# GitHug Android

Native Android adaptation of the Ruby [Githug](https://github.com/Gazler/githug) learning game, built with **Kotlin + Jetpack Compose**. The product goal is a shippable mobile implementation that preserves GitHug's CLI-first learning style while making repository state easier to inspect on a phone.

## Implementation Strategy

The app is organized around GitHug parity rather than simplified command quizzes:

- The level catalog follows the upstream Ruby Githug order from `Githug::Level::LEVELS`.
- Each exercise lives in its own Kotlin source file under `app/src/main/java/solutions/tretter/githugandroid/levels/`.
- Each level file documents the intended repository setup, evaluation strategy, hints, command suggestions, and embedded solution scenarios.
- Validators prefer repository state and Git objects over raw command text. Direct command-answer validation is reserved for upstream answer-style levels such as identifying a hash, filename, remote URL, author, or count.
- Shared tests execute the embedded solution scenarios for every level and assert that the Android catalog still matches the upstream level order.
- The runtime prepares an isolated sandbox per level. When a bundled native Git binary is present, Git commands run against real repository directories; otherwise the Kotlin fallback engine keeps development and tests deterministic.

The UI supports a terminal-centered workflow with optional inspection panes:

- **CLI ONLY**: hide visualization and play with terminal-style input.
- **HYBRID**: command line with optional repository panels.
- **VISUAL**: repository panels visible by default, still backed by the same command engine.

## Development Workflow

Development tasks should be run through the project tooling script. It provisions the local toolchain, keeps paths project-relative, and runs Gradle with the project configuration expected by this repository.

## Android project tooling

This repo includes a root-level tooling script:

```bash
bash ./AndroidProjectTooling.sh
```

It is designed to be idempotent and uses project-relative paths to:

- install a project-local JDK into `./jdk`
- install Android command-line tools into `./android-sdk`
- restore `gradle/wrapper/gradle-wrapper.jar` if missing
- install required Android SDK packages
- write `local.properties`

To run the JVM unit test suite after ensuring the local toolchain is ready:

```bash
bash ./AndroidProjectTooling.sh --test
```

To build the debug APK:

```bash
bash ./AndroidProjectTooling.sh --build
```

The script avoids depending on the system Java version by provisioning a project-local **JDK 17**, which is required by current Android SDK command-line tools.

To avoid repeated expensive SDK verification, the script writes a small state file named:

`./.android-project-tooling.state`

If all required components were verified successfully, the script will skip SDK verification/reinstallation for the next **24 hours** unless required directories are missing.

When `--build` is used, the script also:

- increments `versionCode` by 1
- increments the patch component of `versionName`, for example `0.1.0` to `0.1.1`
- renames the debug APK to `githug-android-debug.apk`
- attempts to create a git commit after a successful build if there are source changes

## Runtime Architecture

The command engine has two execution paths behind one app-facing runtime:

- **Native Git path**: if the packaged executable is present for the device ABI, Git commands execute in a real per-level repository sandbox in app-private storage.
- **Kotlin fallback path**: the in-memory sandbox engine mirrors the same observable repository facts for development, JVM tests, and environments without a bundled native Git binary.

Both paths expose the same `RepoState` surface to validators. In addition to files, commits, branches, tags, remotes, and config, the model tracks learning-relevant effects such as stashes, fetched remote refs, pushed branches/tags, submodules, and repository maintenance actions.

Helper shell-like commands (`ls`, `pwd`, `cat`, `touch`, `mkdir`, `rm`, `echo`, `cd`) remain implemented in Kotlin so the mobile terminal behaves consistently across devices.

## Level Authoring

When adding or changing a level:

- Keep one source file per exercise.
- Keep `allGithugLevels()` in upstream Ruby Githug order.
- Document the setup and validation intent in the level file.
- Prefer validators that inspect `RepoState` over validators that match command strings.
- Add multiple `LevelTestCase` scenarios when more than one solution path should be accepted.
- Run `bash ./AndroidProjectTooling.sh --test` before building.

## Production Focus

Current work is focused on:

- improving parity with upstream Ruby Githug setup and validation semantics
- expanding native-Git-backed behavior across complex repository workflows
- preserving robust fallback tests for every level
- improving onboarding, accessibility, UI polish, icons, and Play Store readiness