import uuid
from datetime import datetime, timezone
from fastapi import APIRouter, Depends, HTTPException, status, Request
from sqlalchemy.orm import Session

from app.core.database import get_db
from app.models import User, Task, Blocker, AuditAction
from app.schemas.blocker import (
    BlockerCreate, BlockerResolve, BlockerResponse, BlockerListResponse, BlockerUserInfo
)
from app.middleware.auth import get_current_user, check_task_access, check_task_edit_access
from app.middleware.audit import get_audit_metadata
from app.services.notification_service import NotificationService
from app.services.audit_service import AuditService

router = APIRouter(tags=["blockers"])


def blocker_to_response(blocker: Blocker) -> BlockerResponse:
    """Convert Blocker model to BlockerResponse."""
    return BlockerResponse(
        id=blocker.id,
        task_id=blocker.task_id,
        reason=blocker.reason,
        resolution_note=blocker.resolution_note,
        created_at=blocker.created_at,
        resolved_at=blocker.resolved_at,
        reporter=BlockerUserInfo(
            id=blocker.reporter.id,
            name=blocker.reporter.name,
            email=blocker.reporter.email,
        ),
        resolver=BlockerUserInfo(
            id=blocker.resolver.id,
            name=blocker.resolver.name,
            email=blocker.resolver.email,
        ) if blocker.resolver else None,
    )


@router.post("/api/tasks/{task_id}/blockers", response_model=BlockerResponse, status_code=status.HTTP_201_CREATED)
async def create_blocker(
    task_id: str,
    blocker_data: BlockerCreate,
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Mark a task as blocked with a reason."""
    task = db.query(Task).filter(Task.id == task_id).first()

    if not task:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Task not found",
        )

    if not check_task_edit_access(current_user, task, task.project):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Permission denied",
        )

    # Check if task is already blocked with an unresolved blocker
    existing_blocker = db.query(Blocker).filter(
        Blocker.task_id == task_id,
        Blocker.resolved_at == None,
    ).first()

    if existing_blocker:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Task already has an unresolved blocker",
        )

    # Create blocker record
    blocker = Blocker(
        id=str(uuid.uuid4()),
        task_id=task_id,
        reported_by=current_user.id,
        reason=blocker_data.reason,
    )
    db.add(blocker)

    # Update task blocker_flag
    task.blocker_flag = True

    # Notify project owner (auto-publishes after commit)
    NotificationService.notify_blocker(db, task, current_user, blocker_data.reason)

    # Audit log
    AuditService.log_event(
        db=db,
        event_type="task.blocker",
        resource_type="task",
        action=AuditAction.UPDATE,
        user_id=current_user.id,
        resource_id=task.id,
        changes=[{"field": "blocker_flag", "old_value": False, "new_value": True}],
        request_metadata=get_audit_metadata(request),
    )

    db.commit()
    db.refresh(blocker)

    return blocker_to_response(blocker)


@router.put("/api/blockers/{blocker_id}/resolve", response_model=BlockerResponse)
async def resolve_blocker(
    blocker_id: str,
    resolve_data: BlockerResolve,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Resolve a blocker with a resolution note."""
    blocker = db.query(Blocker).filter(Blocker.id == blocker_id).first()

    if not blocker:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Blocker not found",
        )

    if blocker.resolved_at is not None:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Blocker is already resolved",
        )

    task = blocker.task
    if not check_task_edit_access(current_user, task, task.project):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Permission denied",
        )

    # Update blocker
    blocker.resolved_by = current_user.id
    blocker.resolution_note = resolve_data.resolution_note
    # Use naive datetime for consistency with database storage
    blocker.resolved_at = datetime.now(timezone.utc).replace(tzinfo=None)

    # Check if there are other unresolved blockers
    other_blockers = db.query(Blocker).filter(
        Blocker.task_id == task.id,
        Blocker.id != blocker_id,
        Blocker.resolved_at == None,
    ).count()

    if other_blockers == 0:
        task.blocker_flag = False

    # Notify reporter that blocker is resolved (auto-publishes after commit)
    NotificationService.notify_blocker_resolved(db, task, current_user, blocker.reported_by)

    db.commit()
    db.refresh(blocker)

    return blocker_to_response(blocker)


@router.get("/api/tasks/{task_id}/blockers", response_model=BlockerListResponse)
async def list_blockers(
    task_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """List all blockers (history) for a task."""
    task = db.query(Task).filter(Task.id == task_id).first()

    if not task:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Task not found",
        )

    if not check_task_access(current_user, task, task.project):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Access denied",
        )

    blockers = db.query(Blocker).filter(
        Blocker.task_id == task_id,
    ).order_by(Blocker.created_at.desc()).all()

    return BlockerListResponse(
        blockers=[blocker_to_response(b) for b in blockers],
        total=len(blockers),
    )


@router.get("/api/blockers/{blocker_id}", response_model=BlockerResponse)
async def get_blocker(
    blocker_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Get a specific blocker by ID."""
    blocker = db.query(Blocker).filter(Blocker.id == blocker_id).first()

    if not blocker:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Blocker not found",
        )

    task = blocker.task
    if not check_task_access(current_user, task, task.project):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Access denied",
        )

    return blocker_to_response(blocker)