-- sessions table stores high-level chat session metadata.
CREATE TABLE IF NOT EXISTS sessions (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    model_name TEXT NOT NULL,
    summary TEXT
);

CREATE UNIQUE INDEX IF NOT EXISTS idx_sessions_name ON sessions(name);

-- messages table stores individual conversation messages linked to sessions.
CREATE TABLE IF NOT EXISTS messages (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    session_id INTEGER NOT NULL,
    role TEXT NOT NULL,
    content TEXT NOT NULL,
    token_count INTEGER,
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY(session_id) REFERENCES sessions(id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_messages_session_created_at ON messages(session_id, created_at);

-- models table tracks available models and usage metadata.
CREATE TABLE IF NOT EXISTS models (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    display_name TEXT,
    provider TEXT,
    is_default BOOLEAN NOT NULL DEFAULT 0,
    last_used_at DATETIME
);

CREATE UNIQUE INDEX IF NOT EXISTS idx_models_name ON models(name);