# Codebase Analysis: arma3-web-server

## Identity
- **Language / runtime**: Go 1.25 (backend), TypeScript 6 + React 19 (frontend)
- **Framework(s)**: Gin v1.12 (HTTP router), gorilla/websocket (WS), TanStack Query v5 (data fetching), Tailwind CSS 4 (styling), Vite 8 (bundler)
- **Build system**: Go toolchain (`go build`), Vite/Rollup for frontend, multi-stage Docker build
- **Test framework**: Go `testing` + Vitest + React Testing Library

## Code Style

- **Commits**: [Conventional Commits](https://www.conventionalcommits.org/) — format: `type(scope): description`
  - Types: `feat`, `fix`, `docs`, `style`, `refactor`, `test`, `chore`, `ci`, `perf`
  - Scopes: `backend`, `frontend`, `ci`, `docker`, or omit for project-wide changes
  - Examples: `feat(backend): add mod cleanup endpoint`, `fix(frontend): resolve race in modlist editor`, `docs: update PLAN.md to reflect current architecture`

## Directory map

```
arma3-web-server/
├── backend/                         # Go backend
│   ├── cmd/server/main.go           # Entry point, env parsing, dir creation, startup auto-tasks, wiring
│   ├── embed/
│   │   ├── embed.go                 # //go:embed dist — embeds frontend into Go binary
│   │   └── dist/                    # Pre-built frontend SPA assets
│   ├── internal/
│   │   ├── api/                     # Gin HTTP handlers + WebSocket endpoints
│   │   │   ├── router.go            # Route registration, Handler struct + New()
│   │   │   ├── settings.go          # Settings CRUD + server start/stop/restart + steamcmd
│   │   │   ├── configs.go           # .cfg file CRUD handlers
│   │   │   ├── modlists.go          # Modlist CRUD + import + export + check/download-missing/update-all
│   │   │   ├── mods.go              # Mod listing, deletion, bulk cleanup
│   │   │   ├── health.go            # Comprehensive health check endpoint
│   │   │   └── logs.go              # WS streaming (server, steamcmd, rpt) + log file listing
│   │   ├── models/                  # Data structs
│   │   │   ├── settings.go          # ServerSettings (singleton)
│   │   │   └── modlist.go           # Modlist + ModEntry + ModlistListItem
│   │   └── services/                # Business logic layer
│   │       ├── settings.go          # JSON load/save from data/settings.json
│   │       ├── config_manager.go    # .cfg file I/O in $CFG_DIR
│   │       ├── modlist_manager.go   # Modlist CRUD against data/modlists/*.json
│   │       ├── modlist_parser.go    # HTML Arma Launcher preset parser + renderer
│   │       ├── mod_manager.go       # Workshop + local mod discovery + usage map
│   │       ├── server_process.go    # Process lifecycle, arg builder, mod path resolver (atomic state machine)
│   │       ├── steamcmd.go          # SteamCMD manager (UpdateGame, DownloadMod, DownloadMods)
│   │       ├── scheduler.go         # Cron-based scheduled updates
│   │       ├── log_streamer.go      # Pub/sub fan-out for stdout/stderr via channels
│   │       └── testdata/            # Stub binaries for testing
│   │           ├── arma3server_x64  # Server stub: logs args, heartbeat, -t N exit, RPT writes
│   │           └── steamcmd         # SteamCMD stub: fake downloads, creates mod dirs
│   ├── go.mod / go.sum
│   └── serverfiles/                 # Default SERVERFILE_DIR (created at startup)
├── frontend/                        # React SPA
│   ├── src/
│   │   ├── App.tsx                  # Router setup (React Router v7)
│   │   ├── main.tsx                 # Entry point (QueryClient + BrowserRouter)
│   │   ├── index.css                # Tailwind v4 imports
│   │   ├── api/client.ts            # Typed fetch wrappers + WS URL builders
│   │   ├── types/index.ts           # ServerSettings, Modlist, ModEntry, ConfigInfo, ServerPaths
│   │   ├── pages/                   # 7 route-level page components
│   │   │   ├── Dashboard.tsx        # Overview cards (status, configs, modlists)
│   │   │   ├── Settings.tsx         # Main settings tab + userconfig tabs + SteamCMD + automation
│   │   │   ├── Configs.tsx          # List/create/duplicate/delete configs
│   │   │   ├── ConfigEditor.tsx     # Full-page Monaco editor for a single config
│   │   │   ├── Modlists.tsx         # List/create/duplicate/delete + HTML import
│   │   │   ├── ModlistEditor.tsx    # Mod list reorder + enable/disable + check/download-missing/update-all
│   │   │   ├── Mods.tsx             # Installed mods table + search + delete + cleanup
│   │   │   ├── Logs.tsx             # Tabbed LiveTerminal (Server Console / RPT / SteamCMD) + file browser
│   │   │   └── Status.tsx           # Health check / deploy status dashboard
│   │   └── components/
│   │       ├── ConfigEditor.tsx      # Monaco editor wrapper
│   │       ├── LiveTerminal.tsx      # xterm.js + auto-reconnect WebSocket
│   │       └── Layout.tsx            # Sidebar navigation shell
│   ├── package.json
│   ├── vite.config.ts               # Proxy /api + /ws to :8080
│   └── tsconfig*.json
├── data/                            # Runtime data (mounted volume in Docker)
│   ├── presets/                     # (unused)
│   └── servers/                     # (unused)
├── dev-deploy/                      # Local development runtime data (git-ignored)
├── .gitea/workflows/
│   ├── ci.yml                       # Build-only CI (Go + frontend)
│   └── release.yml                  # GoReleaser-based release on tag push
├── Dockerfile                       # Multi-stage: Go build -> npm build -> alpine runtime
├── Dockerfile.goreleaser            # Single-stage for GoReleaser (pre-built artifacts injected)
├── .goreleaser.yaml                 # GoReleaser v2 config (Gitea release target)
├── docker-compose.yml               # Single service with volume mounts + env vars
└── Makefile                         # Convenience targets: backend, frontend, build, run, dev, clean
```

## Dependencies

### Backend (Go)

| Module | Type | Version | Purpose |
|---|---|---|---|
| `github.com/gin-gonic/gin` | framework | v1.12.0 | HTTP routing, middleware, request binding |
| `github.com/gorilla/websocket` | library | v1.5.3 | WebSocket upgrade + message I/O |
| `github.com/google/uuid` | utility | v1.6.0 | UUID generation for modlists |
| `github.com/robfig/cron/v3` | scheduler | v3.0.1 | Cron expression parsing and scheduled task execution |
| `golang.org/x/net` | stdlib | v0.51.0 | HTML parser for modlist import |

### Frontend (npm)

| Package | Type | Version | Purpose |
|---|---|---|---|
| `react` / `react-dom` | framework | ^19.2.7 | UI rendering |
| `react-router-dom` | routing | ^7.18.1 | Client-side routing (7 pages) |
| `@tanstack/react-query` | data fetching | ^5.101.2 | Server state, caching, polling, mutations |
| `tailwindcss` | styling | ^4.3.2 | Utility-first CSS |
| `@monaco-editor/react` | editor | ^4.7.0 | Monaco code editor for .cfg files |
| `@xterm/xterm` / `@xterm/addon-fit` | terminal | ^6.0.0 / ^0.11.0 | In-browser xterm.js terminal |
| `vite` | bundler | ^8.1.1 | Dev server + production build |
| `@vitejs/plugin-react` | tooling | ^6.0.3 | React fast-refresh / JSX transform |
| `typescript` | language | ~6.0.2 | Type checking |
| `oxlint` | linter | ^1.71.0 | Linting |
| `vitest` | test runner | ^4.1.10 | Frontend unit/integration tests |
| `@testing-library/react` | test utility | ^16.3.0 | React component testing |
| `@testing-library/jest-dom` | test matcher | ^7.0.0 | DOM assertion matchers |
| `jsdom` | test env | ^29.1.1 | Browser environment for tests |

## Architecture

### Pattern: Layered (API -> Service -> Model), file-based persistence

```
HTTP/WS                    Gin Router             Services              Filesystem
---------                  ----------             --------              ----------
Browser -- REST/WS -->  api.Handler -->  SettingsManager    -->  data/settings.json
                             |              ConfigManager     -->  $CFG_DIR/*.cfg
                             |              ModlistManager    -->  data/modlists/*.json
                             |              ProcessManager    -->  spawn arma3server_x64
                             |              SteamCmdManager   -->  spawn steamcmd
                             |              LogStreamer       -->  pub/sub (channels)
                             +--->  WebSocket clients (xterm.js)
```

### Key abstractions
- **Handler** (api package) -- stateless; receives service pointers via constructor injection. All handlers are methods on Handler.
- ***Manager** (services package) -- stateful structs for each concern. Hold their own `sync.Mutex` for thread safety.
- **LogStreamer** -- pub/sub per named stream (`"server"`, `"steamcmd"`). Subscribe returns a `chan string`; Stream reads from an `io.Reader` (process stdout/stderr) and broadcasts to all subscribers of that key.
- **ProcessManager** -- manages the Arma 3 server child process lifecycle. Uses `atomic.Int32` state machine (idle/starting/running/stopping) with `CompareAndSwap` for lock-free state transitions. Builds the command line from settings, resolves mod paths, monitors process exit.

### Notable design decisions
1. **No database** -- everything is files: `settings.json`, `*.cfg` in `$CFG_DIR`, modlist JSON files. Backup means copying directories.
2. **Single server instance** -- ProcessManager allows only one running process at a time.
3. **`%command%` substitution** -- if ServerParameters contains `%command%`, the entire textarea is treated as a shell template, with `%command%` replaced by the binary path and auto-args (`-config=`, `-mod=`, `-profiles=`, `-port=`) appended. Enables Wine wrappers.
4. **Two-tier mod resolution** -- resolveModPath checks `$MODS_DIR/@name` first (manual/symlinked), then falls back to `$SERVERFILE_DIR/steamapps/workshop/content/107410/<id>` for workshop downloads.
5. **SteamCMD async with live streaming** -- all steamcmd operations run in background goroutines, output broadcast to `"steamcmd"` key.
6. **Env-defined paths** -- all dirs set via env vars with hardcoded defaults, resolved to absolute paths at startup. `SERVER_BINARY`, `SERVER_PARAMS`, `STEAMCMD_PATH` override defaults at runtime.
7. **Atomic state machine** -- ProcessManager and SteamCmdManager use `atomic.Int32`/`atomic.Bool` with `CompareAndSwap` for lock-free state transitions, eliminating race conditions between concurrent Start/Stop calls.

## Data flow (example: Start server)

```
User clicks "Start" (Settings.tsx)
  --> handleSaveThen() -- auto-saves if dirty
  --> POST /api/server/start
  --> Handler.StartServer() (settings.go)
    --> process.Start() (server_process.go)
      --> Load settings.json
      --> SERVER_PARAMS env overrides ServerParameters if set
      --> SERVER_BINARY env overrides platform default binary name if set
      --> If %command% in ServerParameters:
          --> Replace %command% with binPath
          --> Split into command + args
          --> Append buildAutoArgs(s): -config=, -mod=, -profiles=, -port=
          --> exec.CommandContext(ctx, parts[0], append(parts[1:], autoArgs...)...)
        Else:
          --> buildArgs(s): split parameters + append auto-args
          --> exec.CommandContext(ctx, binPath, args...)
      --> cmd.Dir = serverfileDir
      --> Pipe stdout/stderr
      --> cmd.Start()
      --> Stream stdout/stderr to LogStreamer("server")
      --> Monitor exit, broadcast [SERVER_PROCESS_EXITED]
  --> Returns {"status": "starting"}
  --> Frontend polls GET /api/server/status every 3s
  --> Shows "Running" badge
```

## CI/CD

### Gitea Actions (`/.gitea/workflows/`)

- **`ci.yml`** — Triggered on push to any branch or PR. Runs `go build ./...`, `npm ci && npm run build`, `go test ./...`, and `npm test`. Build + test CI.
- **`release.yml`** — Triggered on `v*` tag push. Runs GoReleaser v2 with `release --clean`, which builds Go binaries (linux/amd64 + windows/amd64), builds frontend via `before.hooks`, creates archives, builds + pushes a Docker image using `Dockerfile.goreleaser`, and publishes a Gitea release.

### Docker

- **`Dockerfile`** — Multi-stage build: Go compile → npm build → Debian slim runtime + SteamCMD. Single self-contained image.
- **`Dockerfile.goreleaser`** — Single-stage assembly-only Dockerfile for GoReleaser CI. Expects pre-built artifacts injected by GoReleaser.

### Local dev

- **Makefile targets** — `make run` starts backend, `make dev` starts both backend + Vite dev server with hot reload (copies test stubs to dev-deploy, passes `SERVER_BINARY`/`SERVER_PARAMS`/`STEAMCMD_PATH` env vars). `make test` runs both backend and frontend tests.