# -*- coding: utf-8 -*-

"""
This python module implements the FORCE flux
for the shallow water equations

Copyright (C) 2016  SINTEF ICT

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

#Import packages we need
from GPUSimulators import Simulator, Common
from GPUSimulators.Simulator import BaseSimulator, BoundaryCondition
import numpy as np



        
        
        
        
        
        


"""
Class that solves the SW equations 
"""
class FORCE (Simulator.BaseSimulator):

    """
    Initialization routine
    h0: Water depth incl ghost cells, (nx+1)*(ny+1) cells
    hu0: Initial momentum along x-axis incl ghost cells, (nx+1)*(ny+1) cells
    hv0: Initial momentum along y-axis incl ghost cells, (nx+1)*(ny+1) cells
    nx: Number of cells along x-axis
    ny: Number of cells along y-axis
    dx: Grid cell spacing along x-axis (20 000 m)
    dy: Grid cell spacing along y-axis (20 000 m)
    dt: Size of each timestep (90 s)
    g: Gravitational accelleration (9.81 m/s^2)
    """
    def __init__(self, 
                 context, 
                 h0, hu0, hv0, 
                 nx, ny, 
                 dx, dy, dt, 
                 g, 
                 boundary_conditions=BoundaryCondition(), 
                 block_width=16, block_height=16):
                 
        # Call super constructor
        super().__init__(context, 
            nx, ny, 
            dx, dy, dt, 
            block_width, block_height);
        self.g = np.float32(g) 
        self.boundary_conditions = boundary_conditions.asCodedInt()

        #Get kernels
        module = context.get_module("cuda/SWE2D_FORCE.cu",
                                        defines={
                                            'BLOCK_WIDTH': self.block_size[0], 
                                            'BLOCK_HEIGHT': self.block_size[1]
                                        }, 
                                        compile_args={
                                            'no_extern_c': True,
                                            'options': ["--use_fast_math"], 
                                        }, 
                                        jit_compile_args={})
        self.kernel = module.get_function("FORCEKernel")
        self.kernel.prepare("iiffffiPiPiPiPiPiPi")
    
        #Create data by uploading to device
        self.u0 = Common.ArakawaA2D(self.stream, 
                        nx, ny, 
                        1, 1, 
                        [h0, hu0, hv0])
        self.u1 = Common.ArakawaA2D(self.stream, 
                        nx, ny, 
                        1, 1, 
                        [None, None, None])
        
    def step(self, dt):
        self.kernel.prepared_async_call(self.grid_size, self.block_size, self.stream, 
                self.nx, self.ny, 
                self.dx, self.dy, dt, 
                self.g, 
                self.boundary_conditions, 
                self.u0[0].data.gpudata, self.u0[0].data.strides[0], 
                self.u0[1].data.gpudata, self.u0[1].data.strides[0], 
                self.u0[2].data.gpudata, self.u0[2].data.strides[0], 
                self.u1[0].data.gpudata, self.u1[0].data.strides[0], 
                self.u1[1].data.gpudata, self.u1[1].data.strides[0], 
                self.u1[2].data.gpudata, self.u1[2].data.strides[0])
        self.u0, self.u1 = self.u1, self.u0
        self.t += dt
        self.nt += 1
        
    def download(self):
        return self.u0.download(self.stream)
        
    def check(self):
        self.u0.check()
        self.u1.check()