"""Fixture used in type-related test cases.

It contains class TypeInfos and Type objects.
"""

from typing import List

from mypy.types import (
    Type, TypeVarType, AnyType, Void, ErrorType, NoneTyp,
    Instance, CallableType, TypeVarDef, TypeType,
)
from mypy.nodes import (
    TypeInfo, ClassDef, Block, ARG_POS, ARG_OPT, ARG_STAR, SymbolTable,
    COVARIANT)


class TypeFixture:
    """Helper class that is used as a fixture in type-related unit tests.

    The members are initialized to contain various type-related values.
    """

    def __init__(self, variance: int=COVARIANT) -> None:
        # The 'object' class
        self.oi = self.make_type_info('builtins.object')               # class object
        self.o = Instance(self.oi, [])                        # object

        # Type variables (these are effectively global)

        def make_type_var(name: str, id: int, values: List[Type], upper_bound: Type,
                          variance: int) -> TypeVarType:
            return TypeVarType(TypeVarDef(name, id, values, upper_bound, variance))

        self.t = make_type_var('T', 1, [], self.o, variance)     # T`1 (type variable)
        self.tf = make_type_var('T', -1, [], self.o, variance)   # T`-1 (type variable)
        self.tf2 = make_type_var('T', -2, [], self.o, variance)  # T`-2 (type variable)
        self.s = make_type_var('S', 2, [], self.o, variance)     # S`2 (type variable)
        self.s1 = make_type_var('S', 1, [], self.o, variance)    # S`1 (type variable)
        self.sf = make_type_var('S', -2, [], self.o, variance)   # S`-2 (type variable)
        self.sf1 = make_type_var('S', -1, [], self.o, variance)  # S`-1 (type variable)

        # Simple types
        self.anyt = AnyType()
        self.void = Void()
        self.err = ErrorType()
        self.nonet = NoneTyp()

        # Abstract class TypeInfos

        # class F
        self.fi = self.make_type_info('F', is_abstract=True)

        # class F2
        self.f2i = self.make_type_info('F2', is_abstract=True)

        # class F3(F)
        self.f3i = self.make_type_info('F3', is_abstract=True, mro=[self.fi])

        # Class TypeInfos
        self.std_tuplei = self.make_type_info('builtins.tuple')        # class tuple
        self.type_typei = self.make_type_info('builtins.type')         # class type
        self.functioni = self.make_type_info('builtins.function')  # function TODO
        self.ai = self.make_type_info('A', mro=[self.oi])              # class A
        self.bi = self.make_type_info('B', mro=[self.ai, self.oi])     # class B(A)
        self.ci = self.make_type_info('C', mro=[self.ai, self.oi])     # class C(A)
        self.di = self.make_type_info('D', mro=[self.oi])              # class D
        # class E(F)
        self.ei = self.make_type_info('E', mro=[self.fi, self.oi])
        # class E2(F2, F)
        self.e2i = self.make_type_info('E2', mro=[self.f2i, self.fi, self.oi])
        # class E3(F, F2)
        self.e3i = self.make_type_info('E3', mro=[self.fi, self.f2i, self.oi])

        # Generic class TypeInfos
        # G[T]
        self.gi = self.make_type_info('G', mro=[self.oi],
                                      typevars=['T'],
                                      variances=[variance])
        # G2[T]
        self.g2i = self.make_type_info('G2', mro=[self.oi],
                                       typevars=['T'],
                                       variances=[variance])
        # H[S, T]
        self.hi = self.make_type_info('H', mro=[self.oi],
                                      typevars=['S', 'T'],
                                      variances=[variance, variance])
        # GS[T, S] <: G[S]
        self.gsi = self.make_type_info('GS', mro=[self.gi, self.oi],
                                       typevars=['T', 'S'],
                                       variances=[variance, variance],
                                       bases=[Instance(self.gi, [self.s])])
        # GS2[S] <: G[S]
        self.gs2i = self.make_type_info('GS2', mro=[self.gi, self.oi],
                                        typevars=['S'],
                                        variances=[variance],
                                        bases=[Instance(self.gi, [self.s1])])
        # list[T]
        self.std_listi = self.make_type_info('builtins.list', mro=[self.oi],
                                             typevars=['T'],
                                             variances=[variance])

        # Instance types
        self.std_tuple = Instance(self.std_tuplei, [])        # tuple
        self.type_type = Instance(self.type_typei, [])        # type
        self.function = Instance(self.functioni, [])  # function TODO
        self.a = Instance(self.ai, [])          # A
        self.b = Instance(self.bi, [])          # B
        self.c = Instance(self.ci, [])          # C
        self.d = Instance(self.di, [])          # D

        self.e = Instance(self.ei, [])          # E
        self.e2 = Instance(self.e2i, [])        # E2
        self.e3 = Instance(self.e3i, [])        # E3

        self.f = Instance(self.fi, [])          # F
        self.f2 = Instance(self.f2i, [])        # F2
        self.f3 = Instance(self.f3i, [])        # F3

        # Generic instance types
        self.ga = Instance(self.gi, [self.a])        # G[A]
        self.gb = Instance(self.gi, [self.b])        # G[B]
        self.gd = Instance(self.gi, [self.d])        # G[D]
        self.go = Instance(self.gi, [self.o])        # G[object]
        self.gt = Instance(self.gi, [self.t])        # G[T`1]
        self.gtf = Instance(self.gi, [self.tf])      # G[T`-1]
        self.gtf2 = Instance(self.gi, [self.tf2])    # G[T`-2]
        self.gs = Instance(self.gi, [self.s])        # G[S]
        self.gdyn = Instance(self.gi, [self.anyt])    # G[Any]

        self.g2a = Instance(self.g2i, [self.a])      # G2[A]

        self.gsaa = Instance(self.gsi, [self.a, self.a])  # GS[A, A]
        self.gsab = Instance(self.gsi, [self.a, self.b])  # GS[A, B]
        self.gsba = Instance(self.gsi, [self.b, self.a])  # GS[B, A]

        self.gs2a = Instance(self.gs2i, [self.a])    # GS2[A]
        self.gs2b = Instance(self.gs2i, [self.b])    # GS2[B]
        self.gs2d = Instance(self.gs2i, [self.d])    # GS2[D]

        self.hab = Instance(self.hi, [self.a, self.b])    # H[A, B]
        self.haa = Instance(self.hi, [self.a, self.a])    # H[A, A]
        self.hbb = Instance(self.hi, [self.b, self.b])    # H[B, B]
        self.hts = Instance(self.hi, [self.t, self.s])    # H[T, S]
        self.had = Instance(self.hi, [self.a, self.d])    # H[A, D]

        self.lsta = Instance(self.std_listi, [self.a])  # List[A]
        self.lstb = Instance(self.std_listi, [self.b])  # List[B]

        self.type_a = TypeType(self.a)
        self.type_b = TypeType(self.b)
        self.type_c = TypeType(self.c)
        self.type_d = TypeType(self.d)
        self.type_t = TypeType(self.t)
        self.type_any = TypeType(self.anyt)

    # Helper methods

    def callable(self, *a: Type) -> CallableType:
        """callable(a1, ..., an, r) constructs a callable with argument types
        a1, ... an and return type r.
        """
        return CallableType(list(a[:-1]), [ARG_POS] * (len(a) - 1),
                        [None] * (len(a) - 1), a[-1], self.function)

    def callable_type(self, *a: Type) -> CallableType:
        """callable_type(a1, ..., an, r) constructs a callable with
        argument types a1, ... an and return type r, and which
        represents a type.
        """
        return CallableType(list(a[:-1]), [ARG_POS] * (len(a) - 1),
                        [None] * (len(a) - 1), a[-1], self.type_type)

    def callable_default(self, min_args: int, *a: Type) -> CallableType:
        """callable_default(min_args, a1, ..., an, r) constructs a
        callable with argument types a1, ... an and return type r,
        with min_args mandatory fixed arguments.
        """
        n = len(a) - 1
        return CallableType(list(a[:-1]),
                            [ARG_POS] * min_args + [ARG_OPT] * (n - min_args),
                            [None] * n,
                            a[-1], self.function)

    def callable_var_arg(self, min_args: int, *a: Type) -> CallableType:
        """callable_var_arg(min_args, a1, ..., an, r) constructs a callable
        with argument types a1, ... *an and return type r.
        """
        n = len(a) - 1
        return CallableType(list(a[:-1]),
                            [ARG_POS] * min_args +
                            [ARG_OPT] * (n - 1 - min_args) +
                            [ARG_STAR], [None] * n,
                            a[-1], self.function)

    def make_type_info(self, name: str,
                       module_name: str = None,
                       is_abstract: bool = False,
                       mro: List[TypeInfo] = None,
                       bases: List[Instance] = None,
                       typevars: List[str] = None,
                       variances: List[int] = None) -> TypeInfo:
        """Make a TypeInfo suitable for use in unit tests."""

        class_def = ClassDef(name, Block([]), None, [])
        class_def.fullname = name

        if module_name is None:
            if '.' in name:
                module_name = name.rsplit('.', 1)[0]
            else:
                module_name = '__main__'

        if typevars:
            v = []  # type: List[TypeVarDef]
            for id, n in enumerate(typevars, 1):
                if variances:
                    variance = variances[id - 1]
                else:
                    variance = COVARIANT
                v.append(TypeVarDef(n, id, None, self.o, variance=variance))
            class_def.type_vars = v

        info = TypeInfo(SymbolTable(), class_def, module_name)
        if mro is None:
            mro = []
            if name != 'builtins.object':
                mro.append(self.oi)
        info.mro = [info] + mro
        if bases is None:
            if mro:
                # By default, assume that there is a single non-generic base.
                bases = [Instance(mro[0], [])]
            else:
                bases = []
        info.bases = bases

        return info


class InterfaceTypeFixture(TypeFixture):
    """Extension of TypeFixture that contains additional generic
    interface types."""

    def __init__(self) -> None:
        super().__init__()
        # GF[T]
        self.gfi = self.make_type_info('GF', typevars=['T'], is_abstract=True)

        # M1 <: GF[A]
        self.m1i = self.make_type_info('M1',
                                       is_abstract=True,
                                       mro=[self.gfi, self.oi],
                                       bases=[Instance(self.gfi, [self.a])])

        self.gfa = Instance(self.gfi, [self.a])  # GF[A]
        self.gfb = Instance(self.gfi, [self.b])  # GF[B]

        self.m1 = Instance(self.m1i, [])  # M1
