#!/usr/bin/env python3
# Simple program to save the 'Dolartoday' extra official dollar rates from CSV to a custom format
# Revisited to use 'contexts' to avoid using finally on exception handling
# @author Jose Vicente Nunez, josevnz@kodegeek.com
import os, sys, datetime, re, gzip, struct
from optparse import OptionParser, OptionValueError
from datetime import datetime
 
class DollarToday:
 
    def __init__(self, ddate, value):
        if isinstance(ddate, datetime):
            self.__date = ddate
        else:
            self.__date = datetime.strptime(ddate, "%m-%d-%Y")
        self.__value = float(value)
        assert self.__value > 0.0, "{} for date {} is invalid!".format(value, self.__date)
 
    @property
    def date(self):
        return self.__date
 
    @date.setter
    def date(self, date):
        assert isinstance(date, datetime), "Invalid date {}".format(date)
        self.__date = date
 
    @property
    def value(self):
        return self.__value
 
    def __str__(self):
        return "DollarToday[date={}, value={}]".format(self.__date, self.__value)
 
    def __hash__(self):
        return str(id(self))
 
class DollarCollection(dict):
 
    # https://en.wikipedia.org/wiki/List_of_file_signatures
    __FILE_MAGIC = b"DLR\x00"
    __FILE_VERSION = b"\x00\x01"
    __dollarStruct = struct.Struct("<id ")
 
    def values(self):
        for dateId in sorted(self.keys()):
            yield self[dateId]
 
    def items(self):
        for dateId in self.keys():
            yield (dateId, self[dateId])
 
    def __iter__(self):
        for dateId in sorted(super().keys()):
            yield dateId
 
    def save(self, file):
        try:
            with gzip.open(file, "wb") as fh:
                fh.write(self.__FILE_MAGIC)
                fh.write(self.__FILE_VERSION)
                for dollar in self.values():
                    data = bytearray()
                    data.extend(
                           self.__dollarStruct.pack(
                                dollar.date.toordinal(),
                                dollar.value
                           )
                                )
                    fh.write(data)
        except (Exception) as err:
            raise
 
    def readBinary(self, file, verbose=False):
        try:
            with gzip.open(file, "rb") as fh:
                magic = fh.read(len(self.__FILE_MAGIC))
                if magic != self.__FILE_MAGIC:
                    raise "File doesn't look like a KodeGeek.com binary file!"
                version = fh.read(len(self.__FILE_VERSION))
                if version > self.__FILE_VERSION:
                    raise "Unsupported file version: {}, expected {}".format(version, self.__FILE_VERSION)
                self.clear()
                while True:
                    data = fh.read(self.__dollarStruct.size)
                    if len(data) == 0:
                        break
                    numbers = self.__dollarStruct.unpack(data)
                    #if verbose:
                    #    print("{}".format(",".join([str(x) for x in numbers])))
                    dolar = DollarToday(
                                    datetime.fromordinal(numbers[0]),
                                    numbers[1]
                                    )
                    self[dolar.date] = dolar
        except (Exception) as err:
            raise
 
    def readCsv(self, file):
        tempMap = {}
        try:
            with open(file, "r", encoding="UTF-8") as fh:
                for line in fh.readlines():
                    # 6-23-2010       9.92
                    (date, value) = line.strip().split("\t")
                    if re.match("Fecha", date):
                        continue
                    try:
                        dolVsBol = DollarToday(date, value)
                        tempMap[dolVsBol.date] = dolVsBol
                    except (Exception) as err:
                        print(err)
            self.clear()
            self.update(tempMap)
        except (Exception) as err:
            raise
 
    def __str__(self):
        return "Records={},\n{}".format(len(self), ",\n".join([str(date) for date in self.values()]))
 
def main(options):
 
    verbose = options.verbose
    dc = DollarCollection()
    if options.report == None:
        dc.readCsv(options.read)
        dc.save(options.write)
    else:
        dc.readBinary(options.report, verbose)
    if verbose:
        print("{}".format(dc))
 
if __name__ == "__main__":
 
    usagetext = """
%prog --read csv.file --write binary.file
 
Or:
 
%prog --report binary.file
 
"""
 
    op = OptionParser(usage=usagetext)
    op.add_option(
                  "-r", "--read",
                  action="store", 
                  dest="read", 
                  help="Full path to CSV file with date,value pairs per line")
    op.add_option(
                  "-w", "--write", 
                  action="store", 
                  dest="write", 
                  help="Full path to destination file in binary format")
    op.add_option(
                  "-p", "--report", 
                  action="store", 
                  dest="report",
                  help="Read the contents of the binary storage and generate a report. Incompatible with --read and --write")
    op.add_option(
                  "-v", "--verbose", 
                  action="store_true", 
                  default=False, 
                  dest="verbose", 
                  help="Enable verbose mode")
 
    (options, values) = op.parse_args()
 
    main(options)
</id>