#!/usr/bin/env python

import os
import re
import sys

def read_feature_defines_override(feature_defines):
    feature_defines_overriding_file = 'WebKitFeatureOverrides.txt'
    if not os.path.exists(feature_defines_overriding_file):
        return

    print("The following feature defines were overriden:")
    with open(feature_defines_overriding_file) as f:
        match_iter = re.findall(r"((?:ENABLE_)\w+)=(0|1)", f.read())

    for match in match_iter:
        feature = match[0]
        value = int(match[1])

        if feature in feature_defines and value != feature_defines[feature]:
            print("\t{0}: {1} => {2}".format(feature, feature_defines[feature], value))
        feature_defines[feature] = value

def write_file_if_contents_changed(filename, contents):
    if os.path.exists(filename):
        with open(filename, 'r') as f:
            old_contents = f.read()
        if old_contents == contents:
            return
    with open(filename, 'w') as f:
        f.write(contents)

def write_feature_defines_header(feature_defines):
    contents = ''
    for (feature, value) in feature_defines.items():
        contents += '#define {0} {1}\n'.format(feature, value)
    write_file_if_contents_changed("WebKitFeatures.h", contents)

def write_flattened_feature_defines_file(feature_defines):
    contents = ''
    for (feature, value) in feature_defines.items():
        contents += '{0}={1}\n'.format(feature, value)
    write_file_if_contents_changed("WebKitFeatures.txt", contents)

def generate_feature_defines_files(default_features):
    build_dir = os.getcwd()
    feature_defines = {}

    for feature_define in default_features:
        (feature, value) = feature_define.split("=")
        feature_defines[feature] = int(value)

    read_feature_defines_override(feature_defines)
    write_feature_defines_header(feature_defines)
    write_flattened_feature_defines_file(feature_defines)

if __name__=='__main__':
    generate_feature_defines_files(sys.argv[1:])