from decimal import Decimal

from django.contrib.auth import get_user_model
from rest_framework import serializers

from commerce.models import SourceSystem
from projects.models import (
    Project,
    ProjectExternalBinding,
    ProjectMembership,
    ProjectResource,
    ProjectStage,
)


class ProjectSerializer(serializers.ModelSerializer):
    manager_name = serializers.SerializerMethodField()
    can_manage = serializers.SerializerMethodField()
    can_view_finances = serializers.SerializerMethodField()

    class Meta:
        model = Project
        fields = [
            "id",
            "name",
            "description",
            "customer",
            "manager",
            "manager_name",
            "status",
            "starts_on",
            "ends_on",
            "created_at",
            "updated_at",
            "can_manage",
            "can_view_finances",
        ]
        read_only_fields = ["created_at", "updated_at"]
        extra_kwargs = {
            "manager": {"queryset": get_user_model().objects.filter(is_active=True)}
        }

    def get_manager_name(self, obj) -> str:
        return str(obj.manager)

    def get_can_manage(self, obj) -> bool:
        from projects.permissions import can_manage

        return can_manage(self.context["request"].user, obj)

    def get_can_view_finances(self, obj) -> bool:
        cached = getattr(self, "_can_view_finances", None)
        if cached is None:
            from finance.payroll.access import can_access_payroll_management

            cached = can_access_payroll_management(self.context["request"].user)
            self._can_view_finances = cached
        return cached

    def validate(self, attrs):
        start = attrs.get(
            "starts_on", self.instance.starts_on if self.instance else None
        )
        end = attrs.get("ends_on", self.instance.ends_on if self.instance else None)
        if start and end and end < start:
            raise serializers.ValidationError("Окончание не может быть раньше начала.")
        return attrs


class MembershipSerializer(serializers.ModelSerializer):
    employee_name = serializers.SerializerMethodField()

    class Meta:
        model = ProjectMembership
        fields = [
            "id",
            "employee",
            "employee_name",
            "role",
            "planned_percent",
            "starts_on",
            "ends_on",
        ]
        extra_kwargs = {
            "planned_percent": {"min_value": 0, "max_value": 100},
            "employee": {"queryset": get_user_model().objects.filter(is_active=True)},
        }

    def get_employee_name(self, obj):
        return str(obj.employee)

    def validate(self, attrs):
        if (
            attrs.get("starts_on")
            and attrs.get("ends_on")
            and attrs["ends_on"] < attrs["starts_on"]
        ):
            raise serializers.ValidationError("Окончание участия раньше начала.")
        return attrs


class StageSerializer(serializers.ModelSerializer):
    class Meta:
        model = ProjectStage
        fields = ["id", "name", "due_on", "done", "position"]


class BindingSerializer(serializers.ModelSerializer):
    source_name = serializers.CharField(source="source.name", read_only=True)

    class Meta:
        model = ProjectExternalBinding
        fields = [
            "id",
            "source",
            "source_name",
            "object_type",
            "external_id",
            "external_name",
        ]
        validators = []


class ResourceSerializer(serializers.ModelSerializer):
    class Meta:
        model = ProjectResource
        fields = ["id", "title", "kind", "url"]

    def validate(self, attrs):
        from urllib.parse import urlsplit

        url = urlsplit(attrs["url"])
        prefix = {
            "task": "/tasks",
            "procurement": "/procurement",
            "document": "/documents",
        }[attrs["kind"]]
        if (
            url.scheme
            or url.netloc
            or "\\" in attrs["url"]
            or not (url.path == prefix or url.path.startswith(prefix + "/"))
        ):
            raise serializers.ValidationError(
                "Укажите внутреннюю ссылку соответствующего раздела портала."
            )
        return attrs


class AllocationRowSerializer(serializers.Serializer):
    project = serializers.IntegerField(min_value=1, required=False, allow_null=True)
    activity = serializers.ChoiceField(
        choices=["", "department", "training", "support"], default=""
    )
    percent = serializers.DecimalField(
        max_digits=5, decimal_places=2, min_value=Decimal("0.01"), max_value=100
    )


class DaySerializer(serializers.Serializer):
    date = serializers.DateField()
    version = serializers.IntegerField(min_value=0)
    status = serializers.ChoiceField(choices=["draft", "confirmed"])
    note = serializers.CharField(max_length=2000, allow_blank=True, default="")
    allocations = AllocationRowSerializer(many=True, max_length=50)


class DayProjectSerializer(serializers.Serializer):
    id = serializers.IntegerField()
    name = serializers.CharField()


class DayAllocationResponseSerializer(serializers.Serializer):
    project = serializers.IntegerField(allow_null=True)
    project_name = serializers.CharField()
    activity = serializers.CharField()
    percent = serializers.CharField()


class CalendarDayResponseSerializer(serializers.Serializer):
    date = serializers.DateField()
    status = serializers.ChoiceField(choices=["draft", "confirmed"])
    hours = serializers.FloatField(allow_null=True)
    hours_source = serializers.CharField()
    version = serializers.IntegerField()


class DayResponseSerializer(CalendarDayResponseSerializer):
    attendance_changed = serializers.BooleanField()
    note = serializers.CharField()
    allocations = DayAllocationResponseSerializer(many=True)
    projects = DayProjectSerializer(many=True)


class ReminderRequestSerializer(serializers.Serializer):
    snooze = serializers.BooleanField(required=False, default=False)


class ReminderResponseSerializer(serializers.Serializer):
    date = serializers.DateField(allow_null=True)


class ExternalProjectImportSerializer(serializers.Serializer):
    source = serializers.PrimaryKeyRelatedField(queryset=SourceSystem.objects.all())
    external_id = serializers.CharField(max_length=255)
    name = serializers.CharField(max_length=255)
    description = serializers.CharField(max_length=5000, allow_blank=True, default="")
    customer = serializers.CharField(max_length=255, allow_blank=True, default="")
    manager = serializers.PrimaryKeyRelatedField(
        queryset=get_user_model().objects.filter(is_active=True)
    )
    status = serializers.ChoiceField(choices=Project.Status.choices, default="planned")
    starts_on = serializers.DateField(required=False, allow_null=True)
    ends_on = serializers.DateField(required=False, allow_null=True)

    def validate(self, attrs):
        if attrs.get("starts_on") and attrs.get("ends_on"):
            if attrs["ends_on"] < attrs["starts_on"]:
                raise serializers.ValidationError(
                    "Окончание не может быть раньше начала."
                )
        return attrs