import numpy
import time

import matplotlib
import matplotlib.pyplot as plt
matplotlib.use('AGG')

from lbm import Lattice, Geometry

import symbolic.D3Q19 as D3Q19

def MLUPS(cells, steps, time):
    return cells * steps / time * 1e-6

def generate_moment_plots(lattice, moments):
    for i, m in enumerate(moments):
        print("Generating plot %d of %d." % (i+1, len(moments)))

        velocity = numpy.ndarray(shape=tuple(reversed(lattice.geometry.inner_span())))

        # plot x-z-plane
        y = lattice.geometry.size_y//2
        for z in range(1,lattice.geometry.size_z-1):
            for x in range(1,lattice.geometry.size_x-1):
                velocity[z-1,y,x-1] = numpy.sqrt(m[1,lattice.idx(x,y,z)]**2 + m[2,lattice.idx(x,y,z)]**2 + m[3,lattice.idx(x,y,z)]**2)

        plt.figure(figsize=(20, 10))

        plt.subplot(1, 2, 1)
        plt.imshow(velocity[:,y,:], origin='lower', vmin=0.0, vmax=0.12, cmap=plt.get_cmap('seismic'))

        # plot y-z-plane
        x = lattice.geometry.size_x//2
        for z in range(1,lattice.geometry.size_z-1):
            for y in range(1,lattice.geometry.size_y-1):
                velocity[z-1,y-1,x] = numpy.sqrt(m[1,lattice.idx(x,y,z)]**2 + m[2,lattice.idx(x,y,z)]**2 + m[3,lattice.idx(x,y,z)]**2)

        plt.subplot(1, 2, 2)
        plt.imshow(velocity[:,:,x], origin='lower', vmin=0.0, vmax=0.15, cmap=plt.get_cmap('seismic'))

        plt.savefig("result/ldc_3d_%02d.png" % i, bbox_inches='tight', pad_inches=0)

def cavity(geometry, x, y, z):
    if x == 1 or y == 1 or z == 1 or x == geometry.size_x-2 or y == geometry.size_y-2:
        return 2
    elif z == geometry.size_z-2:
        return 3
    else:
        return 1

boundary = """
    if ( m == 2 ) {
        u_0 = 0.0;
        u_1 = 0.0;
        u_2 = 0.0;
    }
    if ( m == 3 ) {
        u_0 = 0.1;
        u_1 = 0.0;
        u_2 = 0.0;
    }
"""

nUpdates = 20000
nStat    = 500

moments = []

print("Initializing simulation...\n")

lattice = Lattice(
    descriptor = D3Q19,
    geometry   = Geometry(128, 128, 128),

    moments = D3Q19.moments(optimize = False),
    collide = D3Q19.bgk(tau = 0.52),

    boundary_src = boundary)

lattice.setup_geometry(cavity)

print("Starting simulation using %d cells...\n" % lattice.geometry.volume)

lastStat = time.time()

for i in range(1,nUpdates+1):
    lattice.evolve()

    if i % nStat == 0:
        lattice.sync()
        print("i = %4d; %3.0f MLUPS" % (i, MLUPS(lattice.geometry.volume, nStat, time.time() - lastStat)))
        moments.append(lattice.get_moments())
        lastStat = time.time()

print("\nConcluded simulation.\n")

generate_moment_plots(lattice, moments)