Implement Leaderboard Service

internal/app/router.go

@@ -26,5 +26,9 @@ func NewRouter(deps Dependencies) http.Handler {
 	router.HandleFunc("GET /api/v1/user/repositories/{repo_id}", middleware.Authentication(deps.RepositoryHandler.FetchParticularRepoDetails, deps.AppCfg))
 	router.HandleFunc("GET /api/v1/user/repositories/contributions/recent/{repo_id}", middleware.Authentication(deps.RepositoryHandler.FetchUserContributionsInRepo, deps.AppCfg))
 	router.HandleFunc("GET /api/v1/user/repositories/languages/{repo_id}", middleware.Authentication(deps.RepositoryHandler.FetchLanguagePercentInRepo, deps.AppCfg))
+
+	router.HandleFunc("GET /api/v1/leaderboard", middleware.Authentication(deps.UserHandler.ListUserRanks, deps.AppCfg))
+	router.HandleFunc("GET /api/v1/user/leaderboard", middleware.Authentication(deps.UserHandler.GetCurrentUserRank, deps.AppCfg))
+
 	return middleware.CorsMiddleware(router, deps.AppCfg)
 }

internal/app/user/domain.go

@@ -45,3 +45,11 @@ type Transaction struct {
 	CreatedAt         time.Time `db:"created_at"`
 	UpdatedAt         time.Time `db:"updated_at"`
 }
+
+type LeaderboardUser struct {
+	Id             int    `db:"id"`
+	GithubUsername string `db:"github_username"`
+	AvatarUrl      string `db:"avatar_url"`
+	CurrentBalance int    `db:"current_balance"`
+	Rank           int    `db:"rank"`
+}

internal/app/user/handler.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 
 	"github.com/joshsoftware/code-curiosity-2025/internal/pkg/apperrors"
+	"github.com/joshsoftware/code-curiosity-2025/internal/pkg/middleware"
 	"github.com/joshsoftware/code-curiosity-2025/internal/pkg/response"
 )
 
@@ -15,6 +16,8 @@ type handler struct {
 
 type Handler interface {
 	UpdateUserEmail(w http.ResponseWriter, r *http.Request)
+	ListUserRanks(w http.ResponseWriter, r *http.Request)
+	GetCurrentUserRank(w http.ResponseWriter, r *http.Request)
 }
 
 func NewHandler(userService Service) Handler {
@@ -44,3 +47,41 @@ func (h *handler) UpdateUserEmail(w http.ResponseWriter, r *http.Request) {
 
 	response.WriteJson(w, http.StatusOK, "email updated successfully", nil)
 }
+
+func (h *handler) ListUserRanks(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	leaderboard, err := h.userService.GetAllUsersRank(ctx)
+	if err != nil {
+		slog.Error("failed to get all users rank", "error", err)
+		status, errorMessage := apperrors.MapError(err)
+		response.WriteJson(w, status, errorMessage, nil)
+		return
+	}
+
+	response.WriteJson(w, http.StatusOK, "leaderboard fetched successfully", leaderboard)
+}
+
+func (h *handler) GetCurrentUserRank(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	userIdValue := ctx.Value(middleware.UserIdKey)
+
+	userId, ok := userIdValue.(int)
+	if !ok {
+		slog.Error("error obtaining user id from context")
+		status, errorMessage := apperrors.MapError(apperrors.ErrContextValue)
+		response.WriteJson(w, status, errorMessage, nil)
+		return
+	}
+
+	currentUserRank, err := h.userService.GetCurrentUserRank(ctx, userId)
+	if err != nil {
+		slog.Error("failed to get current user rank", "error", err)
+		status, errorMessage := apperrors.MapError(err)
+		response.WriteJson(w, status, errorMessage, nil)
+		return
+	}
+
+	response.WriteJson(w, http.StatusOK, "current user rank fetched successfully", currentUserRank)
+}

internal/app/user/service.go

@@ -19,6 +19,8 @@ type Service interface {
 	CreateUser(ctx context.Context, userInfo CreateUserRequestBody) (User, error)
 	UpdateUserEmail(ctx context.Context, email string) error
 	UpdateUserCurrentBalance(ctx context.Context, transaction Transaction) error
+	GetAllUsersRank(ctx context.Context) ([]LeaderboardUser, error)
+	GetCurrentUserRank(ctx context.Context, userId int) (LeaderboardUser, error)
 }
 
 func NewService(userRepository repository.UserRepository) Service {
@@ -98,3 +100,28 @@ func (s *service) UpdateUserCurrentBalance(ctx context.Context, transaction Tran
 
 	return nil
 }
+
+func (s *service) GetAllUsersRank(ctx context.Context) ([]LeaderboardUser, error) {
+	userRanks, err := s.userRepository.GetAllUsersRank(ctx, nil)
+	if err != nil {
+		slog.Error("error obtaining all users rank", "error", err)
+		return nil, err
+	}
+
+	Leaderboard := make([]LeaderboardUser, len(userRanks))
+	for i, l := range userRanks {
+		Leaderboard[i] = LeaderboardUser(l)
+	}
+
+	return Leaderboard, nil
+}
+
+func (s *service) GetCurrentUserRank(ctx context.Context, userId int) (LeaderboardUser, error) {
+	currentUserRank, err := s.userRepository.GetCurrentUserRank(ctx, nil, userId)
+	if err != nil {
+		slog.Error("error obtaining current user rank", "error", err)
+		return LeaderboardUser{}, err
+	}
+
+	return LeaderboardUser(currentUserRank), nil
+}

internal/db/migrations/1752476063_create-index-users-current-balance.down.sql

@@ -0,0 +1 @@
+drop index idx_users_current_balance

internal/db/migrations/1752476063_create-index-users-current-balance.up.sql

@@ -0,0 +1 @@
+CREATE INDEX idx_users_current_balance ON users(current_balance DESC);

internal/pkg/apperrors/errors.go

@@ -6,6 +6,7 @@ import (
 )
 
 var (
+	ErrContextValue   = errors.New("error obtaining value from context")
 	ErrInternalServer = errors.New("internal server error")
 
 	ErrInvalidRequestBody = errors.New("invalid or missing parameters in the request body")
@@ -52,7 +53,7 @@ var (
 
 func MapError(err error) (statusCode int, errMessage string) {
 	switch err {
-	case ErrInvalidRequestBody, ErrInvalidQueryParams:
+	case ErrInvalidRequestBody, ErrInvalidQueryParams, ErrContextValue:
 		return http.StatusBadRequest, err.Error()
 	case ErrUnauthorizedAccess:
 		return http.StatusUnauthorized, err.Error()

internal/repository/domain.go

@@ -77,3 +77,11 @@ type Transaction struct {
 	CreatedAt         time.Time `db:"created_at"`
 	UpdatedAt         time.Time `db:"updated_at"`
 }
+
+type LeaderboardUser struct {
+	Id             int    `db:"id"`
+	GithubUsername string `db:"github_username"`
+	AvatarUrl      string `db:"avatar_url"`
+	CurrentBalance int    `db:"current_balance"`
+	Rank           int    `db:"rank"`
+}

internal/repository/user.go

@@ -23,6 +23,8 @@ type UserRepository interface {
 	UpdateUserEmail(ctx context.Context, tx *sqlx.Tx, userId int, email string) error
 	GetAllUsersGithubId(ctx context.Context, tx *sqlx.Tx) ([]int, error)
 	UpdateUserCurrentBalance(ctx context.Context, tx *sqlx.Tx, user User) error
+	GetAllUsersRank(ctx context.Context, tx *sqlx.Tx) ([]LeaderboardUser, error)
+	GetCurrentUserRank(ctx context.Context, tx *sqlx.Tx, userId int) (LeaderboardUser, error)
 }
 
 func NewUserRepository(db *sqlx.DB) UserRepository {
@@ -51,6 +53,31 @@ const (
 	getAllUsersGithubIdQuery = "SELECT github_id from users"
 
 	updateUserCurrentBalanceQuery = "UPDATE users SET current_balance=$1, updated_at=$2 where id=$3"
+
+	getAllUsersRankQuery = `
+	SELECT 
+	id,
+	github_username,
+	avatar_url,
+	current_balance,
+	RANK() over (ORDER BY current_balance DESC) AS rank
+	FROM users 
+	ORDER BY current_balance DESC`
+
+	getCurrentUserRankQuery = `
+	SELECT *
+	FROM 
+	(
+  	SELECT 
+	id, 
+	github_username, 
+	avatar_url,
+	current_balance,
+    RANK() OVER (ORDER BY current_balance DESC) AS rank
+  	FROM users
+	) 
+	ranked_users
+	WHERE id = $1;`
 )
 
 func (ur *userRepository) GetUserById(ctx context.Context, tx *sqlx.Tx, userId int) (User, error) {
@@ -142,3 +169,30 @@ func (ur *userRepository) UpdateUserCurrentBalance(ctx context.Context, tx *sqlx
 
 	return nil
 }
+
+func (ur *userRepository) GetAllUsersRank(ctx context.Context, tx *sqlx.Tx) ([]LeaderboardUser, error) {
+	executer := ur.BaseRepository.initiateQueryExecuter(tx)
+
+	var leaderboard []LeaderboardUser
+	err := executer.SelectContext(ctx, &leaderboard, getAllUsersRankQuery)
+	if err != nil {
+		slog.Error("failed to get users rank", "error", err)
+		return nil, apperrors.ErrInternalServer
+	}
+
+	return leaderboard, nil
+}
+
+func (ur *userRepository) GetCurrentUserRank(ctx context.Context, tx *sqlx.Tx, userId int) (LeaderboardUser, error) {
+
+	executer := ur.BaseRepository.initiateQueryExecuter(tx)
+
+	var currentUserRank LeaderboardUser
+	err := executer.GetContext(ctx, &currentUserRank, getCurrentUserRankQuery, userId)
+	if err != nil {
+		slog.Error("failed to get user rank", "error", err)
+		return LeaderboardUser{}, apperrors.ErrInternalServer
+	}
+
+	return currentUserRank, nil
+}