#!/usr/bin/env python

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"""Merge given *.csv files

Usage: ./$0 <mergedFileName> <csvFile1> <csvFile2> ..."""

import csv
import getopt
import os
import sys

class Global:
    Delimiter = ','

class FileWithValues:
    def __init__(self, filePath, tag, values):
        self.filePath = filePath
        self.tag = tag
        self.values = values

def readCsv(filePath, delimiter):
    lines = []
    with open(filePath, 'rb') as f:
        lines = f.readlines()

    records = []
    for line in lines:
        identifier,value = line.split(delimiter)
        identifier = identifier.strip()
        value = value.strip()
        records.append((identifier, value))

    return records

def readCsvFiles(filePaths):
    files = []

    for filePath in filePaths:
        f = open(filePath, 'rb')
        reader = csv.reader(f, delimiter=Global.Delimiter, quoting=csv.QUOTE_NONE)

        values = []
        for row in reader:
            values.append(row)

        tag = values[0][0] # remember column label
        values = values[1:] # skip header

        myFile = FileWithValues(filePath, tag, values)
        files.append(myFile)

    return files

def checkConsistency(files):
    referenceEntry = files[0]
    referenceEntrySize = len(referenceEntry.values)
    referenceEntryIdentifiers = [v[0] for v in referenceEntry.values]

    # Ensure same size of records
    for f in files:
        if not len(f.values) == referenceEntrySize:
            print >> sys.stderr, 'error: number of entries mismatch between "%s" and "%s".' %(referenceEntry.filePath, f.filePath)
            sys.exit(1)

    # Ensure same identifier on the left
    for f in files:
        identifiers = [v[0] for v in f.values]
        if not identifiers == referenceEntryIdentifiers:
            print >> sys.stderr, 'error: mismatch between identifers in first column between "%s" and "%s".' %(referenceEntry.filePath, f.filePath)
            sys.exit(1)

    return referenceEntryIdentifiers

def mergeFilesHelper(outputFilePath, referenceIdentifiers, files):
    with open(outputFilePath, 'wb') as csvfile:
        writer = csv.writer(csvfile, delimiter=Global.Delimiter, quotechar='"', quoting=csv.QUOTE_MINIMAL)

        # Write header row
        headers = ['action'] + [f.tag for f in files]
        writer.writerow(headers)

        # Write values
        columns = [[v[1] for v in f.values] for f in files]
        rows = zip(referenceIdentifiers, *columns)
        for row in rows:
            writer.writerow(row)

def mergeFiles(outputFilePath, filesToMerge):
    files = readCsvFiles(filesToMerge)
    referenceIdentifiers = checkConsistency(files)
    mergeFilesHelper(outputFilePath, referenceIdentifiers, files)

def printHelpAndExit():
    print __doc__
    sys.exit(0)

def main():
    try:
        opts, args = getopt.getopt(sys.argv[1:], "h", ["help"])
    except getopt.error, msg:
        print msg
        print "for help use --help"
        sys.exit(2)

    for o, a in opts:
        if o in ("-h", "--help"):
            printHelpAndExit()
    if len(args) <= 2:
        printHelpAndExit()

    outputFile = args[0]
    filesToMerge = args[1:]
    mergeFiles(outputFile, filesToMerge)

if __name__ == "__main__":
    main()