package pact

import (
	"context"
	"errors"
	"fmt"
	"io/fs"
	"os/exec"
	"reflect"
	"strings"
	"testing"
	"testing/fstest"

	"git.golem15.com/golem15/summercms/modules/bonfire"
	"github.com/go-gormigrate/gormigrate/v2"
	"gorm.io/gorm"
)

type configOnly struct{}

func (configOnly) ConfigFS() fs.FS {
	return fstest.MapFS{"config/config.yaml": {Data: []byte("k: 1\n")}}
}

type commandsOnly struct{}

func (commandsOnly) Commands() []bonfire.Command {
	return []bonfire.Command{{Name: "demo:run"}}
}

type bothCaps struct {
	configOnly
	commandsOnly
}

type neither struct{}

type migrationsOnly struct{}

func (migrationsOnly) Migrations() []*gormigrate.Migration {
	return []*gormigrate.Migration{{ID: "202609170001_create_users"}}
}

func TestOptionalCapabilitiesDiscoveredByTypeAssertion(t *testing.T) {
	plugins := []any{configOnly{}, commandsOnly{}, bothCaps{}, neither{}, extraMessage{}, migrationsOnly{}}

	var configs, commands, messages, migrations, none int
	for _, p := range plugins {
		_, hasCfg := p.(HasConfig)
		_, hasCmd := p.(HasCommands)
		_, hasMsg := p.(OptionalMessage)
		_, hasMig := p.(HasMigrations)
		if hasCfg {
			configs++
		}
		if hasCmd {
			commands++
		}
		if hasMsg {
			messages++
		}
		if hasMig {
			migrations++
		}
		if !hasCfg && !hasCmd && !hasMsg && !hasMig {
			none++
		}
	}
	if configs != 2 {
		t.Fatalf("HasConfig count = %d, want 2", configs)
	}
	if commands != 2 {
		t.Fatalf("HasCommands count = %d, want 2", commands)
	}
	if messages != 1 {
		t.Fatalf("OptionalMessage count = %d, want 1", messages)
	}
	if migrations != 1 {
		t.Fatalf("HasMigrations count = %d, want 1", migrations)
	}
	if none != 1 {
		t.Fatalf("neither count = %d, want 1", none)
	}
}

func TestHasMigrationsReturnsOrderedSet(t *testing.T) {
	var p HasMigrations = migrationsOnly{}
	set := p.Migrations()
	if len(set) != 1 || set[0].ID != "202609170001_create_users" {
		t.Fatalf("Migrations = %+v", set)
	}
}

func TestHasConfigReturnsFilesystem(t *testing.T) {
	var p HasConfig = configOnly{}
	fsys := p.ConfigFS()
	if fsys == nil {
		t.Fatal("ConfigFS returned nil")
	}
	raw, err := fs.ReadFile(fsys, "config/config.yaml")
	if err != nil {
		t.Fatal(err)
	}
	if string(raw) != "k: 1\n" {
		t.Fatalf("ConfigFS body = %q", raw)
	}
}

func TestHasCommandsReturnsNamespacedCommand(t *testing.T) {
	var p HasCommands = commandsOnly{}
	cmds := p.Commands()
	if len(cmds) != 1 || cmds[0].Name != "demo:run" {
		t.Fatalf("Commands = %+v", cmds)
	}
}

func TestOptionalMessageContract(t *testing.T) {
	var msg OptionalMessage = extraMessage{s: "hello-from-optional"}
	if msg.Message() != "hello-from-optional" {
		t.Fatalf("Message = %q", msg.Message())
	}
}

type extraMessage struct{ s string }

func (e extraMessage) Message() string { return e.s }

type routesOnly struct{}

func (routesOnly) Routes(Router) error { return nil }

type middlewareOnly struct{}

func (middlewareOnly) Middlewares() map[string]Middleware {
	return map[string]Middleware{"jwt.auth": nil}
}

type modelsOnly struct{}

func (modelsOnly) Models() []any { return []any{struct{}{}} }

func TestHTTPCapabilitiesDiscoveredByTypeAssertion(t *testing.T) {
	var r HasRoutes = routesOnly{}
	if err := r.Routes(nil); err != nil {
		t.Fatal(err)
	}
	var m HasMiddleware = middlewareOnly{}
	if _, ok := m.Middlewares()["jwt.auth"]; !ok {
		t.Fatal("missing jwt.auth")
	}
	var models HasModels = modelsOnly{}
	if len(models.Models()) != 1 {
		t.Fatalf("Models = %+v", models.Models())
	}
}

// relationHooks implements every relation child hook with the documented
// signature and records the calls.
type relationHooks struct{ calls *[]string }

func (h relationHooks) record(name, relation string, parent, child any) error {
	*h.calls = append(*h.calls, name+":"+relation+":"+parent.(string)+":"+child.(string))
	if relation == "fail" {
		return errors.New(name + " refused")
	}
	return nil
}

func (h relationHooks) RelationBeforeCreate(_ context.Context, relation string, parent, child any) error {
	return h.record("BeforeCreate", relation, parent, child)
}
func (h relationHooks) RelationAfterCreate(_ context.Context, relation string, parent, child any) error {
	return h.record("AfterCreate", relation, parent, child)
}
func (h relationHooks) RelationBeforeUpdate(_ context.Context, relation string, parent, child any) error {
	return h.record("BeforeUpdate", relation, parent, child)
}
func (h relationHooks) RelationAfterUpdate(_ context.Context, relation string, parent, child any) error {
	return h.record("AfterUpdate", relation, parent, child)
}
func (h relationHooks) RelationBeforeDelete(_ context.Context, relation string, parent, child any) error {
	return h.record("BeforeDelete", relation, parent, child)
}
func (h relationHooks) RelationAfterDelete(_ context.Context, relation string, parent, child any) error {
	return h.record("AfterDelete", relation, parent, child)
}

var (
	_ RelationBeforeCreate = relationHooks{}
	_ RelationAfterCreate  = relationHooks{}
	_ RelationBeforeUpdate = relationHooks{}
	_ RelationAfterUpdate  = relationHooks{}
	_ RelationBeforeDelete = relationHooks{}
	_ RelationAfterDelete  = relationHooks{}
)

// TestRelationHookInterfaces: each of the six optional relation child hooks
// is discovered by a type assertion on the controller value, receives the
// relation name, the parent and the child, and passes its error back; a
// controller without them asserts false.
func TestRelationHookInterfaces(t *testing.T) {
	var calls []string
	var ctl any = relationHooks{calls: &calls}
	hooks := []func(context.Context, string, any, any) error{}
	if h, ok := ctl.(RelationBeforeCreate); ok {
		hooks = append(hooks, h.RelationBeforeCreate)
	}
	if h, ok := ctl.(RelationAfterCreate); ok {
		hooks = append(hooks, h.RelationAfterCreate)
	}
	if h, ok := ctl.(RelationBeforeUpdate); ok {
		hooks = append(hooks, h.RelationBeforeUpdate)
	}
	if h, ok := ctl.(RelationAfterUpdate); ok {
		hooks = append(hooks, h.RelationAfterUpdate)
	}
	if h, ok := ctl.(RelationBeforeDelete); ok {
		hooks = append(hooks, h.RelationBeforeDelete)
	}
	if h, ok := ctl.(RelationAfterDelete); ok {
		hooks = append(hooks, h.RelationAfterDelete)
	}
	if len(hooks) != 6 {
		t.Fatalf("discovered %d hooks, want 6", len(hooks))
	}
	for _, hook := range hooks {
		if err := hook(t.Context(), "parts", "gadget", "part"); err != nil {
			t.Fatal(err)
		}
		if err := hook(t.Context(), "fail", "gadget", "part"); err == nil {
			t.Fatal("hook error was not passed back")
		}
	}
	want := "BeforeCreate:parts:gadget:part,BeforeCreate:fail:gadget:part,AfterCreate:parts:gadget:part,AfterCreate:fail:gadget:part," +
		"BeforeUpdate:parts:gadget:part,BeforeUpdate:fail:gadget:part,AfterUpdate:parts:gadget:part,AfterUpdate:fail:gadget:part," +
		"BeforeDelete:parts:gadget:part,BeforeDelete:fail:gadget:part,AfterDelete:parts:gadget:part,AfterDelete:fail:gadget:part"
	if got := strings.Join(calls, ","); got != want {
		t.Fatalf("calls = %s", got)
	}
	var plain any = struct{}{}
	for name, ok := range map[string]bool{
		"BeforeCreate": func() bool { _, ok := plain.(RelationBeforeCreate); return ok }(),
		"AfterCreate":  func() bool { _, ok := plain.(RelationAfterCreate); return ok }(),
		"BeforeUpdate": func() bool { _, ok := plain.(RelationBeforeUpdate); return ok }(),
		"AfterUpdate":  func() bool { _, ok := plain.(RelationAfterUpdate); return ok }(),
		"BeforeDelete": func() bool { _, ok := plain.(RelationBeforeDelete); return ok }(),
		"AfterDelete":  func() bool { _, ok := plain.(RelationAfterDelete); return ok }(),
	} {
		if ok {
			t.Fatalf("a plain value implements Relation%s", name)
		}
	}
}

// TestRowStateValues pins the wire values of the fixed row-state set: the
// admin SPA and plugin CSS match on these exact strings.
func TestRowStateValues(t *testing.T) {
	got := []RowState{RowStateDeleted, RowStateNegative, RowStateDisabled}
	want := []string{"deleted", "negative", "disabled"}
	for i, state := range got {
		if string(state) != want[i] {
			t.Fatalf("row state %d = %q, want %q", i, state, want[i])
		}
	}
}

type formSeams struct{}

func (formSeams) FormVirtualFields() []string { return []string{"password", "password_confirmation"} }

func (formSeams) FormRules(_ context.Context, op string) map[string]string {
	if op == "create" {
		return map[string]string{"password": "required|confirmed"}
	}
	return map[string]string{"password": "nullable|confirmed"}
}

func TestFormSeamsDiscoveredByTypeAssertion(t *testing.T) {
	var ctl any = formSeams{}
	virtual, ok := ctl.(FormVirtualFields)
	if !ok || len(virtual.FormVirtualFields()) != 2 {
		t.Fatalf("FormVirtualFields = %v ok=%v", virtual, ok)
	}
	rules, ok := ctl.(FormRules)
	if !ok {
		t.Fatal("FormRules is not implemented")
	}
	if got := rules.FormRules(context.Background(), "create")["password"]; got != "required|confirmed" {
		t.Fatalf("create rules = %q", got)
	}
	if got := rules.FormRules(context.Background(), "update")["password"]; got != "nullable|confirmed" {
		t.Fatalf("update rules = %q", got)
	}
	if _, ok := any(neither{}).(FormVirtualFields); ok {
		t.Fatal("a plugin without the method implements FormVirtualFields")
	}
}

// sampleRoster is a controller value that implements every admin contract of
// Phase 12.1: declared bulk and record actions, row states and controller
// filter choices.
type sampleRoster struct{ ran *[]string }

func (s sampleRoster) AdminBulkActions() []AdminBulkAction {
	return []AdminBulkAction{{
		Name: "activate", Label: "acme::lang.activate", Confirm: "acme::lang.activate_confirm",
		Permissions: []string{"acme.manage"},
		Run: func(_ context.Context, in AdminBulkActionInput) (AdminBulkActionResult, error) {
			*s.ran = append(*s.ran, "bulk")
			return AdminBulkActionResult{Message: "acme::lang.activated", Affected: len(in.Records)}, nil
		},
	}}
}

func (s sampleRoster) AdminRecordActions() []AdminRecordAction {
	return []AdminRecordAction{{
		Name: "reinstate", Label: "acme::lang.reinstate",
		Applies: func(_ context.Context, record any) (bool, error) {
			if record == nil {
				return false, errors.New("no record")
			}
			return record.(string) == "banned", nil
		},
		Run: func(_ context.Context, in AdminRecordActionInput) (AdminRecordActionResult, error) {
			*s.ran = append(*s.ran, "record")
			return AdminRecordActionResult{Message: "acme::lang.reinstated"}, nil
		},
	}}
}

func (sampleRoster) ListRowStates(_ context.Context, _ *gorm.DB, records []any) ([][]RowState, error) {
	out := make([][]RowState, len(records))
	for i, record := range records {
		if record.(string) == "banned" {
			out[i] = []RowState{RowStateNegative}
		}
	}
	return out, nil
}

func (sampleRoster) FilterOptions(scope string) []Option {
	if scope != "tagged" {
		return nil
	}
	return []Option{{Value: "1", Label: "acme::lang.tag"}}
}

var (
	_ HasAdminBulkActions   = sampleRoster{}
	_ HasAdminRecordActions = sampleRoster{}
	_ ListRowStates         = sampleRoster{}
	_ FilterOptions         = sampleRoster{}
)

// TestPhase121ContractsOnSampleController: the bulk action, record action,
// row state and filter choice contracts are discovered by a type assertion
// on a controller value and carry exactly the documented fields.
func TestPhase121ContractsOnSampleController(t *testing.T) {
	var ran []string
	var ctl any = sampleRoster{ran: &ran}

	bulk, ok := ctl.(HasAdminBulkActions)
	if !ok || len(bulk.AdminBulkActions()) != 1 {
		t.Fatal("HasAdminBulkActions is not discovered")
	}
	action := bulk.AdminBulkActions()[0]
	result, err := action.Run(t.Context(), AdminBulkActionInput{Records: []any{"a", "b"}})
	if err != nil || result.Affected != 2 || result.Message != "acme::lang.activated" {
		t.Fatalf("bulk result = %+v err=%v", result, err)
	}
	if action.Name != "activate" || action.Confirm == "" || len(action.Permissions) != 1 {
		t.Fatalf("bulk action = %+v", action)
	}
	// The input of a bulk action is the loaded records and nothing else: an id
	// list would let a plugin skip the list scope.
	if n := reflect.TypeOf(AdminBulkActionInput{}).NumField(); n != 1 {
		t.Fatalf("AdminBulkActionInput has %d fields, want only Records", n)
	}

	record, ok := ctl.(HasAdminRecordActions)
	if !ok || len(record.AdminRecordActions()) != 1 {
		t.Fatal("HasAdminRecordActions is not discovered")
	}
	one := record.AdminRecordActions()[0]
	for input, want := range map[string]bool{"banned": true, "active": false} {
		if applies, err := one.Applies(t.Context(), input); err != nil || applies != want {
			t.Fatalf("Applies(%s) = %v err=%v", input, applies, err)
		}
	}
	if _, err := one.Applies(t.Context(), nil); err == nil {
		t.Fatal("Applies did not pass its error back")
	}
	out, err := one.Run(t.Context(), AdminRecordActionInput{RecordID: 7, Record: "banned"})
	if err != nil || out.Message != "acme::lang.reinstated" || one.Confirm != "" {
		t.Fatalf("record result = %+v err=%v", out, err)
	}
	// RecordID, Record and (phase 19.7) the prompt Value: still no id list.
	if fields := reflect.TypeOf(AdminRecordActionInput{}).NumField(); fields != 3 {
		t.Fatalf("AdminRecordActionInput has %d fields, want RecordID, Record and Value", fields)
	}
	if strings.Join(ran, ",") != "bulk,record" {
		t.Fatalf("ran = %v", ran)
	}

	states, ok := ctl.(ListRowStates)
	if !ok {
		t.Fatal("ListRowStates is not discovered")
	}
	got, err := states.ListRowStates(t.Context(), nil, []any{"active", "banned"})
	if err != nil || len(got) != 2 || got[0] != nil || len(got[1]) != 1 || got[1][0] != RowStateNegative {
		t.Fatalf("row states = %v err=%v", got, err)
	}
	// The fixed set has exactly three values, each its own string.
	set := map[RowState]bool{RowStateDeleted: true, RowStateNegative: true, RowStateDisabled: true}
	if len(set) != 3 || string(RowStateDeleted) != "deleted" || string(RowStateNegative) != "negative" || string(RowStateDisabled) != "disabled" {
		t.Fatalf("row state set = %v", set)
	}

	options, ok := ctl.(FilterOptions)
	if !ok || len(options.FilterOptions("tagged")) != 1 || options.FilterOptions("other") != nil {
		t.Fatal("FilterOptions is not discovered or answers an unknown scope")
	}

	var plain any = neither{}
	for name, implemented := range map[string]bool{
		"HasAdminBulkActions":   func() bool { _, ok := plain.(HasAdminBulkActions); return ok }(),
		"HasAdminRecordActions": func() bool { _, ok := plain.(HasAdminRecordActions); return ok }(),
		"ListRowStates":         func() bool { _, ok := plain.(ListRowStates); return ok }(),
		"FilterOptions":         func() bool { _, ok := plain.(FilterOptions); return ok }(),
	} {
		if implemented {
			t.Fatalf("a plain value implements %s", name)
		}
	}
}

// samplePier is a plugin value that implements the phase 19.7 contracts:
// MCP tools and prompts, frontend permission codes and a My account
// contribution with a prompted record action on another controller.
type samplePier struct{}

type samplePostInput struct {
	ID    uint   `path:"id"`
	Query string `query:"q"`
	Title string `json:"title" jsonschema:"the post title"`
}

func (samplePier) MCP() MCP {
	ro := true
	return MCP{
		Tools: []MCPTool{{
			Name: "show_post", Title: "Show a post", Description: "Returns one post.",
			Guard: "backend", Method: "GET", Path: "/_blog/api/v1/posts/{id}",
			Input: samplePostInput{}, Permissions: []string{"acme.blog.access_posts"}, ReadOnly: &ro,
		}},
		Prompts: []MCPPrompt{{
			Name: "draft_post", Title: "Draft a post", Guard: "backend",
			Arguments: []MCPPromptArgument{{Name: "topic", Required: true}},
			Render: func(_ context.Context, args map[string]string) ([]MCPPromptMessage, error) {
				return []MCPPromptMessage{{Role: "user", Text: "Draft a post about " + args["topic"]}}, nil
			},
		}},
	}
}

func (samplePier) FrontendPermissions() []FrontendPermission {
	return []FrontendPermission{{Code: "acme.blog.comment", Label: "acme::lang.comment", Tab: "acme::lang.tab"}}
}

func (samplePier) AccountContributions() []AccountContribution {
	return []AccountContribution{{
		Name: "site_link", Label: "acme::lang.site_link", Description: "acme::lang.site_link_hint",
		Status: func(_ context.Context, adminID uint) (string, error) { return "linked", nil },
		Actions: []AccountAction{{
			Name: "link", Label: "acme::lang.link", Confirm: "acme::lang.link_confirm",
			Applies: func(_ context.Context, adminID uint) (bool, error) { return adminID != 0, nil },
			Run: func(_ context.Context, in AccountActionInput) (AccountActionResult, error) {
				return AccountActionResult{Message: "acme::lang.linked", URL: "https://blog.example.com/link"}, nil
			},
		}},
	}}
}

func (samplePier) AdminActionExtensions() []AdminActionExtension {
	return []AdminActionExtension{{
		Controller: "summercms.cabana.users",
		RecordActions: []AdminRecordAction{{
			Name: "link_site_account", Label: "acme::lang.link_site_account",
			Prompt: &AdminActionPrompt{Label: "acme::lang.site_login", MaxLength: 64},
			Run: func(_ context.Context, in AdminRecordActionInput) (AdminRecordActionResult, error) {
				return AdminRecordActionResult{Message: "linked " + in.Value}, nil
			},
		}},
	}}
}

var (
	_ HasMCP                   = samplePier{}
	_ HasFrontendPermissions   = samplePier{}
	_ HasAccountContributions  = samplePier{}
	_ HasAdminActionExtensions = samplePier{}
)

// sampleGuard is a guard provider with a fixed name.
type sampleGuard struct{ name string }

func (g sampleGuard) MCPGuardName() string { return g.name }
func (sampleGuard) MCPTokenGuarded(middleware []string) bool {
	return strings.Contains(strings.Join(middleware, " "), "api_token")
}
func (sampleGuard) MCPRequirements(middleware []string) (MCPRequirements, error) {
	return MCPRequirements{Scopes: []string{"read"}}, nil
}
func (sampleGuard) MCPAllows(context.Context, MCPSubject, MCPRequirements, []string) (bool, error) {
	return true, nil
}
func (sampleGuard) MCPDispatch(context.Context, MCPSubject, string) (MCPDispatch, error) {
	return MCPDispatch{Principal: "principal", Guards: []string{"api_token"}}, nil
}

// TestPhase197ContractsOnSamplePlugin: the MCP, frontend permission, account
// contribution and prompted record action contracts are discovered by type
// assertion on a plugin value and carry the documented fields.
func TestPhase197ContractsOnSamplePlugin(t *testing.T) {
	var plugin any = samplePier{}

	mcp, ok := plugin.(HasMCP)
	if !ok {
		t.Fatal("HasMCP is not discovered")
	}
	decl := mcp.MCP()
	if len(decl.Tools) != 1 || len(decl.Prompts) != 1 {
		t.Fatalf("declaration = %+v", decl)
	}
	tool := decl.Tools[0]
	if tool.Name != "show_post" || tool.Guard != "backend" || tool.Method != "GET" || tool.Path != "/_blog/api/v1/posts/{id}" || tool.ReadOnly == nil || !*tool.ReadOnly || tool.Destructive != nil {
		t.Fatalf("tool = %+v", tool)
	}
	if _, isStruct := tool.Input.(samplePostInput); !isStruct || tool.Output != nil {
		t.Fatalf("tool input/output = %T %T", tool.Input, tool.Output)
	}
	prompt := decl.Prompts[0]
	msgs, err := prompt.Render(t.Context(), map[string]string{"topic": "beaches"})
	if err != nil || len(msgs) != 1 || msgs[0].Role != "user" || !strings.HasSuffix(msgs[0].Text, "beaches") || !prompt.Arguments[0].Required {
		t.Fatalf("prompt = %+v msgs=%v err=%v", prompt, msgs, err)
	}

	fp, ok := plugin.(HasFrontendPermissions)
	if !ok || len(fp.FrontendPermissions()) != 1 || fp.FrontendPermissions()[0].Code != "acme.blog.comment" {
		t.Fatal("HasFrontendPermissions is not discovered")
	}

	ac, ok := plugin.(HasAccountContributions)
	if !ok || len(ac.AccountContributions()) != 1 {
		t.Fatal("HasAccountContributions is not discovered")
	}
	section := ac.AccountContributions()[0]
	status, err := section.Status(t.Context(), 7)
	if err != nil || status != "linked" || section.Name != "site_link" || len(section.Actions) != 1 {
		t.Fatalf("section = %+v status=%q err=%v", section, status, err)
	}
	action := section.Actions[0]
	if applies, err := action.Applies(t.Context(), 0); err != nil || applies {
		t.Fatalf("Applies(0) = %v err=%v", applies, err)
	}
	res, err := action.Run(t.Context(), AccountActionInput{AdminID: 7})
	if err != nil || res.URL == "" || res.Message != "acme::lang.linked" {
		t.Fatalf("account action result = %+v err=%v", res, err)
	}
	// The input of an account action is the signed-in admin and nothing else.
	if n := reflect.TypeOf(AccountActionInput{}).NumField(); n != 1 {
		t.Fatalf("AccountActionInput has %d fields, want only AdminID", n)
	}

	ext := plugin.(HasAdminActionExtensions).AdminActionExtensions()[0].RecordActions[0]
	if ext.Prompt == nil || ext.Prompt.Label == "" || ext.Prompt.MaxLength != 64 {
		t.Fatalf("prompted action = %+v", ext)
	}
	out, err := ext.Run(t.Context(), AdminRecordActionInput{RecordID: 3, Value: "editor"})
	if err != nil || out.Message != "linked editor" {
		t.Fatalf("prompted run = %+v err=%v", out, err)
	}
	if len(MCPSubjectChanged{Guard: "backend", UserID: 7, Kind: MCPSubjectLink}.Kind) == 0 || MCPSubjectPermissions == MCPSubjectRevoked || MCPSubjectDeleted == "" {
		t.Fatal("subject change kinds")
	}
	if grant := (MCPGrant{UserID: 1, Scopes: []string{"read"}}); grant.ExpiresAt.IsZero() != true || !errors.Is(fmt.Errorf("wrap: %w", ErrMCPTokenInvalid), ErrMCPTokenInvalid) {
		t.Fatal("grant and sentinel")
	}
	var _ LinkedBackendUser = LinkedBackendUser{ID: 1, Login: "admin", DisplayName: "Admin"}
	var _ MCPSubject = MCPSubject{Guard: "user", UserID: 1, Scopes: []string{"read"}, ClientID: "cli", TokenID: 0}
}

// TestMCPGuardsRegistry: register, duplicate and empty names refused with a
// pact error naming the guard, lookup, and sorted names.
func TestMCPGuardsRegistry(t *testing.T) {
	reg := NewMCPGuards()
	for _, name := range []string{"user", "backend"} {
		if err := reg.Register(sampleGuard{name: name}); err != nil {
			t.Fatal(err)
		}
	}
	err := reg.Register(sampleGuard{name: "user"})
	if err == nil || !strings.Contains(err.Error(), `pact: mcp guard "user"`) {
		t.Fatalf("duplicate: %v", err)
	}
	if err := reg.Register(sampleGuard{}); err == nil || !strings.HasPrefix(err.Error(), "pact: ") {
		t.Fatalf("empty name: %v", err)
	}
	if err := reg.Register(nil); err == nil || !strings.HasPrefix(err.Error(), "pact: ") {
		t.Fatalf("nil provider: %v", err)
	}
	if got := reg.Names(); strings.Join(got, ",") != "backend,user" {
		t.Fatalf("Names = %v", got)
	}
	g, ok := reg.Lookup("backend")
	if !ok || g.MCPGuardName() != "backend" || !g.MCPTokenGuarded([]string{"user.api_token"}) {
		t.Fatalf("Lookup(backend) = %v %v", g, ok)
	}
	if _, ok := reg.Lookup("other"); ok {
		t.Fatal("Lookup found an unregistered guard")
	}
	d, err := g.MCPDispatch(t.Context(), MCPSubject{Guard: "backend", UserID: 1}, "GET")
	if err != nil || d.Principal != "principal" || len(d.Guards) != 1 {
		t.Fatalf("dispatch = %+v err=%v", d, err)
	}
	var nilReg *MCPGuards
	if _, ok := nilReg.Lookup("user"); ok || nilReg.Names() != nil || nilReg.Register(sampleGuard{name: "x"}) == nil {
		t.Fatal("nil registry is not inert")
	}
}

// TestPactStaysSDKFree: the package's dependency list names neither the MCP
// SDK, the JSON schema library nor bouncer, so plugins compile without them.
func TestPactStaysSDKFree(t *testing.T) {
	goTool, err := exec.LookPath("go")
	if err != nil {
		t.Skip("go tool not on PATH")
	}
	out, err := exec.Command(goTool, "list", "-deps", ".").Output()
	if err != nil {
		t.Fatalf("go list -deps: %v", err)
	}
	for _, dep := range strings.Split(string(out), "\n") {
		for _, banned := range []string{"modelcontextprotocol", "jsonschema-go", "modules/bouncer"} {
			if strings.Contains(dep, banned) {
				t.Fatalf("pact depends on %s", dep)
			}
		}
	}
}