# Copyright (c) 2016 Ansible, Inc.
# All Rights Reserved.

from collections import OrderedDict

# Django
from django.core.exceptions import PermissionDenied
from django.http import Http404
from django.utils.encoding import force_text, smart_text
from django.utils.translation import ugettext_lazy as _

# Django REST Framework
from rest_framework import exceptions
from rest_framework import metadata
from rest_framework import serializers
from rest_framework.relations import RelatedField, ManyRelatedField
from rest_framework.request import clone_request

# AWX
from awx.main.models import InventorySource, NotificationTemplate


class Metadata(metadata.SimpleMetadata):

    def get_field_info(self, field):
        field_info = OrderedDict()
        field_info['type'] = self.label_lookup[field]
        field_info['required'] = getattr(field, 'required', False)

        text_attrs = [
            'read_only', 'label', 'help_text',
            'min_length', 'max_length',
            'min_value', 'max_value',
            'category', 'category_slug',
            'defined_in_file'
        ]

        for attr in text_attrs:
            value = getattr(field, attr, None)
            if value is not None and value != '':
                field_info[attr] = force_text(value, strings_only=True)

        placeholder = getattr(field, 'placeholder', serializers.empty)
        if placeholder is not serializers.empty:
            field_info['placeholder'] = placeholder

        serializer = getattr(field, 'parent', None)
        if serializer and hasattr(serializer, 'Meta') and hasattr(serializer.Meta, 'model'):
            # Update help text for common fields.
            field_help_text = {
                'id': _('Database ID for this {}.'),
                'name': _('Name of this {}.'),
                'description': _('Optional description of this {}.'),
                'type': _('Data type for this {}.'),
                'url': _('URL for this {}.'),
                'related': _('Data structure with URLs of related resources.'),
                'summary_fields': _('Data structure with name/description for related resources.'),
                'created': _('Timestamp when this {} was created.'),
                'modified': _('Timestamp when this {} was last modified.'),
            }
            if field.field_name in field_help_text:
                opts = serializer.Meta.model._meta.concrete_model._meta
                verbose_name = smart_text(opts.verbose_name)
                field_info['help_text'] = field_help_text[field.field_name].format(verbose_name)
            # If field is not part of the model, then show it as non-filterable
            else:
                is_model_field = False
                for model_field in serializer.Meta.model._meta.fields:
                    if field.field_name == model_field.name:
                        is_model_field = True
                        break
                if not is_model_field:
                    field_info['filterable'] = False

        # Indicate if a field has a default value.
        # FIXME: Still isn't showing all default values?
        try:
            default = field.get_default()
            if field.field_name == 'TOWER_URL_BASE' and default == 'https://towerhost':
                default = '{}://{}'.format(self.request.scheme, self.request.get_host())
            field_info['default'] = default
        except serializers.SkipField:
            pass

        if getattr(field, 'child', None):
            field_info['child'] = self.get_field_info(field.child)
        elif getattr(field, 'fields', None):
            field_info['children'] = self.get_serializer_info(field)

        if not isinstance(field, (RelatedField, ManyRelatedField)) and hasattr(field, 'choices'):
            field_info['choices'] = [(choice_value, choice_name) for choice_value, choice_name in field.choices.items()]

        # Indicate if a field is write-only.
        if getattr(field, 'write_only', False):
            field_info['write_only'] = True

        # Special handling of inventory source_region choices that vary based on
        # selected inventory source.
        if field.field_name == 'source_regions':
            for cp in ('azure_rm', 'ec2', 'gce'):
                get_regions = getattr(InventorySource, 'get_%s_region_choices' % cp)
                field_info['%s_region_choices' % cp] = get_regions()

        # Special handling of group_by choices for EC2.
        if field.field_name == 'group_by':
            for cp in ('ec2',):
                get_group_by_choices = getattr(InventorySource, 'get_%s_group_by_choices' % cp)
                field_info['%s_group_by_choices' % cp] = get_group_by_choices()

        # Special handling of notification configuration where the required properties
        # are conditional on the type selected.
        if field.field_name == 'notification_configuration':
            for (notification_type_name, notification_tr_name, notification_type_class) in NotificationTemplate.NOTIFICATION_TYPES:
                field_info[notification_type_name] = notification_type_class.init_parameters

        # Update type of fields returned...
        if field.field_name == 'type':
            field_info['type'] = 'choice'
        elif field.field_name == 'url':
            field_info['type'] = 'string'
        elif field.field_name in ('related', 'summary_fields'):
            field_info['type'] = 'object'
        elif field.field_name in ('created', 'modified'):
            field_info['type'] = 'datetime'

        return field_info

    def get_serializer_info(self, serializer, method=None):
        filterer = getattr(serializer, 'filter_field_metadata', lambda fields, method: fields)
        return filterer(
            super(Metadata, self).get_serializer_info(serializer),
            method
        )

    def determine_actions(self, request, view):
        # Add field information for GET requests (so field names/labels are
        # available even when we can't POST/PUT).
        actions = {}
        for method in {'GET', 'PUT', 'POST'} & set(view.allowed_methods):
            view.request = clone_request(request, method)
            obj = None
            try:
                # Test global permissions
                if hasattr(view, 'check_permissions'):
                    view.check_permissions(view.request)
                # Test object permissions
                if method == 'PUT' and hasattr(view, 'get_object'):
                    obj = view.get_object()
            except (exceptions.APIException, PermissionDenied, Http404):
                continue
            else:
                # If user has appropriate permissions for the view, include
                # appropriate metadata about the fields that should be supplied.
                serializer = view.get_serializer(instance=obj)
                actions[method] = self.get_serializer_info(serializer, method=method)
            finally:
                view.request = request

            for field, meta in actions[method].items():
                if not isinstance(meta, dict):
                    continue

                # Add type choices if available from the serializer.
                if field == 'type' and hasattr(serializer, 'get_type_choices'):
                    meta['choices'] = serializer.get_type_choices()

                # For GET method, remove meta attributes that aren't relevant
                # when reading a field and remove write-only fields.
                if method == 'GET':
                    attrs_to_remove = ('required', 'read_only', 'default', 'min_length', 'max_length', 'placeholder')
                    for attr in attrs_to_remove:
                        meta.pop(attr, None)
                        meta.get('child', {}).pop(attr, None)
                    if meta.pop('write_only', False):
                        actions['GET'].pop(field)

                # For PUT/POST methods, remove read-only fields.
                if method in ('PUT', 'POST'):
                    # This value should always be False for PUT/POST, so don't
                    # show it (file-based read-only settings can't be updated)
                    meta.pop('defined_in_file', False)

                    if meta.pop('read_only', False):
                        if field == 'id' and hasattr(view, 'attach'):
                            continue
                        actions[method].pop(field)

        return actions

    def determine_metadata(self, request, view):
        # store request on self so we can use it to generate field defaults
        # (such as TOWER_URL_BASE)
        self.request = request

        try:
            setattr(view, '_request', request)
            metadata = super(Metadata, self).determine_metadata(request, view)
        finally:
            delattr(view, '_request')

        # Add type(s) handled by this view/serializer.
        if hasattr(view, 'get_serializer'):
            serializer = view.get_serializer()
            if hasattr(serializer, 'get_types'):
                metadata['types'] = serializer.get_types()

        # Add search fields if available from the view.
        if getattr(view, 'search_fields', None):
            metadata['search_fields'] = view.search_fields

        # Add related search fields if available from the view.
        if getattr(view, 'related_search_fields', None):
            metadata['related_search_fields'] = view.related_search_fields

        from rest_framework import generics
        if isinstance(view, generics.ListAPIView) and hasattr(view, 'paginator'):
            metadata['max_page_size'] = view.paginator.max_page_size

        return metadata


class RoleMetadata(Metadata):
    def determine_metadata(self, request, view):
        metadata = super(RoleMetadata, self).determine_metadata(request, view)
        if 'actions' in metadata:
            metadata['actions'].pop('POST')
            metadata['actions']['POST'] = {
                "id": {"type": "integer", "label": "ID", "help_text": "Database ID for this role."},
                "disassociate": {"type": "integer", "label": "Disassociate", "help_text": "Provide to remove this role."},
            }
        return metadata


# TODO: Tower 3.3 remove class and all uses in views.py when API v1 is removed
class JobTypeMetadata(Metadata):
        def get_field_info(self, field):
            res = super(JobTypeMetadata, self).get_field_info(field)

            if field.field_name == 'job_type':
                index = 0
                for choice in res['choices']:
                    if choice[0] == 'scan':
                        res['choices'].pop(index)
                        break
                    index += 1
            return res


class SublistAttachDetatchMetadata(Metadata):

    def determine_actions(self, request, view):
        actions = super(SublistAttachDetatchMetadata, self).determine_actions(request, view)
        method = 'POST'
        if method in actions:
            for field in actions[method]:
                if field == 'id':
                    continue
                actions[method].pop(field)
        return actions
