#!/usr/bin/python3

"""
a simple script to take in airfoil data from http://airfoiltools.com
and convert it into inch data points which could be put into a CAD program.

use like so:

python convert-airfoil.py airfoil.dat 45

where airfoil.dat is the file full of airfoil points, and 45 is the number
of inches (or whatever unit, this script is units-agnostic) you want the
chord-line to be.
"""

import sys

def read_points(filename):
    """
    open up filename and read in the data points
    """
    data = []
    with open(filename) as fp:
        filedata = fp.readlines()
    for line in filedata:
        x, y = line.split()
        data.append((x,y))
    return data


def scale_data(data, length):
    """
    scale up all our data to the requested length
    """
    scaled_data = []
    for item in data:
        new_x = float(item[0]) * float(length)
        new_y = float(item[1]) * float(length)
        scaled_data.append((new_x, new_y))
    return scaled_data


def main():
    data = read_points(sys.argv[1])
    scaled_data = scale_data(data, sys.argv[2])
    for item in scaled_data:
        print('x: {}, y: {}'.format(item[0], item[1]))


if __name__ == '__main__':
    main()