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"""Read an IDL file or complete IDL interface, producing an IdlDefinitions object.

Design doc:
http://www.chromium.org/developers/design-documents/idl-compiler#TOC-Front-end
"""

import os

import blink_idl_parser
from blink_idl_parser import BlinkIDLParser
from idl_definitions import IdlDefinitions
from idl_validator import EXTENDED_ATTRIBUTES_RELATIVE_PATH, IDLInvalidExtendedAttributeError, IDLExtendedAttributeValidator
from interface_dependency_resolver import InterfaceDependencyResolver
from utilities import idl_filename_to_component


def validate_blink_idl_definitions(idl_filename, idl_file_basename,
                                   definitions):
    """Validate file contents with filename convention.

       The Blink IDL conventions are:
       - If an IDL file defines an interface, a dictionary, or an exception,
         the IDL file must contain exactly one definition. The definition
         name must agree with the file's basename, unless it is a partial
         definition. (e.g., 'partial interface Foo' can be in FooBar.idl).
       - An IDL file can contain typedefs and enums without having other
         definitions. There is no filename convention in this case.
       - Otherwise, an IDL file is invalid.
    """
    targets = (definitions.interfaces.values() +
               definitions.dictionaries.values())
    number_of_targets = len(targets)
    if number_of_targets > 1:
        raise Exception(
            'Expected exactly 1 definition in file {0}, but found {1}'
            .format(idl_filename, number_of_targets))
    if number_of_targets == 0:
        if not (definitions.enumerations or definitions.typedefs):
            raise Exception(
                'No definition found in %s' % idl_filename)
        return
    target = targets[0]
    if not target.is_partial and target.name != idl_file_basename:
        raise Exception(
            'Definition name "{0}" disagrees with IDL file basename "{1}".'
            .format(target.name, idl_file_basename))


class IdlReader(object):
    def __init__(self, interfaces_info=None, outputdir=''):
        self.extended_attribute_validator = IDLExtendedAttributeValidator()
        self.interfaces_info = interfaces_info

        if interfaces_info:
            self.interface_dependency_resolver = InterfaceDependencyResolver(interfaces_info, self)
        else:
            self.interface_dependency_resolver = None

        self.parser = BlinkIDLParser(outputdir=outputdir)

    def read_idl_definitions(self, idl_filename):
        """Returns a dictionary whose key is component and value is an IdlDefinitions object for an IDL file, including all dependencies."""
        definitions = self.read_idl_file(idl_filename)
        component = idl_filename_to_component(idl_filename)

        if not self.interface_dependency_resolver:
            return {component: definitions}

        # This definitions should have a dictionary. No need to resolve any
        # dependencies.
        if not definitions.interfaces:
            return {component: definitions}

        return self.interface_dependency_resolver.resolve_dependencies(definitions, component)

    def read_idl_file(self, idl_filename):
        """Returns an IdlDefinitions object for an IDL file, without any dependencies.

        The IdlDefinitions object is guaranteed to contain a single
        IdlInterface; it may also contain other definitions, such as
        callback functions and enumerations."""
        ast = blink_idl_parser.parse_file(self.parser, idl_filename)
        if not ast:
            raise Exception('Failed to parse %s' % idl_filename)
        idl_file_basename, _ = os.path.splitext(os.path.basename(idl_filename))
        definitions = IdlDefinitions(idl_file_basename, ast)

        validate_blink_idl_definitions(
            idl_filename, idl_file_basename, definitions)

        # Validate extended attributes
        if not self.extended_attribute_validator:
            return definitions

        try:
            self.extended_attribute_validator.validate_extended_attributes(definitions)
        except IDLInvalidExtendedAttributeError as error:
            raise IDLInvalidExtendedAttributeError("""
IDL ATTRIBUTE ERROR in file:
%s:
    %s
If you want to add a new IDL extended attribute, please add it to:
    %s
and add an explanation to the Blink IDL documentation at:
    http://www.chromium.org/blink/webidl/blink-idl-extended-attributes
    """ % (idl_filename, str(error), EXTENDED_ATTRIBUTES_RELATIVE_PATH))

        return definitions
