-- Enable pgvector (requires extension installed)
CREATE EXTENSION IF NOT EXISTS vector;

-- Namespaces: unique logical scope (e.g., 'project:metal', 'thread:abc')
CREATE TABLE IF NOT EXISTS namespaces (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  name TEXT NOT NULL UNIQUE,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- Users (optional link)
CREATE TABLE IF NOT EXISTS users (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  external_id TEXT UNIQUE,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- Threads (within a namespace)
CREATE TABLE IF NOT EXISTS threads (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  namespace_id UUID NOT NULL REFERENCES namespaces(id) ON DELETE CASCADE,
  external_id TEXT,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);
CREATE INDEX IF NOT EXISTS threads_ns_idx ON threads(namespace_id);

-- Memory items: logical notes/contexts (JSONB content + normalized text)
CREATE TABLE IF NOT EXISTS memory_items (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  namespace_id UUID NOT NULL REFERENCES namespaces(id) ON DELETE CASCADE,
  thread_id UUID REFERENCES threads(id) ON DELETE SET NULL,
  user_id UUID REFERENCES users(id) ON DELETE SET NULL,
  key TEXT,
  content JSONB NOT NULL,
  text TEXT,
  tags TEXT[] DEFAULT '{}',
  metadata JSONB DEFAULT '{}'::jsonb,
  revision INTEGER NOT NULL DEFAULT 1,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  expires_at TIMESTAMPTZ,
  deleted_at TIMESTAMPTZ
);
CREATE INDEX IF NOT EXISTS mem_items_ns_idx ON memory_items(namespace_id, thread_id, created_at DESC);
CREATE INDEX IF NOT EXISTS mem_items_tags_gin ON memory_items USING GIN(tags);
CREATE INDEX IF NOT EXISTS mem_items_meta_gin ON memory_items USING GIN(metadata);

-- Chunks: embedding units derived from items
CREATE TABLE IF NOT EXISTS memory_chunks (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  item_id UUID NOT NULL REFERENCES memory_items(id) ON DELETE CASCADE,
  ord INTEGER NOT NULL,
  text TEXT NOT NULL,
  metadata JSONB DEFAULT '{}'::jsonb,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);
CREATE INDEX IF NOT EXISTS chunks_item_idx ON memory_chunks(item_id, ord);

-- Embeddings: one per chunk (per model)
CREATE TABLE IF NOT EXISTS embeddings (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  chunk_id UUID NOT NULL REFERENCES memory_chunks(id) ON DELETE CASCADE,
  model TEXT NOT NULL,
  dim INTEGER NOT NULL,
  vector VECTOR(1536) NOT NULL, -- adjust dim per model
  normalized BOOLEAN DEFAULT FALSE,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  UNIQUE(chunk_id, model)
);
CREATE INDEX IF NOT EXISTS embeddings_model_dim ON embeddings(model, dim);
-- For ivfflat you must first create a HNSW/IVFFLAT index; pgvector uses different syntax depending on version
CREATE INDEX IF NOT EXISTS embeddings_vector_ivfflat ON embeddings USING ivfflat (vector) WITH (lists = 100);

-- Helper upsert function for memory_items revision bump
CREATE OR REPLACE FUNCTION bump_revision() RETURNS trigger AS $$
BEGIN
  NEW.revision := COALESCE(OLD.revision, 0) + 1;
  NEW.updated_at := now();
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS trg_bump_revision ON memory_items;
CREATE TRIGGER trg_bump_revision
BEFORE UPDATE ON memory_items
FOR EACH ROW EXECUTE FUNCTION bump_revision();