from amuse.community import *
from amuse.community.interface.gd import GravitationalDynamics
from amuse.community.interface.gd import GravitationalDynamicsInterface
from amuse.community.interface.gd import GravityFieldInterface
from amuse.community.interface.gd import GravityFieldCode

# *** This script, together with the defaults in
# *** GravitationalDynamicsInterface, will be used to generate both
# *** the header file interface.h and the stub interface.cc.  Since
# *** interface.cc has been  hand-coded to implement the details,
# *** MAKE SURE TO SAVE IT SOMEWHERE, as build.py can overwrite it!

class ph4Interface(CodeInterface,
                   LiteratureReferencesMixIn,
                   GravitationalDynamicsInterface,
                   StoppingConditionInterface,
                   GravityFieldInterface):
    """
    Parallel, GPU-accelerated, N-body integration module with block
    time steps, using a 4th-order Hermite integration scheme.

        .. [#] ADS:2018araa.book.....P (Portegies Zwart, S. & McMillan, S.L.W., 2018)
    """

    # Interface specification.

    include_headers = ['interface.h', 'stopcond.h']

    MODE_GPU = 'gpu'
    MODE_CPU = 'cpu'
    
    def __init__(self, mode = MODE_CPU, **options):
        CodeInterface.__init__(
            self,
            name_of_the_worker=self.name_of_the_muse_worker(mode),
            **options
        )
        LiteratureReferencesMixIn.__init__(self)

    # Interface functions:
    @legacy_function
    def new_particle():
        """
        Define a new particle in the stellar dynamics code. The
        particle is initialized with the provided mass, radius,
        position and velocity. This function returns an index that
        can be used to refer to this particle.
        """
        function = LegacyFunctionSpecification()
        function.can_handle_array = True
        function.addParameter('index_of_the_particle', dtype='int32',
                              direction=function.OUT, description =
            """
            An index assigned to the newly created particle.
            This index is supposed to be a local index for the code
            (and not valid in other instances of the code or in other codes)
            """,
            unit = INDEX
            )

        function.addParameter('mass', dtype='float64', direction=function.IN,
                 description = "The mass of the particle", 
                 unit = nbody_system.mass)
        function.addParameter('x', dtype='float64', direction=function.IN,
                 description = "The initial position vector of the particle",
                 unit = nbody_system.length)
        function.addParameter('y', dtype='float64', direction=function.IN,
                 description = "The initial position vector of the particle",
                 unit = nbody_system.length)
        function.addParameter('z', dtype='float64', direction=function.IN,
                 description = "The initial position vector of the particle",
                 unit = nbody_system.length)
        function.addParameter('vx', dtype='float64', direction=function.IN,
                 description = "The initial velocity vector of the particle",
                 unit = nbody_system.speed)
        function.addParameter('vy', dtype='float64', direction=function.IN,
                 description = "The initial velocity vector of the particle",
                 unit = nbody_system.speed)
        function.addParameter('vz', dtype='float64', direction=function.IN,
                 description = "The initial velocity vector of the particle",
                 unit = nbody_system.speed)
        function.addParameter('radius', dtype='float64', direction=function.IN,
                 description = "The radius of the particle",
                 default = -1, unit = nbody_system.length)
        function.addParameter('id', dtype='int32', direction=function.IN,
                 description = "Identifier of the particle, "
                               +"option for restoring state after loading",
                 default = -1, unit = NO_UNIT)
        function.result_type = 'int32'
        function.result_doc = """ 0 - OK
            particle was created and added to the model
        -1 - ERROR
            particle could not be created"""
        return function
    
    @legacy_function
    def get_particle_timestep():
        """
        Retrieve the timestep of a particle.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('index_of_the_particle',
                              dtype='int32',
                              direction=function.IN,
                              description = "Index of the particle to get the timestep from. This index must have been returned by an earlier call to :meth:`new_particle`")
        function.addParameter('timestep',
                              dtype='float64',
                              unit=nbody_system.time,
                              direction=function.OUT,
                              description = "The current timestep of the particle")
        function.result_type = 'int32'
        function.can_handle_array = True
        return function
    
    def name_of_the_muse_worker(self, mode):
        if mode == self.MODE_CPU:
            return 'ph4_worker'
        elif mode == self.MODE_GPU:
            return 'ph4_worker_gpu'
        else:
            return 'ph4_worker'
        
    # Inheritance from GravitationalDynamicsInterface means that
    # functions in the standard interface don't need to be defined.
    # See interface.py.2 for a laboriously hand-coded version written
    # before I discovered this fact!    (Steve McMillan, 10/10)

    # Additional functions defined here will be reflected in
    # interface.h and must be provided in interface.cc in order for
    # ph4_worker to build.

    # The following functions aren't defined in the default interface:
    @legacy_function
    def set_time():
        """
        Set the model time. Should use set_begin_time!
        """
        function = LegacyFunctionSpecification()
        function.addParameter('time', dtype='float64', direction=function.IN,
            description = "The model time to start at", unit = nbody_system.time)
        function.result_type = 'int32'
        function.result_doc = """
        0 - OK
            Time value was changed
        -2 - ERROR
            The code does not support setting the  time
        """
        return function
        
    @legacy_function
    def set_eta():
        """
        Set the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('eta', dtype='float64',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_eta():
        """
        Get the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('eta', dtype='float64',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_gpu():
        """
        Set use_gpu.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('gpu', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_gpu():
        """
        Get use_gpu.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('gpu', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_gpu_id():
        """
        Set gpu_id.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('gpu_id', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_gpu_id():
        """
        Get gpu_id.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('gpu_id', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_manage_encounters():
        """
        Set the value of manage_encounters.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('manage_encounters', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_manage_encounters():
        """
        Get the value of manage_encounters.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('manage_encounters', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_zero_step_mode():
        """
        Set the value of zero_step_mode.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('zero_step_mode', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_zero_step_mode():
        """
        Get the value of zero_step_mode.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('zero_step_mode', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_force_sync():
        """
        Set the value of force_sync.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('force_sync', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_force_sync():
        """
        Get the value of force_sync.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('force_sync', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_sync_time():
        """
        Set the value of sync_time.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('sync_time', dtype='float64',
                              direction=function.IN, unit = nbody_system.time)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_sync_time():
        """
        Get the value of sync_time.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('sync_time', dtype='float64',
                              direction=function.OUT, unit = nbody_system.time)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_block_steps():
        """
        Set the value of block_steps.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('set_block_steps', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_block_steps():
        """
        Get the value of block_steps.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('get_block_steps', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_total_steps():
        """
        Set the value of total_steps.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('set_total_steps', dtype='int32',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_total_steps():
        """
        Get the value of total_steps.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('get_total_steps', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_number_of_particles_updated():
        """
        Return the number of particles added or deleted during the last evolve.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('index', dtype='int32',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function
    
    @legacy_function
    def get_id_of_updated_particle():
        """
        Return the number of particles added or deleted during the last evolve.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('index_of_update', dtype='int32',
                              direction=function.IN, 
                 description = 'index in the updated particles list')
        function.addParameter('index_of_particle', dtype='int32',
                              direction=function.OUT)
        function.addParameter('kind_of_update', dtype='int32',
                              direction=function.OUT,
                 description = 'kind of update (2, addition), (1, deletion)')
        function.can_handle_array = True
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_binary_energy():
        """
        Return the total energy in all binaries.
        """
        function = LegacyFunctionSpecification()
        function.addParameter(
            'binary_energy', 
            dtype='float64',
            direction=function.OUT,
            unit = nbody_system.energy
        )
        function.result_type = 'int32'
        return function

    @legacy_function
    def set_initial_timestep_fac():
        """
        Set the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('initial_timestep_fac', dtype='float64',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_initial_timestep_fac():
        """
        Get the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('initial_timestep_fac', dtype='float64',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function
    
    @legacy_function
    def set_initial_timestep_limit():
        """
        Set the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('initial_timestep_limit', dtype='float64',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_initial_timestep_limit():
        """
        Get the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('initial_timestep_limit', dtype='float64',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function
    
    @legacy_function
    def set_initial_timestep_median():
        """
        Set the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('initial_timestep_median', dtype='float64',
                              direction=function.IN)
        function.result_type = 'int32'
        return function

    @legacy_function
    def get_initial_timestep_median():
        """
        Get the current accuracy parameter.
        """
        function = LegacyFunctionSpecification()
        function.addParameter('initial_timestep_median', dtype='float64',
                              direction=function.OUT)
        function.result_type = 'int32'
        return function
    
    @legacy_function
    def recompute_timesteps():
        """
        Force recomputation of all timesteps (assume a synchronized system),
        """
        function = LegacyFunctionSpecification()
        function.result_type = 'int32'
        return function


class ph4(GravitationalDynamics,GravityFieldCode):

    # The actual module.

    def __init__(self, convert_nbody = None, **keyword_arguments):
        legacy_interface = ph4Interface(**keyword_arguments)

        self.stopping_conditions = StoppingConditions(self)
        
        GravitationalDynamics.__init__(self,
                                       legacy_interface,
                                       convert_nbody,
                                       **keyword_arguments)
                                       
    def define_state(self, handler):
        GravitationalDynamics.define_state(self, handler)
        handler.add_method('RUN', 'get_particle_timestep')
        GravityFieldCode.define_state(self, handler)
        
        handler.add_method('EDIT', 'set_state')
        handler.add_method('EDIT', 'set_velocity')
        handler.add_method('EDIT', 'set_mass')
        handler.add_method('EDIT', 'set_position')
        handler.add_method('CHANGED','before_get_parameter')
        
        handler.add_transition('RUN', 'CHANGED', 'set_state', False)
        handler.add_transition('RUN', 'CHANGED', 'set_velocity', False)
        handler.add_transition('RUN', 'CHANGED', 'set_mass', False)
        handler.add_transition('RUN', 'CHANGED', 'set_position', False)
        handler.add_transition('CHANGED', 'RUN', 'synchronize_model')
        handler.add_method('CHANGED', 'get_state')
        handler.add_method('CHANGED', 'get_mass')
        handler.add_method('CHANGED', 'get_position')
        handler.add_method('CHANGED', 'get_velocity')
        handler.add_method('CHANGED', 'get_particle_timestep')
        
        self.stopping_conditions.define_state(handler)

    def define_parameters(self, handler):

        # Set/get parameters specific to the module, not part of the
        # standard interface.  Accessors used here must be defined
        # above and reflected in interface.cc.  Python access is
        # (e.g.)
        #
        #        ph4.parameters.timestep_parameter = xxx

        handler.add_method_parameter(
            "get_eta",                   # getter name in interface.cc
            "set_eta",                   # setter name in interface.cc
            "timestep_parameter",        # python parameter name
            "timestep parameter",        # description
            default_value = 0.14
        )

        handler.add_method_parameter(
            "get_eps2",                  # already defined in standard interface
            "set_eps2",                  # already defined in standard interface
            "epsilon_squared", 
            "smoothing parameter for gravity calculations", 
            default_value = 0.0 | nbody_system.length * nbody_system.length
        )

        handler.add_method_parameter(
            "get_gpu",                   # getter name in interface.cc
            "set_gpu",                   # setter name in interface.cc
            "use_gpu",                   # python parameter name
            "use GPU",                   # description
            default_value = 1
        )
        
        handler.add_method_parameter(
            "get_gpu_id",                # getter name in interface.cc
            "set_gpu_id",                # setter name in interface.cc
            "gpu_id",                    # python parameter name
            "GPU ID",                    # description
            default_value = -1
        )
        
        handler.add_method_parameter(
            "get_manage_encounters",     # getter name in interface.cc
            "set_manage_encounters",     # setter name in interface.cc
            "manage_encounters",	 # python parameter name
            "manage close encounters",   # description
            default_value = 4
        )
        
        handler.add_method_parameter(
            "get_begin_time",
            "set_begin_time",
            "begin_time",
            "model time at which to start the simulation",
            default_value = 0.0 | nbody_system.time
        )

        handler.add_method_parameter(
            "get_sync_time",
            "set_sync_time",
            "sync_time",
            "last model synchronization time",
            default_value = 0.0 | nbody_system.time
        )

        handler.add_method_parameter(
            "get_zero_step_mode",
            "set_zero_step_mode",
            "zero_step_mode",
            "force evolve_model to take zero-length steps",
            default_value = 0
        )

        handler.add_method_parameter(
            "get_force_sync",
            "set_force_sync",
            "force_sync",
            "force evolve_model to sync at specified time",
            default_value = 0
        )

        handler.add_method_parameter(
            "get_block_steps",
            "set_block_steps",
            "block_steps",
            "number of block steps",
            default_value = 0
        )

        handler.add_method_parameter(
            "get_total_steps",
            "set_total_steps",
            "total_steps",
            "total number of steps",
            default_value = 0
        )

        handler.add_method_parameter(
            "get_initial_timestep_fac",  # getter name in interface.cc
            "set_initial_timestep_fac",  # setter name in interface.cc
            "initial_timestep_fac",      # python parameter name
            "initial timestep factor",   # description
            default_value = 0.0625
        )

        handler.add_method_parameter(
            "get_initial_timestep_limit", # getter name in interface.cc
            "set_initial_timestep_limit", # setter name in interface.cc
            "initial_timestep_limit",     # python parameter name
            "initial timestep limit",     # description
            default_value = 0.03125
        )

        handler.add_method_parameter(
            "get_initial_timestep_median", # getter name in interface.cc
            "set_initial_timestep_median", # setter name in interface.cc
            "initial_timestep_median",     # python parameter name
            "initial timestep median factor", # description
            default_value = 8.0
        )

        self.stopping_conditions.define_parameters(handler)
        
    def update_particle_set(self):
        """
        update the particle set after changes in the code
        
        this implementation needs to move to the
        amuse.datamodel.incode_storage module, as
        it uses a lot of internal methods and info!
        
        """
        number_of_updated_particles = self.get_number_of_particles_updated()
        
        if number_of_updated_particles == 0:
            return
        
        indices_in_update_list = list(range(number_of_updated_particles))
        particle_indices, updates \
            = self.get_id_of_updated_particle(indices_in_update_list)
        
        incode_storage = self.particles._private.attribute_storage
        
        indices_to_remove = []
        indices_to_add = []
        for index, status in zip(particle_indices, updates):
            if status == 1:                        # deletion
                indices_to_remove.append(index)
            elif status == 2:                        # addition
                indices_to_add.append(index)

        print('')
        print("indices_to_remove:", indices_to_remove)
        print("indices_to_add:", indices_to_add)

        if len(indices_to_remove) > 0:
            incode_storage._remove_indices(indices_to_remove)
        if len(indices_to_add) > 0:
            incode_storage._add_indices(indices_to_add)
        
    def define_methods(self, handler):
        GravitationalDynamics.define_methods(self, handler)

        # Turn interface functions into methods.
        handler.add_method(
            "new_particle",
            (
                nbody_system.mass,
                nbody_system.length,
                nbody_system.length,
                nbody_system.length,
                nbody_system.speed,
                nbody_system.speed,
                nbody_system.speed,
                nbody_system.length,
                handler.NO_UNIT
            ),
            (
                handler.INDEX,
                handler.ERROR_CODE
            )
        )

        handler.add_method(
            "set_eps2",
            (
                nbody_system.length * nbody_system.length
            ),
            (
                handler.ERROR_CODE
            )
        )

        handler.add_method(
            "get_eps2",
            (),
            (
                nbody_system.length * nbody_system.length,
                handler.ERROR_CODE
            )
        )

        self.stopping_conditions.define_methods(handler)

    def define_particle_sets(self, handler):
        GravitationalDynamics.define_particle_sets(self, handler)
        
        handler.add_getter('particles', 'get_particle_timestep',
                          names = ('timestep',))
        handler.add_getter('particles', 'get_potential',
                          names=('potential_in_code',))
        
        self.stopping_conditions.define_particle_set(handler)


Ph4 = ph4
