#!/usr/bin/env python

import sys
import os
import imp
import difflib
import itertools

DEFAULT_PATH = 'submit.py'
CORRECT_OUTPUT_PATH = 'correct_output.txt'
DATABASE_PATH = 'flights.db'

def main(argv):
    print "This is a sanity checking script. It will run your queries and compare them against the output of our solution."
    print "However, grading will be done with a different data set to make sure your solutions don't rely on hard-coded answers."

    # get path to where the sanity check script lives 
    # (which presumably will also be where the reference correct output lives)
    sanity_check_folder = os.path.dirname(os.path.realpath(__file__))

    # get path to the submission
    submission = argv[1] if len(argv) > 1 else DEFAULT_PATH
    submissionPath = os.path.join(os.getcwdu(), submission)

    # Check if path exists and is a file.
    print("Sanity checking file '{}'...".format(submissionPath))
    if not os.path.isfile(submissionPath):
        print("ERROR: File '{}' does not exist.".format(submissionPath))
        return 1
    # Attempt to load file as script.
    foo = imp.load_source('submit', submissionPath)

    # Attempt to connect datatbase
    foo.connect_database(os.path.join(sanity_check_folder, DATABASE_PATH))
    results = foo.get_all_query_results(debug_print=False)

    # turn a list of lists of strings into a list of strings
    # https://stackoverflow.com/questions/716477/join-list-of-lists-in-python
    listStrings = list(itertools.chain.from_iterable(results))

    # read the correct output file
    correctOutputStrings = None
    with open(os.path.join(sanity_check_folder, CORRECT_OUTPUT_PATH)) as f:
        correctOutputStrings = f.readlines()
    correctOutputStrings = [s.strip() for s in correctOutputStrings]

    # diff the correct output file
    diff = difflib.ndiff(listStrings, correctOutputStrings)
    diffPrinted = False
    for s in diff:
        if s[0] == '-' or s[0] == '+':
            diffPrinted = True
        print s

    qwer =  foo.conn.execute(foo.Q7)
    for i in qwer:
        print i[0]


    # special case run for Q7, which actually looks at the query result and does some math. Unfortunately, this requires hard coding the location of the answer into the code.
    print "For Q7, we'll be allowing answers within %.2 of our answer. Checking your answer to Q7..."
    q7correctAnswerIndex = correctOutputStrings.index("The result for Q7 was:")
    q7correctAnswer = float(correctOutputStrings[q7correctAnswerIndex+4][1:-1])
    q7query =  foo.conn.execute(foo.Q7)
    q7answer = q7query.fetchone()
    relativeDifference = abs(q7correctAnswer-q7answer[0])/q7correctAnswer
    print "Your answer for Q7 was %.8f, and ours was %.8f. The relative difference is %f." % (q7answer[0], q7correctAnswer, relativeDifference)
    if relativeDifference < .002:
        print "Your answer for Q7 is within the error tolerance. You can ignore an error in the diff for Q7."
    else:
        print "Your answer for Q7 is outside the error tolerance. You should look at the error in the diff for Q7."


    # print error message
    if diffPrinted:
        print "Your output may not match the correct output. Check the diff above for the difference between your output and the correct output."
        return 1
    else:
        print "Your output matches the correct-output exactly! You're good to go."

if __name__ == '__main__':
    sys.exit(main(sys.argv))