#!/usr/bin/env python3
#
# Copyright 2020 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import re
import sys
import zipfile

from util import build_utils  # pylint: disable=unused-import
from util import java_cpp_utils
import action_helpers  # build_utils adds //build to sys.path.
import zip_helpers


class FeatureParserDelegate(java_cpp_utils.CppConstantParser.Delegate):
    # Ex. 'BASE_FEATURE(kConstantName, "StringNameOfTheFeature", ...);'
    # or 'BASE_FEATURE(kConstantName, ...);'
    # would parse as:
    #   ExtractConstantName() -> 'ConstantName'
    #   ExtractValue() -> '"StringNameOfTheFeature"' or '"ConstantName"'
    # TODO(crbug.com/482451012): Support parsing `BASE_RUNTIME_MUTABLE_FEATURE`
    # macros with mutabilty support in the generated Java code.
    _FEATURE_RE = re.compile(r'BASE_FEATURE\(\s*(k\w+),')
    _STRING_LITERAL_RE = re.compile(r'"(?:\\"|[^"])*"')
    _constant_name = None  # The name of the current macro.
    _comma_count = 0  # Number of commas seen in the current macro.
    _string_literals = []  # All string literals seen in the current macro.

    def ExtractConstantName(self, line):
        # Reset to a clean state when extracting constant name.
        self._comma_count = 0
        self._string_literals = []
        self._constant_name = None

        match = self._FEATURE_RE.match(line)
        if match:
            # The regex ensures that the feature name starts with 'k'.
            feature_name = match.group(1)
            self._constant_name = feature_name[1:]
            return self._constant_name
        return None

    def ExtractValue(self, line):
        if line.strip().startswith('#') or line.strip().startswith("//"):
            # Skip C++ directives and comments within macros
            return None

        # Track all string literals.
        self._string_literals.extend(self._STRING_LITERAL_RE.findall(line))

        self._comma_count += line.count(',')

        # The value of a feature is determined once the whole macro has been parsed.
        if ')' not in line:
            return None

        # If there is exactly one string literal, that is the value. This handles
        # the 3-arg form of BASE_FEATURE.
        if len(self._string_literals) == 1:
            return self._string_literals[0]

        # If there are multiple string literals, we can't be sure which is correct.
        if len(self._string_literals) > 1:
            return None

        # If there is no string literal, this might be the 2-arg form. The value is
        # the constant name, quoted.
        if self._comma_count == 1:
            return f'"{self._constant_name}"'

        return None

    def CreateJavaConstant(self, name, value, comments):
        return java_cpp_utils.JavaString(name, value, comments)

    # This delegate requires multiline parsing to determine the feature string.
    def RequiresMultilineValueParsing(self):
        return True


def _GenerateOutput(template, source_paths, features):
    description_template = """
    // This following string constants were inserted by
    //     {SCRIPT_NAME}
    // From
    //     {SOURCE_PATHS}

"""
    values = {
        'SCRIPT_NAME': java_cpp_utils.GetScriptName(),
        'SOURCE_PATHS': ',\n    //     '.join(source_paths),
    }
    description = description_template.format(**values)
    native_features = '\n\n'.join(x.Format() for x in features)

    # TODO(agrieve): Remove {{ and }} from input templates.
    template = template.replace('{{', '{').replace('}}', '}')
    return template.replace('{NATIVE_FEATURES}', description + native_features)


def _ParseFeatureFile(path):
    with open(path, encoding='utf-8') as f:
        feature_file_parser = java_cpp_utils.CppConstantParser(
            FeatureParserDelegate(), f.readlines()
        )
    return feature_file_parser.Parse()


def _Generate(source_paths, template):
    package, class_name = java_cpp_utils.ParseTemplateFile(template)
    output_path = java_cpp_utils.GetJavaFilePath(package, class_name)

    features = []
    for source_path in source_paths:
        features.extend(_ParseFeatureFile(source_path))

    output = _GenerateOutput(template, source_paths, features)
    return output, output_path


def _Main(argv):
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--srcjar',
        required=True,
        help='The path at which to generate the .srcjar file',
    )
    parser.add_argument(
        '--template',
        help='The template file with which to generate the Java '
        'class. Must have "{NATIVE_FEATURES}" somewhere in '
        'the template.',
    )
    parser.add_argument('--class-name', help='FQN of Java class to generate')
    parser.add_argument(
        'inputs', nargs='+', help='Input file(s)', metavar='INPUTFILE'
    )
    args = parser.parse_args(argv)

    if args.template:
        with open(args.template, encoding='utf-8') as f:
            template = f.read()
    else:
        template = java_cpp_utils.CreateDefaultTemplate(
            args.class_name, '{NATIVE_FEATURES}'
        )

    with action_helpers.atomic_output(args.srcjar) as f:
        with zipfile.ZipFile(f, 'w', zipfile.ZIP_STORED) as srcjar:
            data, path = _Generate(args.inputs, template)
            zip_helpers.add_to_zip_hermetic(srcjar, path, data=data)


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