"""Phase 5G — Conflict detection on entity promote.

When a candidate entity is promoted to active, we check whether another
active entity is already claiming the "same slot" with an incompatible
value. If so, we emit a conflicts row + conflict_members rows so the
human can resolve.

Slot keys are per-entity-type (from ``conflict-model.md``). V1 starts
narrow with 3 slot kinds to avoid false positives:

1. **component.material** — a component should normally have ONE
   dominant material (via USES_MATERIAL edge). Two active USES_MATERIAL
   edges from the same component pointing at different materials =
   conflict.
2. **component.part_of** — a component should belong to AT MOST one
   subsystem (via PART_OF). Two active PART_OF edges = conflict.
3. **requirement.value** — two active Requirements with the same name in
   the same project but different descriptions = conflict.

Rule: **flag, never block**. The promote succeeds; the conflict row is
just a flag for the human. Users see conflicts in the dashboard and on
wiki entity pages with a "⚠️ Disputed" badge.
"""

from __future__ import annotations

import uuid
from datetime import datetime, timezone

from atocore.models.database import get_connection
from atocore.observability.logger import get_logger

log = get_logger("conflicts")


def detect_conflicts_for_entity(entity_id: str) -> list[str]:
    """Run conflict detection for a newly-promoted active entity.

    Returns a list of conflict_ids created. Fail-open: any detection error
    is logged and returns an empty list; the promote itself is not affected.
    """
    try:
        with get_connection() as conn:
            row = conn.execute(
                "SELECT * FROM entities WHERE id = ? AND status = 'active'",
                (entity_id,),
            ).fetchone()
        if row is None:
            return []

        created: list[str] = []
        etype = row["entity_type"]
        project = row["project"] or ""

        if etype == "component":
            created.extend(_check_component_conflicts(entity_id, project))
        elif etype == "requirement":
            created.extend(_check_requirement_conflicts(entity_id, row["name"], project))

        return created
    except Exception as e:
        log.warning("conflict_detection_failed", entity_id=entity_id, error=str(e))
        return []


def _check_component_conflicts(component_id: str, project: str) -> list[str]:
    """Check material + part_of slot uniqueness for a component."""
    created: list[str] = []
    with get_connection() as conn:
        # component.material conflicts
        mat_edges = conn.execute(
            "SELECT r.id AS rel_id, r.target_entity_id, e.name "
            "FROM relationships r "
            "JOIN entities e ON e.id = r.target_entity_id "
            "WHERE r.source_entity_id = ? AND r.relationship_type = 'uses_material' "
            "AND e.status = 'active'",
            (component_id,),
        ).fetchall()
        if len(mat_edges) > 1:
            cid = _record_conflict(
                slot_kind="component.material",
                slot_key=component_id,
                project=project,
                note=f"component has {len(mat_edges)} active material edges",
                members=[
                    {
                        "kind": "entity",
                        "id": m["target_entity_id"],
                        "snapshot": m["name"],
                    }
                    for m in mat_edges
                ],
            )
            if cid:
                created.append(cid)

        # component.part_of conflicts
        pof_edges = conn.execute(
            "SELECT r.id AS rel_id, r.target_entity_id, e.name "
            "FROM relationships r "
            "JOIN entities e ON e.id = r.target_entity_id "
            "WHERE r.source_entity_id = ? AND r.relationship_type = 'part_of' "
            "AND e.status = 'active'",
            (component_id,),
        ).fetchall()
        if len(pof_edges) > 1:
            cid = _record_conflict(
                slot_kind="component.part_of",
                slot_key=component_id,
                project=project,
                note=f"component is part_of {len(pof_edges)} subsystems",
                members=[
                    {
                        "kind": "entity",
                        "id": p["target_entity_id"],
                        "snapshot": p["name"],
                    }
                    for p in pof_edges
                ],
            )
            if cid:
                created.append(cid)

    return created


def _check_requirement_conflicts(requirement_id: str, name: str, project: str) -> list[str]:
    """Two active Requirements with the same name in the same project."""
    with get_connection() as conn:
        peers = conn.execute(
            "SELECT id, description FROM entities "
            "WHERE entity_type = 'requirement' AND status = 'active' "
            "AND project = ? AND LOWER(name) = LOWER(?) AND id != ?",
            (project, name, requirement_id),
        ).fetchall()
    if not peers:
        return []

    members = [{"kind": "entity", "id": requirement_id, "snapshot": name}]
    for p in peers:
        members.append({"kind": "entity", "id": p["id"],
                        "snapshot": (p["description"] or "")[:200]})

    cid = _record_conflict(
        slot_kind="requirement.name",
        slot_key=f"{project}|{name.lower()}",
        project=project,
        note=f"{len(peers)+1} active requirements share the name '{name}'",
        members=members,
    )
    return [cid] if cid else []


def _record_conflict(
    slot_kind: str,
    slot_key: str,
    project: str,
    note: str,
    members: list[dict],
) -> str | None:
    """Persist a conflict + its members; skip if an open conflict already
    exists for the same (slot_kind, slot_key)."""
    try:
        with get_connection() as conn:
            existing = conn.execute(
                "SELECT id FROM conflicts WHERE slot_kind = ? AND slot_key = ? "
                "AND status = 'open'",
                (slot_kind, slot_key),
            ).fetchone()
            if existing:
                return None  # don't dup

            conflict_id = str(uuid.uuid4())
            conn.execute(
                "INSERT INTO conflicts (id, slot_kind, slot_key, project, "
                "status, note) VALUES (?, ?, ?, ?, 'open', ?)",
                (conflict_id, slot_kind, slot_key, project, note[:500]),
            )
            for m in members:
                conn.execute(
                    "INSERT INTO conflict_members (id, conflict_id, member_kind, "
                    "member_id, value_snapshot) VALUES (?, ?, ?, ?, ?)",
                    (str(uuid.uuid4()), conflict_id,
                     m.get("kind", "entity"), m.get("id", ""),
                     (m.get("snapshot") or "")[:500]),
                )

        log.info("conflict_detected", conflict_id=conflict_id,
                 slot_kind=slot_kind, project=project)

        # Emit a warning alert so the operator sees it
        try:
            from atocore.observability.alerts import emit_alert
            emit_alert(
                severity="warning",
                title=f"Entity conflict: {slot_kind}",
                message=note,
                context={"project": project, "slot_key": slot_key,
                         "member_count": len(members)},
            )
        except Exception:
            pass

        return conflict_id
    except Exception as e:
        log.warning("conflict_record_failed", error=str(e))
        return None


def list_open_conflicts(project: str | None = None) -> list[dict]:
    """Return open conflicts with their members."""
    with get_connection() as conn:
        query = "SELECT * FROM conflicts WHERE status = 'open'"
        params: list = []
        if project:
            query += " AND project = ?"
            params.append(project)
        query += " ORDER BY detected_at DESC"
        rows = conn.execute(query, params).fetchall()

        conflicts = []
        for r in rows:
            member_rows = conn.execute(
                "SELECT * FROM conflict_members WHERE conflict_id = ?",
                (r["id"],),
            ).fetchall()
            conflicts.append({
                "id": r["id"],
                "slot_kind": r["slot_kind"],
                "slot_key": r["slot_key"],
                "project": r["project"] or "",
                "status": r["status"],
                "note": r["note"] or "",
                "detected_at": r["detected_at"],
                "members": [
                    {
                        "id": m["id"],
                        "member_kind": m["member_kind"],
                        "member_id": m["member_id"],
                        "snapshot": m["value_snapshot"] or "",
                    }
                    for m in member_rows
                ],
            })
    return conflicts


def resolve_conflict(
    conflict_id: str,
    action: str,  # "dismiss", "supersede_others", "no_action"
    winner_id: str | None = None,
    actor: str = "api",
) -> bool:
    """Resolve a conflict. Optionally marks non-winner members as superseded."""
    if action not in ("dismiss", "supersede_others", "no_action"):
        raise ValueError(f"Invalid action: {action}")

    now = datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M:%S")

    with get_connection() as conn:
        row = conn.execute(
            "SELECT * FROM conflicts WHERE id = ?", (conflict_id,)
        ).fetchone()
        if row is None or row["status"] != "open":
            return False

        if action == "supersede_others":
            if not winner_id:
                raise ValueError("winner_id required for supersede_others")
            # Mark non-winner member entities as superseded
            member_rows = conn.execute(
                "SELECT member_id FROM conflict_members WHERE conflict_id = ?",
                (conflict_id,),
            ).fetchall()
            for m in member_rows:
                if m["member_id"] != winner_id:
                    conn.execute(
                        "UPDATE entities SET status = 'superseded', updated_at = ? "
                        "WHERE id = ? AND status = 'active'",
                        (now, m["member_id"]),
                    )

        conn.execute(
            "UPDATE conflicts SET status = 'resolved', resolution = ?, "
            "resolved_at = ? WHERE id = ?",
            (action, now, conflict_id),
        )

    log.info("conflict_resolved", conflict_id=conflict_id,
             action=action, actor=actor)
    return True