-- Email Activity Log System
-- Tracks all actions and events for emails

CREATE TABLE IF NOT EXISTS email_activity_log (
    id SERIAL PRIMARY KEY,
    email_id INTEGER NOT NULL REFERENCES email_messages(id) ON DELETE CASCADE,
    event_type VARCHAR(50) NOT NULL, -- fetched, saved, classified, workflow_executed, rule_matched, status_changed, read, attachment_downloaded, linked, etc.
    event_category VARCHAR(30) NOT NULL DEFAULT 'system', -- system, user, workflow, rule, integration
    description TEXT NOT NULL,
    metadata JSONB, -- Flexible storage for event-specific data
    user_id INTEGER REFERENCES users(user_id) ON DELETE SET NULL, -- NULL for system events
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    created_by VARCHAR(255) -- email or system identifier
);

-- Indexes for performance
CREATE INDEX IF NOT EXISTS idx_email_activity_log_email_id ON email_activity_log(email_id);
CREATE INDEX IF NOT EXISTS idx_email_activity_log_event_type ON email_activity_log(event_type);
CREATE INDEX IF NOT EXISTS idx_email_activity_log_created_at ON email_activity_log(created_at DESC);
CREATE INDEX IF NOT EXISTS idx_email_activity_log_category ON email_activity_log(event_category);

-- View for easy email timeline
CREATE OR REPLACE VIEW email_timeline AS
SELECT 
    eal.id,
    eal.email_id,
    em.subject,
    em.sender_email,
    eal.event_type,
    eal.event_category,
    eal.description,
    eal.metadata,
    eal.user_id,
    u.username as user_name,
    eal.created_at,
    eal.created_by
FROM email_activity_log eal
LEFT JOIN email_messages em ON eal.email_id = em.id
LEFT JOIN users u ON eal.user_id = u.user_id
ORDER BY eal.created_at DESC;

-- Helper function to log email events
CREATE OR REPLACE FUNCTION log_email_event(
    p_email_id INTEGER,
    p_event_type VARCHAR(50),
    p_event_category VARCHAR(30),
    p_description TEXT,
    p_metadata JSONB DEFAULT NULL,
    p_user_id INTEGER DEFAULT NULL,
    p_created_by VARCHAR(255) DEFAULT 'system'
) RETURNS INTEGER AS $$
DECLARE
    v_log_id INTEGER;
BEGIN
    INSERT INTO email_activity_log (
        email_id,
        event_type,
        event_category,
        description,
        metadata,
        user_id,
        created_by
    ) VALUES (
        p_email_id,
        p_event_type,
        p_event_category,
        p_description,
        p_metadata,
        p_user_id,
        p_created_by
    ) RETURNING id INTO v_log_id;
    
    RETURN v_log_id;
END;
$$ LANGUAGE plpgsql;

COMMENT ON TABLE email_activity_log IS 'Complete audit trail of all email events and actions';
COMMENT ON FUNCTION log_email_event IS 'Helper function to log email events with consistent format';