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/npcs"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/identity"
	npcregistry "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/registry"
)

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

func TestValidatorRejectsOwnedCanonicalNameReferenceOrderListOrderAndDuplicates(t *testing.T) {
	references := registryReferences(t, "Aria", "Borin")
	for _, test := range []struct {
		name   string
		mutate func(*dnd.NPCInteractionList)
		want   string
	}{
		{"canonical name", func(value *dnd.NPCInteractionList) { value.Interactions[0].Name = " aria " }, "canonical NPC display name"},
		{"reference order", func(value *dnd.NPCInteractionList) {
			value.Interactions[0].SourceRefs = []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}, {SourceID: "session", StartUnitID: 10, EndUnitID: 10}}
		}, "not in canonical order"},
		{"duplicate reference", func(value *dnd.NPCInteractionList) {
			value.Interactions[0].SourceRefs = append(value.Interactions[0].SourceRefs, value.Interactions[0].SourceRefs[0])
		}, "duplicates the previous reference"},
		{"list order", func(value *dnd.NPCInteractionList) {
			value.Interactions[0], value.Interactions[1] = value.Interactions[1], value.Interactions[0]
		}, "interactions are not in canonical order"},
		{"name tie breaker", func(value *dnd.NPCInteractionList) {
			value.Interactions[0] = dnd.NPCInteraction{Name: "Borin", Kind: dnd.NPCInteractionKindDialogue, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 10}}}
			value.Interactions[1] = dnd.NPCInteraction{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 10}}}
		}, "interactions are not in canonical order"},
		{"duplicate record", func(value *dnd.NPCInteractionList) {
			value.Interactions = append(value.Interactions, value.Interactions[0])
		}, "duplicates interaction"},
	} {
		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 TestValidatorAcceptsValidEvidenceBeforeInvalidEvidence(t *testing.T) {
	references := registryReferences(t, "Aria", "Borin")
	value := dnd.NPCInteractionList{Interactions: []dnd.NPCInteraction{
		{Name: "Borin", Kind: dnd.NPCInteractionKindMentioned, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}}},
		{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, 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("Validate() = %#v, %v", result, err)
	}
}

func TestValidatorDefersShapeAndSourceReferenceFailuresAndRequiresRegistry(t *testing.T) {
	references := registryReferences(t, "Aria", "Borin")
	for _, value := range []dnd.NPCInteractionList{
		{Interactions: []dnd.NPCInteraction{{Name: "Aria"}}},
		{Interactions: []dnd.NPCInteraction{{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, 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)
		}
	}
	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 TestValidatorResolvesGeneratedRegistryAndKeepsMetadataAndInputsImmutable(t *testing.T) {
	references := registryReferences(t, "Aria", "Borin")
	validator := newValidator(t)
	value := normalizedList()
	before := cloneList(value)
	result, err := validator.Validate(context.Background(), request(references, value))
	if err != nil || !result.Approved || !reflect.DeepEqual(value, before) {
		t.Fatalf("generated validation = %#v, %v; value=%#v", result, err, value)
	}
	metadata, err := json.Marshal(newValidator(t, references).ManifestMetadata())
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(metadata), "Aria") || strings.Contains(string(metadata), "other-session") {
		t.Fatalf("metadata leaked registry content: %s", metadata)
	}
	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 _, 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.NPCInteractionList) contracts.TypedValidationRequest[dnd.NPCInteractionList] {
	return contracts.TypedValidationRequest[dnd.NPCInteractionList]{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.NPCInteractionList {
	return dnd.NPCInteractionList{Interactions: []dnd.NPCInteraction{
		{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 10}}},
		{Name: "Borin", Kind: dnd.NPCInteractionKindMentioned, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}}},
	}}
}

func cloneList(value dnd.NPCInteractionList) dnd.NPCInteractionList {
	copyValue := dnd.NPCInteractionList{Interactions: make([]dnd.NPCInteraction, len(value.Interactions))}
	for index, interaction := range value.Interactions {
		copyValue.Interactions[index] = interaction
		copyValue.Interactions[index].SourceRefs = append([]source.SourceRef(nil), interaction.SourceRefs...)
	}
	return copyValue
}

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-session", 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"}}},
		},
	}}
}