# Task 08: Server Wiring

## Objective
Wire `cmd/server/main.go` — load config, connect to MongoDB, create all handlers, set up routes, start HTTP server with graceful shutdown.

## Implementation

```go
func main() {
    // 1. Load config
    cfg, err := config.Load()
    // exit on error

    // 2. Set up structured logging
    slog.SetDefault(slog.New(slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelInfo})))

    // 3. Connect to MongoDB
    store, err := store.NewStore(ctx, cfg.MongoURI)
    defer store.Close(ctx)

    // 4. Create clients
    castClient := cast.NewClient(cfg.CastAPIURL, cfg.CastAPIKey, cfg.CastSenderID)
    ghlAPI := ghl.NewAPIClient()

    // 5. Create handlers
    oauthHandler := ghl.NewOAuthHandler(cfg.GHLClientID, cfg.GHLClientSecret, cfg.BaseURL, cfg.GHLConversationProviderID, store)
    webhookHandler, err := ghl.NewWebhookHandler(cfg.GHLWebhookPublicKey, castClient, ghlAPI, oauthHandler)
    // exit on error (PEM parsing failure)

    // 6. Set up router (chi)
    r := chi.NewRouter()

    // Middleware
    r.Use(middleware.RequestID)
    r.Use(middleware.RealIP)
    r.Use(middleware.Recoverer)
    r.Use(middleware.Timeout(60 * time.Second))

    // Routes
    r.Get("/health", healthCheck)
    r.Get("/install", oauthHandler.HandleInstall)
    r.Get("/oauth-callback", oauthHandler.HandleCallback)
    r.Post("/api/ghl/v1/webhook/messages", webhookHandler.HandleWebhook)

    // 7. Start server with graceful shutdown
    srv := &http.Server{
        Addr:    ":" + cfg.Port,
        Handler: r,
    }

    // Signal handling
    go func() {
        sigCh := make(chan os.Signal, 1)
        signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
        <-sigCh
        slog.Info("shutting down...")
        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
        defer cancel()
        srv.Shutdown(ctx)
    }()

    slog.Info("cast-ghl-provider started", "port", cfg.Port, "base_url", cfg.BaseURL)
    if err := srv.ListenAndServe(); err != http.ErrServerClosed {
        slog.Error("server error", "err", err)
        os.Exit(1)
    }
}

func healthCheck(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(200)
    w.Write([]byte(`{"status":"ok","service":"cast-ghl-provider"}`))
}
```

## Middleware
Use chi's built-in middleware:
- `middleware.RequestID` — adds X-Request-Id
- `middleware.RealIP` — trusts X-Forwarded-For / X-Real-IP
- `middleware.Recoverer` — recovers panics, returns 500
- `middleware.Timeout` — 60s request timeout

Do NOT add a custom logging middleware for now — slog in handlers is sufficient.

## Key behaviors
- Config validation at startup — fail fast with clear error messages
- MongoDB connection at startup — fail fast if can't connect
- PEM key parsing at startup — fail fast if invalid
- Graceful shutdown: wait up to 10s for in-flight requests
- Health check always returns 200 + JSON (no auth required)
- All slog output goes to stderr (not stdout)
- Port defaults to 3002

## Acceptance Criteria
- [ ] `go build ./cmd/server/` produces working binary
- [ ] Missing config → clear error message + exit
- [ ] MongoDB connection failure → clear error message + exit
- [ ] Invalid PEM key → clear error message + exit
- [ ] `GET /health` returns `{"status":"ok"}`
- [ ] `GET /install` redirects to GHL OAuth
- [ ] `GET /oauth-callback` handles code exchange
- [ ] `POST /api/ghl/v1/webhook/messages` processes webhooks
- [ ] SIGINT/SIGTERM triggers graceful shutdown
- [ ] Server logs startup info with port and base_url