-- Sessions
CREATE TABLE IF NOT EXISTS sessions (
    id TEXT PRIMARY KEY,
    title TEXT NOT NULL,
    message_count INTEGER NOT NULL DEFAULT 0 CHECK (message_count >= 0),
    prompt_tokens  INTEGER NOT NULL DEFAULT 0 CHECK (prompt_tokens >= 0),
    completion_tokens  INTEGER NOT NULL DEFAULT 0 CHECK (completion_tokens>= 0),
    cost REAL NOT NULL DEFAULT 0.0 CHECK (cost >= 0.0),
    updated_at INTEGER NOT NULL,  -- Unix timestamp in milliseconds
    created_at INTEGER NOT NULL   -- Unix timestamp in milliseconds
);

CREATE TRIGGER IF NOT EXISTS update_sessions_updated_at
AFTER UPDATE ON sessions
BEGIN
UPDATE sessions SET updated_at = strftime('%s', 'now')
WHERE id = new.id;
END;

-- Messages
CREATE TABLE IF NOT EXISTS messages (
    id TEXT PRIMARY KEY,
    session_id TEXT NOT NULL,
    message_data TEXT NOT NULL,  -- JSON string of message content
    created_at INTEGER NOT NULL,  -- Unix timestamp in milliseconds
    updated_at INTEGER NOT NULL,  -- Unix timestamp in milliseconds
    FOREIGN KEY (session_id) REFERENCES sessions (id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_messages_session_id ON messages (session_id);

CREATE TRIGGER IF NOT EXISTS update_messages_updated_at
AFTER UPDATE ON messages
BEGIN
UPDATE messages SET updated_at = strftime('%s', 'now')
WHERE id = new.id;
END;

CREATE TRIGGER IF NOT EXISTS update_session_message_count_on_insert
AFTER INSERT ON messages
BEGIN
UPDATE sessions SET
    message_count = message_count + 1
WHERE id = new.session_id;
END;

CREATE TRIGGER IF NOT EXISTS update_session_message_count_on_delete
AFTER DELETE ON messages
BEGIN
UPDATE sessions SET
    message_count = message_count - 1
WHERE id = old.session_id;
END;
