"""Snapshot endpoints — coverage snapshots CRUD and comparison.

Provides periodic and manual snapshots of the organisation's coverage
state, plus temporal comparison between any two snapshots.
"""

import logging
import uuid
from typing import Optional

from fastapi import APIRouter, Depends, Query
from pydantic import BaseModel
from sqlalchemy.orm import Session

from app.database import get_db
from app.dependencies.auth import get_current_user, require_any_role, require_role
from app.domain.errors import BusinessRuleViolation
from app.domain.unit_of_work import UnitOfWork
from app.models.user import User
from app.services.snapshot_service import (
    create_snapshot,
    compare_snapshots,
    cleanup_old_snapshots,
    get_coverage_evolution,
    serialize_snapshot_summary,
    list_snapshots as list_snapshots_svc,
    get_snapshot_or_raise,
    get_snapshot_detail,
    delete_snapshot,
)
from app.services.audit_service import log_action

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/snapshots", tags=["snapshots"])


# ── Pydantic schemas ─────────────────────────────────────────────────

class SnapshotCreate(BaseModel):
    name: Optional[str] = None


# ---------------------------------------------------------------------------
# GET /snapshots — List snapshots (paginated)
# ---------------------------------------------------------------------------

@router.get("")
def list_snapshots(
    offset: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=200),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """List coverage snapshots ordered by creation date (newest first)."""
    return list_snapshots_svc(db, offset=offset, limit=limit)


# ---------------------------------------------------------------------------
# POST /snapshots — Create snapshot manually
# ---------------------------------------------------------------------------

@router.post("", status_code=201)
def create_snapshot_endpoint(
    payload: SnapshotCreate,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_any_role("red_lead", "blue_lead", "admin")),
):
    """Create a manual coverage snapshot with an optional name."""
    snapshot = create_snapshot(db, name=payload.name, user_id=current_user.id)

    with UnitOfWork(db) as uow:
        log_action(
            db,
            user_id=current_user.id,
            action="create_snapshot",
            entity_type="snapshot",
            entity_id=snapshot.id,
            details={"name": snapshot.name, "score": snapshot.organization_score},
        )
        uow.commit()

    return serialize_snapshot_summary(snapshot)


# ---------------------------------------------------------------------------
# GET /snapshots/evolution — Coverage trend over time
# ---------------------------------------------------------------------------


@router.get("/evolution")
def coverage_evolution(
    months: int = Query(12, ge=1, le=36),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Return coverage snapshots for trend charts (last *months* months)."""
    return get_coverage_evolution(db, months=months)


# ---------------------------------------------------------------------------
# GET /snapshots/compare — Compare two snapshots
# ---------------------------------------------------------------------------

@router.get("/compare")
def compare_snapshots_endpoint(
    a: str = Query(..., description="Snapshot A ID"),
    b: str = Query(..., description="Snapshot B ID"),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Compare two snapshots showing improved, worsened, and unchanged techniques."""
    try:
        a_id = uuid.UUID(a)
        b_id = uuid.UUID(b)
    except ValueError:
        raise BusinessRuleViolation("Invalid snapshot ID format")

    return compare_snapshots(db, a_id, b_id)


# ---------------------------------------------------------------------------
# GET /snapshots/{id} — Snapshot detail
# ---------------------------------------------------------------------------

@router.get("/{snapshot_id}")
def get_snapshot(
    snapshot_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Get detailed snapshot information including per-technique states."""
    return get_snapshot_detail(db, snapshot_id)


# ---------------------------------------------------------------------------
# DELETE /snapshots/{id} — Delete snapshot (admin only)
# ---------------------------------------------------------------------------

@router.delete("/{snapshot_id}")
def delete_snapshot_endpoint(
    snapshot_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_role("admin")),
):
    """Delete a snapshot (admin only)."""
    snapshot = get_snapshot_or_raise(db, snapshot_id)

    with UnitOfWork(db) as uow:
        log_action(
            db,
            user_id=current_user.id,
            action="delete_snapshot",
            entity_type="snapshot",
            entity_id=snapshot.id,
            details={"name": snapshot.name},
        )
        delete_snapshot(db, snapshot_id)
        uow.commit()

    return {"detail": "Snapshot deleted"}
