#!/usr/bin/python3
import pandas as pd
import numpy as np
from glob import glob
import re

def natural_keys(text):
    # use a regex to sort in natural order
    return [int(text) if text.isdigit() else text.lower()
            for text in re.split('([0-9]+)', text) ]


class Parser:
    # obtain the list of files
    # read them
    # normalize them
    # assign them to the correct gesture (according to filename)

    def __init__(self, dataDir):
        self.wFiles, self.xFiles, self.yFiles, self.zFiles = self.get_files(dataDir);
        # sort lists of file IN PLACE
        # needed for assign()
        self.wFiles.sort(key=natural_keys)
        self.xFiles.sort(key=natural_keys)
        self.yFiles.sort(key=natural_keys)
        self.zFiles.sort(key=natural_keys)

    def _read_(self, csvFile):
        dfile = pd.read_csv(csvFile, delimiter=',', header=None)
        return dfile

    # called on __init__
    # obtain all files (recursively, even if not needed)
    def get_files(self, dDir):
        wExpr = dDir + "/W/*.csv"
        xExpr = dDir + "/X/*.csv"
        yExpr = dDir + "/Y/*.csv"
        zExpr = dDir + "/Z/*.csv"
        wFiles = glob(wExpr)
        xFiles = glob(xExpr)
        yFiles = glob(yExpr)
        zFiles = glob(zExpr)
        return wFiles, xFiles, yFiles, zFiles

#### min - max utilities (easier than pandas way)
    def _min_(self, dframe):
        minCol = dframe.min()
        res = minCol[0]
        for num in minCol:
            if res > num:
                res = num
        return res

    def _max_(self, dframe):
        maxCol = dframe.max()
        res = maxCol[0]
        for num in maxCol:
            if res < num:
                res = num
        return res
#### end of min-max utilities

    # normalize in [-1,1] included
    # normalizing a file here
    # this should be called for each file
    def normalize(self, csvFile):
        dfile = self._read_(csvFile)
        minimum = self._min_(dfile)
        maximum = self._max_(dfile)
        # apply a lambda to normalize in [-1,1]
        normDfile = dfile.apply(lambda x: ((x - minimum) / (maximum - minimum))*2 - 1)
        # print(normDfile, normDfile.max(), normDfile.min())
        return normDfile

    # assign to each gesture the corresponding files
    # (according to readme)
    def assign(self, files):
        assignedFiles1 = []
        assignedFiles2 = []
        assignedFiles3 = []

        for i in range(0,93):
            if (i < 31):
                assignedFiles1.append(files[i])
            elif (i < 62):
                assignedFiles2.append(files[i])
            else:
                assignedFiles3.append(files[i])
        return assignedFiles1,assignedFiles2,assignedFiles3