add redis cache to competitions

internal/competition/repository/postgres/competition.go

@@ -2,6 +2,7 @@ package postgres
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"strings"
 	"time"
@@ -11,18 +12,31 @@ import (
 
 	"github.com/google/uuid"
 	"github.com/jmoiron/sqlx"
+	"github.com/redis/go-redis/v9"
+)
+
+const (
+	competitionCachePrefix = "competition:"
 )
 
 type CompetitionRepository struct {
-	db *sqlx.DB
+	db           *sqlx.DB
+	redisClient  *redis.Client
+	cacheEnabled bool
 }
 
-func NewCompetitionRepository(db *sqlx.DB) repository.CompetitionRepository {
+func NewCompetitionRepository(db *sqlx.DB, redisClient *redis.Client, cacheEnabled bool) repository.CompetitionRepository {
 	return &CompetitionRepository{
-		db: db,
+		db:           db,
+		redisClient:  redisClient,
+		cacheEnabled: cacheEnabled,
 	}
 }
 
+func (r *CompetitionRepository) cacheKey(id string) string {
+	return competitionCachePrefix + id
+}
+
 func (r *CompetitionRepository) Create(ctx context.Context, c *pb.Competition) (*pb.Competition, error) {
 	query := `INSERT INTO competitions (state, title, description, image_url, start_time, end_time, type, participation_type)
 				VALUES ($1, $2, $3, $4, $5, $6, $7, $8) RETURNING id, created_at, updated_at`
@@ -45,14 +59,42 @@ func (r *CompetitionRepository) Create(ctx context.Context, c *pb.Competition) (
 	c.CreatedAt = createdCompetition.CreatedAt
 	c.UpdatedAt = createdCompetition.UpdatedAt
 
+	if r.cacheEnabled {
+		data, err := json.Marshal(c)
+		if err == nil {
+			r.redisClient.Set(ctx, r.cacheKey(c.Id), data, 10*time.Minute).Err()
+		}
+	}
+
 	return c, nil
 }
 
 func (r *CompetitionRepository) Get(ctx context.Context, id uuid.UUID) (*pb.Competition, error) {
+	if r.cacheEnabled {
+		val, err := r.redisClient.Get(ctx, r.cacheKey(id.String())).Result()
+		if err == nil {
+			var competition pb.Competition
+			if json.Unmarshal([]byte(val), &competition) == nil {
+				return &competition, nil
+			}
+		}
+	}
+
 	query := `SELECT id, state, title, description, image_url, start_time, end_time, type, participation_type, created_at, updated_at FROM competitions WHERE id = $1`
 	var competition pb.Competition
 	err := r.db.GetContext(ctx, &competition, query, id)
-	return &competition, err
+	if err != nil {
+		return nil, err
+	}
+
+	if r.cacheEnabled {
+		data, err := json.Marshal(&competition)
+		if err == nil {
+			r.redisClient.Set(ctx, r.cacheKey(id.String()), data, 10*time.Minute).Err()
+		}
+	}
+
+	return &competition, nil
 }
 
 func (r *CompetitionRepository) Update(ctx context.Context, c *pb.Competition) (*pb.Competition, error) {
@@ -77,13 +119,25 @@ func (r *CompetitionRepository) Update(ctx context.Context, c *pb.Competition) (
 	}
 	c.UpdatedAt = updatedCompetition.UpdatedAt
 
+	if r.cacheEnabled {
+		r.redisClient.Del(ctx, r.cacheKey(c.Id)).Err()
+	}
+
 	return c, nil
 }
 
 func (r *CompetitionRepository) Delete(ctx context.Context, id uuid.UUID) error {
 	query := `DELETE FROM competitions WHERE id = $1`
 	_, err := r.db.ExecContext(ctx, query, id)
-	return err
+	if err != nil {
+		return err
+	}
+
+	if r.cacheEnabled {
+		r.redisClient.Del(ctx, r.cacheKey(id.String())).Err()
+	}
+
+	return nil
 }
 
 func (r *CompetitionRepository) List(ctx context.Context, opts repository.ListCompetitionsOptions) ([]*pb.Competition, int, error) {
@@ -149,5 +203,9 @@ func (r *CompetitionRepository) ChangeState(ctx context.Context, id uuid.UUID, s
 		return nil, err
 	}
 
+	if r.cacheEnabled {
+		r.redisClient.Del(ctx, r.cacheKey(id.String())).Err()
+	}
+
 	return r.Get(ctx, id)
 }