package invariants

import (
	"context"
	"encoding/json"
	"reflect"
	"strings"
	"testing"

	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
	npccodec "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/codec/npcregistry"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/identity"
	npcregistry "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/registry"
)

func TestValidatorApprovesNormalizedEventsAndGenericGroups(t *testing.T) {
	references := registryReferences(t, "Ária")
	value := normalizedList()
	result, err := newValidator(t, references).Validate(context.Background(), request(references, value))
	if err != nil || !result.Approved {
		t.Fatalf("Validate() = %#v, %v", result, err)
	}
}

func TestValidatorRejectsNormalizationDrift(t *testing.T) {
	references := registryReferences(t, "Ária")
	for _, test := range []struct {
		name   string
		mutate func(*dnd.EnemyEventList)
		want   string
	}{
		{"registry display", func(value *dnd.EnemyEventList) { value.Events[0].Name = " ária " }, "canonical NPC display name"},
		{"generic whitespace", func(value *dnd.EnemyEventList) { value.Events[1].Name = " Remaining\tOrcs " }, "whitespace-normalized"},
		{"evidence order", func(value *dnd.EnemyEventList) {
			value.Events[0].SourceRefs = []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}, {SourceID: "session", StartUnitID: 10, EndUnitID: 10}}
		}, "not in canonical order"},
		{"duplicate evidence", func(value *dnd.EnemyEventList) {
			value.Events[0].SourceRefs = append(value.Events[0].SourceRefs, value.Events[0].SourceRefs[0])
		}, "duplicates the previous reference"},
		{"event order", func(value *dnd.EnemyEventList) { value.Events[0], value.Events[1] = value.Events[1], value.Events[0] }, "events are not in canonical order"},
		{"exact duplicate", func(value *dnd.EnemyEventList) { value.Events = append(value.Events, value.Events[0]) }, "duplicates event"},
	} {
		t.Run(test.name, func(t *testing.T) {
			value := normalizedList()
			test.mutate(&value)
			result, err := newValidator(t, references).Validate(context.Background(), request(references, value))
			if err != nil || result.Approved || result.ReasonCode != ReasonCode || !strings.Contains(result.Message, test.want) {
				t.Fatalf("Validate() = %#v, %v; want %q", result, err, test.want)
			}
		})
	}
}

func TestValidatorDefersEarlierFailuresAndResolvesOperationRegistryWithoutMutation(t *testing.T) {
	references := registryReferences(t, "Ária")
	for _, value := range []dnd.EnemyEventList{
		{Events: []dnd.EnemyEvent{{Name: "Ária"}}},
		{Events: []dnd.EnemyEvent{{Name: "Ária", Kind: dnd.EnemyEventKindEngaged, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 99, EndUnitID: 99}}}}},
	} {
		result, err := newValidator(t, references).Validate(context.Background(), request(references, value))
		if err != nil || !result.Approved {
			t.Fatalf("deferral = %#v, %v", result, err)
		}
	}
	value := normalizedList()
	before := cloneList(value)
	result, err := newValidator(t).Validate(context.Background(), request(references, value))
	if err != nil || !result.Approved || !reflect.DeepEqual(value, before) {
		t.Fatalf("operation registry = %#v, %v; value=%#v", result, err, value)
	}
	result, err = newValidator(t).Validate(context.Background(), request(contracts.ReferenceSet{}, normalizedList()))
	if err != nil || result.Approved || result.ReasonCode != ReasonCode || !strings.Contains(result.Message, "required") {
		t.Fatalf("unbound registry = %#v, %v", result, err)
	}
}

func TestValidatorMetadataFingerprintsAndRegistrationAreSafe(t *testing.T) {
	references := registryReferences(t, "Ária")
	metadata, err := json.Marshal(newValidator(t, references).ManifestMetadata())
	if err != nil || strings.Contains(string(metadata), "Ária") {
		t.Fatalf("ManifestMetadata() = %s, %v", metadata, err)
	}
	if got := newValidator(t, references).CheckpointFingerprints(); len(got) != 2 || got[0].Value != policy || !strings.HasPrefix(got[1].Value, "sha256:") {
		t.Fatalf("CheckpointFingerprints() = %#v", got)
	}
	registry := pipeline.NewValidatorRegistry()
	if err := Register(registry); err != nil {
		t.Fatal(err)
	}
	if Spec().Key != Key || Spec().ExecutionClass != contracts.ExecutionClassDeterministic {
		t.Fatalf("Spec() = %#v", Spec())
	}
	if _, err := DecodeOptions(map[string]any{"unexpected": true}); err == nil {
		t.Fatal("DecodeOptions() accepted unknown option")
	}
}

func newValidator(t *testing.T, references ...contracts.ReferenceSet) *Validator {
	t.Helper()
	validator, err := New(Options{}, references...)
	if err != nil {
		t.Fatal(err)
	}
	return validator
}

func request(references contracts.ReferenceSet, value dnd.EnemyEventList) contracts.TypedValidationRequest[dnd.EnemyEventList] {
	return contracts.TypedValidationRequest[dnd.EnemyEventList]{Source: document(), References: references, Value: value}
}

func document() *source.SourceDocument {
	return &source.SourceDocument{ID: "session", Units: []source.SourceUnit{{ID: 10}, {ID: 20}}}
}

func normalizedList() dnd.EnemyEventList {
	return dnd.EnemyEventList{Events: []dnd.EnemyEvent{
		{Name: "Ária", Kind: dnd.EnemyEventKindEngaged, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 10}}},
		{Name: "Remaining Orcs", Kind: dnd.EnemyEventKindFled, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}}},
	}}
}

func cloneList(value dnd.EnemyEventList) dnd.EnemyEventList {
	clone := dnd.EnemyEventList{Events: make([]dnd.EnemyEvent, len(value.Events))}
	for index, event := range value.Events {
		clone.Events[index] = event
		clone.Events[index].SourceRefs = append([]source.SourceRef(nil), event.SourceRefs...)
	}
	return clone
}

func registryReferences(t *testing.T, names ...string) contracts.ReferenceSet {
	t.Helper()
	npcs := make([]dnd.NPC, len(names))
	for index, name := range names {
		npcs[index] = dnd.NPC{ID: identity.DeriveID(name), Name: name, SourceRefs: []source.SourceRef{{SourceID: "other", StartUnitID: index + 1, EndUnitID: index + 1}}}
	}
	content, err := npccodec.New().Encode(dnd.NPCRegistry{NPCs: npcs})
	if err != nil {
		t.Fatal(err)
	}
	return contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{npcregistry.ReferenceSlot: {Slot: contracts.ReferenceSlot{Name: npcregistry.ReferenceSlot}, Items: []contracts.ReferenceItem{{SlotName: npcregistry.ReferenceSlot, MediaType: npccodec.MediaType, Content: content, Origin: contracts.ReferenceOrigin{Type: "generated"}}}}}}
}