"""Advanced metrics endpoints — coverage by tactic, never-tested, avg validation time."""

from datetime import datetime

from fastapi import APIRouter, Depends
from sqlalchemy import func, case
from sqlalchemy.orm import Session

from app.database import get_db
from app.dependencies.auth import get_current_user
from app.models.audit import AuditLog
from app.models.technique import Technique
from app.models.test import Test
from app.models.user import User

router = APIRouter(prefix="/metrics/advanced", tags=["advanced-metrics"])


@router.get("/coverage-by-tactic")
def coverage_by_tactic(
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """Coverage percentage broken down by MITRE ATT&CK tactic."""
    results = (
        db.query(
            Technique.tactic,
            func.count(Technique.id).label("total"),
            func.sum(
                case((Technique.status_global == "validated", 1), else_=0)
            ).label("validated"),
            func.sum(
                case((Technique.status_global == "partial", 1), else_=0)
            ).label("partial"),
            func.sum(
                case((Technique.status_global == "not_covered", 1), else_=0)
            ).label("not_covered"),
            func.sum(
                case((Technique.status_global == "in_progress", 1), else_=0)
            ).label("in_progress"),
        )
        .group_by(Technique.tactic)
        .order_by(Technique.tactic)
        .all()
    )
    return [
        {
            "tactic": r[0] or "Unknown",
            "total": r[1],
            "validated": int(r[2]),
            "partial": int(r[3]),
            "not_covered": int(r[4]),
            "in_progress": int(r[5]),
            "coverage_pct": round((int(r[2]) / r[1]) * 100, 1) if r[1] > 0 else 0,
        }
        for r in results
    ]


@router.get("/never-tested")
def never_tested_techniques(
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """Techniques that have never had a test created."""
    tested_technique_ids = (
        db.query(Test.technique_id).distinct().subquery()
    )
    techniques = (
        db.query(Technique)
        .filter(~Technique.id.in_(db.query(tested_technique_ids)))
        .order_by(Technique.mitre_id)
        .all()
    )
    return [
        {
            "mitre_id": t.mitre_id,
            "name": t.name,
            "tactic": t.tactic,
            "is_subtechnique": t.is_subtechnique,
        }
        for t in techniques
    ]


@router.get("/avg-validation-time")
def avg_validation_time(
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """Average time from test creation to validation, computed from audit logs.

    Returns overall average and per-phase averages where data is available.
    """
    validated_tests = (
        db.query(Test)
        .filter(Test.state == "validated")
        .all()
    )

    if not validated_tests:
        return {
            "total_validated": 0,
            "avg_total_hours": 0,
            "avg_red_phase_hours": 0,
            "avg_blue_phase_hours": 0,
        }

    total_durations = []
    red_durations = []
    blue_durations = []

    for test in validated_tests:
        if test.created_at and test.red_validated_at:
            total_seconds = (test.red_validated_at - test.created_at).total_seconds()
            total_durations.append(total_seconds)

        if test.red_started_at and test.blue_started_at:
            red_sec = (test.blue_started_at - test.red_started_at).total_seconds()
            red_paused = test.red_paused_seconds or 0
            red_durations.append(max(red_sec - red_paused, 0))

        if test.blue_started_at and test.blue_validated_at:
            blue_sec = (test.blue_validated_at - test.blue_started_at).total_seconds()
            blue_paused = test.blue_paused_seconds or 0
            blue_durations.append(max(blue_sec - blue_paused, 0))

    def avg_hours(durations: list[float]) -> float:
        if not durations:
            return 0
        return round(sum(durations) / len(durations) / 3600, 2)

    return {
        "total_validated": len(validated_tests),
        "avg_total_hours": avg_hours(total_durations),
        "avg_red_phase_hours": avg_hours(red_durations),
        "avg_blue_phase_hours": avg_hours(blue_durations),
    }


@router.get("/detection-rate-trend")
def detection_rate_trend(
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """Monthly detection rate trend for the last 12 months."""
    from datetime import timedelta

    now = datetime.utcnow()
    months = []

    for i in range(11, -1, -1):
        month_start = datetime(now.year, now.month, 1) - timedelta(days=i * 30)
        month_end = month_start + timedelta(days=30)

        validated = (
            db.query(func.count(Test.id))
            .filter(
                Test.state == "validated",
                Test.created_at >= month_start,
                Test.created_at < month_end,
            )
            .scalar() or 0
        )

        detected = (
            db.query(func.count(Test.id))
            .filter(
                Test.state == "validated",
                Test.detection_result == "detected",
                Test.created_at >= month_start,
                Test.created_at < month_end,
            )
            .scalar() or 0
        )

        months.append({
            "month": month_start.strftime("%Y-%m"),
            "validated": validated,
            "detected": detected,
            "detection_rate": round((detected / validated) * 100, 1) if validated > 0 else 0,
        })

    return months