import arcpy

class Toolbox(object):
    def __init__(self):
        self.label = "Station Offset toolbox"
        self.alias = "StationOffset"

        # List of tool classes associated with this toolbox
        self.tools = [CalculateStationOffset]

class CalculateStationOffset(object):
    def __init__(self):
        self.label = "Calculate Station Offset"
        self.description = "Calculate Station Offset"

def getParameterInfo(self):
    #Define parameter definitions

    # Input Features parameter
    in_features = arcpy.Parameter(
        displayName="Input Features",
        name="in_features",
        datatype="GPFeatureLayer",
        parameterType="Required",
        direction="Input")

    in_features.filter.list = ["Point"]

    # Alignment parameter
    in_alignment = arcpy.Parameter(
        displayName="Alignment",
        name="in_alignment",
        datatype="GPFeatureLayer",
        parameterType="Required",
        direction="Input")

    in_alignment.filter.list = ["Polyline"]

    # Derived Output Features parameter
    out_features = arcpy.Parameter(
        displayName="Output Features",
        name="out_features",
        datatype="GPFeatureLayer",
        parameterType="Derived",
        direction="Output")

    out_features.parameterDependencies = [in_features.name]
    out_features.schema.clone = True

    parameters = [in_features, in_alignment, out_features]

    return parameters

    def isLicensed(self):
        return True

    def updateParameters(self, parameters):
        if parameters[0].altered:
            parameters[1].value = arcpy.ValidateFieldName(parameters[1].value, parameters[0].value)
        return

    def updateMessages(self, parameters):
        return

def execute(self, parameters, messages):
    fc_pnt         = parameters[0].valueAsText
    fc_line        = parameters[1].valueAsText

    # Fields
    fields = ['SHAPE@', 'MEAS', 'Distance', 'NEAR_X', 'NEAR_Y', 'Orient', 'POINT_X', 'POINT_Y', 'NEAR_ANGLE']

    # Get line geometry - assumes only one feature in feature class
    polyline = arcpy.da.SearchCursor(fc_line, "SHAPE@").next()[0]

    # Loop over the point feature class
    with arcpy.da.UpdateCursor(fc_pnt, fields) as cursor:
        for row in cursor:
            dist=polyline.queryPointAndDistance(row[0], False)
            row[1] = dist[1]
            row[2] = dist[2]
            row[3] = dist[0].centroid.X
            row[4] = dist[0].centroid.Y
            if dist[3] == 0:
                row[5]="Left"
            else:
                row[5]="Right"
            row[6] = row[0].centroid.X
            row[7] = row[0].centroid.Y
            print(dist)
            cursor.updateRow(row)