#!/usr/bin/python
#
# Copyright (C) 2013 Google Inc. All rights reserved.
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"""Generate event interfaces .in file (EventInterfaces.in).

The event interfaces .in file contains a list of all Event interfaces, i.e.,
all interfaces that inherit from Event, including Event itself,
together with certain extended attributes.

Paths are in POSIX format, and relative to Source/.

This list is used in core/ to generate EventFactory and EventNames.
The .in format is documented in build/scripts/in_file.py.
"""

from optparse import OptionParser
import os
import posixpath
import sys

from utilities import get_file_contents, read_file_to_list, write_file, get_interface_extended_attributes_from_idl

EXPORTED_EXTENDED_ATTRIBUTES = (
    'ImplementedAs',
    'RuntimeEnabled',
)
module_path = os.path.dirname(os.path.realpath(__file__))
source_dir = os.path.normpath(os.path.join(module_path, os.pardir, os.pardir))


def parse_options():
    parser = OptionParser()
    parser.add_option('--event-idl-files-list', help='file listing event IDL files')
    parser.add_option('--event-interfaces-file', help='output file')
    parser.add_option('--write-file-only-if-changed', type='int', help='if true, do not write an output file if it would be identical to the existing one, which avoids unnecessary rebuilds in ninja')
    parser.add_option('--suffix', help='specify a suffix to the namespace, i.e., "Modules". Default is None.')

    options, args = parser.parse_args()
    if options.event_idl_files_list is None:
        parser.error('Must specify a file listing event IDL files using --event-idl-files-list.')
    if options.event_interfaces_file is None:
        parser.error('Must specify an output file using --event-interfaces-file.')
    if options.write_file_only_if_changed is None:
        parser.error('Must specify whether file is only written if changed using --write-file-only-if-changed.')
    options.write_file_only_if_changed = bool(options.write_file_only_if_changed)
    if args:
        parser.error('No arguments allowed, but %d given.' % len(args))
    return options


def write_event_interfaces_file(event_idl_files, destination_filename, only_if_changed, suffix):
    def extended_attribute_string(name, value):
        if name == 'RuntimeEnabled':
            value += 'Enabled'
        return name + '=' + value

    def interface_line(full_path):
        relative_path_local, _ = os.path.splitext(os.path.relpath(full_path, source_dir))
        relative_path_posix = relative_path_local.replace(os.sep, posixpath.sep)

        idl_file_contents = get_file_contents(full_path)
        extended_attributes = get_interface_extended_attributes_from_idl(idl_file_contents)
        extended_attributes_list = [
            extended_attribute_string(name, extended_attributes[name])
            for name in EXPORTED_EXTENDED_ATTRIBUTES
            if name in extended_attributes]

        return '%s %s\n' % (relative_path_posix,
                            ', '.join(extended_attributes_list))

    lines = ['namespace="Event"\n']
    if suffix:
        lines.append('suffix="' + suffix + '"\n')
        lines.append('export=%s_EXPORT\n' % suffix.upper())
    else:
        lines.append('export=CORE_EXPORT\n')
    lines.append('\n')
    interface_lines = [interface_line(event_idl_file)
                       for event_idl_file in event_idl_files]
    interface_lines.sort()
    lines.extend(interface_lines)
    write_file(''.join(lines), destination_filename, only_if_changed)


################################################################################

def main():
    options = parse_options()
    event_idl_files = read_file_to_list(options.event_idl_files_list)
    write_event_interfaces_file(event_idl_files,
                                options.event_interfaces_file,
                                options.write_file_only_if_changed,
                                options.suffix)


if __name__ == '__main__':
    sys.exit(main())