from pydantic import BaseModel, computed_field, Field, field_validator
from typing import Optional, List, Any, Dict
from datetime import datetime
from decimal import Decimal
from enum import Enum


class Priority(str, Enum):
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"
    URGENT = "urgent"


class CustomValueInput(BaseModel):
    """Input for setting a custom field value."""
    field_id: str
    value: Optional[Any] = None  # Can be string, number, date string, or user id


class CustomValueResponse(BaseModel):
    """Response for a custom field value."""
    field_id: str
    field_name: str
    field_type: str
    value: Optional[Any] = None
    display_value: Optional[str] = None  # Formatted for display


class TaskBase(BaseModel):
    title: str = Field(..., min_length=1, max_length=500)
    description: Optional[str] = Field(None, max_length=10000)
    priority: Priority = Priority.MEDIUM
    original_estimate: Optional[Decimal] = Field(None, ge=0, le=99999)
    start_date: Optional[datetime] = None
    due_date: Optional[datetime] = None


class TaskCreate(TaskBase):
    parent_task_id: Optional[str] = None
    assignee_id: Optional[str] = None
    status_id: Optional[str] = None
    custom_values: Optional[List[CustomValueInput]] = None


class TaskUpdate(BaseModel):
    title: Optional[str] = Field(None, min_length=1, max_length=500)
    description: Optional[str] = Field(None, max_length=10000)
    priority: Optional[Priority] = None
    status_id: Optional[str] = None
    assignee_id: Optional[str] = None
    original_estimate: Optional[Decimal] = Field(None, ge=0, le=99999)
    time_spent: Optional[Decimal] = Field(None, ge=0, le=99999)
    start_date: Optional[datetime] = None
    due_date: Optional[datetime] = None
    position: Optional[int] = Field(None, ge=0)
    custom_values: Optional[List[CustomValueInput]] = None
    version: Optional[int] = Field(None, ge=1, description="Version for optimistic locking")


class TaskStatusUpdate(BaseModel):
    status_id: str


class TaskAssignUpdate(BaseModel):
    assignee_id: Optional[str] = None


class TaskResponse(TaskBase):
    id: str
    project_id: str
    parent_task_id: Optional[str] = None
    assignee_id: Optional[str] = None
    status_id: Optional[str] = None
    time_spent: Decimal
    blocker_flag: bool
    position: int
    created_by: str
    created_at: datetime
    updated_at: datetime
    version: int = 1  # Optimistic locking version

    class Config:
        from_attributes = True

    # Alias for original_estimate for frontend compatibility
    @computed_field
    @property
    def time_estimate(self) -> Optional[Decimal]:
        return self.original_estimate


class TaskWithDetails(TaskResponse):
    assignee_name: Optional[str] = None
    status_name: Optional[str] = None
    status_color: Optional[str] = None
    creator_name: Optional[str] = None
    subtask_count: int = 0
    custom_values: Optional[List[CustomValueResponse]] = None


class TaskListResponse(BaseModel):
    tasks: List[TaskWithDetails]
    total: int


class TaskRestoreRequest(BaseModel):
    """Request body for restoring a soft-deleted task."""
    cascade: bool = Field(
        default=True,
        description="If True, also restore child tasks deleted at the same time. If False, restore only the parent task."
    )


class TaskRestoreResponse(BaseModel):
    """Response for task restore operation."""
    restored_task: TaskResponse
    restored_children_count: int = 0
    restored_children_ids: List[str] = []


class TaskDeleteWarningResponse(BaseModel):
    """Response when task has unresolved blockers and force_delete is False."""
    warning: str
    blocker_count: int
    message: str = "Task has unresolved blockers. Use force_delete=true to delete anyway."


class TaskDeleteResponse(BaseModel):
    """Response for task delete operation."""
    task: TaskResponse
    blockers_resolved: int = 0
    force_deleted: bool = False