#!/usr/bin/python

from interpreter import INTERP_OK
import math

def g740(self, **words):
    # G74 is typically called like so:
    # G74 x ? z ? k ? (x = diameter, usually 0; z = hole endpoint; k = peck length) 

    # get position
    if (self.params['_lathe_diameter_mode']):  # if is_lathe_mode
        x_mode = 2
    else:
        x_mode = 1

    x_start = self.params[5420] * x_mode
    z_start = self.params[5422]

    if 'x' in words:
        x_end = words['x'] * x_mode
    else:
        x_end = x_start * x_mode

    if 'z' in words:
        z_end = words['z']
        if z_end > z_start:
            return "G74 error - Z cannot be larger than the starting Z position"
    else:
        z_end = z_start

    if 'k' in words:
        peck_length = words['k']
        if peck_length < 0:
            return "G74 error - K cannot be negative"
    else:
        peck_length = 0

    if (self.params['_metric']):  # if is_metric
        backoff_length = 0.50  # mm
        rounding_fudge = 0.0001
    else:
        backoff_length = 0.020  # inch
        rounding_fudge = 0.00001

    z_range = math.fabs(z_end - z_start) - rounding_fudge  # rounding_fudge prevents extra peck
    if peck_length > 0:
        num_pecks = int(z_range / peck_length)
    else:
        num_pecks = 0

    z_list = []
    for i in range(num_pecks + 1):
        z_list.append(z_start - (i * peck_length))
    z_list.append(z_end)

    print "--kaw - z_list =", z_list

    if math.fabs(x_end - x_start) > rounding_fudge:  # We're groove'n
        for i in range(num_pecks + 1):
            self.execute("G0 Z %s" % z_list[i])
            self.execute("G1 Z %s" % z_list[i + 1])
            self.execute("G1 X %s" % x_end)
            self.execute("G1 Z %s" % (z_list[i] + backoff_length))
            self.execute("G0 X %s" % x_start)

    else:  # We're drilling
        for i in range(num_pecks + 1):
            self.execute("G1 Z %s" % z_list[i + 1])
            self.execute("G0 Z %s" % (z_list[i + 1] + backoff_length))

    self.execute("G0 Z %s" % z_start)

    return INTERP_OK