#!/usr/bin/env python
#
# Copyright (c) 2015, Arista Networks, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#  - Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#  - Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
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# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#pylint: disable=W0703

BOOT_CONFIG = '/mnt/flash/boot-config'

def main(attributes):
    '''Installs new software image.

    If the current software image is the same as the 'version'
    attribute value, then this action is a no-op.  Otherwise, the
    action will replace the existing software image.

    For dual supervisor systems, the image on the active supervisor is
    used as reference.

    This action is dual-supervisor compatible.

    Attributes:
        url: path to source image file
        version: EOS version of new image file
        downgrade: Boolean - Should EOS images be downgraded to match?
                   (Default: True)

    Special_attributes: 
        NODE: API object - see documentation for details

    Example:
        ::

            -
              action: install_image
              always_execute: true
              attributes:
                url: files/images/vEOS.swi
                version: 4.13.5F
                downgrade: true
              name: "validate image"
              onstart: "Starting to install image"
              onsuccess: "SUCCESS: 4.13.5F installed"
              onfailure: "FAIL: IM nick@example.com for help"

    '''

    node = attributes.get('NODE')
    url = attributes.get('url')

    if not url:
        raise Exception('Missing attribute(\'url\')')

    downgrade = attributes.get('downgrade', True)

    version = attributes.get('version')
    if not version:
        raise Exception('Missing attribute(\'version\')')

    # Return if version matches
    current_version = node.api_enable_cmds(['show version'])[0]['version']
    if current_version == version:
        node.log_msg('install_image: nothing to do: '
                     'already running the configured version')
        return

    # Don't downgrade images if flag is set
    if downgrade is not True:
        from pkg_resources import parse_version
        if parse_version(version) < parse_version(current_version):
            node.log_msg('install_image: nothing to do: '
                         'downgrade disabled')
            return

    # In all other cases, copy the image
    image = 'EOS-%s.swi' % version
    try:
        node.retrieve_url(url, '%s/%s' % (node.flash(), image))
    except Exception as exc:
        raise Exception('Unable to retrieve image file from URL (%s)' % 
                        exc)

    node.api_enable_cmds(['install source flash:%s' % image])
