-- Enable pgvector
create extension if not exists vector;

-- Add embedding column to incidents (nullable — populated async after creation)
alter table incidents
  add column if not exists embedding vector(1024);

-- IVFFlat index for cosine similarity (10 lists sufficient for <10k rows)
create index if not exists incidents_embedding_idx
  on incidents using ivfflat (embedding vector_cosine_ops)
  with (lists = 10);

-- Similarity search — returns top-N most similar incidents (cosine)
create or replace function match_incidents(
  query_embedding vector(1024),
  exclude_id      uuid,
  match_count     int default 5
)
returns table (
  id            uuid,
  reference_no  text,
  incident_type text,
  description   text,
  severity      int,
  similarity    float
)
language sql
security definer
as $$
  select
    i.id,
    i.reference_no,
    i.incident_type,
    i.description,
    i.severity,
    1 - (i.embedding <=> query_embedding) as similarity
  from incidents i
  where i.id != exclude_id
    and i.embedding is not null
  order by i.embedding <=> query_embedding
  limit match_count;
$$;