import os
import os.path
import logging
import ycm_core

BASE_FLAGS = [
        # '-Wall',
        # '-Wextra',
        # '-Werror',
        '-Wno-long-long',
        '-Wno-variadic-macros',
        '-fexceptions',
        '-DNDEBUG',
        '-std=c++11',
        '-stdlib=libc++',
        '-isystem', '/usr/local/include',
        '-isystem', '/Library/Developer/CommandLineTools/usr/include/c++/v1',
        '-isystem', '/Library/Developer/CommandLineTools/usr/lib/clang/10.0.0/include',
        '-isystem', '/Library/Developer/CommandLineTools/usr/include',
        '-isystem', '/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include',
        '-I', 'include',
        '-I.',
        '-xc++',
        ]

SOURCE_EXTENSIONS = [
        '.cpp',
        '.cxx',
        '.cc',
        '.c',
        '.m',
        '.mm'
        ]

HEADER_EXTENSIONS = [
        '.h',
        '.hxx',
        '.hpp',
        '.hh'
        ]


def IsHeaderFile(filename):
    extension = os.path.splitext(filename)[1]
    return extension in HEADER_EXTENSIONS


def GetCompilationInfoForFile(database, filename):
    if IsHeaderFile(filename):
        basename = os.path.splitext(filename)[0]
        for extension in SOURCE_EXTENSIONS:
            replacement_file = basename + extension
            if os.path.exists(replacement_file):
                compilation_info = database.GetCompilationInfoForFile(
                        replacement_file)
                if compilation_info.compiler_flags_:
                    return compilation_info
        return None
    return database.GetCompilationInfoForFile(filename)


def FindNearest(path, target, build_folder):
    candidate = os.path.join(path, target)
    if(os.path.isfile(candidate) or os.path.isdir(candidate)):
        logging.info("Found nearest " + target + " at " + candidate)
        return candidate

    parent = os.path.dirname(os.path.abspath(path))
    if(parent == path):
        raise RuntimeError("Could not find " + target)

    if(build_folder):
        candidate = os.path.join(parent, build_folder, target)
        if(os.path.isfile(candidate) or os.path.isdir(candidate)):
            logging.info(
                    "Found nearest " + target +
                    " in build folder at " + candidate)
            return candidate

    return FindNearest(parent, target, build_folder)


def MakeRelativePathsInFlagsAbsolute(flags, working_directory):
    if not working_directory:
        return list(flags)
    new_flags = []
    make_next_absolute = False
    path_flags = ['-isystem', '-I', '-iquote', '--sysroot=']
    for flag in flags:
        new_flag = flag

        if make_next_absolute:
            make_next_absolute = False
            if not flag.startswith('/'):
                new_flag = os.path.join(working_directory, flag)

        for path_flag in path_flags:
            if flag == path_flag:
                make_next_absolute = True
                break

            if flag.startswith(path_flag):
                path = flag[len(path_flag):]
                new_flag = path_flag + os.path.join(working_directory, path)
                break

        if new_flag:
            new_flags.append(new_flag)
    return new_flags


def FlagsForClangComplete(root):
    try:
        clang_complete_path = FindNearest(root, '.clang_complete')
        clang_complete_flags = open(
                clang_complete_path, 'r').read().splitlines()
        return clang_complete_flags
    except:
        return None


def FlagsForInclude(root):
    try:
        include_path = FindNearest(root, 'include')
        flags = []
        for dirroot, dirnames, filenames in os.walk(include_path):
            for dir_path in dirnames:
                real_path = os.path.join(dirroot, dir_path)
                flags = flags + ["-I" + real_path]
        return flags
    except:
        return None


def FlagsForCompilationDatabase(root, filename):
    try:
        # Last argument of next function is the name of the build folder for
        # out of source projects
        compilation_db_path = FindNearest(
                root, 'compile_commands.json', 'build')
        compilation_db_dir = os.path.dirname(compilation_db_path)
        logging.info(
                "Set compilation database directory to " + compilation_db_dir)
        compilation_db = ycm_core.CompilationDatabase(compilation_db_dir)
        if not compilation_db:
            logging.info("Compilation database file found but unable to load")
            return None
        compilation_info = GetCompilationInfoForFile(compilation_db, filename)
        if not compilation_info:
            logging.info(
                    "No compilation info for " + filename
                    + " in compilation database")
            return None
        return MakeRelativePathsInFlagsAbsolute(
                compilation_info.compiler_flags_,
                compilation_info.compiler_working_dir_)
    except:
        return None


def FlagsForFile(filename):
    root = os.path.realpath(filename)
    compilation_db_flags = FlagsForCompilationDatabase(root, filename)
    if compilation_db_flags:
        final_flags = compilation_db_flags
    else:
        final_flags = BASE_FLAGS
        clang_flags = FlagsForClangComplete(root)
        if clang_flags:
            final_flags = final_flags + clang_flags
        include_flags = FlagsForInclude(root)
        if include_flags:
            final_flags = final_flags + include_flags
    return {
            'flags': final_flags,
            'do_cache': True
            }