"""
Workflow schema definitions using Pydantic
"""

from pydantic import BaseModel, Field, field_validator
from typing import List, Dict, Any, Optional


class WorkflowTask(BaseModel):
    """
    Single task in a workflow.

    Attributes:
        id: Unique task identifier
        tool: Tool name to execute
        args: Arguments to pass to tool
        depends_on: List of task IDs this task depends on
        retry_on_failure: Whether to retry if task fails
        max_retries: Maximum retry attempts
        timeout_seconds: Task timeout in seconds
    """
    id: str = Field(..., description="Unique task ID")
    tool: str = Field(..., description="Tool name to execute")
    args: Dict[str, Any] = Field(default_factory=dict, description="Tool arguments")
    depends_on: List[str] = Field(default_factory=list, description="Task dependencies")
    retry_on_failure: bool = Field(default=True, description="Retry on failure")
    max_retries: int = Field(default=3, ge=0, le=10, description="Max retries")
    timeout_seconds: int = Field(default=60, ge=1, le=600, description="Task timeout")

    @field_validator("id")
    @classmethod
    def validate_id(cls, v: str) -> str:
        """Validate task ID is alphanumeric with underscores/hyphens"""
        if not v.replace("_", "").replace("-", "").isalnum():
            raise ValueError("Task ID must be alphanumeric with underscores/hyphens")
        return v


class WorkflowDefinition(BaseModel):
    """
    Complete workflow definition with tasks and execution config.

    Attributes:
        name: Workflow name
        description: Optional workflow description
        tasks: List of tasks to execute
        final_task: ID of final task (workflow result)
        max_parallel: Maximum parallel task execution
        timeout_seconds: Total workflow timeout
    """
    name: str = Field(..., description="Workflow name")
    description: Optional[str] = Field(default=None, description="Workflow description")
    tasks: List[WorkflowTask] = Field(..., min_length=1, description="Workflow tasks")
    final_task: str = Field(..., description="Final task ID for result")
    max_parallel: int = Field(default=3, ge=1, le=10, description="Max parallel tasks")
    timeout_seconds: int = Field(default=600, ge=1, le=3600, description="Workflow timeout")

    @field_validator("final_task")
    @classmethod
    def validate_final_task(cls, v: str, info) -> str:
        """Validate final_task exists in tasks"""
        # Note: info.data contains previously validated fields
        tasks = info.data.get("tasks", [])
        task_ids = {task.id for task in tasks}
        if v not in task_ids:
            raise ValueError(f"final_task '{v}' not found in tasks")
        return v

    @field_validator("tasks")
    @classmethod
    def validate_dependencies(cls, v: List[WorkflowTask]) -> List[WorkflowTask]:
        """Validate task dependencies exist and form DAG (no cycles)"""
        task_ids = {task.id for task in v}

        # Check all dependencies exist
        for task in v:
            for dep in task.depends_on:
                if dep not in task_ids:
                    raise ValueError(
                        f"Task '{task.id}' depends on non-existent task '{dep}'"
                    )

        # Check for cycles using DFS
        def has_cycle(task_id: str, visited: set, rec_stack: set) -> bool:
            visited.add(task_id)
            rec_stack.add(task_id)

            # Get dependencies for this task
            task = next(t for t in v if t.id == task_id)
            for dep in task.depends_on:
                if dep not in visited:
                    if has_cycle(dep, visited, rec_stack):
                        return True
                elif dep in rec_stack:
                    return True

            rec_stack.remove(task_id)
            return False

        visited = set()
        for task in v:
            if task.id not in visited:
                if has_cycle(task.id, visited, set()):
                    raise ValueError(
                        f"Workflow contains cycle involving task '{task.id}'"
                    )

        return v

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary"""
        return self.model_dump()

    @classmethod
    def from_dict(cls, data: Dict[str, Any]) -> "WorkflowDefinition":
        """Create from dictionary"""
        return cls(**data)