"""
Implements validation and conversion for the Schema2 config JSON.

Example:
{
  "architecture": "amd64",
  "config": {
    "Hostname": "",
    "Domainname": "",
    "User": "",
    "AttachStdin": false,
    "AttachStdout": false,
    "AttachStderr": false,
    "Tty": false,
    "OpenStdin": false,
    "StdinOnce": false,
    "Env": [
      "HTTP_PROXY=http:\/\/localhost:8080",
      "http_proxy=http:\/\/localhost:8080",
      "PATH=\/usr\/local\/sbin:\/usr\/local\/bin:\/usr\/sbin:\/usr\/bin:\/sbin:\/bin"
    ],
    "Cmd": [
      "sh"
    ],
    "Image": "",
    "Volumes": null,
    "WorkingDir": "",
    "Entrypoint": null,
    "OnBuild": null,
    "Labels": {
      
    }
  },
  "container": "b7a43694b435c8e9932615643f61f975a9213e453b15cd6c2a386f144a2d2de9",
  "container_config": {
    "Hostname": "b7a43694b435",
    "Domainname": "",
    "User": "",
    "AttachStdin": true,
    "AttachStdout": true,
    "AttachStderr": true,
    "Tty": true,
    "OpenStdin": true,
    "StdinOnce": true,
    "Env": [
      "HTTP_PROXY=http:\/\/localhost:8080",
      "http_proxy=http:\/\/localhost:8080",
      "PATH=\/usr\/local\/sbin:\/usr\/local\/bin:\/usr\/sbin:\/usr\/bin:\/sbin:\/bin"
    ],
    "Cmd": [
      "sh"
    ],
    "Image": "somenamespace\/somerepo",
    "Volumes": null,
    "WorkingDir": "",
    "Entrypoint": null,
    "OnBuild": null,
    "Labels": {
      
    }
  },
  "created": "2018-04-16T10:41:19.079522722Z",
  "docker_version": "17.09.0-ce",
  "history": [
    {
      "created": "2018-04-03T18:37:09.284840891Z",
      "created_by": "\/bin\/sh -c #(nop) ADD file:9e4ca21cbd24dc05b454b6be21c7c639216ae66559b21ba24af0d665c62620dc in \/ "
    },
    {
      "created": "2018-04-03T18:37:09.613317719Z",
      "created_by": "\/bin\/sh -c #(nop)  CMD [\"sh\"]",
      "empty_layer": true
    },
    {
      "created": "2018-04-16T10:37:44.418262777Z",
      "created_by": "sh"
    },
    {
      "created": "2018-04-16T10:41:19.079522722Z",
      "created_by": "sh"
    }
  ],
  "os": "linux",
  "rootfs": {
    "type": "layers",
    "diff_ids": [
      "sha256:3e596351c689c8827a3c9635bc1083cff17fa4a174f84f0584bd0ae6f384195b",
      "sha256:4552be273c71275a88de0b8c8853dcac18cb74d5790f5383d9b38d4ac55062d5",
      "sha256:1319c76152ca37fbeb7fb71e0ffa7239bc19ffbe3b95c00417ece39d89d06e6e"
    ]
  }
}
"""

import copy
import json

from collections import namedtuple
from jsonschema import validate as validate_schema, ValidationError
from dateutil.parser import parse as parse_date

from digest import digest_tools

DOCKER_SCHEMA2_CONFIG_HISTORY_KEY = "history"
DOCKER_SCHEMA2_CONFIG_ROOTFS_KEY = "rootfs"
DOCKER_SCHEMA2_CONFIG_CREATED_KEY = "created"
DOCKER_SCHEMA2_CONFIG_CREATED_BY_KEY = "created_by"
DOCKER_SCHEMA2_CONFIG_EMPTY_LAYER_KEY = "empty_layer"
DOCKER_SCHEMA2_CONFIG_TYPE_KEY = "type"


LayerHistory = namedtuple('LayerHistory', ['created', 'created_datetime', 'command', 'is_empty'])


class MalformedSchema2Config(Exception):
  """
  Raised when a config fails an assertion that should be true according to the Docker Manifest
  v2.2 Config Specification.
  """
  pass


class DockerSchema2Config(object):
  METASCHEMA = {
    'type': 'object',
    'description': 'The container configuration found in a schema 2 manifest',
    'required': [DOCKER_SCHEMA2_CONFIG_HISTORY_KEY, DOCKER_SCHEMA2_CONFIG_ROOTFS_KEY],
    'properties': {
      DOCKER_SCHEMA2_CONFIG_HISTORY_KEY: {
        'type': 'array',
        'description': 'The history used to create the container image',
        'items': {
          'type': 'object',
          'properties': {
            DOCKER_SCHEMA2_CONFIG_EMPTY_LAYER_KEY: {
              'type': 'boolean',
              'description': 'If present, this layer is empty',
            },
            DOCKER_SCHEMA2_CONFIG_CREATED_KEY: {
              'type': 'string',
              'description': 'The date/time that the layer was created',
              'format': 'date-time',
              'x-example': '2018-04-03T18:37:09.284840891Z',
            },
            DOCKER_SCHEMA2_CONFIG_CREATED_BY_KEY: {
              'type': 'string',
              'description': 'The command used to create the layer',
              'x-example': '\/bin\/sh -c #(nop) ADD file:somesha in /',
            },
          },
          'required': [DOCKER_SCHEMA2_CONFIG_CREATED_KEY, DOCKER_SCHEMA2_CONFIG_CREATED_BY_KEY],
          'additionalProperties': True,
        },
      },
      DOCKER_SCHEMA2_CONFIG_ROOTFS_KEY: {
        'type': 'object',
        'description': 'Describes the root filesystem for this image',
        'properties': {
          DOCKER_SCHEMA2_CONFIG_TYPE_KEY: {
            'type': 'string',
            'description': 'The type of the root file system entries',
          },
        },
        'required': [DOCKER_SCHEMA2_CONFIG_TYPE_KEY],
        'additionalProperties': True,
      },
    },
    'additionalProperties': True,
  }

  def __init__(self, config_bytes):
    self._config_bytes = config_bytes
    
    try:
      self._parsed = json.loads(config_bytes)
    except ValueError as ve:
      raise MalformedSchema2Config('malformed config data: %s' % ve)

    try:
      validate_schema(self._parsed, DockerSchema2Config.METASCHEMA)
    except ValidationError as ve:
      raise MalformedSchema2Config('config data does not match schema: %s' % ve)

  @property
  def digest(self):
    """ Returns the digest of this config object. """
    return digest_tools.sha256_digest(self._config_bytes)

  @property
  def size(self):
    """ Returns the size of this config object. """
    return len(self._config_bytes)

  @property
  def labels(self):
    """ Returns a dictionary of all the labels defined in this configuration. """
    return self._parsed.get('config', {}).get('Labels', {}) or {}

  @property
  def history(self):
    """ Returns the history of the image, started at the base layer. """
    for history_entry in self._parsed[DOCKER_SCHEMA2_CONFIG_HISTORY_KEY]:
      created_datetime = parse_date(history_entry[DOCKER_SCHEMA2_CONFIG_CREATED_KEY])
      yield LayerHistory(created_datetime=created_datetime,
                         created=history_entry[DOCKER_SCHEMA2_CONFIG_CREATED_KEY],
                         command=history_entry[DOCKER_SCHEMA2_CONFIG_CREATED_BY_KEY],
                         is_empty=history_entry.get(DOCKER_SCHEMA2_CONFIG_EMPTY_LAYER_KEY, False))

  def build_v1_compatibility(self, layer_index, v1_id, v1_parent_id):
    """ Builds the V1 compatibility block for the given layer.

        Note that the layer_index is 0-indexed, with the *base* layer being 0, and the leaf
        layer being last.
    """
    history = list(self.history)

    # If the layer is the leaf, it gets the full config (minus 2 fields). Otherwise, it gets only
    # IDs.
    v1_compatibility = copy.deepcopy(self._parsed) if layer_index == len(history) - 1 else {}
    v1_compatibility['id'] = v1_id
    if v1_parent_id is not None:
      v1_compatibility['parent'] = v1_parent_id

    if 'created' not in v1_compatibility:
      v1_compatibility['created'] = history[layer_index].created

    if 'container_config' not in v1_compatibility:
      v1_compatibility['container_config'] = {
        'Cmd': history[layer_index].command,
      }

    # The history and rootfs keys are schema2-config specific.
    v1_compatibility.pop(DOCKER_SCHEMA2_CONFIG_HISTORY_KEY, None)
    v1_compatibility.pop(DOCKER_SCHEMA2_CONFIG_ROOTFS_KEY, None)
    return v1_compatibility