package gamemaster

import (
	"context"
	"net/http"
	"path/filepath"
	"runtime"
	"testing"

	"github.com/getkin/kin-openapi/openapi3"
	"github.com/stretchr/testify/require"
)

var expectedInternalOperationIDs = []string{
	"internalHealthz",
	"internalReadyz",
	"internalRegisterRuntime",
	"internalGetRuntime",
	"internalListRuntimes",
	"internalForceNextTurn",
	"internalStopRuntime",
	"internalPatchRuntime",
	"internalBanishRace",
	"internalInvalidateMemberships",
	"internalGameLiveness",
	"internalListEngineVersions",
	"internalCreateEngineVersion",
	"internalGetEngineVersion",
	"internalUpdateEngineVersion",
	"internalDeprecateEngineVersion",
	"internalResolveEngineVersionImageRef",
	"internalExecuteCommands",
	"internalPutOrders",
	"internalGetReport",
}

// gmOwnedClosedSchemas lists every component schema for which Game Master
// owns the wire shape and therefore must reject unknown fields. The list
// is curated; the matching test fails if any schema in this list opens up.
var gmOwnedClosedSchemas = []string{
	"ProbeResponse",
	"LivenessResponse",
	"ImageRefResponse",
	"RegisterRuntimeMember",
	"RegisterRuntimeRequest",
	"RuntimeRecord",
	"RuntimeListResponse",
	"StopRuntimeRequest",
	"PatchRuntimeRequest",
	"EngineVersion",
	"EngineVersionListResponse",
	"CreateEngineVersionRequest",
	"UpdateEngineVersionRequest",
	"ErrorResponse",
	"ErrorBody",
}

// engineOwnedPassthroughSchemas lists every component schema that forwards
// engine-owned payloads verbatim and therefore deliberately uses
// `additionalProperties: true`. The matching test fails if any schema in
// this list closes up.
var engineOwnedPassthroughSchemas = []string{
	"ExecuteCommandsRequest",
	"ExecuteCommandsResponse",
	"PutOrdersRequest",
	"PutOrdersResponse",
	"ReportResponse",
}

// TestInternalOpenAPISpecValidates loads internal-openapi.yaml and verifies
// it is a syntactically valid OpenAPI 3.0 document.
func TestInternalOpenAPISpecValidates(t *testing.T) {
	t.Parallel()
	loadInternalSpec(t)
}

// TestInternalSpecHasAllOperationIDs verifies that the spec declares every
// operationId required by gamemaster/PLAN.md Stage 06 and no extras. Adding
// a new operation requires updating expectedInternalOperationIDs in the same
// patch as the spec change.
func TestInternalSpecHasAllOperationIDs(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	got := make([]string, 0, len(expectedInternalOperationIDs))
	for _, pathItem := range doc.Paths.Map() {
		for _, op := range pathItem.Operations() {
			require.NotEmpty(t, op.OperationID, "every operation must declare a non-empty operationId")
			got = append(got, op.OperationID)
		}
	}

	require.ElementsMatch(t, expectedInternalOperationIDs, got)
}

// TestInternalSpecRegisterRuntime verifies the register-runtime contract
// used by Game Lobby after a successful container start.
func TestInternalSpecRegisterRuntime(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/games/{game_id}/register-runtime", http.MethodPost)

	require.Equal(t, "internalRegisterRuntime", op.OperationID)
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")
	assertSchemaRef(t, requestSchemaRef(t, op), "#/components/schemas/RegisterRuntimeRequest", "internalRegisterRuntime request")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/RuntimeRecord", "internalRegisterRuntime 200")
	assertResponseRef(t, op, http.StatusBadRequest, "#/components/responses/InvalidRequestError")
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/EngineVersionNotFoundError")
	assertResponseRef(t, op, http.StatusConflict, "#/components/responses/ConflictError")
	assertResponseRef(t, op, http.StatusBadGateway, "#/components/responses/EngineUnreachableError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
	assertResponseRef(t, op, http.StatusServiceUnavailable, "#/components/responses/ServiceUnavailableError")

	req := componentSchemaRef(t, doc, "RegisterRuntimeRequest")
	assertRequiredFields(t, req,
		"engine_endpoint", "members", "target_engine_version", "turn_schedule")

	member := componentSchemaRef(t, doc, "RegisterRuntimeMember")
	assertRequiredFields(t, member, "user_id", "race_name")
}

// TestInternalSpecGetRuntime verifies the runtime read contract.
func TestInternalSpecGetRuntime(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/runtimes/{game_id}", http.MethodGet)

	require.Equal(t, "internalGetRuntime", op.OperationID)
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/RuntimeRecord", "internalGetRuntime 200")
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/NotFoundError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
}

// TestInternalSpecListRuntimes verifies the list contract and the optional
// status query parameter.
func TestInternalSpecListRuntimes(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/runtimes", http.MethodGet)

	require.Equal(t, "internalListRuntimes", op.OperationID)
	assertOperationParameterRefs(t, op, "#/components/parameters/RuntimeStatusQuery")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/RuntimeListResponse", "internalListRuntimes 200")
	assertResponseRef(t, op, http.StatusBadRequest, "#/components/responses/InvalidRequestError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")

	param := componentParameterRef(t, doc, "RuntimeStatusQuery")
	require.Equal(t, "status", param.Value.Name)
	require.Equal(t, "query", param.Value.In)
	require.False(t, param.Value.Required, "status filter must be optional")
	require.Equal(t, "#/components/schemas/RuntimeStatus", param.Value.Schema.Ref,
		"status filter schema must reference RuntimeStatus")
}

// TestInternalSpecForceNextTurn verifies the force-next-turn admin contract.
func TestInternalSpecForceNextTurn(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/runtimes/{game_id}/force-next-turn", http.MethodPost)

	require.Equal(t, "internalForceNextTurn", op.OperationID)
	require.Nil(t, op.RequestBody, "internalForceNextTurn must have no request body")
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/RuntimeRecord", "internalForceNextTurn 200")
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/NotFoundError")
	assertResponseRef(t, op, http.StatusConflict, "#/components/responses/ConflictError")
	assertResponseRef(t, op, http.StatusBadGateway, "#/components/responses/EngineUnreachableError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
}

// TestInternalSpecStopRuntime verifies the stop admin contract.
func TestInternalSpecStopRuntime(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/runtimes/{game_id}/stop", http.MethodPost)

	require.Equal(t, "internalStopRuntime", op.OperationID)
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")
	assertSchemaRef(t, requestSchemaRef(t, op), "#/components/schemas/StopRuntimeRequest", "internalStopRuntime request")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/RuntimeRecord", "internalStopRuntime 200")
	assertResponseRef(t, op, http.StatusBadRequest, "#/components/responses/InvalidRequestError")
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/NotFoundError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
	assertResponseRef(t, op, http.StatusServiceUnavailable, "#/components/responses/ServiceUnavailableError")

	req := componentSchemaRef(t, doc, "StopRuntimeRequest")
	assertRequiredFields(t, req, "reason")
	reason := req.Value.Properties["reason"]
	require.NotNil(t, reason)
	require.Equal(t, "#/components/schemas/StopReason", reason.Ref,
		"StopRuntimeRequest.reason must reference StopReason")
}

// TestInternalSpecPatchRuntime verifies the patch admin contract.
func TestInternalSpecPatchRuntime(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/runtimes/{game_id}/patch", http.MethodPost)

	require.Equal(t, "internalPatchRuntime", op.OperationID)
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")
	assertSchemaRef(t, requestSchemaRef(t, op), "#/components/schemas/PatchRuntimeRequest", "internalPatchRuntime request")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/RuntimeRecord", "internalPatchRuntime 200")
	assertResponseRef(t, op, http.StatusBadRequest, "#/components/responses/InvalidRequestError")
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/NotFoundError")
	assertResponseRef(t, op, http.StatusConflict, "#/components/responses/ConflictError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
	assertResponseRef(t, op, http.StatusServiceUnavailable, "#/components/responses/ServiceUnavailableError")

	req := componentSchemaRef(t, doc, "PatchRuntimeRequest")
	assertRequiredFields(t, req, "version")
}

// TestInternalSpecBanishRace verifies the engine-side race banish contract
// called by Game Lobby after a permanent membership removal.
func TestInternalSpecBanishRace(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/games/{game_id}/race/{race_name}/banish", http.MethodPost)

	require.Equal(t, "internalBanishRace", op.OperationID)
	require.Nil(t, op.RequestBody, "internalBanishRace must have no request body; the race_name is on the path")
	assertOperationParameterRefs(t, op,
		"#/components/parameters/GameIDPath",
		"#/components/parameters/RaceNamePath",
	)

	assertNoContentResponse(t, op, http.StatusNoContent)
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/NotFoundError")
	assertResponseRef(t, op, http.StatusBadGateway, "#/components/responses/EngineUnreachableError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
}

// TestInternalSpecInvalidateMemberships verifies the membership cache hook
// called by Game Lobby on every roster mutation.
func TestInternalSpecInvalidateMemberships(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/games/{game_id}/memberships/invalidate", http.MethodPost)

	require.Equal(t, "internalInvalidateMemberships", op.OperationID)
	require.Nil(t, op.RequestBody)
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")

	assertNoContentResponse(t, op, http.StatusNoContent)
	assertResponseRef(t, op, http.StatusNotFound, "#/components/responses/NotFoundError")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")
}

// TestInternalSpecGameLiveness verifies the liveness reply used by Lobby's
// resume flow.
func TestInternalSpecGameLiveness(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	op := getOperation(t, doc, "/api/v1/internal/games/{game_id}/liveness", http.MethodGet)

	require.Equal(t, "internalGameLiveness", op.OperationID)
	assertOperationParameterRefs(t, op, "#/components/parameters/GameIDPath")
	assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/LivenessResponse", "internalGameLiveness 200")
	assertResponseRef(t, op, http.StatusInternalServerError, "#/components/responses/InternalError")

	resp := componentSchemaRef(t, doc, "LivenessResponse")
	assertRequiredFields(t, resp, "ready", "status")
	status := resp.Value.Properties["status"]
	require.NotNil(t, status)
	require.Equal(t, "#/components/schemas/RuntimeStatus", status.Ref,
		"LivenessResponse.status must reference RuntimeStatus")
}

// TestInternalSpecEngineVersionsCRUD verifies all six engine version
// registry operations: list, create, get, update, deprecate, resolve.
func TestInternalSpecEngineVersionsCRUD(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	listOp := getOperation(t, doc, "/api/v1/internal/engine-versions", http.MethodGet)
	require.Equal(t, "internalListEngineVersions", listOp.OperationID)
	assertOperationParameterRefs(t, listOp, "#/components/parameters/EngineVersionStatusQuery")
	assertSchemaRef(t, responseSchemaRef(t, listOp, http.StatusOK), "#/components/schemas/EngineVersionListResponse", "internalListEngineVersions 200")

	createOp := getOperation(t, doc, "/api/v1/internal/engine-versions", http.MethodPost)
	require.Equal(t, "internalCreateEngineVersion", createOp.OperationID)
	assertSchemaRef(t, requestSchemaRef(t, createOp), "#/components/schemas/CreateEngineVersionRequest", "create request")
	assertSchemaRef(t, responseSchemaRef(t, createOp, http.StatusCreated), "#/components/schemas/EngineVersion", "internalCreateEngineVersion 201")
	assertResponseRef(t, createOp, http.StatusConflict, "#/components/responses/ConflictError")

	getOp := getOperation(t, doc, "/api/v1/internal/engine-versions/{version}", http.MethodGet)
	require.Equal(t, "internalGetEngineVersion", getOp.OperationID)
	assertOperationParameterRefs(t, getOp, "#/components/parameters/VersionPath")
	assertSchemaRef(t, responseSchemaRef(t, getOp, http.StatusOK), "#/components/schemas/EngineVersion", "internalGetEngineVersion 200")
	assertResponseRef(t, getOp, http.StatusNotFound, "#/components/responses/NotFoundError")

	updateOp := getOperation(t, doc, "/api/v1/internal/engine-versions/{version}", http.MethodPatch)
	require.Equal(t, "internalUpdateEngineVersion", updateOp.OperationID)
	assertOperationParameterRefs(t, updateOp, "#/components/parameters/VersionPath")
	assertSchemaRef(t, requestSchemaRef(t, updateOp), "#/components/schemas/UpdateEngineVersionRequest", "update request")
	assertSchemaRef(t, responseSchemaRef(t, updateOp, http.StatusOK), "#/components/schemas/EngineVersion", "internalUpdateEngineVersion 200")

	deprecateOp := getOperation(t, doc, "/api/v1/internal/engine-versions/{version}", http.MethodDelete)
	require.Equal(t, "internalDeprecateEngineVersion", deprecateOp.OperationID)
	assertNoContentResponse(t, deprecateOp, http.StatusNoContent)
	assertResponseRef(t, deprecateOp, http.StatusConflict, "#/components/responses/EngineVersionInUseError")

	resolveOp := getOperation(t, doc, "/api/v1/internal/engine-versions/{version}/image-ref", http.MethodGet)
	require.Equal(t, "internalResolveEngineVersionImageRef", resolveOp.OperationID)
	assertOperationParameterRefs(t, resolveOp, "#/components/parameters/VersionPath")
	assertSchemaRef(t, responseSchemaRef(t, resolveOp, http.StatusOK), "#/components/schemas/ImageRefResponse", "internalResolveEngineVersionImageRef 200")
	assertResponseRef(t, resolveOp, http.StatusNotFound, "#/components/responses/EngineVersionNotFoundError")

	createReq := componentSchemaRef(t, doc, "CreateEngineVersionRequest")
	assertRequiredFields(t, createReq, "version", "image_ref")
}

// TestInternalSpecHotPathContracts verifies the three Edge Gateway hot-path
// operations and their pass-through schema treatment.
func TestInternalSpecHotPathContracts(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	cmdOp := getOperation(t, doc, "/api/v1/internal/games/{game_id}/commands", http.MethodPost)
	require.Equal(t, "internalExecuteCommands", cmdOp.OperationID)
	assertOperationParameterRefs(t, cmdOp,
		"#/components/parameters/GameIDPath",
		"#/components/parameters/XUserIDHeader",
	)
	assertSchemaRef(t, requestSchemaRef(t, cmdOp), "#/components/schemas/ExecuteCommandsRequest", "internalExecuteCommands request")
	assertSchemaRef(t, responseSchemaRef(t, cmdOp, http.StatusOK), "#/components/schemas/ExecuteCommandsResponse", "internalExecuteCommands 200")
	assertResponseRef(t, cmdOp, http.StatusForbidden, "#/components/responses/ForbiddenError")
	assertResponseRef(t, cmdOp, http.StatusBadGateway, "#/components/responses/EngineUnreachableError")

	orderOp := getOperation(t, doc, "/api/v1/internal/games/{game_id}/orders", http.MethodPost)
	require.Equal(t, "internalPutOrders", orderOp.OperationID)
	assertOperationParameterRefs(t, orderOp,
		"#/components/parameters/GameIDPath",
		"#/components/parameters/XUserIDHeader",
	)
	assertSchemaRef(t, requestSchemaRef(t, orderOp), "#/components/schemas/PutOrdersRequest", "internalPutOrders request")
	assertSchemaRef(t, responseSchemaRef(t, orderOp, http.StatusOK), "#/components/schemas/PutOrdersResponse", "internalPutOrders 200")

	reportOp := getOperation(t, doc, "/api/v1/internal/games/{game_id}/reports/{turn}", http.MethodGet)
	require.Equal(t, "internalGetReport", reportOp.OperationID)
	assertOperationParameterRefs(t, reportOp,
		"#/components/parameters/GameIDPath",
		"#/components/parameters/TurnPath",
		"#/components/parameters/XUserIDHeader",
	)
	require.Nil(t, reportOp.RequestBody, "internalGetReport must have no request body")
	assertSchemaRef(t, responseSchemaRef(t, reportOp, http.StatusOK), "#/components/schemas/ReportResponse", "internalGetReport 200")
	assertResponseRef(t, reportOp, http.StatusForbidden, "#/components/responses/ForbiddenError")
	assertResponseRef(t, reportOp, http.StatusBadGateway, "#/components/responses/EngineUnreachableError")
}

// TestInternalSpecProbes verifies the two probe operations.
func TestInternalSpecProbes(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	for _, path := range []string{"/healthz", "/readyz"} {
		op := getOperation(t, doc, path, http.MethodGet)
		assertSchemaRef(t, responseSchemaRef(t, op, http.StatusOK), "#/components/schemas/ProbeResponse", op.OperationID+" 200")
		assertResponseRef(t, op, http.StatusServiceUnavailable, "#/components/responses/ServiceUnavailableError")
	}

	healthz := getOperation(t, doc, "/healthz", http.MethodGet)
	require.Equal(t, "internalHealthz", healthz.OperationID)
	readyz := getOperation(t, doc, "/readyz", http.MethodGet)
	require.Equal(t, "internalReadyz", readyz.OperationID)
}

// TestInternalSpecRuntimeRecordSchema verifies that RuntimeRecord declares
// the required field set documented in gamemaster/README.md §Persistence
// Layout, with the optional lifecycle timestamps present in properties.
func TestInternalSpecRuntimeRecordSchema(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	schema := componentSchemaRef(t, doc, "RuntimeRecord")

	assertRequiredFields(t, schema,
		"game_id",
		"runtime_status",
		"engine_endpoint",
		"current_image_ref",
		"current_engine_version",
		"turn_schedule",
		"current_turn",
		"next_generation_at",
		"skip_next_tick",
		"engine_health_summary",
		"created_at",
		"updated_at",
	)

	for _, optional := range []string{"started_at", "stopped_at", "finished_at"} {
		require.Contains(t, schema.Value.Properties, optional,
			"RuntimeRecord.%s must be present in properties", optional)
	}

	runtimeStatus := schema.Value.Properties["runtime_status"]
	require.NotNil(t, runtimeStatus)
	require.Equal(t, "#/components/schemas/RuntimeStatus", runtimeStatus.Ref,
		"RuntimeRecord.runtime_status must reference RuntimeStatus")
}

// TestInternalSpecEngineVersionSchema verifies the EngineVersion schema's
// required field set and the deliberate `additionalProperties: true` on
// the free-form `options` field.
func TestInternalSpecEngineVersionSchema(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	schema := componentSchemaRef(t, doc, "EngineVersion")

	assertRequiredFields(t, schema,
		"version", "image_ref", "options", "status", "created_at", "updated_at")

	options := schema.Value.Properties["options"]
	require.NotNil(t, options)
	require.NotNil(t, options.Value.AdditionalProperties.Has,
		"EngineVersion.options must declare additionalProperties explicitly")
	require.True(t, *options.Value.AdditionalProperties.Has,
		"EngineVersion.options is free-form jsonb and must keep additionalProperties: true")

	status := schema.Value.Properties["status"]
	require.NotNil(t, status)
	require.Equal(t, "#/components/schemas/EngineVersionStatus", status.Ref,
		"EngineVersion.status must reference EngineVersionStatus")
}

// TestInternalSpecRuntimeStatusEnum verifies the seven-value RuntimeStatus
// enum from gamemaster/README.md §Scope.
func TestInternalSpecRuntimeStatusEnum(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	schema := componentSchemaRef(t, doc, "RuntimeStatus")

	got := stringEnumValues(t, schema)
	require.ElementsMatch(t,
		[]string{
			"starting",
			"running",
			"generation_in_progress",
			"generation_failed",
			"stopped",
			"engine_unreachable",
			"finished",
		},
		got)
}

// TestInternalSpecEngineVersionStatusEnum verifies the EngineVersionStatus
// enum from gamemaster/README.md §Engine Version Registry.
func TestInternalSpecEngineVersionStatusEnum(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	schema := componentSchemaRef(t, doc, "EngineVersionStatus")

	got := stringEnumValues(t, schema)
	require.ElementsMatch(t, []string{"active", "deprecated"}, got)
}

// TestInternalSpecStopReasonEnum verifies the StopReason enum from
// gamemaster/README.md §Lifecycles -> Stop.
func TestInternalSpecStopReasonEnum(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)
	schema := componentSchemaRef(t, doc, "StopReason")

	got := stringEnumValues(t, schema)
	require.ElementsMatch(t, []string{"admin_request", "finished", "timeout"}, got)
}

// TestInternalSpecErrorEnvelope verifies the error envelope shape, which
// must be identical to the Lobby and Runtime Manager envelopes.
func TestInternalSpecErrorEnvelope(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	envelope := componentSchemaRef(t, doc, "ErrorResponse")
	assertRequiredFields(t, envelope, "error")
	assertAdditionalPropertiesFalse(t, envelope, "ErrorResponse")
	errRef := envelope.Value.Properties["error"]
	require.NotNil(t, errRef)
	require.Equal(t, "#/components/schemas/ErrorBody", errRef.Ref,
		"ErrorResponse.error must reference ErrorBody")

	body := componentSchemaRef(t, doc, "ErrorBody")
	assertRequiredFields(t, body, "code", "message")
	assertAdditionalPropertiesFalse(t, body, "ErrorBody")
}

// TestInternalSpecGMOwnedSchemasAreClosed verifies that every schema for
// which Game Master owns the wire shape rejects unknown fields.
func TestInternalSpecGMOwnedSchemasAreClosed(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	for _, name := range gmOwnedClosedSchemas {
		name := name
		t.Run(name, func(t *testing.T) {
			t.Parallel()
			schema := componentSchemaRef(t, doc, name)
			assertAdditionalPropertiesFalse(t, schema, name)
		})
	}
}

// TestInternalSpecHotPathSchemasArePassthrough verifies that every engine
// pass-through schema deliberately keeps `additionalProperties: true`.
// The matching test guards against a refactor that closes these by mistake.
func TestInternalSpecHotPathSchemasArePassthrough(t *testing.T) {
	t.Parallel()

	doc := loadInternalSpec(t)

	for _, name := range engineOwnedPassthroughSchemas {
		name := name
		t.Run(name, func(t *testing.T) {
			t.Parallel()
			schema := componentSchemaRef(t, doc, name)
			require.NotNil(t, schema.Value.AdditionalProperties.Has,
				"%s must declare additionalProperties explicitly", name)
			require.True(t, *schema.Value.AdditionalProperties.Has,
				"%s must keep additionalProperties: true (engine pass-through)", name)
		})
	}
}

// loadInternalSpec loads and validates gamemaster/api/internal-openapi.yaml
// relative to this test file.
func loadInternalSpec(t *testing.T) *openapi3.T {
	t.Helper()
	return loadSpec(t, filepath.Join("api", "internal-openapi.yaml"))
}

func loadSpec(t *testing.T, rel string) *openapi3.T {
	t.Helper()

	_, thisFile, _, ok := runtime.Caller(0)
	if !ok {
		require.FailNow(t, "runtime.Caller failed")
	}

	specPath := filepath.Join(filepath.Dir(thisFile), rel)
	loader := openapi3.NewLoader()
	doc, err := loader.LoadFromFile(specPath)
	if err != nil {
		require.Failf(t, "test failed", "load spec %s: %v", specPath, err)
	}
	if doc == nil {
		require.Failf(t, "test failed", "load spec %s: returned nil document", specPath)
	}
	if err := doc.Validate(context.Background()); err != nil {
		require.Failf(t, "test failed", "validate spec %s: %v", specPath, err)
	}

	return doc
}

func getOperation(t *testing.T, doc *openapi3.T, path, method string) *openapi3.Operation {
	t.Helper()

	if doc.Paths == nil {
		require.FailNow(t, "spec is missing paths")
	}
	pathItem := doc.Paths.Value(path)
	if pathItem == nil {
		require.Failf(t, "test failed", "spec is missing path %s", path)
	}
	op := pathItem.GetOperation(method)
	if op == nil {
		require.Failf(t, "test failed", "spec is missing %s operation for path %s", method, path)
	}

	return op
}

func requestSchemaRef(t *testing.T, op *openapi3.Operation) *openapi3.SchemaRef {
	t.Helper()

	if op.RequestBody == nil || op.RequestBody.Value == nil {
		require.FailNow(t, "operation is missing request body")
	}
	mt := op.RequestBody.Value.Content.Get("application/json")
	if mt == nil || mt.Schema == nil {
		require.FailNow(t, "operation is missing application/json request schema")
	}

	return mt.Schema
}

func responseSchemaRef(t *testing.T, op *openapi3.Operation, status int) *openapi3.SchemaRef {
	t.Helper()

	ref := op.Responses.Status(status)
	if ref == nil || ref.Value == nil {
		require.Failf(t, "test failed", "operation is missing %d response", status)
	}
	mt := ref.Value.Content.Get("application/json")
	if mt == nil || mt.Schema == nil {
		require.Failf(t, "test failed", "operation is missing application/json schema for %d response", status)
	}

	return mt.Schema
}

func componentSchemaRef(t *testing.T, doc *openapi3.T, name string) *openapi3.SchemaRef {
	t.Helper()

	if doc.Components.Schemas == nil {
		require.FailNow(t, "spec is missing component schemas")
	}
	ref := doc.Components.Schemas[name]
	if ref == nil {
		require.Failf(t, "test failed", "spec is missing component schema %s", name)
	}

	return ref
}

func componentParameterRef(t *testing.T, doc *openapi3.T, name string) *openapi3.ParameterRef {
	t.Helper()

	if doc.Components.Parameters == nil {
		require.FailNow(t, "spec is missing component parameters")
	}
	ref := doc.Components.Parameters[name]
	if ref == nil {
		require.Failf(t, "test failed", "spec is missing component parameter %s", name)
	}

	return ref
}

func assertSchemaRef(t *testing.T, schemaRef *openapi3.SchemaRef, want, name string) {
	t.Helper()
	require.NotNil(t, schemaRef, "%s schema ref", name)
	require.Equal(t, want, schemaRef.Ref, "%s schema ref", name)
}

func assertRequiredFields(t *testing.T, schemaRef *openapi3.SchemaRef, fields ...string) {
	t.Helper()
	require.NotNil(t, schemaRef)
	require.ElementsMatch(t, fields, schemaRef.Value.Required)
}

func assertOperationParameterRefs(t *testing.T, op *openapi3.Operation, refs ...string) {
	t.Helper()

	got := make([]string, 0, len(op.Parameters))
	for _, p := range op.Parameters {
		got = append(got, p.Ref)
	}

	require.ElementsMatch(t, refs, got)
}

func assertResponseRef(t *testing.T, op *openapi3.Operation, status int, want string) {
	t.Helper()

	ref := op.Responses.Status(status)
	if ref == nil {
		require.Failf(t, "test failed", "operation %s is missing %d response", op.OperationID, status)
	}
	require.Equal(t, want, ref.Ref,
		"operation %s response %d must reference %s", op.OperationID, status, want)
}

func assertNoContentResponse(t *testing.T, op *openapi3.Operation, status int) {
	t.Helper()

	ref := op.Responses.Status(status)
	if ref == nil || ref.Value == nil {
		require.Failf(t, "test failed", "operation %s is missing %d response", op.OperationID, status)
	}
	require.Empty(t, ref.Value.Content,
		"operation %s response %d must have no content body", op.OperationID, status)
}

func assertAdditionalPropertiesFalse(t *testing.T, schemaRef *openapi3.SchemaRef, name string) {
	t.Helper()
	require.NotNil(t, schemaRef.Value.AdditionalProperties.Has,
		"%s must declare additionalProperties explicitly", name)
	require.False(t, *schemaRef.Value.AdditionalProperties.Has,
		"%s must reject unknown fields (additionalProperties: false)", name)
}

func stringEnumValues(t *testing.T, schemaRef *openapi3.SchemaRef) []string {
	t.Helper()

	require.NotNil(t, schemaRef)
	got := make([]string, 0, len(schemaRef.Value.Enum))
	for _, value := range schemaRef.Value.Enum {
		s, ok := value.(string)
		require.True(t, ok, "enum value %v is not a string", value)
		got = append(got, s)
	}
	return got
}