package facts

import (
	"reflect"
	"strings"
	"testing"
	"time"
)

// A snapshot the controller wrote before grants and bindings existed is read as one that has none. The body
// is the format 1 document facts_test.go's TestANewerSnapshotIsRefusedNotHalfRead reads (mesh-controller
// 6c2a8d62, internal/facts/facts_test.go), with the fields of a machine that format 1 wrote.
func TestASnapshotWithoutGrantsOrBindingsReadsAsHavingNone(t *testing.T) {
	f, err := Decode([]byte(`{"facts": 1, "machines": [{"name": "abc", "length": 3}, {"name": "defgh", "length": 5,
		"pins": [{"provision": "store", "machine": "xyz", "module": "postgres"}]}]}`))
	if err != nil {
		t.Fatal(err)
	}
	for _, m := range f.Machines {
		if len(m.Grants) != 0 || len(m.Bindings) != 0 {
			t.Errorf("%s reads grants %v and bindings %v from a snapshot that carries none", m.Name, m.Grants, m.Bindings)
		}
	}
	body, err := f.Encode()
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(body), "grants") || strings.Contains(string(body), "bindings") {
		t.Errorf("a machine with none wrote them anyway:\n%s", body)
	}
}

// A snapshot that carries them reads back what it carried, and writes the same bytes again.
func TestGrantsAndBindingsRoundTripByteForByte(t *testing.T) {
	f := Facts{Format: Format, Taken: time.Date(2026, 10, 20, 8, 0, 0, 0, time.UTC), Machines: []Machine{{
		Name: "abcdef", Length: 6,
		Grants: []Grant{
			{Provision: "store", ConsumerNode: "ghijkl", ConsumerModule: "mesh-issues", Local: "database"},
			{Provision: "store", ConsumerNode: "abcdef", ConsumerModule: "records"},
		},
		Bindings: []Binding{
			{ConsumerModule: "records", Provision: "store", ProviderNode: "abcdef", ProviderModule: "postgres"},
		},
	}}}
	first, err := f.Encode()
	if err != nil {
		t.Fatal(err)
	}
	for _, want := range []string{`"grants"`, `"bindings"`, `"consumer-node": "ghijkl"`, `"consumer-module": "mesh-issues"`,
		`"provider-node": "abcdef"`, `"provider-module": "postgres"`, `"local": "database"`} {
		if !strings.Contains(string(first), want) {
			t.Errorf("the snapshot does not say %s:\n%s", want, first)
		}
	}
	back, err := Decode(first)
	if err != nil {
		t.Fatal(err)
	}
	second, err := back.Encode()
	if err != nil {
		t.Fatal(err)
	}
	if string(first) != string(second) {
		t.Errorf("the snapshot did not round-trip:\nfirst  %s\nsecond %s", first, second)
	}
	m, _ := back.Machine("abcdef")
	// Sorted, so two snapshots of one mesh are the same bytes: the grant for the lower node name comes first.
	if len(m.Grants) != 2 || m.Grants[0].ConsumerNode != "abcdef" || len(m.Bindings) != 1 {
		t.Errorf("read back grants %+v and bindings %+v", m.Grants, m.Bindings)
	}
}

// A machine name in a grant or a binding is scrubbed as a pin's is: to the machine's pseudonym, never kept.
func TestTheScrubberScrubsTheMachineNamesOfGrantsAndBindings(t *testing.T) {
	s := NewScrubber()
	pin := Pin{Provision: "store", Machine: s.Machine("homeserver"), Module: "postgres"}
	grant := s.Grant("store", "laptop2", "mesh-issues", "database")
	binding := s.Binding("records", "store", "homeserver", "postgres")
	if grant.ConsumerNode != s.Machine("laptop2") || grant.ConsumerNode == "laptop2" {
		t.Errorf("the grant's consumer node is %q", grant.ConsumerNode)
	}
	if binding.ProviderNode != pin.Machine || binding.ProviderNode == "homeserver" {
		t.Errorf("the binding's provider node is %q, not the pin's pseudonym %q", binding.ProviderNode, pin.Machine)
	}
	if grant.Provision != "store" || grant.ConsumerModule != "mesh-issues" || grant.Local != "database" ||
		binding.ConsumerModule != "records" || binding.Provision != "store" || binding.ProviderModule != "postgres" {
		t.Errorf("the scrubber changed what is not a machine's name: %+v %+v", grant, binding)
	}
	if len(grant.ConsumerNode) != len("laptop2") {
		t.Errorf("the pseudonym %q does not keep the length of the name", grant.ConsumerNode)
	}
}

// A grant says that a credential was made and for whom, never the credential: no field of either type is
// a sealed value, a secret or a hash.
func TestNoFieldOfAGrantOrABindingHoldsASecret(t *testing.T) {
	for _, typ := range []reflect.Type{reflect.TypeOf(Grant{}), reflect.TypeOf(Binding{})} {
		for i := 0; i < typ.NumField(); i++ {
			name := typ.Field(i).Name
			for _, banned := range []string{"Sealed", "Secret", "Hash", "Password"} {
				if strings.Contains(strings.ToLower(name), strings.ToLower(banned)) {
					t.Errorf("%s.%s may hold a secret", typ.Name(), name)
				}
			}
			if typ.Field(i).Type.Kind() != reflect.String {
				t.Errorf("%s.%s is a %s, not a name", typ.Name(), name, typ.Field(i).Type)
			}
		}
	}
}

// The format number says from which number a snapshot carries them: a reader of 1 refuses 2 rather than
// judge without them, and a reader of 2 reads 1.
func TestTheFormatSaysFromWhichNumberGrantsAndBindingsAreWritten(t *testing.T) {
	if GrantsFrom != 2 {
		t.Errorf("grants and bindings are written from format %d, not 2", GrantsFrom)
	}
	if Format < GrantsFrom {
		t.Errorf("the format is %d, below %d, where grants and bindings begin", Format, GrantsFrom)
	}
	if _, err := Decode([]byte(`{"facts": 2, "machines": []}`)); err != nil {
		t.Errorf("format 2 is not read: %v", err)
	}
	if _, err := Decode([]byte(`{"facts": 1, "machines": []}`)); err != nil {
		t.Errorf("format 1 is not read: %v", err)
	}
	if _, err := Decode([]byte(`{"facts": 3, "machines": []}`)); err == nil {
		t.Error("format 3 is read by a reader of format 2")
	}
}