from __future__ import absolute_import

from dune.perftool.options import get_option
from dune.perftool.generation import (base_class,
                                      class_basename,
                                      class_member,
                                      constructor_parameter,
                                      include_file,
                                      initializer_list,
                                      symbol,
                                      template_parameter,
                                      )
from dune.perftool.cgen.clazz import (AccessModifier,
                                      BaseClass,
                                      ClassMember,
                                      )

from pytools import memoize


@template_parameter("operator")
def lop_template_ansatz_gfs():
    return "GFSU"


@template_parameter("operator")
def lop_template_test_gfs():
    return "GFSV"


@symbol
def name_initree_constructor_param():
    return "iniParams"


@class_member("operator")
def define_initree(name):
    param_name = name_initree_constructor_param()
    include_file('dune/common/parametertree.hh', filetag="operatorfile")
    constructor_parameter("const Dune::ParameterTree&", param_name, classtag="operator", constructortag="iniconstructor")
    initializer_list(name, [param_name], classtag="operator")

    return "const Dune::ParameterTree& {};".format(name)


@class_member(classtag="operator", access=AccessModifier.PUBLIC)
def enum_pattern(which):
    return "enum {{ doPattern{} = true }};".format(which)


@class_member(classtag="operator", access=AccessModifier.PUBLIC)
def enum_alpha(which):
    return "enum {{ doAlpha{} = true }};".format(which)


@symbol
def name_initree_member():
    define_initree("_iniParams")
    return "_iniParams"


@class_basename("operator")
def localoperator_basename():
    return "LocalOperator"


def class_type_from_cache(classtag):
    from dune.perftool.generation import retrieve_cache_items

    # get the basename
    basename = [i for i in retrieve_cache_items(condition="{} and basename".format(classtag))]
    assert len(basename) == 1
    basename = basename[0]

    # get the template parameters
    tparams = [i for i in retrieve_cache_items(condition="{} and template_param".format(classtag))]
    tparam_str = ''
    if len(tparams) > 0:
        tparam_str = '<{}>'.format(', '.join(t for t in tparams))

    return basename, basename + tparam_str


@memoize
def measure_specific_details(measure):
    # The return dictionary that this memoized method will grant direct access to.
    ret = {}

    def numerical_jacobian(which):
        if get_option("numerical_jacobian"):
            # Add a base class
            _, loptype = class_type_from_cache("operator")
            base_class("Dune::PDELab::NumericalJacobian{}<{}>".format(which, loptype), classtag="operator")

            # Add the initializer list for that base class
            ini = name_initree_member()
            ini_constructor = name_initree_constructor_param()
            initializer_list("Dune::PDELab::NumericalJacobian{}<{}>".format(which, loptype),
                             ["{}.get<double>(\"numerical_epsilon.{}\", 1e-9)".format(ini_constructor, ini, which.lower())],
                             classtag="operator")

    if measure == "cell":
        base_class('Dune::PDELab::FullVolumePattern', classtag="operator")
        numerical_jacobian("Volume")
        enum_pattern("Volume")
        enum_alpha("Volume")

        ret["residual_signature"] = ['template<typename EG, typename LFSU, typename X, typename LFSV, typename R>',
                                     'void alpha_volume(const EG& eg, const LFSU& lfsu, const X& x, const LFSV& lfsv, R& r) const']
        ret["jacobian_signature"] = ['template<typename EG, typename LFSU, typename X, typename LFSV, typename J>',
                                     'void jacobian_volume(const EG& eg, const LFSU& lfsu, const X& x, const LFSV& lfsv, J& jac) const']

    if measure == "exterior_facet":
        base_class('Dune::PDELab::FullBoundaryPattern', classtag="operator")
        numerical_jacobian("Boundary")
        enum_pattern("Boundary")
        enum_alpha("Boundary")

        ret["residual_signature"] = ['template<typename IG, typename LFSV0, typename X, typename LFSV1, typename R>',
                                     'void alpha_boundary(const IG& ig, const LFSV0& lfsv0, const X& x, const LFSV1& lfsv1, R& r) const']
        ret["jacobian_signature"] = ['template<typename IG, typename LFSV0, typename X, typename LFSV1, typename J>',
                                     'void jacobian_boundary(const IG& ig, const LFSV0& lfsv0, const X& x, const LFSV1& lfsv1, J& jac) const']

    if measure == "interior_facet":
        base_class('Dune::PDELab::FullSkeletonPattern', classtag="operator")
        numerical_jacobian("Skeleton")
        enum_pattern("Skeleton")
        enum_alpha("Skeleton")

        ret["residual_signature"] = ['template<typename IG, typename LFSV0_S, typename X, typename LFSV1_S, typename LFSV0_N, typename R, typename LFSV1_N>',
                                     'void alpha_skeleton(const IG& ig, const LFSV0_S& lfsv0_s, const X& x_s, const LFSV1_S& lfsv1_s, const LFSV0_N& lfsv0_n, const X& x_n, const LFSV1_N& lfsv1_n, R& r_s, R& r_n) const']
        ret["jacobian_signature"] = ['template<typename IG, typename LFSV0_S, typename X, typename LFSV1_S, typename LFSV0_N, typename LFSV1_N, typename Jac>',
                                     'void jacobian_skeleton(const IG& ig, const LFSV0_S& lfsv0_s, const X& x_s, const LFSV1_S& lfsv1_s, const LFSV0_N& lfsv0_n, const X& x_n, const LFSV1_N& lfsv1_n, Jac& jac_ss, Jac& jac_sn, Jac& jac_ns, Jac& jac_nn) const']

    return ret


def generate_kernel(integrand=None, measure=None):
    assert integrand and measure

    # Get the measure specifics
    specifics = measure_specific_details(measure)

    # Now split the given integrand into accumulation expressions
    from dune.perftool.ufl.transformations.extract_accumulation_terms import split_into_accumulation_terms
    accterms = split_into_accumulation_terms(integrand)

    # Iterate over the terms and generate a kernel
    for term in accterms:
        from dune.perftool.loopy.transformer import transform_accumulation_term
        transform_accumulation_term(term)

    # Extract the information, which is needed to create a loopy kernel.
    # First extracting it, might be useful to alter it before kernel generation.
    from dune.perftool.generation import retrieve_cache_items
    from dune.perftool.loopy.target import DuneTarget
    domains = [i for i in retrieve_cache_items("domain")]
    instructions = [i for i in retrieve_cache_items("instruction")]
    temporaries = {i.name: i for i in retrieve_cache_items("temporary")}
    preambles = [(i, p) for i, p in enumerate(retrieve_cache_items("preamble"))]
    arguments = [i for i in retrieve_cache_items("argument")]

    # Create the kernel
    from loopy import make_kernel, preprocess_kernel
    # kernel = make_kernel(domains, instructions, arguments, temporary_variables=temporaries, preambles=preambles, target=DuneTarget())
    kernel = make_kernel(domains, instructions, arguments, temporary_variables=temporaries, target=DuneTarget(), preambles=preambles)
    kernel = preprocess_kernel(kernel)

    # All items with the kernel tags can be destroyed once a kernel has been generated
    from dune.perftool.generation import delete_cache_items
    delete_cache_items("kernel")

    # Return the actual code (might instead return kernels...)
    return kernel


class AssemblyMethod(ClassMember):
    def __init__(self, signature, kernel):
        from loopy import generate_code
        from cgen import LiteralLines, Block
        content = signature
        content.append('{')
        content.extend('  ' + l for l in generate_code(kernel)[0].split('\n'))
        content.append('}')
        ClassMember.__init__(self, content)


def cgen_class_from_cache(tag, members=[]):
    from dune.perftool.generation import retrieve_cache_items

    # Generate the name by concatenating basename and template parameters
    basename, fullname = class_type_from_cache("operator")

    base_classes = [bc for bc in retrieve_cache_items('{} and baseclass'.format(tag))]
    constructor_params = [bc for bc in retrieve_cache_items('{} and constructor_param'.format(tag))]
    il = [i for i in retrieve_cache_items('{} and initializer'.format(tag))]
    pm = [m for m in retrieve_cache_items('{} and member'.format(tag))]
    tparams = [i for i in retrieve_cache_items('{} and template_param'.format(tag))]

    from dune.perftool.cgen.clazz import Constructor
    constructor = Constructor(arg_decls=constructor_params, clsname=basename, initializer_list=il)

    from dune.perftool.cgen import Class
    return Class(basename, base_classes=base_classes, members=members + pm, constructors=[constructor], tparam_decls=tparams)


def generate_localoperator_kernels(form, namedata):
    # For the moment, I do assume that there is but one integral of each type. This might differ
    # if you use different quadrature orders for different terms.
    assert len(form.integrals()) == len(set(i.integral_type() for i in form.integrals()))

    # Reset the generation cache
    from dune.perftool.generation import delete_cache_items
    delete_cache_items()

    # Manage includes and base classes that we always need
    include_file('dune/pdelab/gridfunctionspace/gridfunctionspaceutilities.hh', filetag="operatorfile")
    include_file('dune/pdelab/localoperator/idefault.hh', filetag="operatorfile")
    include_file('dune/pdelab/localoperator/flags.hh', filetag="operatorfile")
    include_file('dune/pdelab/localoperator/pattern.hh', filetag="operatorfile")

    # Trigger this one once early on to avoid wrong stuff happening
    localoperator_basename()
    lop_template_ansatz_gfs()
    lop_template_test_gfs()
    from dune.perftool.pdelab.parameter import parameterclass_basename
    parameterclass_basename()

    base_class('Dune::PDELab::LocalOperatorDefaultFlags', classtag="operator")

    # Have a data structure collect the generated kernels
    operator_kernels = {}

    from dune.perftool.generation import namedata_context

    # Generate the necessary residual methods
    for integral in form.integrals():
        with namedata_context(namedata):
            kernel = generate_kernel(integrand=integral.integrand(), measure=integral.integral_type())
        operator_kernels[(integral.integral_type(), 'residual')] = kernel

    # Generate the necessary jacobian methods
    from dune.perftool.options import get_option
    if get_option("numerical_jacobian"):
        include_file("dune/pdelab/localoperator/defaultimp.hh", filetag="operatorfile")
    else:
        from ufl import derivative
        from ufl.algorithms import expand_derivatives
        jacform = expand_derivatives(derivative(form, form.coefficients()[0]))

        for integral in jacform.integrals():
            with namedata_context(namedata):
                kernel = generate_kernel(integrand=integral.integrand(), measure=integral.integral_type())
            operator_kernels[(integral.integral_type(), 'jacobian')] = kernel

    # TODO: JacobianApply for matrix-free computations.

    # Return the set of generated kernels
    return operator_kernels


def generate_localoperator_file(kernels):
    operator_methods = []

    # Make generables from the given kernels
    for method, kernel in kernels.items():
        signature = measure_specific_details(method[0])["{}_signature".format(method[1])]
        operator_methods.append(AssemblyMethod(signature, kernel))

    # Write the file!
    from dune.perftool.file import generate_file

    # TODO take the name of this thing from the UFL file
    lop = cgen_class_from_cache("operator", members=operator_methods)
    generate_file(get_option("operator_file"), "operatorfile", [lop])