-- RAG vector DB schema (runs automatically on first Postgres init).
-- GigaChat Embeddings = 1024; for OpenAI use vector(1536).

CREATE EXTENSION IF NOT EXISTS vector;

CREATE TABLE IF NOT EXISTS stories (
    id SERIAL PRIMARY KEY,
    slug TEXT UNIQUE NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT (NOW() AT TIME ZONE 'utc'),
    indexed_base_ref TEXT,
    indexed_head_ref TEXT,
    indexed_at TIMESTAMPTZ
);

CREATE TABLE IF NOT EXISTS documents (
    id SERIAL PRIMARY KEY,
    story_id INTEGER NOT NULL REFERENCES stories(id) ON DELETE CASCADE,
    path TEXT NOT NULL,
    version TEXT NOT NULL,
    updated_at TIMESTAMPTZ NOT NULL,
    UNIQUE(story_id, path)
);

CREATE TABLE IF NOT EXISTS chunks (
    id SERIAL PRIMARY KEY,
    document_id INTEGER NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
    chunk_index INTEGER NOT NULL,
    hash TEXT NOT NULL,
    content TEXT NOT NULL,
    embedding vector(1024) NOT NULL,
    start_line INTEGER,
    end_line INTEGER,
    change_type TEXT NOT NULL DEFAULT 'added'
        CHECK (change_type IN ('added', 'modified', 'unchanged')),
    previous_content TEXT
);

CREATE INDEX IF NOT EXISTS idx_documents_story_id ON documents(story_id);
CREATE INDEX IF NOT EXISTS idx_chunks_document_id ON chunks(document_id);
CREATE INDEX IF NOT EXISTS idx_chunks_embedding ON chunks USING ivfflat (embedding vector_cosine_ops);
CREATE INDEX IF NOT EXISTS idx_chunks_change_type ON chunks(change_type);