from __future__ import print_function
from __future__ import absolute_import
from __future__ import division

import os
import glob
import subprocess
from distutils import sysconfig
from distutils.version import StrictVersion
from SCons.Errors import BuildError
from SCons.Environment import Environment

# Useful constants
try:
    RATROOT = os.environ["RATROOT"]
except KeyError:
    RATROOT = ""

RATCONFIGDIR = os.path.join(RATROOT, "config")
RATENVFILE = os.path.join(RATCONFIGDIR, "RAT.scons")
PSQLENVFILE = os.path.join(RATCONFIGDIR, "PSQL.scons")

try:
    ROOTSYS = os.path.join(os.environ["ROOTSYS"], 'bin')
except KeyError:
    ROOTSYS = ""

try:
    rootarch_cmd = [os.path.join(ROOTSYS, "root-config"), "--arch"]
    p_ra = subprocess.Popen(rootarch_cmd, universal_newlines=True, stdout=subprocess.PIPE)
    ROOTARCH = p_ra.communicate()[0].strip()
except OSError:
    # If architecture cannot be extracted, use generic GCC default.
    ROOTARCH = "gcc"


def testenv(envname):
    '''
    Test for the presence of an environment var and if it set to 1.
    '''
    return envname in os.environ and os.environ[envname] == '1'

def rat_path(*args):
    '''
    Returns the canonical path to join(RATROOT, *args) by
    eliminating any symbolic links encountered in the path.
    Without this, scons will rebuild everything when compiling
    over NFS.
    '''
    return os.path.realpath(os.path.join(RATROOT, *args))

def build_list(src_paths, build_dir, exclude=()):
    '''
    Construct a list of build targets from a source path or paths.
    '''
    # Check if first argument is a list or string or patterns.
    if isinstance(src_paths, (tuple, list)):
        src_files = []
        for sp in src_paths:
            src_files += glob.glob(sp)
    else:
        src_files = glob.glob(src_paths)

    # Get all files in the src path, excluding desired files.
    l = [os.path.join(build_dir, os.path.basename(item)) for item in src_files
         if os.path.basename(item) not in exclude]

    # Add Version.cc manually since this is called before the scons target is built.
    if build_dir.split(os.sep)[-1] == 'core':
        l.append(os.path.join(build_dir, 'Version.cc'))

    # Remove duplicate entries, if any, and sort the list.
    # This is to prevent unnecessary rebuilds.
    return sorted(set(l))

def src_module(env, module_name, header_subdir="", exclude=()):
    '''
    Create targets from a source directory, and add headers to the build list.
    '''
    modbuilddir = os.path.join(env['BUILDDIR'], module_name)
    srcdir = os.path.join('src', module_name)
    env.VariantDir(modbuilddir, srcdir, duplicate=0)

    # 09-Aug-2006 WGS: Add a "builder" for the headers so that only
    # those headers that are needed or revised are copied.

    headers = glob.glob(srcdir + '/*.hh') + \
              glob.glob(srcdir + '/*.hpp') + \
              glob.glob(srcdir + '/*.tpp') + \
              glob.glob(srcdir + '/*.icc') + \
              glob.glob(srcdir + '/*.h')

    # Create a separate environment for copying the header files.
    # This ensures that the file is only copied if it changes.
    # If any dependencies change, since there is no path to search,
    # the header file will NOT be recopied (as happened before).
    env_builder = Environment()
    env_builder['BUILDERS'] = env['BUILDERS']
    env_builder['INCLUDE_SUBDIR'] = header_subdir
    for h in headers:
        if os.path.basename(h) not in exclude:
            env.Append(RATHEADERS=env_builder.RATHeader(h))

    src_paths = [os.path.join(srcdir, "*" + ext) for ext in (".cc", ".cpp")]

    src_files = build_list(src_paths,
                           build_dir=modbuilddir,
                           exclude=exclude)

    return env.Object(src_files)

def src_psql(env):
    '''
    Creates targets for PSQL.
    '''
    assert 'PSQLSRCDIR' in env
    assert 'PSQLDEFINES' in env
    assert 'PSQLMODBUILDIR' in env
    assert 'PSQLINCSUBDIRS' in env
    srcdir = env['PSQLSRCDIR']
    srclist = glob.glob(os.path.join(srcdir, '*.c'))
    local_defines = env['PSQLDEFINES']
    if 'USE_REPL_SNPRINTF' not in local_defines:
        for entry in srclist:
            if os.path.basename(entry) == 'snprintf.c':
                srclist.remove(entry)

    if 'HAVE_GETPEEREID' in local_defines:
        for entry in srclist:
            if os.path.basename(entry) == 'getpeereid.c':
                srclist.remove(entry)

    # If this define exists, remove the source from the list
    if 'HAVE_DECL_STRLCPY' in local_defines:
        for entry in srclist:
            if os.path.basename(entry) == 'strlcpy.c':
                srclist.remove(entry)

    # If this define exists, remove the source from the list
    if 'HAVE_DECL_STRLCAT' in local_defines:
        for entry in srclist:
            if os.path.basename(entry) == 'strlcat.c':
                srclist.remove(entry)

    env.VariantDir(env['PSQLMODBUILDIR'], srcdir, duplicate=0)

    headers = glob.glob(srcdir + '/include/*.h')
    for sdir in env['PSQLINCSUBDIRS']:
        headers += glob.glob(srcdir + '/include/' + sdir + '/*.h')

    # Now attach the ta proper
    # Just Force copy the object into the include directory
    for h in headers:
        split_dir = str(h).split('/')[3:]
        if len(split_dir) > 1:
            env.Append(PSQLHEADERS=env.Install('/'.join(['#/include/libpq'] + split_dir[:-1]), h))
        else:
            env.Append(PSQLHEADERS=env.Install('#/include/libpq', h))

        env.Append(PSQLSRCS=env.Object([os.path.join(env['PSQLMODBUILDIR'], os.path.basename(item)) for item in srclist]))

def check_and_parse_config(env, config_command, current_file):
    '''
    Given a SCons environment, attempt to parse a config command.
    '''
    config_exec = env.WhereIs(config_command[0])

    if config_exec is None:
        error = BuildError()
        error.errstr = "Couldn't find {} in path.".format(config_command[0])
        error.filename = "{}".format(current_file)
        error.status = 2
        error.exitstatus = 2
        raise error

    env.ParseConfig(config_command)

def get_version(config_command, return_strict=True):
    '''
    Get the version number from config.
    '''
    command_list = [config_command, "--version"]
    p_v = subprocess.Popen(command_list, universal_newlines=True, stdout=subprocess.PIPE)
    version = p_v.communicate()[0].strip()

    if return_strict:
        # Replace common separators with the standard period.
        version = version.replace("/", ".")

        # Convert to StrictVersion to ensure comparisons work properly.
        version = StrictVersion(version)

    return version

def find_python_locations():
    '''
    Get various properties of the Python distribution being used.
    Includes version, architecture, and library.
    '''
    headers = sysconfig.get_python_inc()
    libs = sysconfig.get_config_var("LIBDIR")
    arch = sysconfig.get_config_var('MULTIARCH')
    version = sysconfig.get_python_version()
    ldlibrary = sysconfig.get_config_var('LDLIBRARY')

    return headers, libs, arch, version, ldlibrary