import glob
import pathlib
import platform
import re
import shutil
from SCons.Script import *

_SCRIPT_STAMPFILE = '.spp_script_run'


def _git_cook(env: Environment, repo, options: dict = {}) -> dict:
    checkout_root = repo['checkout_root']
    enable_hlsl = options.get('enable_hlsl', False)

    # TODO: windows?
    did_run_script = os.path.exists(os.path.join(repo['checkout_root'], _SCRIPT_STAMPFILE))
    if not did_run_script or env['UPDATE_REPOSITORIES']:
        python_exe = os.path.realpath(sys.executable)
        script_file = os.path.join(repo['checkout_root'], 'update_glslang_sources.py')
        prev_cwd = os.getcwd()
        os.chdir(repo['checkout_root'])
        if env.Execute(f'"{python_exe}" {script_file}'):
            env.Exit(1)
        os.chdir(prev_cwd)
        pathlib.Path(repo['checkout_root'], _SCRIPT_STAMPFILE).touch()

    # generate the build_info.h
    generator_script = os.path.join(repo['checkout_root'], 'build_info.py')
    generator_script_input = os.path.join(repo['checkout_root'], 'build_info.h.tmpl')
    generator_script_output = os.path.join(repo['checkout_root'], 'glslang/build_info.h')
    env.Command(
        target = generator_script_output,
        source = [generator_script, generator_script_input, os.path.join(repo['checkout_root'], 'CHANGES.md')],
        action = f'"$PYTHON" "{generator_script}" "{repo["checkout_root"]}" -i "{generator_script_input}" -o "$TARGET"'
    )

    platform_source_dir = {
        'Linux': 'Unix',
        'Windows': 'Windows',
        'Darwin': 'Unix'
    }.get(platform.system(), 'Unix')
    glslang_source_files = env.RGlob(os.path.join(repo['checkout_root'], 'glslang/GenericCodeGen/'), '*.cpp') \
                           + env.RGlob(os.path.join(repo['checkout_root'], 'glslang/MachineIndependent/'), '*.cpp') \
                           + env.RGlob(os.path.join(repo['checkout_root'], 'glslang/OGLCompilersDLL/'), '*.cpp') \
                           + env.RGlob(os.path.join(repo['checkout_root'], 'glslang/ResourceLimits/'), '*.cpp') \
                           + env.RGlob(os.path.join(repo['checkout_root'], 'SPIRV/'), '*.cpp') \
                           + [os.path.join(repo['checkout_root'], f'glslang/OSDependent/{platform_source_dir}/ossource.cpp')]
    if enable_hlsl:
        glslang_source_files.extend(env.RGlob(os.path.join(repo['checkout_root'], 'glslang/HLSL/'), '*.cpp'))

    # disable warnings
    additional_cxx_flags = {
        'clang': ['-w'],
        'gcc': ['-w'],
        'cl': ['/w']
    }.get(env['COMPILER_FAMILY'], [])
    additional_cppdefines = []

    if enable_hlsl:
        additional_cppdefines.append('ENABLE_HLSL=1')

    env.StaticLibrary(
        CCFLAGS = env['CCFLAGS'] + additional_cxx_flags,
        CPPPATH = repo['checkout_root'],
        CPPDEFINES = list(env['CPPDEFINES']) + additional_cppdefines,
        target = env['LIB_DIR'] + '/glslang_full',
        source = glslang_source_files
    )

    # build the include folder
    include_dir = os.path.join(checkout_root, 'include')
    if not os.path.exists(include_dir) or env['UPDATE_REPOSITORIES']:
        def copy_headers(dst, src):
            os.makedirs(dst, exist_ok=True)
            for file in glob.glob(os.path.join(src, '*.h')):
                shutil.copy(file, dst)

        copy_headers(os.path.join(include_dir, 'glslang/HLSL'), os.path.join(checkout_root, 'glslang/HLSL'))
        copy_headers(os.path.join(include_dir, 'glslang/Include'), os.path.join(checkout_root, 'glslang/Include'))
        copy_headers(os.path.join(include_dir, 'glslang/MachineIndependent'), os.path.join(checkout_root, 'glslang/MachineIndependent'))
        copy_headers(os.path.join(include_dir, 'glslang/Public'), os.path.join(checkout_root, 'glslang/Public'))
        copy_headers(os.path.join(include_dir, 'glslang/SPIRV'), os.path.join(checkout_root, 'SPIRV'))

    return {
        'CPPPATH': [include_dir],
        'LIBS': [os.path.join(env['LIB_DIR'], env.LibFilename('glslang_full'))]
    }



_REPO_NAMES = {
    'default': 'glslang',
    'mewin': 'glslang_mewin'
}
_REPO_URLS = {
    'default': 'https://github.com/KhronosGroup/glslang.git',
    'mewin': 'https://git.mewin.de/mewin/glslang.git'
}
_TAG_PATTERNS = {
    'default': re.compile(r'^([0-9]+)\.([0-9]+)\.([0-9]+)$'),
    'mewin': None
}
def _ref_fn(env: Environment, version) -> str:
    remote = env.get('GLSLANG_REMOTE', 'default')
    if remote == 'default':
        return f'refs/tags/{version[0]}.{version[1]}.{version[2]}'
    elif remote == 'mewin':
        return 'master'
    else:
        raise Exception('invalid glslang remote')

env.GitRecipe(
    globals = globals(),
    repo_name = lambda env: _REPO_NAMES[env.get('GLSLANG_REMOTE', 'default')],
    repo_url = lambda env: _REPO_URLS[env.get('GLSLANG_REMOTE', 'default')],
    tag_pattern = lambda env: _TAG_PATTERNS[env.get('GLSLANG_REMOTE', 'default')],
    cook_fn = _git_cook,
    ref_fn = _ref_fn
)