is-it-christmas/specs/001-christmas-checker/plan.md

Implementation Plan: Christmas Checker Website

Branch: 001-christmas-checker | Date: 2025-11-11 | Spec: spec.md Input: Feature specification from /specs/001-christmas-checker/spec.md

Note: This template is filled in by the /speckit.plan command. See .specify/templates/commands/plan.md for the execution workflow.

Summary

A simple, delightful website that tells users whether today is Christmas Day (December 25th-26th). On non-Christmas days (363 days/year), displays "NO" with a sad smiley face. On Christmas (2 days/year), displays "YES" with festive falling snow animation using Canvas API. The website uses client-side date checking with user's local timezone, works offline, and includes automatic midnight transitions via page reload.

Technical Context

Language/Version: Java 21 (backend), Vanilla JavaScript ES6+ (frontend) Primary Dependencies: Java stdlib HttpServer (backend), nginx (frontend serving), Docker Compose (orchestration) Storage: N/A (ephemeral, no persistence required) Testing: Optional - not explicitly requested in specification Target Platform: Linux containers (backend: eclipse-temurin:21-jre-alpine, frontend: nginx:alpine) Project Type: Web application (backend + frontend) Performance Goals: <1s date check, <2s page load, 30-60 FPS snow animation Constraints: <2s page load on broadband, responsive 320px-1920px+, prefers-reduced-motion support Scale/Scope: Single-page application, 2 user stories, minimal dependencies (YAGNI)

Constitution Check

GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.

Principle I: User Story-Driven Development ✅ PASS

• ✅ Two prioritized user stories (P1: Non-Christmas day, P2: Christmas day)
• ✅ Each story independently testable and deployable
• ✅ Given/When/Then acceptance scenarios provided
• ✅ MVP = P1 story (363 days/year coverage)

Principle II: Specification-First Planning ✅ PASS

• ✅ spec.md includes user stories, functional requirements, success criteria
• ✅ plan.md (this file) includes technical context and constitution check
• ✅ research.md, data-model.md, contracts/ generated in Phases 0-1
• ✅ Specification uses technology-agnostic language focused on "what"

Principle III: Test-Optional with Clear Intent ✅ PASS

• ✅ Tests not explicitly requested in specification
• ✅ Task list will mark any test tasks as "OPTIONAL - only if tests requested"
• ✅ No TDD cycle required for this feature

Principle IV: Independent User Story Implementation ✅ PASS

• ✅ Two user stories can be implemented independently
• ✅ Foundational phase will establish shared infrastructure (date checking, page structure)
• ✅ P1 can deploy without P2 (show "NO" always, skip snow animation)
• ✅ P2 adds snow animation without modifying P1 logic

Principle V: Simplicity and Justified Complexity ✅ PASS

• ✅ Minimal dependencies: Java stdlib (no Spring), vanilla JS (no React)
• ✅ Client-side date checking (simplest approach, no server roundtrip)
• ✅ Docker Compose (requested by user for deployment)
• ✅ nginx for static files (standard, lightweight)
• ⚠️ Java backend existence: While spec allows offline client-only, plan includes backend API as optional fallback - justification in Complexity Tracking

Project Structure

Documentation (this feature)

specs/001-christmas-checker/
├── plan.md              # This file (/speckit.plan command output)
├── research.md          # Phase 0 output (/speckit.plan command)
├── data-model.md        # Phase 1 output (/speckit.plan command)
├── quickstart.md        # Phase 1 output (/speckit.plan command)
├── contracts/           # Phase 1 output (/speckit.plan command)
│   └── api.md          # REST API contract for /api/christmas endpoint
└── tasks.md             # Phase 2 output (/speckit.tasks command - NOT created by /speckit.plan)

Source Code (repository root)

backend/
├── src/main/java/christmas/
│   ├── ChristmasChecker.java    # Date logic (December 25-26 check)
│   ├── ChristmasServer.java     # HTTP server (GET /api/christmas)
│   └── Main.java                # Entry point
└── tests/                       # Optional - not included unless requested

frontend/
├── index.html                   # UI structure (loading, content, canvas)
├── styles.css                   # Styling & animations (NO/YES states, snow canvas)
├── script.js                    # Date check, rendering, Canvas snow animation
└── tests/                       # Optional - not included unless requested

docker/
├── Dockerfile.backend           # Java 21 multi-stage build
├── Dockerfile.frontend          # nginx alpine with static files
├── nginx.conf                   # nginx configuration (gzip, cache headers)
└── docker-compose.yml           # Two services: backend (8080), frontend (80)

.gitignore                       # Java, IDE, OS patterns
.dockerignore                    # Exclude specs, docs, IDE files from build context
README.md                        # Quickstart, features, tech stack

Structure Decision: Web application pattern selected due to backend (Java API) + frontend (HTML/CSS/JS) separation. Backend provides optional server-side date checking API at /api/christmas, though primary flow is client-side. Frontend served via nginx on port 80, backend on port 8080. Docker Compose orchestrates both services with health checks.

Complexity Tracking

Violation	Why Needed	Simpler Alternative Rejected Because
Java backend inclusion	User specified "Java application with minimalistic frontend" and "deployment via docker compose" in planning input. Backend provides consistent server-side fallback for date checking and demonstrates full-stack architecture as requested.	Pure client-side single HTML file would meet functional requirements but contradicts user's explicit request for Java backend component.
Docker Compose orchestration	User explicitly requested "deployment is done via docker compose" in planning input. Multi-service setup (backend + frontend) aligns with web application pattern.	Single container with embedded server could work but violates user's specified deployment approach.

Phase 1 Complete: Constitution Re-Check

Re-evaluation after design documents generated

All Principles: ✅ PASS

• ✅ Principle I: User stories remain independent (P1: Non-Christmas day, P2: Christmas day with snow)
• ✅ Principle II: Complete specification with research.md, data-model.md, contracts/api.md, quickstart.md
• ✅ Principle III: No tests requested, documentation marks tests as optional
• ✅ Principle IV: Foundational phase (date checking, page structure) followed by independent user story phases
• ✅ Principle V: Minimal complexity maintained - Java stdlib only, vanilla JS, Canvas API, no frameworks

Clarifications Applied:

• Christmas now includes December 25th AND 26th (Boxing Day) per clarification session
• Midnight transitions use hard reload (location.reload()) per clarification
• Canvas API confirmed for snow animation per clarification

Ready for Phase 2: Task generation with /speckit.tasks