Trekko Backend

Introduction

Trekko is a comprehensive interface designed for managing user profiles, trips, and tracking information in Flutter applications. This interface offers a variety of methods to perform operations like initializing the service, managing user profiles and trips, handling real-time tracking, and more.

Installation & Setup

Prerequisites

• Flutter ^3.19.3
• Dart ^3.3.1
• Android Emulator and/or iOS Simulator + Xcode

Note: Same as for frontend.

Install packages

Install the packages & libraries from pom.xml using:

flutter pub get

Run tests

All tests can be ran using:

flutter test

Documentation

Main Interface: Trekko

Methods:

• Future<void> init(): Initializes the Trekko service.
• Stream<Profile> getProfile(): Retrieves the user's profile as a stream.
• Future<void> saveProfile(Profile profile): Saves the user's profile.
• Future<String> loadText(OnboardingTextType type): Loads onboarding text based on the specified type.
• Future<void> saveTrip(Trip trip): Saves a trip.
• Future<bool> deleteTrip(int tripId): Deletes a trip by its ID.
• Future<Trip> mergeTrips(Query<Trip> trips): Merges multiple trips into one.
• QueryBuilder<Trip, Trip, QWhere> getTripQuery(): Provides a query builder for trips.
• Stream<TripsAnalysis> analyze(Query<Trip> query): Analyzes trips based on a given query.
• Future<void> donate(Query<Trip> query): Handles donation-related actions.
• Future<Stream<Position>> getPosition(): Retrieves the current position as a stream.
• Stream<TrackingState> getTrackingState(): Retrieves the tracking state as a stream.
• Future<bool> setTrackingState(TrackingState state): Sets the tracking state.

Getting an instance of Trekko

To get an instance of Trekko, use one of the following builders with the required data:

• RegistrationBuilder: Register a new profile
• LoginBuilder: Login a profile
• LastLoginBuilder: Use the last logged in profile

These builders return a ProfiledTrekko instance, which is the concrete implementation of the Trekko interface.

Each of these builders may throw a BuildException if the required data is invalid or missing. The exception will include a reason, which will either be a LoginResult or a RegistrationResult.

Handling Streams in Flutter

Streams in Flutter are used to handle asynchronous data sequences. The StreamBuilder widget is particularly useful for this purpose.

The following example shows how to use the StreamBuilder widget to handle a stream of Profile objects:

StreamBuilder<Profile>(
  stream: trekko.getProfile(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.active) {
      if (snapshot.hasData) {
        final profile = snapshot.data;
        // Use profile here
      } else if (snapshot.hasError) {
        return Text('Error: ${snapshot.error}');
      }
    }
    return CircularProgressIndicator(); // Loading state
  },
);