feat: add method to find user

can find user by id, email or phone

firebase/auth/findUser.go

@@ -0,0 +1,50 @@
+package auth
+
+import (
+	"context"
+	"fmt"
+
+	"firebase.google.com/go/auth"
+	"github.com/mainawycliffe/kamanda/firebase"
+)
+
+type FindUserCriteria int
+
+const (
+	ByUserUIDCriteria   FindUserCriteria = 0
+	ByUserEmailCriteria FindUserCriteria = 1
+	ByUserPhoneCriteria FindUserCriteria = 2
+)
+
+//IsValid check if user criteria is valid i.e by uid, email or phone
+func (c FindUserCriteria) IsValid() bool {
+	if c != ByUserUIDCriteria && c != ByUserEmailCriteria && c != ByUserPhoneCriteria {
+		return false
+	}
+	return true
+}
+
+// GetUser find a user by either uid, email or phone number
+func GetUser(ctx context.Context, query string, criteria FindUserCriteria, includeCustomClaims bool) (*auth.UserRecord, error) {
+	if isValid := criteria.IsValid(); !isValid {
+		return nil, fmt.Errorf("Invalid find user criteria.")
+	}
+	client, err := firebase.Auth(ctx, "")
+	if err != nil {
+		return nil, fmt.Errorf("Error authenticating firebase account: %w", err)
+	}
+	var user *auth.UserRecord
+	var getUserErr error
+	switch criteria {
+	case ByUserEmailCriteria:
+		user, getUserErr = client.GetUserByEmail(ctx, query)
+	case ByUserPhoneCriteria:
+		user, getUserErr = client.GetUserByPhoneNumber(ctx, query)
+	default: // by UID
+		user, getUserErr = client.GetUser(ctx, query)
+	}
+	if getUserErr != nil {
+		return nil, fmt.Errorf("Error while find user: %w", getUserErr)
+	}
+	return user, nil
+}