#!/usr/bin/env python

import unittest

def vlan_parser(vlan_list):
    '''
        Input: Unsorted list of vlan integers
        Output: Sorted list of integers according to Cisco IOS vlan list rules

        1. Vlans are listed in ascending order
        2. Runs of 3 or more consecutive vlans are listed with a dash
        3. The first line of the list can be 48 characters long
        4. Subsequents list line can be 44 characters

        Example 1:
        interface GigabitEthernet1/36
         description EXAMPLE_1
         switchport trunk encapsulation dot1q
         switchport trunk allowed vlan 100,1688,3002-3005,3102-3105,3802,3900,3998,3999
         switchport mode trunk

        Example 2:
        interface GigabitEthernet1/37
         description EXAMPLE_2
         switchport trunk encapsulation dot1q
         switchport trunk allowed vlan 100,1688,3002,3004,3005,3050,3102,3104,3105,3151
         switchport trunk allowed vlan add 3802,3900,3998,3999
         switchport mode trunk
    '''

    #Sort and remove duplicates
    sorted_list = sorted(set(vlan_list))

    parse_list = []
    idx = 0
    while idx < len(sorted_list):
        start = idx
        end = start
        while end < len(sorted_list) - 1:
            if sorted_list[end + 1] - sorted_list[end] == 1:
                end += 1
            else:
                break
        #print start, end
        if start == end:
            # Single VLAN
            parse_list.append(str(sorted_list[idx]))
        elif start + 1 == end:
            # Run of 2 VLANs
            parse_list.append(str(sorted_list[start]))
            parse_list.append(str(sorted_list[end]))
        else:
            # Run of 3 or more VLANs
            parse_list.append(str(sorted_list[start]) + '-' + str(sorted_list[end]))
        idx = end + 1

    line_count = 0
    result = ['']
    for vlans in parse_list:
        #First line (" switchport trunk allowed vlan ")
        if line_count == 0:
            if len(result[line_count] + vlans) > 48:
                result.append('')
                line_count += 1
                result[line_count] += vlans + ','
            else:
                result[line_count] += vlans + ','

        #Subsequent lines (" switchport trunk allowed vlan add ")
        else:
            if len(result[line_count] + vlans) > 44:
                result.append('')
                line_count += 1
                result[line_count] += vlans + ','
            else:
                result[line_count] += vlans + ','

    #Remove trailing orphan commas
    for idx in range(0, len(result)):
        result[idx] = result[idx].rstrip(',')

    #Sometimes text wraps to next line, but there are no remaining VLANs
    if '' in result:
        result.remove('')

    return result

class VLANParserMethods(unittest.TestCase):
    '''
        Example1: Sorted single line with compression
        Example2: Sorted multiple line, no compression
        Example3: Unsorted duplicates, single line with compression
    '''

    line1 = ' switchport trunk allowed vlan '
    line2 = ' switchport trunk allowed vlan add '
    ex1 = [100, 1688, 3002, 3003, 3004, 3005, 3102, 3103, 3104, 3105, 3802, 3900, 3998, 3999]
    ex2 = [100, 1688, 3002, 3004, 3005, 3050, 3102, 3104, 3105, 3151, 3802, 3900, 3998, 3999]
    ex3 = [3, 2, 1, 1, 2, 3, 1, 2, 3]

    def test_example1(self):
        '''
             switchport trunk allowed vlan 100,1688,3002-3005,3102-3105,3802,3900,3998,3999
        '''

        #Check number of lines in result
        self.assertTrue(len(vlan_parser(self.ex1)) == 1)

        #Verify VLAN list isn't too long
        self.assertTrue(len(vlan_parser(self.ex1)[0]) <= 48)
        for i in range(1, len(vlan_parser(self.ex1))):
            self.assertTrue(len(vlan_parser(self.ex1)[i]) <= 44)

        #Verify entire command less than 80 chars
        self.assertTrue(len(self.line1 + vlan_parser(self.ex1)[0]) <= 80)

        #Validate parsing rules
        self.assertTrue(vlan_parser(self.ex1)
                        == ['100,1688,3002-3005,3102-3105,3802,3900,3998,3999'])

    def test_example2(self):
        '''
             switchport trunk allowed vlan 100,1688,3002,3004,3005,3050,3102,3104,3105,3151
             switchport trunk allowed vlan add 3802,3900,3998,3999
        '''

        #Check number of lines in result
        self.assertTrue(len(vlan_parser(self.ex2)) == 2)

        #Verify VLAN list isn't too long
        self.assertTrue(len(vlan_parser(self.ex2)[0]) <= 48)
        for i in range(1, len(vlan_parser(self.ex2))):
            self.assertTrue(len(vlan_parser(self.ex2)[i]) <= 44)

        #Verify entire command less than 80 chars
        self.assertTrue(len(self.line1 + vlan_parser(self.ex2)[0]) <= 80)
        for i in range(1, len(vlan_parser(self.ex2))):
            self.assertTrue(len(self.line2 + vlan_parser(self.ex2)[i]) <= 80)

        #Validate parsing rules
        self.assertTrue(vlan_parser(self.ex2)
                        == ['100,1688,3002,3004,3005,3050,3102,3104,3105,3151',
                            '3802,3900,3998,3999'])

    def test_example3(self):
        '''
             switchport trunk allowed vlan 1,2,3
        '''

        #Check number of lines in result
        self.assertTrue(len(vlan_parser(self.ex3)) == 1)

        #Verify VLAN list isn't too long
        self.assertTrue(len(vlan_parser(self.ex3)[0]) <= 48)
        for i in range(1, len(vlan_parser(self.ex3))):
            self.assertTrue(len(vlan_parser(self.ex3)[i]) <= 44)

        #Verify entire command less than 80 chars
        self.assertTrue(len(self.line1 + vlan_parser(self.ex3)[0]) <= 80)

        #Validate parsing rules
        self.assertTrue(vlan_parser(self.ex3) == ['1-3'])

if __name__ == '__main__':
    unittest.main()