import os
import os.path
import string

import SCons.Action
import SCons.Builder
import SCons.Tool
import SCons.Util

# This is what we search for to find mingw:
prefixes = SCons.Util.Split("""
  mingw32-
  i386-mingw32msvc-
  i486-mingw32msvc-
  i586-mingw32msvc-
  i686-mingw32msvc-
""")


def find(env):
    for prefix in prefixes:
        # First search in the SCons path and then the OS path:
        if env.WhereIs(prefix + 'gcc') or SCons.Util.WhereIs(prefix + 'gcc'):
            return prefix

    return ''


def shlib_generator(target, source, env, for_signature):
    cmd = SCons.Util.CLVar(['$SHLINK', '$SHLINKFLAGS'])

    dll = env.FindIxes(target, 'SHLIBPREFIX', 'SHLIBSUFFIX')
    if dll:
        cmd.extend(['-o', dll])

    cmd.extend(['$SOURCES', '$_LIBDIRFLAGS', '$_LIBFLAGS'])

    implib = env.FindIxes(target, 'LIBPREFIX', 'LIBSUFFIX')
    if implib:
        cmd.append('-Wl,--out-implib,' + implib.get_string(for_signature))

    def_target = env.FindIxes(target, 'WIN32DEFPREFIX', 'WIN32DEFSUFFIX')
    if def_target:
        cmd.append('-Wl,--output-def,' + def_target.get_string(for_signature))

    return [cmd]


def shlib_emitter(target, source, env):
    dll = env.FindIxes(target, 'SHLIBPREFIX', 'SHLIBSUFFIX')
    no_import_lib = env.get('no_import_lib', 0)

    if not dll:
        raise SCons.Errors.UserError, "A shared library should have exactly one target with the suffix: %s" % env.subst("$SHLIBSUFFIX")

    if not no_import_lib and \
            not env.FindIxes(target, 'LIBPREFIX', 'LIBSUFFIX'):

        # Append an import library to the list of targets.
        target.append(env.ReplaceIxes(dll,
                                      'SHLIBPREFIX', 'SHLIBSUFFIX',
                                      'LIBPREFIX', 'LIBSUFFIX'))

    # Append a def file target if there isn't already a def file target
    # or a def file source. There is no option to disable def file
    # target emitting, because I can't figure out why someone would ever
    # want to turn it off.
    def_source = env.FindIxes(source, 'WIN32DEFPREFIX', 'WIN32DEFSUFFIX')
    def_target = env.FindIxes(target, 'WIN32DEFPREFIX', 'WIN32DEFSUFFIX')
    if not def_source and not def_target:
        target.append(env.ReplaceIxes(dll,
                      'SHLIBPREFIX', 'SHLIBSUFFIX',
                      'WIN32DEFPREFIX', 'WIN32DEFSUFFIX'))

    return (target, source)

# TODO: Backported to old scons version
# shlib_action = SCons.Action.CommandGenerator(shlib_generator)
shlib_action = SCons.Action.Action(shlib_generator, generator=1)

res_action = SCons.Action.Action('$RCCOM', '$RCCOMSTR')

res_builder = SCons.Builder.Builder(action=res_action, suffix='.res.o',
                                    source_scanner=SCons.Tool.SourceFileScanner)
SCons.Tool.SourceFileScanner.add_scanner('.rc', SCons.Defaults.CScan)


def generate(env):
    mingw_prefix = find(env)

    if mingw_prefix:
        dir = os.path.dirname(env.WhereIs(
            mingw_prefix + 'gcc') or SCons.Util.WhereIs(mingw_prefix + 'gcc'))

        # The mingw bin directory must be added to the path:
        path = env['ENV'].get('PATH', [])
        if not path:
            path = []
        if SCons.Util.is_String(path):
            path = string.split(path, os.pathsep)

        env['ENV']['PATH'] = string.join([dir] + path, os.pathsep)

    # Most of mingw is the same as gcc and friends...
    gnu_tools = ['gcc', 'g++', 'gnulink', 'ar', 'gas']
    for tool in gnu_tools:
        SCons.Tool.Tool(tool)(env)

    #... but a few things differ:
    env['CC'] = mingw_prefix + 'gcc'
    env['SHCCFLAGS'] = SCons.Util.CLVar('$CCFLAGS')
    env['CXX'] = mingw_prefix + 'g++'
    env['SHCXXFLAGS'] = SCons.Util.CLVar('$CXXFLAGS')
    env['SHLINKFLAGS'] = SCons.Util.CLVar('$LINKFLAGS -shared')
    env['SHLINKCOM'] = shlib_action
    env.Append(SHLIBEMITTER=[shlib_emitter])
    # This line isn't required and breaks C++ linking
    # env['LINK'] = mingw_prefix + 'g++'
    env['AS'] = mingw_prefix + 'as'
    env['AR'] = mingw_prefix + 'ar'
    env['RANLIB'] = mingw_prefix + 'ranlib'
    env['WIN32DEFPREFIX'] = ''
    env['WIN32DEFSUFFIX'] = '.def'
    env['SHOBJSUFFIX'] = '.o'
    env['STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME'] = 1

    env['RC'] = mingw_prefix + 'windres'
    env['RCFLAGS'] = SCons.Util.CLVar('')
    env['RCINCFLAGS'] = '$( ${_concat(RCINCPREFIX, CPPPATH, RCINCSUFFIX, __env__, RDirs, TARGET)} $)'
    env['RCINCPREFIX'] = '--include-dir '
    env['RCINCSUFFIX'] = ''
    env['RCCOM'] = '$RC $RCINCFLAGS $RCINCPREFIX $SOURCE.dir $RCFLAGS -i $SOURCE -o $TARGET'
    env['BUILDERS']['RES'] = res_builder

    # Some setting from the platform also have to be overridden:
    env['OBJPREFIX'] = ''
    env['OBJSUFFIX'] = '.o'
    env['LIBPREFIX'] = 'lib'
    env['LIBSUFFIX'] = '.a'
    env['SHOBJPREFIX'] = '$OBJPREFIX'
    env['SHOBJSUFFIX'] = '$OBJSUFFIX'
    env['PROGPREFIX'] = ''
    env['PROGSUFFIX'] = '.exe'
    env['LIBPREFIX'] = 'lib'
    env['LIBSUFFIX'] = '.lib'
    env['SHLIBPREFIX'] = 'lib'
    env['SHLIBSUFFIX'] = '.dll'
    env['LIBPREFIXES'] = ['$LIBPREFIX']
    env['LIBSUFFIXES'] = ['$LIBSUFFIX']


def exists(env):
    return find(env)
