gWAR API Endpoints and UI

[grovecj]

Overview

Add API endpoints for gWAR leaderboards and player gWAR breakdown, plus UI integration.

Parent Issue

Part of #94 (WAR and Advanced Stats)

API Endpoints

gWAR Leaderboards

GET /api/players/leaders/gwar/batting?season={year}&limit={n}
GET /api/players/leaders/gwar/pitching?season={year}&limit={n}

gWAR Breakdown (Component Details)

GET /api/players/{id}/gwar-breakdown?season={year}

Response:

{
  "player": { "id": 123, "name": "Shohei Ohtani" },
  "season": 2024,
  "gwar": 8.5,
  "officialWar": 8.3,
  "components": {
    "batting": 65.2,
    "baserunning": 4.1,
    "fielding": 0.0,
    "positional": -10.8,
    "replacement": 26.5
  },
  "methodology": "/docs/gwar"
}

Files to Modify

api/dto/BattingStatsDto.java

Add fields:

• gwar, gwarBatting, gwarBaserunning, gwarFielding, gwarPositional, gwarReplacement, oaa

api/dto/PitchingStatsDto.java

Add fields:

• gwar, gwarPitching, gwarReplacement

api/controller/PlayerController.java

Add endpoints for gWAR leaderboards and breakdown.

api/service/PlayerApiService.java

Add service methods with caching.

domain/stats/PlayerBattingStatsRepository.java

Add query:

List<PlayerBattingStats> findTopGwar(Integer season, Pageable pageable);

Files to Create

api/dto/GwarBreakdownDto.java

public record GwarBreakdownDto(
    PlayerDto player,
    Integer season,
    BigDecimal gwar,
    BigDecimal officialWar,
    BigDecimal batting,
    BigDecimal baserunning,
    BigDecimal fielding,
    BigDecimal positional,
    BigDecimal replacement,
    String methodology
) {}

Frontend Integration

Update existing advanced stats UI to show:

• gWAR alongside official WAR
• Tooltip explaining gWAR methodology
• Component breakdown on player profile

Test Cases

• Leaderboard returns sorted by gWAR
• Breakdown includes all components
• Null handling for players without gWAR
• Caching works correctly

Acceptance Criteria

• gWAR leaderboard endpoints work
• Breakdown endpoint shows components
• DTOs include all gWAR fields
• Leaderboard queries are performant (indexed)
• Frontend shows gWAR on player stats

Dependencies

• gWAR Schema: League Constants and Component Fields #169 (gWAR Schema)
• gWAR Calculation Service #170 (gWAR Calculation Service)
• MLB API Sabermetrics Ingestion #171 (MLB API Sabermetrics Ingestion)