try to allocate & use 256MB in postBuild.
This should fail!
"""
import os
import subprocess
import time

def does_build(builddir, mem_limit, mem_allocate_mb):
    mem_allocate_mb_file = os.path.join(builddir, 'mem_allocate_mb')

    # Cache bust so we actually do a rebuild each time this is run!
    with open(os.path.join(builddir, 'cachebust'), 'w') as cachebust:
        cachebust.write(str(time.time()))

    try:
        # we don't have an easy way to pass env vars or whatever to
        # postBuild from here, so we write a file into the repo that is
        # read by the postBuild script!
        with open(mem_allocate_mb_file, 'w') as f:
            f.write(str(mem_allocate_mb))
        try:
            output = subprocess.check_output(
                [
                    'repo2docker',
                    '--no-run',
                    '--build-memory-limit', '{}M'.format(mem_limit),
                    builddir
                ],
                stderr=subprocess.STDOUT,
            ).decode()
            print(output)
            return True
        except subprocess.CalledProcessError as e:
            output = e.output.decode()
            print(output)
            if "/postBuild' returned a non-zero code: 137" in output:
                return False
            else:
                raise
    finally:
        os.remove(mem_allocate_mb_file)



def test_memlimit_nondockerfile_fail():
    """
    Test if memory limited builds are working for non dockerfile builds
    """
    basedir = os.path.dirname(__file__)
    assert not does_build(
        os.path.join(basedir, 'memlimit/non-dockerfile'),
        128,
        256
    )
    assert does_build(
        os.path.join(basedir, 'memlimit/non-dockerfile'),
        512,
        256
    )


def test_memlimit_dockerfile_fail():
    """
    Test if memory limited builds are working for dockerfile builds
    """
    basedir = os.path.dirname(__file__)
    assert not does_build(
        os.path.join(basedir, 'memlimit/dockerfile'),
        128,
        256
    )

    assert does_build(
        os.path.join(basedir, 'memlimit/dockerfile'),
        512,
        256
    )


def test_memlimit_same_postbuild():
    """
    Validate that the postBuild files for dockerfile & nondockerfile are same

    Until https://github.com/jupyter/repo2docker/issues/160 gets fixed.
    """
    basedir = os.path.dirname(__file__)
    filepaths = [
        os.path.join(basedir, 'memlimit', t, "postBuild")
        for t in ("dockerfile", "non-dockerfile")
    ]
    file_contents = []
    for fp in filepaths:
        with open(fp) as f:
            file_contents.append(f.read())
    # Make sure they're all the same
    assert len(set(file_contents)) == 1