#!/usr/bin/env python

# Copyright 2016 Attic Labs, Inc. All rights reserved.
# Licensed under the Apache License, version 2.0:
# http://www.apache.org/licenses/LICENSE-2.0

'''
This script builds the Noms Go binaries for several OS/ARCH combinations and
generates a tar.gz of the binaries for each of those platforms.
'''

import copy
import os
import os.path
import shutil
import subprocess
import sys

# The list of platforms for which we should execute builds on the following packages
PLATFORMS = [
    ('darwin', 'amd64'),
    ('linux', 'amd64'),
    ('linux', 'arm'),
]

# The list of Go packages for which we should build binaries
PACKAGES = [
    './cmd/noms',
    './samples/go/counter',
    './samples/go/csv/csv-analyze',
    './samples/go/csv/csv-export',
    './samples/go/csv/csv-import',
    # './samples/go/hr',
    './samples/go/json-import',
    './samples/go/nomdex',
    './samples/go/poke',
    './samples/go/url-fetch',
    './samples/go/xml-import',
]

def call_with_env_and_cwd(cmd, env, cwd):
    """Executes a subprocess, waits for it to finish and asserts the return code is zero"""
    print cmd
    proc = subprocess.Popen(cmd, env=env, cwd=cwd, shell=False)
    proc.wait()
    assert proc.returncode == 0

def main():
    """Asserts environment variables and file system is appropriate before executing builds"""
    # Workspace is the root of the Jenkins builder, e.g. "/var/lib/jenkins/workspace/builder".
    workspace = os.getenv('WORKSPACE')
    assert workspace

    # Git SHA revision identifier to insert into built binaries
    # following lead of `git describe --always` in abbreviating to first 7 characters
    noms_rev = os.getenv('NOMS_REVISION')
    assert noms_rev
    noms_rev = noms_rev[:7]

    noms_src_dir = os.path.join(workspace, 'src/github.com/attic-labs/noms')
    assert os.path.isdir(noms_src_dir)

    noms_output_dir = os.path.join(noms_src_dir, 'build_output')
    if os.path.exists(noms_output_dir):
        shutil.rmtree(noms_output_dir)
    os.mkdir(noms_output_dir)
    assert os.path.isdir(noms_output_dir)

    for osname, cpuarch in PLATFORMS:
        osarch = '%s-%s' % (osname, cpuarch)
        platform_output_dir = os.path.join(noms_output_dir, osarch)
        os.mkdir(platform_output_dir)
        assert os.path.isdir(platform_output_dir)

        env = copy.copy(os.environ)
        env.update({
            'GOOS': osname,
            'GOARCH': cpuarch,
            'GOPATH': workspace,
        })

        # Using 'go build' instead of 'go install' per the recommendation:
        # http://dave.cheney.net/2015/08/22/cross-compilation-with-go-1-5
        for pkg in PACKAGES:
            pkg_output_file = os.path.join(platform_output_dir, os.path.basename(pkg))
            # cmd: go build -o pkg_output_file -ldFlags "-X file.Constant=value" package
            cmd = ['go', 'build', '-o', pkg_output_file, '-ldflags',
                   '-X github.com/attic-labs/noms/go/constants.NomsGitSHA=' + noms_rev,
                   pkg]
            call_with_env_and_cwd(cmd, env, noms_src_dir)
            if not os.path.isfile(pkg_output_file):
                print 'Unable to find built binary - %s' % pkg_output_file
                sys.exit(1)

        platform_targz_file = os.path.join(noms_output_dir,
                                           'noms-%s-%s' % (noms_rev, osarch))
        shutil.make_archive(platform_targz_file, 'gztar', platform_output_dir)
        shutil.rmtree(platform_output_dir)
        if not os.path.isfile(platform_targz_file + '.tar.gz'):
            print 'Unable to find built archive - %s' % platform_targz_file
            sys.exit(1)

if __name__ == '__main__':
    main()