"""
Task Models - Clawdbot State Machine
Task lifecycle management with encrypted references

State Machine:
DRAFT -> QUEUED -> RUNNING -> READY
                               |
                   +-----------+----------+
                   |                      |
               APPROVED              REJECTED
                   |                      |
               COMPLETED                DRAFT (revision)

Any State -> EXPIRED (TTL)
Any State -> PAUSED (User Interrupt)
"""
from datetime import datetime
from enum import Enum
from typing import Optional, Dict, Any, List
from pydantic import BaseModel, Field
import uuid


class TaskState(str, Enum):
    """Task state machine states."""
    DRAFT = "draft"
    QUEUED = "queued"
    RUNNING = "running"
    READY = "ready"
    APPROVED = "approved"
    REJECTED = "rejected"
    COMPLETED = "completed"
    EXPIRED = "expired"
    PAUSED = "paused"


class TaskType(str, Enum):
    """Task types for Breakpilot integration."""
    # Gruppe 1: Kurze Notizen
    STUDENT_OBSERVATION = "student_observation"
    REMINDER = "reminder"
    HOMEWORK_CHECK = "homework_check"
    CONFERENCE_TOPIC = "conference_topic"
    CORRECTION_NOTE = "correction_note"

    # Gruppe 2: Arbeitsblatt-Generierung
    WORKSHEET_GENERATE = "worksheet_generate"
    WORKSHEET_DIFFERENTIATE = "worksheet_differentiate"

    # Gruppe 3: Situatives Arbeiten
    QUICK_ACTIVITY = "quick_activity"
    QUIZ_GENERATE = "quiz_generate"
    PARENT_LETTER = "parent_letter"
    CLASS_MESSAGE = "class_message"

    # Gruppe 4: Canvas-Editor
    CANVAS_EDIT = "canvas_edit"
    CANVAS_LAYOUT = "canvas_layout"

    # Gruppe 5: Korrektur-Assistenz
    OPERATOR_CHECKLIST = "operator_checklist"
    EH_PASSAGE = "eh_passage"
    FEEDBACK_SUGGEST = "feedback_suggest"

    # Gruppe 6: Follow-up
    REMINDER_SCHEDULE = "reminder_schedule"
    TASK_SUMMARY = "task_summary"


class Task(BaseModel):
    """
    Task entity for Clawdbot orchestration.
    Stored in Valkey with TTL.
    """
    id: str = Field(default_factory=lambda: str(uuid.uuid4()))
    session_id: str = Field(..., description="Parent session ID")
    namespace_id: str = Field(..., description="Teacher namespace ID")

    # Task definition
    type: TaskType
    state: TaskState = Field(default=TaskState.DRAFT)
    intent_text: str = Field(..., description="Original voice command (encrypted ref)")

    # Task parameters (no PII, only references)
    parameters: Dict[str, Any] = Field(default_factory=dict)
    # Example parameters:
    # - student_ref: encrypted reference to student
    # - class_ref: encrypted reference to class
    # - content_type: "worksheet", "quiz", etc.
    # - source_ref: encrypted reference to source document

    # Execution state
    result_ref: Optional[str] = Field(default=None, description="Encrypted result reference")
    error_message: Optional[str] = Field(default=None)

    # Timestamps
    created_at: datetime = Field(default_factory=datetime.utcnow)
    updated_at: datetime = Field(default_factory=datetime.utcnow)
    completed_at: Optional[datetime] = Field(default=None)
    expires_at: Optional[datetime] = Field(default=None)

    # Audit trail (no PII)
    state_history: List[Dict[str, Any]] = Field(default_factory=list)

    def transition_to(self, new_state: TaskState, reason: Optional[str] = None):
        """Transition to a new state with history tracking."""
        old_state = self.state
        self.state = new_state
        self.updated_at = datetime.utcnow()

        # Add to history (no PII in reason)
        self.state_history.append({
            "from": old_state.value,
            "to": new_state.value,
            "timestamp": self.updated_at.isoformat(),
            "reason": reason,
        })

        if new_state in [TaskState.COMPLETED, TaskState.EXPIRED]:
            self.completed_at = self.updated_at

    class Config:
        json_schema_extra = {
            "example": {
                "id": "task-xyz789",
                "session_id": "session-abc123",
                "namespace_id": "teacher-ns-456",
                "type": "student_observation",
                "state": "ready",
                "intent_text": "encrypted:abc123...",
                "parameters": {
                    "student_ref": "encrypted:student-max-123",
                    "observation_type": "behavior",
                },
                "created_at": "2026-01-26T10:30:00Z",
                "updated_at": "2026-01-26T10:30:05Z",
            }
        }


class TaskCreate(BaseModel):
    """Request to create a new task."""
    session_id: str
    type: TaskType
    intent_text: str = Field(..., description="Voice command text")
    parameters: Dict[str, Any] = Field(default_factory=dict)

    class Config:
        json_schema_extra = {
            "example": {
                "session_id": "session-abc123",
                "type": "student_observation",
                "intent_text": "Notiz zu Max: heute wiederholt gestoert",
                "parameters": {
                    "student_name": "Max",  # Will be encrypted
                    "observation": "wiederholt gestoert",
                },
            }
        }


class TaskResponse(BaseModel):
    """Task response for API."""
    id: str
    session_id: str
    type: TaskType
    state: TaskState
    created_at: datetime
    updated_at: datetime
    result_available: bool = Field(default=False)
    error_message: Optional[str] = Field(default=None)

    class Config:
        json_schema_extra = {
            "example": {
                "id": "task-xyz789",
                "session_id": "session-abc123",
                "type": "student_observation",
                "state": "completed",
                "created_at": "2026-01-26T10:30:00Z",
                "updated_at": "2026-01-26T10:30:10Z",
                "result_available": True,
            }
        }


class TaskTransition(BaseModel):
    """Request to transition task state."""
    new_state: TaskState
    reason: Optional[str] = Field(default=None, description="Transition reason (no PII)")

    class Config:
        json_schema_extra = {
            "example": {
                "new_state": "approved",
                "reason": "user_confirmed",
            }
        }


# Valid state transitions
VALID_TRANSITIONS: Dict[TaskState, List[TaskState]] = {
    TaskState.DRAFT: [TaskState.QUEUED, TaskState.EXPIRED, TaskState.PAUSED],
    TaskState.QUEUED: [TaskState.RUNNING, TaskState.EXPIRED, TaskState.PAUSED],
    TaskState.RUNNING: [TaskState.READY, TaskState.EXPIRED, TaskState.PAUSED],
    TaskState.READY: [TaskState.APPROVED, TaskState.REJECTED, TaskState.EXPIRED, TaskState.PAUSED],
    TaskState.APPROVED: [TaskState.COMPLETED, TaskState.EXPIRED],
    TaskState.REJECTED: [TaskState.DRAFT, TaskState.EXPIRED],
    TaskState.PAUSED: [TaskState.DRAFT, TaskState.QUEUED, TaskState.EXPIRED],
    TaskState.COMPLETED: [],  # Terminal state
    TaskState.EXPIRED: [],  # Terminal state
}


def is_valid_transition(from_state: TaskState, to_state: TaskState) -> bool:
    """Check if a state transition is valid."""
    return to_state in VALID_TRANSITIONS.get(from_state, [])