"""Phase 11: Lesson Learned service."""

from datetime import datetime
from typing import List, Optional
from uuid import UUID

from sqlalchemy.orm import Session

from app.domain.errors import DomainError
from app.models.knowledge import LessonLearned


def _get_or_404(db: Session, ll_id: UUID) -> LessonLearned:
    ll = db.query(LessonLearned).filter(
        LessonLearned.id == ll_id,
        LessonLearned.is_active == True,
    ).first()
    if not ll:
        raise DomainError(f"Lesson Learned {ll_id} not found", status_code=404)
    return ll


# ── Read ──────────────────────────────────────────────────────────────────────

def get_lesson_learned(db: Session, ll_id: UUID) -> LessonLearned:
    return _get_or_404(db, ll_id)


def list_lessons_learned(
    db: Session,
    entity_type:  Optional[str] = None,
    entity_id:    Optional[UUID] = None,
    severity:     Optional[str] = None,
    tag:          Optional[str] = None,
    technique_id: Optional[str] = None,
    include_inactive: bool = False,
) -> List[LessonLearned]:
    q = db.query(LessonLearned)
    if not include_inactive:
        q = q.filter(LessonLearned.is_active == True)
    if entity_type:
        q = q.filter(LessonLearned.entity_type == entity_type)
    if entity_id:
        q = q.filter(LessonLearned.entity_id == entity_id)
    if severity:
        q = q.filter(LessonLearned.severity == severity)
    if tag:
        # JSONB contains operator — filter lessons that have this tag
        q = q.filter(LessonLearned.tags.contains([tag]))
    if technique_id:
        q = q.filter(LessonLearned.technique_ids.contains([technique_id]))
    return q.order_by(LessonLearned.created_at.desc()).all()


# ── Create ────────────────────────────────────────────────────────────────────

def create_lesson_learned(db: Session, data: dict, user_id: UUID) -> LessonLearned:
    ll = LessonLearned(
        title         = data["title"],
        what_happened = data.get("what_happened", ""),
        root_cause    = data.get("root_cause", ""),
        fix_applied   = data.get("fix_applied"),
        severity      = data.get("severity", "medium"),
        entity_type   = data.get("entity_type", "manual"),
        entity_id     = data.get("entity_id"),
        technique_ids = data.get("technique_ids") or [],
        tags          = data.get("tags") or [],
        created_by    = user_id,
    )
    db.add(ll)
    db.commit()
    db.refresh(ll)
    return ll


# ── Update ────────────────────────────────────────────────────────────────────

def update_lesson_learned(db: Session, ll_id: UUID, data: dict, user_id: UUID) -> LessonLearned:
    ll = _get_or_404(db, ll_id)

    for field in ("title", "what_happened", "root_cause", "fix_applied",
                  "severity", "technique_ids", "tags"):
        if field in data and data[field] is not None:
            setattr(ll, field, data[field])

    ll.updated_at = datetime.utcnow()
    db.commit()
    db.refresh(ll)
    return ll


# ── Delete (soft) ─────────────────────────────────────────────────────────────

def delete_lesson_learned(db: Session, ll_id: UUID, user_id: UUID) -> None:
    """Soft-delete — admin-only enforcement is done at the router level."""
    ll = _get_or_404(db, ll_id)
    ll.is_active  = False
    ll.updated_at = datetime.utcnow()
    db.commit()


# ── Stats ─────────────────────────────────────────────────────────────────────

def get_knowledge_stats(db: Session) -> dict:
    """Summary counts for the knowledge base dashboard."""
    from app.models.knowledge import Playbook

    total_playbooks = db.query(Playbook).filter(Playbook.is_active == True).count()
    total_lessons   = db.query(LessonLearned).filter(LessonLearned.is_active == True).count()

    severity_counts: dict = {}
    for sev in ("critical", "high", "medium", "low", "info"):
        severity_counts[sev] = (
            db.query(LessonLearned)
            .filter(LessonLearned.is_active == True, LessonLearned.severity == sev)
            .count()
        )

    playbook_type_counts: dict = {}
    from app.schemas.knowledge_schema import VALID_PLAYBOOK_TYPES
    for ptype in VALID_PLAYBOOK_TYPES:
        playbook_type_counts[ptype] = (
            db.query(Playbook)
            .filter(Playbook.is_active == True, Playbook.playbook_type == ptype)
            .count()
        )

    return {
        "total_playbooks":      total_playbooks,
        "total_lessons":        total_lessons,
        "lessons_by_severity":  severity_counts,
        "playbooks_by_type":    playbook_type_counts,
    }