#!/usr/bin/env python3

from pywarpx import picmi

# Physical constants
c = picmi.constants.c
q_e = picmi.constants.q_e

# Number of time steps
max_steps = 200

# Number of cells
nx = 64
nz = 512

# Physical domain
xmin = -30e-06
xmax =  30e-06
zmin = -56e-06
zmax =  12e-06
xmin_refined = -5e-06
xmax_refined =  5e-06
zmin_refined = -35e-06
zmax_refined = -25e-06

# Domain decomposition
max_grid_size = 64
blocking_factor = 32

# Create grid
grid = picmi.Cartesian2DGrid(
    number_of_cells = [nx, nz],
    lower_bound = [xmin, zmin],
    upper_bound = [xmax, zmax],
    lower_boundary_conditions = ['open', 'open'],
    upper_boundary_conditions = ['open', 'open'],
    lower_boundary_conditions_particles = ['absorbing', 'absorbing'],
    upper_boundary_conditions_particles = ['absorbing', 'absorbing'],
    moving_window_velocity = [0., c],
    warpx_max_grid_size = max_grid_size,
    warpx_blocking_factor = blocking_factor,
    refined_regions = [[1, [xmin_refined, zmin_refined], [xmax_refined, zmax_refined]]])

# Particles: plasma electrons
plasma_density = 2e23
plasma_xmin = -20e-06
plasma_ymin = None
plasma_zmin = 10e-06
plasma_xmax = 20e-06
plasma_ymax = None
plasma_zmax = None
uniform_distribution = picmi.UniformDistribution(
    density = plasma_density,
    lower_bound = [plasma_xmin, plasma_ymin, plasma_zmin],
    upper_bound = [plasma_xmax, plasma_ymax, plasma_zmax],
    fill_in = True)
electrons = picmi.Species(
    particle_type = 'electron',
    name = 'electrons',
    initial_distribution = uniform_distribution)

# Particles: beam electrons
q_tot = 1e-12
x_m = 0.
y_m = 0.
z_m = -28e-06
x_rms = 0.5e-06
y_rms = 0.5e-06
z_rms = 0.5e-06
ux_m = 0.
uy_m = 0.
uz_m = 500.
ux_th = 2.
uy_th = 2.
uz_th = 50.
gaussian_bunch_distribution = picmi.GaussianBunchDistribution(
    n_physical_particles = q_tot / q_e,
    rms_bunch_size = [x_rms, y_rms, z_rms],
    rms_velocity = [c*ux_th, c*uy_th, c*uz_th],
    centroid_position = [x_m, y_m, z_m],
    centroid_velocity = [c*ux_m, c*uy_m, c*uz_m])
beam = picmi.Species(
    particle_type = 'electron',
    name = 'beam',
    initial_distribution = gaussian_bunch_distribution)

# Laser
e_max = 16e12
position_z = 9e-06
profile_t_peak = 30.e-15
profile_focal_distance = 100e-06
laser = picmi.GaussianLaser(
    wavelength = 0.8e-06,
    waist = 5e-06,
    duration = 15e-15,
    focal_position = [0, 0, profile_focal_distance + position_z],
    centroid_position = [0, 0, position_z - c*profile_t_peak],
    propagation_direction = [0, 0, 1],
    polarization_direction = [0, 1, 0],
    E0 = e_max,
    fill_in = False)
laser_antenna = picmi.LaserAntenna(
    position = [0., 0., position_z],
    normal_vector = [0, 0, 1])

# Electromagnetic solver
solver = picmi.ElectromagneticSolver(
    grid = grid,
    method = 'Yee',
    cfl = 1.,
    divE_cleaning = 0)

# Diagnostics
diag_field_list = ['B', 'E', 'J', 'rho']
field_diag = picmi.FieldDiagnostic(
    name = 'diag1',
    grid = grid,
    period = 200,
    data_list = diag_field_list,
    write_dir = '.',
    warpx_file_prefix = 'Python_LaserAccelerationMR_plt')

# Set up simulation
sim = picmi.Simulation(
    solver = solver,
    max_steps = max_steps,
    verbose = 1,
    particle_shape = 'cubic',
    warpx_use_filter = 1,
    warpx_serialize_initial_conditions = 1)

# Add plasma electrons
sim.add_species(
    electrons,
    layout = picmi.GriddedLayout(grid = grid, n_macroparticle_per_cell = [1, 1, 1]))

# Add beam electrons
sim.add_species(
    beam,
    layout = picmi.PseudoRandomLayout(grid = grid, n_macroparticles = 100))

# Add laser
sim.add_laser(
    laser,
    injection_method = laser_antenna)

# Add diagnostics
sim.add_diagnostic(field_diag)

# Write input file that can be used to run with the compiled version
sim.write_input_file(file_name = 'inputs_2d_picmi')

# Initialize inputs and WarpX instance
sim.initialize_inputs()
sim.initialize_warpx()

# Advance simulation until last time step
sim.step(max_steps)