-- Unified Search: Document chunks table for RAG indexing
-- Creates document_chunks table with HNSW index on embedding,
-- and adds content_text/content_tsv columns to files if missing.

CREATE EXTENSION IF NOT EXISTS vector;

-- ─── Document Chunks Table ───
CREATE TABLE IF NOT EXISTS document_chunks (
    id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    tenant_id    UUID NOT NULL,
    file_id      UUID NOT NULL REFERENCES files(id) ON DELETE CASCADE,
    chunk_index  INTEGER NOT NULL,
    chunk_text   TEXT NOT NULL,
    chunk_hash   VARCHAR(64) NOT NULL,
    embedding    vector(768),
    deleted_at   TIMESTAMPTZ,
    created_at   TIMESTAMPTZ NOT NULL DEFAULT now(),
    updated_at   TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX IF NOT EXISTS ix_document_chunks_tenant ON document_chunks(tenant_id);
CREATE INDEX IF NOT EXISTS ix_document_chunks_file ON document_chunks(file_id);
CREATE INDEX IF NOT EXISTS ix_document_chunks_tenant_file ON document_chunks(tenant_id, file_id);

-- HNSW index for fast cosine similarity search on chunk embeddings
CREATE INDEX IF NOT EXISTS ix_document_chunks_embedding
    ON document_chunks USING hnsw(embedding vector_cosine_ops);

-- ─── Files: content_text and content_tsv (idempotent) ───
DO $$ BEGIN
  IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'files') THEN
    ALTER TABLE files ADD COLUMN IF NOT EXISTS content_text text;
    ALTER TABLE files ADD COLUMN IF NOT EXISTS content_tsv tsvector;

    -- GIN index for full-text search on file content
    CREATE INDEX IF NOT EXISTS ix_files_content_tsv ON files USING gin(content_tsv);
  END IF;
END $$;