#!/usr/bin/env python
# Generate extruder pressure advance motion graphs
#
# Copyright (C) 2019-2021  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import math, optparse, datetime
import matplotlib

SEG_TIME = .000100
INV_SEG_TIME = 1. / SEG_TIME


######################################################################
# Basic trapezoid motion
######################################################################

# List of moves: [(start_v, end_v, move_t), ...]
Moves = [
    (0., 0., .100),
    (0., 100., None), (100., 100., .200), (100., 60., None),
    (60., 100., None), (100., 100., .200), (100., 0., None),
    (0., 0., .300)
]
EXTRUDE_R = (.4 * .4 * .75) / (math.pi * (1.75 / 2.)**2)
ACCEL = 3000. * EXTRUDE_R

def gen_positions():
    out = []
    start_d = start_t = t = 0.
    for start_v, end_v, move_t in Moves:
        start_v *= EXTRUDE_R
        end_v *= EXTRUDE_R
        if move_t is None:
            move_t = abs(end_v - start_v) / ACCEL
        half_accel = 0.
        if end_v > start_v:
            half_accel = .5 * ACCEL
        elif start_v > end_v:
            half_accel = -.5 * ACCEL
        end_t = start_t + move_t
        while t <= end_t:
            rel_t = t - start_t
            out.append(start_d + (start_v + half_accel * rel_t) * rel_t)
            t += SEG_TIME
        start_d += (start_v + half_accel * move_t) * move_t
        start_t = end_t
    return out


######################################################################
# List helper functions
######################################################################

MARGIN_TIME = 0.050

def time_to_index(t):
    return int(t * INV_SEG_TIME + .5)

def indexes(positions):
    drop = time_to_index(MARGIN_TIME)
    return range(drop, len(positions)-drop)

def trim_lists(*lists):
    keep = len(lists[0]) - time_to_index(2. * MARGIN_TIME)
    for l in lists:
        del l[keep:]


######################################################################
# Common data filters
######################################################################

# Generate estimated first order derivative
def gen_deriv(data):
    return [0.] + [(data[i+1] - data[i]) * INV_SEG_TIME
                   for i in range(len(data)-1)]

# Simple average between two points smooth_time away
def calc_average(positions, smooth_time):
    offset = time_to_index(smooth_time * .5)
    out = [0.] * len(positions)
    for i in indexes(positions):
        out[i] = .5 * (positions[i-offset] + positions[i+offset])
    return out

# Average (via integration) of smooth_time range
def calc_smooth(positions, smooth_time):
    offset = time_to_index(smooth_time * .5)
    weight = 1. / (2*offset - 1)
    out = [0.] * len(positions)
    for i in indexes(positions):
        out[i] = sum(positions[i-offset+1:i+offset]) * weight
    return out

# Time weighted average (via integration) of smooth_time range
def calc_weighted(positions, smooth_time):
    offset = time_to_index(smooth_time * .5)
    weight = 1. / offset**2
    out = [0.] * len(positions)
    for i in indexes(positions):
        weighted_data = [positions[j] * (offset - abs(j-i))
                         for j in range(i-offset, i+offset)]
        out[i] = sum(weighted_data) * weight
    return out


######################################################################
# Pressure advance
######################################################################

SMOOTH_TIME = .040
PRESSURE_ADVANCE = .045

# Calculate raw pressure advance positions
def calc_pa_raw(positions):
    pa = PRESSURE_ADVANCE * INV_SEG_TIME
    out = [0.] * len(positions)
    for i in indexes(positions):
        out[i] = positions[i] + pa * (positions[i+1] - positions[i])
    return out

# Pressure advance after smoothing
def METHOD_NAME(positions):
    return calc_weighted(calc_pa_raw(positions), SMOOTH_TIME)


######################################################################
# Plotting and startup
######################################################################

def plot_motion():
    # Nominal motion
    positions = gen_positions()
    velocities = gen_deriv(positions)
    accels = gen_deriv(velocities)
    # Motion with pressure advance
    pa_positions = calc_pa_raw(positions)
    pa_velocities = gen_deriv(pa_positions)
    # Smoothed motion
    sm_positions = METHOD_NAME(positions)
    sm_velocities = gen_deriv(sm_positions)
    # Build plot
    times = [SEG_TIME * i for i in range(len(positions))]
    trim_lists(times, velocities, accels,
               pa_positions, pa_velocities,
               sm_positions, sm_velocities)
    fig, ax1 = matplotlib.pyplot.subplots(nrows=1, sharex=True)
    ax1.set_title("Extruder Velocity")
    ax1.set_ylabel('Velocity (mm/s)')
    pa_plot, = ax1.plot(times, pa_velocities, 'r',
                        label='Pressure Advance', alpha=0.3)
    nom_plot, = ax1.plot(times, velocities, 'black', label='Nominal')
    sm_plot, = ax1.plot(times, sm_velocities, 'g', label='Smooth PA', alpha=0.9)
    fontP = matplotlib.font_manager.FontProperties()
    fontP.set_size('x-small')
    ax1.legend(handles=[nom_plot, pa_plot, sm_plot], loc='best', prop=fontP)
    ax1.set_xlabel('Time (s)')
    ax1.grid(True)
    fig.tight_layout()
    return fig

def setup_matplotlib(output_to_file):
    global matplotlib
    if output_to_file:
        matplotlib.rcParams.update({'figure.autolayout': True})
        matplotlib.use('Agg')
    import matplotlib.pyplot, matplotlib.dates, matplotlib.font_manager
    import matplotlib.ticker

def main():
    # Parse command-line arguments
    usage = "%prog [options]"
    opts = optparse.OptionParser(usage)
    opts.add_option("-o", "--output", type="string", dest="output",
                    default=None, help="filename of output graph")
    options, args = opts.parse_args()
    if len(args) != 0:
        opts.error("Incorrect number of arguments")

    # Draw graph
    setup_matplotlib(options.output is not None)
    fig = plot_motion()

    # Show graph
    if options.output is None:
        matplotlib.pyplot.show()
    else:
        fig.set_size_inches(6, 2.5)
        fig.savefig(options.output)

if __name__ == '__main__':
    main()