backend barebone done, big chunk of work done

server/internal/store/users.go

@@ -0,0 +1,98 @@
+package store
+
+import (
+	"context"
+	"errors"
+
+	"github.com/jackc/pgconn"
+	"github.com/jackc/pgerrcode"
+	"github.com/jackc/pgx/v5"
+)
+
+// CreateUser inserts a new user returning the created record or ErrDuplicate on conflict.
+func (s *Store) CreateUser(ctx context.Context, username, displayName, passwordHash string) (*User, error) {
+	var u User
+	err := s.pool.QueryRow(ctx, `
+       INSERT INTO users(username, display_name, password_hash)
+       VALUES($1, $2, $3)
+       RETURNING id, username, display_name, password_hash, avatar, created_at
+   `, username, displayName, passwordHash).Scan(
+		&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
+	)
+	if err != nil {
+		var pgErr *pgconn.PgError
+		if errors.As(err, &pgErr) && pgErr.Code == pgerrcode.UniqueViolation {
+			return nil, ErrDuplicate
+		}
+		return nil, err
+	}
+	return &u, nil
+}
+
+// GetUserByUsername retrieves a user by username or returns ErrNotFound.
+func (s *Store) GetUserByUsername(ctx context.Context, username string) (*User, error) {
+	var u User
+	err := s.pool.QueryRow(ctx, `
+       SELECT id, username, display_name, password_hash, avatar, created_at
+       FROM users WHERE username=$1
+   `, username).Scan(
+		&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
+	)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+	return &u, nil
+}
+
+// GetUserByID retrieves a user by ID or returns ErrNotFound.
+func (s *Store) GetUserByID(ctx context.Context, id int64) (*User, error) {
+	var u User
+	err := s.pool.QueryRow(ctx, `
+       SELECT id, username, display_name, password_hash, avatar, created_at
+       FROM users WHERE id=$1
+   `, id).Scan(
+		&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
+	)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+	return &u, nil
+}
+
+// SearchUsers returns users matching query in username or display_name via ILIKE.
+// Empty query returns an empty slice.
+func (s *Store) SearchUsers(ctx context.Context, query string, limit int) ([]User, error) {
+	if query == "" {
+		return []User{}, nil
+	}
+	pattern := "%" + query + "%"
+	rows, err := s.pool.Query(ctx, `
+       SELECT id, username, display_name, password_hash, avatar, created_at
+       FROM users
+       WHERE username ILIKE $1 OR display_name ILIKE $1
+       ORDER BY username
+       LIMIT $2
+   `, pattern, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var users []User
+	for rows.Next() {
+		var u User
+		if err := rows.Scan(
+			&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
+		); err != nil {
+			return nil, err
+		}
+		users = append(users, u)
+	}
+	return users, nil
+}