"""
Provides a JSON API for the Part app
"""

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django_filters.rest_framework import DjangoFilterBackend

from django.db.models import Q, F, Count

from rest_framework import status
from rest_framework.response import Response
from rest_framework import filters, serializers
from rest_framework import generics, permissions

from django.conf.urls import url, include
from django.urls import reverse

from .models import Part, PartCategory, BomItem, PartStar
from .models import PartParameter, PartParameterTemplate

from . import serializers as part_serializers

from InvenTree.views import TreeSerializer
from InvenTree.helpers import str2bool, isNull


class PartCategoryTree(TreeSerializer):

    title = "Parts"
    model = PartCategory
    
    @property
    def root_url(self):
        return reverse('part-index')

    def get_items(self):
        return PartCategory.objects.all().prefetch_related('parts', 'children')


class CategoryList(generics.ListCreateAPIView):
    """ API endpoint for accessing a list of PartCategory objects.

    - GET: Return a list of PartCategory objects
    - POST: Create a new PartCategory object
    """

    queryset = PartCategory.objects.all()
    serializer_class = part_serializers.CategorySerializer

    permission_classes = [
        permissions.IsAuthenticated,
    ]

    def get_queryset(self):
        """
        Custom filtering:
        - Allow filtering by "null" parent to retrieve top-level part categories
        """

        cat_id = self.request.query_params.get('parent', None)

        queryset = super().get_queryset()

        if cat_id is not None:
            
            # Look for top-level categories
            if isNull(cat_id):
                queryset = queryset.filter(parent=None)
            
            else:
                try:
                    cat_id = int(cat_id)
                    queryset = queryset.filter(parent=cat_id)
                except ValueError:
                    pass

        return queryset

    filter_backends = [
        DjangoFilterBackend,
        filters.SearchFilter,
        filters.OrderingFilter,
    ]

    filter_fields = [
    ]

    ordering_fields = [
        'name',
    ]

    ordering = 'name'

    search_fields = [
        'name',
        'description',
    ]


class CategoryDetail(generics.RetrieveUpdateDestroyAPIView):
    """ API endpoint for detail view of a single PartCategory object """
    serializer_class = part_serializers.CategorySerializer
    queryset = PartCategory.objects.all()


class PartThumbs(generics.ListAPIView):
    """ API endpoint for retrieving information on available Part thumbnails """

    serializer_class = part_serializers.PartThumbSerializer

    def list(self, reguest, *args, **kwargs):
        """
        Serialize the available Part images.
        - Images may be used for multiple parts!
        """

        # Get all Parts which have an associated image
        queryset = Part.objects.all().exclude(image='')

        # TODO - We should return the thumbnails here, not the full image!

        # Return the most popular parts first
        data = queryset.values(
            'image',
        ).annotate(count=Count('image')).order_by('-count')

        return Response(data)


class PartDetail(generics.RetrieveUpdateAPIView):
    """ API endpoint for detail view of a single Part object """

    queryset = Part.objects.all()
    serializer_class = part_serializers.PartSerializer

    permission_classes = [
        permissions.IsAuthenticated,
    ]


class PartList(generics.ListCreateAPIView):
    """ API endpoint for accessing a list of Part objects

    - GET: Return list of objects
    - POST: Create a new Part object

    The Part object list can be filtered by:
        - category: Filter by PartCategory reference
        - cascade: If true, include parts from sub-categories
        - starred: Is the part "starred" by the current user?
        - is_template: Is the part a template part?
        - variant_of: Filter by variant_of Part reference
        - assembly: Filter by assembly field
        - component: Filter by component field
        - trackable: Filter by trackable field
        - purchaseable: Filter by purcahseable field
        - salable: Filter by salable field
        - active: Filter by active field
    """

    serializer_class = part_serializers.PartSerializer

    queryset = Part.objects.all()

    starred_parts = None

    def get_serializer(self, *args, **kwargs):

        try:
            cat_detail = str2bool(self.request.query_params.get('category_detail', False))
        except AttributeError:
            cat_detail = None

        # Ensure the request context is passed through
        kwargs['context'] = self.get_serializer_context()

        kwargs['category_detail'] = cat_detail

        # Pass a list of "starred" parts fo the current user to the serializer
        # We do this to reduce the number of database queries required!
        if self.starred_parts is None and self.request is not None:
            self.starred_parts = [star.part for star in self.request.user.starred_parts.all()]

        kwargs['starred_parts'] = self.starred_parts

        return self.serializer_class(*args, **kwargs)

    def create(self, request, *args, **kwargs):
        """ Override the default 'create' behaviour:
        We wish to save the user who created this part!

        Note: Implementation coped from DRF class CreateModelMixin
        """

        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        
        # Record the user who created this Part object
        part = serializer.save()
        part.creation_user = request.user
        part.save()

        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

    def get_queryset(self, *args, **kwargs):

        queryset = super().get_queryset(*args, **kwargs)
        queryset = part_serializers.PartSerializer.prefetch_queryset(queryset)

        return queryset

    def filter_queryset(self, queryset):
        """
        Perform custom filtering of the queryset
        """

        # Perform basic filtering
        queryset = super().filter_queryset(queryset)

        # Filter by 'starred' parts?
        starred = str2bool(self.request.query_params.get('starred', None))

        if starred is not None:
            starred_parts = [star.part.pk for star in self.request.user.starred_parts.all()]

            if starred:
                queryset = queryset.filter(pk__in=starred_parts)
            else:
                queryset = queryset.exclude(pk__in=starred_parts)

        # Cascade?
        cascade = str2bool(self.request.query_params.get('cascade', None))

        # Does the user wish to filter by category?
        cat_id = self.request.query_params.get('category', None)

        if cat_id is None:
            # No category filtering if category is not specified
            pass
        
        else:
            # Category has been specified!
            if isNull(cat_id):
                # A 'null' category is the top-level category
                if cascade is False:
                    # Do not cascade, only list parts in the top-level category
                    queryset = queryset.filter(category=None)

            else:
                try:
                    category = PartCategory.objects.get(pk=cat_id)

                    # If '?cascade=true' then include parts which exist in sub-categories
                    if cascade:
                        queryset = queryset.filter(category__in=category.getUniqueChildren())
                    # Just return parts directly in the requested category
                    else:
                        queryset = queryset.filter(category=cat_id)
                except (ValueError, PartCategory.DoesNotExist):
                    pass

        # Annotate calculated data to the queryset
        # (This will be used for further filtering)
        queryset = part_serializers.PartSerializer.annotate_queryset(queryset)

        # Filter by whether the part has stock
        has_stock = self.request.query_params.get("has_stock", None)
        if has_stock is not None:
            has_stock = str2bool(has_stock)

            if has_stock:
                queryset = queryset.filter(Q(in_stock__gt=0))
            else:
                queryset = queryset.filter(Q(in_stock__lte=0))

        # If we are filtering by 'low_stock' status
        low_stock = self.request.query_params.get('low_stock', None)

        if low_stock is not None:
            low_stock = str2bool(low_stock)

            if low_stock:
                # Ignore any parts which do not have a specified 'minimum_stock' level
                queryset = queryset.exclude(minimum_stock=0)
                # Filter items which have an 'in_stock' level lower than 'minimum_stock'
                queryset = queryset.filter(Q(in_stock__lt=F('minimum_stock')))
            else:
                # Filter items which have an 'in_stock' level higher than 'minimum_stock'
                queryset = queryset.filter(Q(in_stock__gte=F('minimum_stock')))

        return queryset

    permission_classes = [
        permissions.IsAuthenticated,
    ]

    filter_backends = [
        DjangoFilterBackend,
        filters.SearchFilter,
        filters.OrderingFilter,
    ]

    filter_fields = [
        'is_template',
        'variant_of',
        'assembly',
        'component',
        'trackable',
        'purchaseable',
        'salable',
        'active',
    ]

    ordering_fields = [
        'name',
    ]

    # Default ordering
    ordering = 'name'

    search_fields = [
        '$name',
        'description',
        '$IPN',
        'keywords',
    ]


class PartStarDetail(generics.RetrieveDestroyAPIView):
    """ API endpoint for viewing or removing a PartStar object """

    queryset = PartStar.objects.all()
    serializer_class = part_serializers.PartStarSerializer


class PartStarList(generics.ListCreateAPIView):
    """ API endpoint for accessing a list of PartStar objects.

    - GET: Return list of PartStar objects
    - POST: Create a new PartStar object
    """

    queryset = PartStar.objects.all()
    serializer_class = part_serializers.PartStarSerializer

    def create(self, request, *args, **kwargs):

        # Override the user field (with the logged-in user)
        data = request.data.copy()
        data['user'] = str(request.user.id)

        serializer = self.get_serializer(data=data)

        serializer.is_valid(raise_exception=True)
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

    permission_classes = [
        permissions.IsAuthenticated,
    ]

    filter_backends = [
        DjangoFilterBackend,
        filters.SearchFilter
    ]

    filter_fields = [
        'part',
        'user',
    ]

    search_fields = [
        'partname'
    ]


class PartParameterTemplateList(generics.ListCreateAPIView):
    """ API endpoint for accessing a list of PartParameterTemplate objects.

    - GET: Return list of PartParameterTemplate objects
    - POST: Create a new PartParameterTemplate object
    """

    queryset = PartParameterTemplate.objects.all()
    serializer_class = part_serializers.PartParameterTemplateSerializer

    permission_classes = [
        permissions.IsAuthenticated,
    ]

    filter_backends = [
        filters.OrderingFilter,
    ]

    filter_fields = [
        'name',
    ]


class PartParameterList(generics.ListCreateAPIView):
    """ API endpoint for accessing a list of PartParameter objects

    - GET: Return list of PartParameter objects
    - POST: Create a new PartParameter object
    """

    queryset = PartParameter.objects.all()
    serializer_class = part_serializers.PartParameterSerializer

    permission_classes = [
        permissions.IsAuthenticated,
    ]

    filter_backends = [
        DjangoFilterBackend
    ]

    filter_fields = [
        'part',
        'template',
    ]


class BomList(generics.ListCreateAPIView):
    """ API endpoint for accessing a list of BomItem objects.

    - GET: Return list of BomItem objects
    - POST: Create a new BomItem object
    """

    serializer_class = part_serializers.BomItemSerializer
    
    def get_serializer(self, *args, **kwargs):

        # Do we wish to include extra detail?
        try:
            part_detail = str2bool(self.request.GET.get('part_detail', None))
            sub_part_detail = str2bool(self.request.GET.get('sub_part_detail', None))
        except AttributeError:
            part_detail = None
            sub_part_detail = None

        kwargs['part_detail'] = part_detail
        kwargs['sub_part_detail'] = sub_part_detail

        # Ensure the request context is passed through!
        kwargs['context'] = self.get_serializer_context()
        
        return self.serializer_class(*args, **kwargs)

    def get_queryset(self):
        queryset = BomItem.objects.all()
        queryset = self.get_serializer_class().setup_eager_loading(queryset)

        # Filter by part?
        part = self.request.query_params.get('part', None)

        if part is not None:
            queryset = queryset.filter(part=part)
        
        # Filter by sub-part?
        sub_part = self.request.query_params.get('sub_part', None)

        if sub_part is not None:
            queryset = queryset.filter(sub_part=sub_part)

        return queryset

    permission_classes = [
        permissions.IsAuthenticated,
    ]

    filter_backends = [
        DjangoFilterBackend,
        filters.SearchFilter,
        filters.OrderingFilter,
    ]

    filter_fields = [
    ]


class BomDetail(generics.RetrieveUpdateDestroyAPIView):
    """ API endpoint for detail view of a single BomItem object """

    queryset = BomItem.objects.all()
    serializer_class = part_serializers.BomItemSerializer

    permission_classes = [
        permissions.IsAuthenticated,
    ]


class BomItemValidate(generics.UpdateAPIView):
    """ API endpoint for validating a BomItem """

    # Very simple serializers
    class BomItemValidationSerializer(serializers.Serializer):

        valid = serializers.BooleanField(default=False)

    queryset = BomItem.objects.all()
    serializer_class = BomItemValidationSerializer

    def update(self, request, *args, **kwargs):
        """ Perform update request """

        partial = kwargs.pop('partial', False)

        valid = request.data.get('valid', False)

        instance = self.get_object()
        
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)

        if type(instance) == BomItem:
            instance.validate_hash(valid)

        return Response(serializer.data)


cat_api_urls = [

    url(r'^(?P<pk>\d+)/?', CategoryDetail.as_view(), name='api-part-category-detail'),

    url(r'^$', CategoryList.as_view(), name='api-part-category-list'),
]


part_star_api_urls = [
    url(r'^(?P<pk>\d+)/?', PartStarDetail.as_view(), name='api-part-star-detail'),

    # Catchall
    url(r'^.*$', PartStarList.as_view(), name='api-part-star-list'),
]

part_param_api_urls = [
    url(r'^template/$', PartParameterTemplateList.as_view(), name='api-part-param-template-list'),

    url(r'^.*$', PartParameterList.as_view(), name='api-part-param-list'),
]

part_api_urls = [
    url(r'^tree/?', PartCategoryTree.as_view(), name='api-part-tree'),

    url(r'^category/', include(cat_api_urls)),
    url(r'^star/', include(part_star_api_urls)),
    url(r'^parameter/', include(part_param_api_urls)),

    url(r'^thumbs/', PartThumbs.as_view(), name='api-part-thumbs'),

    url(r'^(?P<pk>\d+)/?', PartDetail.as_view(), name='api-part-detail'),

    url(r'^.*$', PartList.as_view(), name='api-part-list'),
]

bom_item_urls = [

    url(r'^validate/?', BomItemValidate.as_view(), name='api-bom-item-validate'),

    url(r'^.*$', BomDetail.as_view(), name='api-bom-item-detail'),
]

bom_api_urls = [
    # BOM Item Detail
    url(r'^(?P<pk>\d+)/', include(bom_item_urls)),

    # Catch-all
    url(r'^.*$', BomList.as_view(), name='api-bom-list'),
]