package harness

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

// LobbyStub answers the single Lobby internal request the start
// service performs ([`internal/adapters/lobbyclient`]). The start
// service treats this response as ancillary diagnostics — the start
// envelope already carries `image_ref` — so the stub returns a
// deterministic 200 OK and lets the runtime ignore the payload.
//
// The stub only validates that the runtime configuration treats the
// Lobby URL as required (so it cannot regress to nil-out the
// ancillary fetch); the response body itself is unused by the
// integration assertions.
type LobbyStub struct {
	Server *httptest.Server
}

// NewLobbyStub returns a started httptest.Server. The caller registers
// `t.Cleanup(stub.Close)` themselves through the runtime helper so the
// stub follows the same lifecycle as the rest of the per-test wiring.
func NewLobbyStub(t testing.TB) *LobbyStub {
	t.Helper()
	mux := http.NewServeMux()
	mux.HandleFunc("GET /api/v1/internal/games/{game_id}", func(w http.ResponseWriter, r *http.Request) {
		gameID := strings.TrimSpace(r.PathValue("game_id"))
		if gameID == "" {
			writeStubError(w, http.StatusBadRequest, "invalid_request", "game_id is required")
			return
		}
		w.Header().Set("Content-Type", "application/json; charset=utf-8")
		w.WriteHeader(http.StatusOK)
		_ = json.NewEncoder(w).Encode(map[string]string{
			"game_id":               gameID,
			"status":                "running",
			"target_engine_version": "1.0.0",
		})
	})
	server := httptest.NewServer(mux)
	t.Cleanup(server.Close)
	return &LobbyStub{Server: server}
}

// URL returns the base URL of the running stub.
func (stub *LobbyStub) URL() string { return stub.Server.URL }

func writeStubError(w http.ResponseWriter, status int, code, message string) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(map[string]any{
		"error": map[string]string{"code": code, "message": message},
	})
}