Week 7 Worklog

Week 7 Objectives:

  • Backend: Build the Media module — Image entity with polymorphic association, AWS S3 integration, and Amazon CloudFront distribution.
  • Frontend: Build SessionDetailScreen, SessionCalendarScreen, and the mediaService mapped to CloudFront URLs for lightning-fast image caching.
  • Enable media to be delivered globally through an optimized CDN architecture.

Tasks to be carried out this week:

DayTaskStart DateCompletion DateReference Material
2- Build Image entity (module/media)
  + Fields: url (≤500), isThumbnail, food (@ManyToOne nullable), workoutPlan (@ManyToOne nullable), exercise (@ManyToOne nullable)
  + DB check constraint chk_image_exclusive: exactly ONE of food_id, workout_plan_id, exercise_id is non-null (exclusive polymorphic FK)
  + Write Flyway V3 migration: image table with exclusive FK constraint		02/24/202602/24/2026
3- Build ImageController (/api/images)
  + POST / — register image record (URL stored; file lives in S3)
  + GET /{id}, GET /food/{foodId}, GET /workout-plan/{workoutPlanId}, GET /exercise/{exerciseId}
  + PUT /{id}, DELETE /{id}		02/25/202602/25/2026
3- Configure AWS S3 integration (config/AwsS3Config.java)
  + AWS SDK v1: AmazonS3 bean configured with region ap-southeast-1
  + Bucket name from env S3_BUCKET_NAME (default crawl.fitness)
  + Upload utility method for media files		02/25/202602/25/2026https://docs.aws.amazon.com/sdk-for-java/
4- Build mediaService (Frontend)
  + getImageUrl(owner, id) — fetch image URL from GET /api/images/{owner}/{id}
  + In-memory URL cache + in-flight deduplication (prevents duplicate API calls for the same image)
  + Bulk helpers: getFoodImageUrlMap(ids[]), getWorkoutPlanImageUrlMap(ids[]), getExerciseImageUrlMap(ids[])		02/26/202602/26/2026
5- Build SessionDetailScreen (Frontend)
  + Past workout recap: exercises grouped by exerciseId
  + Shows sets × reps × weight per exercise
  + Formatted date/time display with utils/date.ts		02/27/202602/27/2026
6- Build SessionCalendarScreen (Frontend)
  + Monthly calendar view with dot indicators on days that have sessions
  + Month navigation (prev/next chevrons)
  + Click a date to show session logs below the calendar
  + Vietnamese day/month labels (Thứ 2–CN, Tháng 1–12)		02/28/202602/28/2026

Week 7 Achievements:

  • Backend & Cloud Architecture — Media module:
    • Flyway V3 migration applied with exclusive FK constraint.
    • AWS S3 bucket configured securely (private, no public ACLs).
    • Amazon CloudFront distribution implemented with Origin Access Control (OAC) to serve S3 media globally with low latency.
    • JSON configuration files (s3_images_upload.json) migrated to use CloudFront domains instead of direct S3 URLs, dramatically reducing data transfer costs.
  • Frontend — Session History:
    • SessionDetailScreen correctly groups workout logs by exercise and renders sets/reps/weight clearly.
    • SessionCalendarScreen marks training days with dots; tap to reveal session details inline.
    • Month navigation works; Vietnamese labels render correctly.
  • Frontend — Media Service:
    • mediaService caches fetched image URLs in memory — no duplicate API calls for images already loaded.
    • In-flight deduplication ensures concurrent requests for the same image share a single promise.
    • Workout plan tiles and exercise list items now display associated images from S3.

AWS Knowledge Learned:

  • Learned how S3 presigned URLs support secure client upload and download without exposing long-lived AWS credentials.
  • Understood how to choose short expiration windows for sensitive URLs while still preserving acceptable UX.
  • Studied upload validation concerns such as MIME type restrictions, size limits, and constrained key paths to reduce abuse.
  • Learned to design lifecycle policies that move stale media to cheaper storage classes and remove obsolete temporary assets.
  • Understood controlled content distribution patterns to prevent uncontrolled reuse or hotlinking of application media.
  • Learned how object ownership and bucket policy rules can create subtle access bugs if not aligned correctly.
  • Connected media caching decisions with both performance improvements and cloud cost reduction.

In summary, week 7 turned S3 knowledge into a practical and secure media delivery model for the app.

Next Week Plan:

  • Backend: Build the Food & Nutrition module — Food, Meal, MealFood, DailyNutrition entities with full CRUD and nutrition calculation.
  • Frontend: Build DietScreen with meal management, food search, and add-food-to-meal flow.