# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

from pants.backend.codegen.thrift.java.java_thrift_library import JavaThriftLibrary
from pants.subsystem.subsystem import Subsystem


class ThriftDefaults(Subsystem):
    """Tracks defaults for java thrift target attributes that influence code generation."""

    options_scope = "thrift-defaults"

    # TODO: These exist to support alternate compilers (specifically scrooge), but this should
    # probably be a scrooge-specific subsystem, tied to a scrooge_thrift_library target type.
    # These options (e.g., language) are relevant to scrooge but may have no meaning
    # in some other compiler (they certainly don't in the apache thrift compiler).
    @classmethod
    def register_options(cls, register):
        register(
            "--compiler",
            type=str,
            advanced=True,
            default="thrift",
            help="The default compiler to use for java_thrift_library targets.",
        )
        register(
            "--language",
            type=str,
            advanced=True,
            default="java",
            help="The default language to generate for java_thrift_library targets.",
        )
        register(
            "--default-java-namespace",
            type=str,
            advanced=True,
            default=None,
            help="The default Java namespace to generate for java_thrift_library targets.",
        )
        register(
            "--namespace-map",
            type=dict,
            advanced=True,
            default={},
            help="The default namespace map to generate for java_thrift_library targets, {old: new}.",
        )
        register(
            "--compiler-args",
            type=list,
            advanced=True,
            default=[],
            help="Extra arguments for the thrift compiler.",
        )

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._default_compiler = self.get_options().compiler
        self._default_language = self.get_options().language
        self._default_default_java_namespace = self.get_options().default_java_namespace
        self._default_namespace_map = self.get_options().namespace_map
        self._default_compiler_args = self.get_options().compiler_args

    def compiler(self, target):
        """Returns the thrift compiler to use for the given target.

        :param target: The target to extract the thrift compiler from.
        :type target: :class:`pants.backend.codegen.thrift.java.java_thrift_library.JavaThriftLibrary`
        :returns: The thrift compiler to use.
        :rtype: string
        """
        self._check_target(target)
        return target.compiler or self._default_compiler

    def language(self, target):
        """Returns the target language to generate thrift stubs for.

        :param target: The target to extract the target language from.
        :type target: :class:`pants.backend.codegen.thrift.java.java_thrift_library.JavaThriftLibrary`
        :returns: The target language to generate stubs for.
        :rtype: string
        """
        self._check_target(target)
        return target.language or self._default_language

    def namespace_map(self, target):
        """Returns the namespace_map used for Thrift generation.

        :param target: The target to extract the namespace_map from.
        :type target: :class:`pants.backend.codegen.targets.java_thrift_library.JavaThriftLibrary`
        :returns: The namespaces to remap (old to new).
        :rtype: dictionary
        """
        self._check_target(target)
        return target.namespace_map or self._default_namespace_map

    def compiler_args(self, target):
        """Returns the compiler_args used for Thrift generation.

        :param target: The target to extract the compiler args from.
        :type target: :class:`pants.backend.codegen.targets.java_thrift_library.JavaThriftLibrary`
        :returns: Extra arguments for the thrift compiler
        :rtype: list
        """
        self._check_target(target)
        return target.compiler_args or self._default_compiler_args

    def default_java_namespace(self, target):
        """Returns the default_java_namespace used for Thrift generation.

        :param target: The target to extract the default_java_namespace from.
        :type target: :class:`pants.backend.codegen.targets.java_thrift_library.JavaThriftLibrary`
        :returns: The default Java namespace used when not specified in the IDL.
        :rtype: string
        """
        self._check_target(target)
        return target.default_java_namespace or self._default_default_java_namespace

    def _check_target(self, target):
        if not isinstance(target, JavaThriftLibrary):
            raise ValueError(
                "Can only determine defaults for JavaThriftLibrary targets, "
                "given {} of type {}".format(target, type(target))
            )

    def _tuple(self):
        return (
            self._default_compiler,
            self._default_language,
            tuple(sorted(self._default_namespace_map.items())),
            tuple(self._default_compiler_args),  # N.B.: Assume compiler arg order can matter.
            self._default_default_java_namespace,
        )

    def __hash__(self):
        return hash(self._tuple())

    def __eq__(self, other):
        return type(self) == type(other) and self._tuple() == other._tuple()