-- Enhanced AI Notification with Predictive Timing
-- Add new fields for scheduled notifications and AI prediction metadata

-- Add new status 'scheduled' and 'cancelled' to existing enum
-- Note: This depends on your Prisma schema, adjust as needed

-- Add new columns for predictive timing
ALTER TABLE `AINotification` 
ADD COLUMN `ScheduledAt_AIN` DATETIME(3) NULL COMMENT 'AI-predicted optimal delivery time',
ADD COLUMN `PredictedConfidence_AIN` INT NULL COMMENT 'AI confidence score (0-100)',
ADD COLUMN `PredictionReasoning_AIN` VARCHAR(255) NULL COMMENT 'AI reasoning for timing prediction',
ADD COLUMN `UserEngagementPattern_AIN` VARCHAR(50) NULL COMMENT 'Detected user pattern: morning_active, evening_active, etc',
ADD COLUMN `DelayMinutes_AIN` INT NULL COMMENT 'Delay in minutes from creation to scheduled delivery';

-- Update SentStatus_AIN to support new statuses
-- If using ENUM, you'll need to modify it:
-- ALTER TABLE `AINotification` 
-- MODIFY COLUMN `SentStatus_AIN` ENUM('pending', 'scheduled', 'sent', 'delivered', 'failed', 'cancelled') NOT NULL DEFAULT 'pending';

-- Add index for scheduled notifications query performance
CREATE INDEX `idx_scheduled_notifications` ON `AINotification`(`SentStatus_AIN`, `ScheduledAt_AIN`);

-- Add index for user engagement pattern analysis
CREATE INDEX `idx_user_pattern` ON `AINotification`(`UserID_AIN`, `UserEngagementPattern_AIN`);

-- Optional: Add constraint to ensure scheduled notifications have ScheduledAt_AIN
-- ALTER TABLE `AINotification`
-- ADD CONSTRAINT `chk_scheduled_has_time` 
-- CHECK (`SentStatus_AIN` != 'scheduled' OR `ScheduledAt_AIN` IS NOT NULL);