PROJECT-CONTORL/backend/app/services/health_service.py

"""Project health calculation service.

Provides functionality to calculate and retrieve project health metrics
including risk scores, schedule status, and resource status.
"""
import uuid
from datetime import datetime
from typing import List, Optional, Dict, Any

from sqlalchemy.orm import Session

from app.models import Project, Task, TaskStatus, Blocker, ProjectHealth
from app.schemas.project_health import (
    RiskLevel,
    ScheduleStatus,
    ResourceStatus,
    ProjectHealthResponse,
    ProjectHealthWithDetails,
    ProjectHealthSummary,
    ProjectHealthDashboardResponse,
)


# Constants for health score calculation
BLOCKER_PENALTY_PER_ITEM = 10
BLOCKER_PENALTY_MAX = 30
OVERDUE_PENALTY_PER_ITEM = 5
OVERDUE_PENALTY_MAX = 30
COMPLETION_PENALTY_THRESHOLD = 50
COMPLETION_PENALTY_FACTOR = 0.4
COMPLETION_PENALTY_MAX = 20

# Risk level thresholds
RISK_LOW_THRESHOLD = 80
RISK_MEDIUM_THRESHOLD = 60
RISK_HIGH_THRESHOLD = 40

# Schedule status thresholds
SCHEDULE_AT_RISK_THRESHOLD = 2

# Resource status thresholds
RESOURCE_CONSTRAINED_THRESHOLD = 2


def calculate_health_metrics(db: Session, project: Project) -> Dict[str, Any]:
    """
    Calculate health metrics for a project.

    Args:
        db: Database session
        project: Project object to calculate metrics for

    Returns:
        Dictionary containing:
        - health_score: 0-100 integer
        - risk_level: low/medium/high/critical
        - schedule_status: on_track/at_risk/delayed
        - resource_status: adequate/constrained/overloaded
        - task_count: Total number of active tasks
        - completed_task_count: Number of completed tasks
        - blocker_count: Number of unresolved blockers
        - overdue_task_count: Number of overdue incomplete tasks
    """
    # Fetch active tasks for this project
    tasks = db.query(Task).filter(
        Task.project_id == project.id,
        Task.is_deleted == False
    ).all()

    task_count = len(tasks)

    # Count completed tasks
    completed_task_count = sum(
        1 for task in tasks
        if task.status and task.status.is_done
    )

    # Count overdue tasks (incomplete with past due date)
    now = datetime.utcnow()
    overdue_task_count = sum(
        1 for task in tasks
        if task.due_date and task.due_date < now
        and not (task.status and task.status.is_done)
    )

    # Count unresolved blockers
    task_ids = [t.id for t in tasks]
    blocker_count = 0
    if task_ids:
        blocker_count = db.query(Blocker).filter(
            Blocker.task_id.in_(task_ids),
            Blocker.resolved_at.is_(None)
        ).count()

    # Calculate completion rate
    completion_rate = 0.0
    if task_count > 0:
        completion_rate = (completed_task_count / task_count) * 100

    # Calculate health score (start at 100, subtract penalties)
    health_score = 100

    # Apply blocker penalty
    blocker_penalty = min(blocker_count * BLOCKER_PENALTY_PER_ITEM, BLOCKER_PENALTY_MAX)
    health_score -= blocker_penalty

    # Apply overdue penalty
    overdue_penalty = min(overdue_task_count * OVERDUE_PENALTY_PER_ITEM, OVERDUE_PENALTY_MAX)
    health_score -= overdue_penalty

    # Apply completion penalty (if below threshold)
    if task_count > 0 and completion_rate < COMPLETION_PENALTY_THRESHOLD:
        completion_penalty = int(
            (COMPLETION_PENALTY_THRESHOLD - completion_rate) * COMPLETION_PENALTY_FACTOR
        )
        health_score -= min(completion_penalty, COMPLETION_PENALTY_MAX)

    # Ensure health score stays within bounds
    health_score = max(0, min(100, health_score))

    # Determine risk level based on health score
    risk_level = _determine_risk_level(health_score)

    # Determine schedule status based on overdue count
    schedule_status = _determine_schedule_status(overdue_task_count)

    # Determine resource status based on blocker count
    resource_status = _determine_resource_status(blocker_count)

    return {
        "health_score": health_score,
        "risk_level": risk_level,
        "schedule_status": schedule_status,
        "resource_status": resource_status,
        "task_count": task_count,
        "completed_task_count": completed_task_count,
        "blocker_count": blocker_count,
        "overdue_task_count": overdue_task_count,
    }


def _determine_risk_level(health_score: int) -> str:
    """Determine risk level based on health score."""
    if health_score >= RISK_LOW_THRESHOLD:
        return "low"
    elif health_score >= RISK_MEDIUM_THRESHOLD:
        return "medium"
    elif health_score >= RISK_HIGH_THRESHOLD:
        return "high"
    else:
        return "critical"


def _determine_schedule_status(overdue_task_count: int) -> str:
    """Determine schedule status based on overdue task count."""
    if overdue_task_count == 0:
        return "on_track"
    elif overdue_task_count <= SCHEDULE_AT_RISK_THRESHOLD:
        return "at_risk"
    else:
        return "delayed"


def _determine_resource_status(blocker_count: int) -> str:
    """Determine resource status based on blocker count."""
    if blocker_count == 0:
        return "adequate"
    elif blocker_count <= RESOURCE_CONSTRAINED_THRESHOLD:
        return "constrained"
    else:
        return "overloaded"


def get_or_create_project_health(db: Session, project: Project) -> ProjectHealth:
    """
    Get existing project health record or create a new one.

    Args:
        db: Database session
        project: Project object

    Returns:
        ProjectHealth record
    """
    health = db.query(ProjectHealth).filter(
        ProjectHealth.project_id == project.id
    ).first()

    if not health:
        health = ProjectHealth(
            id=str(uuid.uuid4()),
            project_id=project.id
        )
        db.add(health)

    return health


def update_project_health(
    db: Session,
    project: Project,
    metrics: Dict[str, Any]
) -> ProjectHealth:
    """
    Update project health record with calculated metrics.

    Args:
        db: Database session
        project: Project object
        metrics: Calculated health metrics

    Returns:
        Updated ProjectHealth record
    """
    health = get_or_create_project_health(db, project)
    health.health_score = metrics["health_score"]
    health.risk_level = metrics["risk_level"]
    health.schedule_status = metrics["schedule_status"]
    health.resource_status = metrics["resource_status"]
    return health


def get_project_health(
    db: Session,
    project_id: str
) -> Optional[ProjectHealthWithDetails]:
    """
    Get health information for a single project.

    Args:
        db: Database session
        project_id: Project ID

    Returns:
        ProjectHealthWithDetails or None if project not found
    """
    project = db.query(Project).filter(Project.id == project_id).first()
    if not project:
        return None

    metrics = calculate_health_metrics(db, project)
    health = update_project_health(db, project, metrics)

    db.commit()
    db.refresh(health)

    return _build_health_with_details(project, health, metrics)


def get_all_projects_health(
    db: Session,
    status_filter: Optional[str] = "active"
) -> ProjectHealthDashboardResponse:
    """
    Get health information for all projects.

    Args:
        db: Database session
        status_filter: Filter projects by status (default: "active")

    Returns:
        ProjectHealthDashboardResponse with projects list and summary
    """
    query = db.query(Project)
    if status_filter:
        query = query.filter(Project.status == status_filter)

    projects = query.all()
    projects_health: List[ProjectHealthWithDetails] = []

    for project in projects:
        metrics = calculate_health_metrics(db, project)
        health = update_project_health(db, project, metrics)

        project_health = _build_health_with_details(project, health, metrics)
        projects_health.append(project_health)

    db.commit()

    # Calculate summary statistics
    summary = _calculate_summary(projects_health)

    return ProjectHealthDashboardResponse(
        projects=projects_health,
        summary=summary
    )


def _build_health_with_details(
    project: Project,
    health: ProjectHealth,
    metrics: Dict[str, Any]
) -> ProjectHealthWithDetails:
    """Build ProjectHealthWithDetails from project, health, and metrics."""
    return ProjectHealthWithDetails(
        id=health.id,
        project_id=project.id,
        health_score=metrics["health_score"],
        risk_level=RiskLevel(metrics["risk_level"]),
        schedule_status=ScheduleStatus(metrics["schedule_status"]),
        resource_status=ResourceStatus(metrics["resource_status"]),
        last_updated=health.last_updated or datetime.utcnow(),
        project_title=project.title,
        project_status=project.status,
        owner_name=project.owner.name if project.owner else None,
        space_name=project.space.name if project.space else None,
        task_count=metrics["task_count"],
        completed_task_count=metrics["completed_task_count"],
        blocker_count=metrics["blocker_count"],
        overdue_task_count=metrics["overdue_task_count"],
    )


def _calculate_summary(
    projects_health: List[ProjectHealthWithDetails]
) -> ProjectHealthSummary:
    """Calculate summary statistics for health dashboard."""
    total_projects = len(projects_health)

    healthy_count = sum(1 for p in projects_health if p.health_score >= 80)
    at_risk_count = sum(1 for p in projects_health if 50 <= p.health_score < 80)
    critical_count = sum(1 for p in projects_health if p.health_score < 50)

    average_health_score = 0.0
    if total_projects > 0:
        average_health_score = sum(p.health_score for p in projects_health) / total_projects

    projects_with_blockers = sum(1 for p in projects_health if p.blocker_count > 0)
    projects_delayed = sum(
        1 for p in projects_health
        if p.schedule_status == ScheduleStatus.DELAYED
    )

    return ProjectHealthSummary(
        total_projects=total_projects,
        healthy_count=healthy_count,
        at_risk_count=at_risk_count,
        critical_count=critical_count,
        average_health_score=round(average_health_score, 1),
        projects_with_blockers=projects_with_blockers,
        projects_delayed=projects_delayed,
    )


class HealthService:
    """
    Service class for project health operations.

    Provides a class-based interface for health calculations,
    following the service pattern used in the codebase.
    """

    def __init__(self, db: Session):
        """Initialize HealthService with database session."""
        self.db = db

    def calculate_metrics(self, project: Project) -> Dict[str, Any]:
        """Calculate health metrics for a project."""
        return calculate_health_metrics(self.db, project)

    def get_project_health(self, project_id: str) -> Optional[ProjectHealthWithDetails]:
        """Get health information for a single project."""
        return get_project_health(self.db, project_id)

    def get_dashboard(
        self,
        status_filter: Optional[str] = "active"
    ) -> ProjectHealthDashboardResponse:
        """Get health dashboard for all projects."""
        return get_all_projects_health(self.db, status_filter)

    def refresh_project_health(self, project: Project) -> ProjectHealth:
        """Refresh and persist health data for a project."""
        metrics = calculate_health_metrics(self.db, project)
        health = update_project_health(self.db, project, metrics)
        self.db.commit()
        self.db.refresh(health)
        return health