#!/usr/bin/env python

import csv
import getopt
import os, sys
import scipy.interpolate
import numpy as np
import matplotlib.pyplot as plt

X_MAX = 100
Y_MAX = 50

def usage():
    print("""usage: {} [OPTION...] CSV-FILE...

    -c  do cubic interpolation
    -l  do linear interpolation
    -h  show this help and exit""".format(os.path.basename(sys.argv[0])))

def plot(x, y, x_max, y_max, x_name, y_name, title, cubic, linear, xnew=None, f=None, f2=None):
    plt.plot(x, y, 'o')
    if linear:
        plt.plot(xnew, f(xnew), '-')
    if cubic:
        plt.plot(xnew, f2(xnew), '--')

    leg = [ 'data' ]
    if linear:
        leg.append('linear')
    if cubic:
        leg.append('cubic')
    plt.legend(leg, loc='best')

    plt.axis([0, x_max, 0, y_max], 'equal')
    plt.xlabel(x_name)
    plt.ylabel(y_name)
    plt.title(title)
    plt.grid(True)

    plt.show()

def read_and_plot_csv(csv_file, cubic, linear, x_max=X_MAX, y_max=Y_MAX):
    print("Reading data...")
    reader = csv.reader(open(csv_file, 'r'), delimiter=',')
    x_name,y_name = reader.next() # header line

    X = np.array([[float(_x), float(_y)] for _x,_y in reader ])
    x = X[:,0]
    y = X[:,1]
    xnew = f = f2 = None

    # interpolate data points
    if cubic or linear:
        xnew = np.linspace(min(x), max(x), len(x)*5)
    if linear:
        print("Calculating linear interpolation...")
        f = scipy.interpolate.interp1d(x, y)
    if cubic:
        print("Calculating cubic interpolation...")
        f2 = scipy.interpolate.interp1d(x, y, kind='cubic')

    plot(x, y, x_max, y_max, x_name, y_name, csv_file, cubic, linear, xnew, f, f2)

def main():
    try:
        opts, args = getopt.getopt(sys.argv[1:], "clh")
    except getopt.GetoptError, err:
        print(str(err))
        usage()
        sys.exit(-1)

    if len(args) < 1:
        usage()
        sys.exit(-1)

    cubic = False
    linear = False
    for o, a in opts:
        if o == '-c':
            cubic = True
        elif o == '-l':
            linear = True
        elif o == '-h':
            usage()
            sys.exit(0)
        else:
            assert False, "unhandled option"

    for csv in args:
        if not os.path.exists(csv):
            print "Error: File %s not found, skipping" % csv
            continue
        read_and_plot_csv(csv, cubic, linear)

if __name__ == '__main__':
    main()