package registry

import (
	"bytes"
	"encoding/json"
	"fmt"
	"strings"
	"sync"
	"testing"
	"unicode/utf8"

	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"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"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared/diagnostics"
)

func TestResolveAbsentRegistryUsesExactEmptyPrompt(t *testing.T) {
	resolved, err := Resolve(contracts.ReferenceSet{})
	if err != nil {
		t.Fatalf("Resolve() error = %v, want nil", err)
	}
	if resolved.Bound() || resolved.Digest() != "" || resolved.Count() != 0 {
		t.Fatalf("resolved unbound registry = %#v, want no semantic metadata", resolved)
	}
	input := resolved.PromptInput()
	if input.Name != ReferenceSlot || input.MediaType != npccodec.MediaType || input.Digest != "" || input.OriginURI != "" {
		t.Fatalf("unbound prompt input metadata = %#v, want name/media type only", input)
	}
	if got := string(input.Content); got != emptyPrompt {
		t.Fatalf("unbound prompt input = %q, want exact empty registry", got)
	}
	if got := string(resolved.CanonicalBytes()); got != emptyPrompt {
		t.Fatalf("unbound canonical bytes = %q, want exact empty registry", got)
	}
}

func TestResolveCanonicalizesAndProvidesSemanticIdentity(t *testing.T) {
	value := validRegistryList()
	canonical := encodeRegistry(t, value)
	raw := append([]byte(" \n"), canonical...)
	raw = append(raw, []byte("\n ")...)

	resolved, err := Resolve(registryReference(raw, "file:///another-session/npcs.json"))
	if err != nil {
		t.Fatalf("Resolve() error = %v, want nil", err)
	}
	if !resolved.Bound() || resolved.Count() != len(value.NPCs) {
		t.Fatalf("resolved registry = %#v, want bound registry with %d NPC", resolved, len(value.NPCs))
	}
	if !bytes.Equal(resolved.CanonicalBytes(), canonical) || !bytes.Equal(resolved.PromptInput().Content, canonical) {
		t.Fatalf("canonical content = %s, want %s", resolved.CanonicalBytes(), canonical)
	}
	if resolved.PromptInput().Digest != resolved.Digest() || !strings.HasPrefix(resolved.Digest(), "sha256:") {
		t.Fatalf("semantic digest = %q, want SHA-256 digest", resolved.Digest())
	}
	if resolved.PromptInput().OriginURI != "" {
		t.Fatalf("prompt input origin = %q, want no provenance path", resolved.PromptInput().OriginURI)
	}
}

func TestResolveRejectsInvalidBoundaryValuesWithoutContent(t *testing.T) {
	valid := validRegistryList()
	second := valid.NPCs[0]
	second.ID = identity.DeriveID("Captain Vale")
	second.Name = "Captain Vale"
	second.Aliases = []string{"The Greencloak"}
	valueWithAliasCollision := dnd.NPCList{NPCs: []dnd.NPC{valid.NPCs[0], second}}
	invalidID := valid
	invalidID.NPCs[0].ID = "not-an-npc-id"

	tests := []struct {
		name      string
		reference contracts.ReferenceSet
		wantError string
		forbidden []string
	}{
		{name: "zero items", reference: contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{ReferenceSlot: {Items: []contracts.ReferenceItem{}}}}, wantError: "exactly one"},
		{name: "multiple", reference: contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{ReferenceSlot: {Items: []contracts.ReferenceItem{{Content: []byte(emptyPrompt)}, {Content: []byte(emptyPrompt)}}}}}, wantError: "exactly one"},
		{name: "wrong media type", reference: registryReferenceWithMedia([]byte(emptyPrompt), "text/plain"), wantError: "must be application/json"},
		{name: "malformed JSON", reference: registryReference([]byte(`{"npcs":[],"MALFORMED_REGISTRY_SECRET":`), "file:///private.json"), wantError: "invalid approved NPC JSON", forbidden: []string{"MALFORMED_REGISTRY_SECRET"}},
		{name: "unknown field", reference: registryReference([]byte(`{"npcs":[],"UNKNOWN_FIELD_SECRET":true}`), "file:///private.json"), wantError: "invalid approved NPC JSON", forbidden: []string{"UNKNOWN_FIELD_SECRET"}},
		{name: "invalid ID", reference: registryReference(marshalRegistry(t, invalidID), "file:///private.json"), wantError: "decode NPC registry"},
		{name: "alias collision", reference: registryReference(encodeRegistry(t, valueWithAliasCollision), "file:///private.json"), wantError: string(identity.IssueAliasOwnershipCollision)},
		{name: "byte limit", reference: registryReference(bytes.Repeat([]byte("x"), MaxBytes+1), "file:///private.json"), wantError: "limit"},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			_, err := Resolve(test.reference)
			if err == nil || !strings.Contains(err.Error(), test.wantError) {
				t.Fatalf("Resolve() error = %v, want %q", err, test.wantError)
			}
			for _, forbidden := range append(test.forbidden, "Mira Thorn", "The Greencloak", "private.json") {
				if strings.Contains(err.Error(), forbidden) {
					t.Fatalf("error leaked registry content or provenance %q: %v", forbidden, err)
				}
			}
		})
	}
}

func TestResolveBoundsIdentityDiagnosticsWithoutContent(t *testing.T) {
	const recordCount = 30
	value := dnd.NPCList{NPCs: make([]dnd.NPC, recordCount)}
	for index := range value.NPCs {
		value.NPCs[index] = dnd.NPC{
			ID:            "npc:sha256:0000000000000000000000000000000000000000000000000000000000000000",
			Name:          fmt.Sprintf("PRIVATE NPC %d", index),
			Aliases:       []string{"PRIVATE SHARED ALIAS"},
			Description:   "PRIVATE DESCRIPTION",
			Relationships: []dnd.NPCRelationship{},
			SourceRefs:    []source.SourceRef{{SourceID: "private-source", StartUnitID: 1, EndUnitID: 1}},
		}
	}
	issues := identity.ValidateList(value)
	if len(issues) <= diagnostics.MaxIssues {
		t.Fatalf("identity issues = %d, want more than display limit", len(issues))
	}

	_, err := Resolve(registryReference(marshalRegistry(t, value), "file:///private-registry.json"))
	if err == nil {
		t.Fatal("Resolve() error = nil, want bounded identity rejection")
	}
	message := err.Error()
	if !utf8.ValidString(message) || len([]byte(message)) > diagnostics.MaxMessageBytes {
		t.Fatalf("identity error has invalid encoding or size: bytes=%d message=%q", len([]byte(message)), message)
	}
	wantOmitted := fmt.Sprintf("%d additional issue(s) omitted", len(issues)-diagnostics.MaxIssues)
	if !strings.Contains(message, wantOmitted) {
		t.Fatalf("identity error = %q, want %q", message, wantOmitted)
	}
	for _, forbidden := range []string{"PRIVATE NPC", "PRIVATE SHARED ALIAS", "PRIVATE DESCRIPTION", "private-source", "private-registry.json"} {
		if strings.Contains(message, forbidden) {
			t.Fatalf("identity error leaked %q: %s", forbidden, message)
		}
	}
}

func TestRegistryAccessorsAndLookupAreDefensive(t *testing.T) {
	resolved, err := Resolve(registryReference(encodeRegistry(t, validRegistryList()), "file:///npc-registry.json"))
	if err != nil {
		t.Fatalf("Resolve() error = %v, want nil", err)
	}

	npcs := resolved.NPCs()
	npcs[0].Name = "changed"
	npcs[0].Aliases[0] = "changed alias"
	npcs[0].Relationships[0].Target = "changed target"
	npcs[0].SourceRefs[0].SourceID = "changed source"
	if got, ok := resolved.Lookup("The Greencloak"); !ok || got.Name != "Mira Thorn" {
		t.Fatalf("Lookup() after NPC mutation = %#v, %v, want original NPC", got, ok)
	}

	wantCanonical := string(resolved.CanonicalBytes())
	content := resolved.CanonicalBytes()
	content[0] = 'X'
	input := resolved.PromptInput()
	input.Content[0] = 'X'
	if string(resolved.CanonicalBytes()) != wantCanonical || string(resolved.PromptInput().Content) != wantCanonical {
		t.Fatal("registry content accessors share mutable state")
	}
	if got, ok := resolved.Lookup("  MIRA\u00a0THORN "); !ok || got.Name != "Mira Thorn" {
		t.Fatalf("Lookup() canonical identity = %#v, %v, want Mira Thorn", got, ok)
	}
	if _, ok := resolved.Lookup("unknown NPC"); ok {
		t.Fatal("Lookup() found unknown NPC")
	}
}

func TestResolverUsesSeededFallbackAndCachesGeneratedCanonicalRegistry(t *testing.T) {
	staticContent := encodeRegistry(t, validRegistryList())
	resolver, err := NewResolver(registryReference(staticContent, "file:///static.json"))
	if err != nil {
		t.Fatalf("NewResolver() error = %v", err)
	}
	if got, err := resolver.Resolve(contracts.ReferenceSet{}); err != nil || got != resolver.Seeded() {
		t.Fatalf("Resolve(absent) = %p, %v, want seeded %p", got, err, resolver.Seeded())
	}

	generated := registryReference(append([]byte("\n"), staticContent...), "file:///generated.json")
	first, err := resolver.Resolve(generated)
	if err != nil {
		t.Fatalf("Resolve(generated) error = %v", err)
	}
	second, err := resolver.Resolve(generated)
	if err != nil {
		t.Fatalf("Resolve(generated second) error = %v", err)
	}
	if first != resolver.Seeded() || second != first {
		t.Fatalf("resolved registries = %p, %p, seeded %p; want seeded reuse", first, second, resolver.Seeded())
	}

	changed := validRegistryList()
	changed.NPCs[0].Description = "A changed generated description."
	changedContent := encodeRegistry(t, changed)
	changedReferences := registryReference(changedContent, "file:///changed.json")
	resolved, err := resolver.Resolve(changedReferences)
	if err != nil {
		t.Fatalf("Resolve(changed) error = %v", err)
	}
	changedReferences.Slots[ReferenceSlot].Items[0].Content[0] = 'X'
	if resolved == first || string(resolved.CanonicalBytes()) != string(changedContent) {
		t.Fatalf("changed registry = %p/%s, want independent canonical cache entry", resolved, resolved.CanonicalBytes())
	}
}

func TestResolverSharesOneCachedRegistryAcrossConcurrentOperations(t *testing.T) {
	content := encodeRegistry(t, validRegistryList())
	resolver, err := NewResolver(contracts.ReferenceSet{})
	if err != nil {
		t.Fatalf("NewResolver() error = %v", err)
	}
	references := registryReference(content, "file:///generated.json")
	const callers = 32
	results := make(chan *Registry, callers)
	errors := make(chan error, callers)
	var wait sync.WaitGroup
	for index := 0; index < callers; index++ {
		wait.Add(1)
		go func() {
			defer wait.Done()
			resolved, resolveErr := resolver.Resolve(references)
			if resolveErr != nil {
				errors <- resolveErr
				return
			}
			results <- resolved
		}()
	}
	wait.Wait()
	close(results)
	close(errors)
	for err := range errors {
		t.Fatalf("concurrent Resolve() error = %v", err)
	}
	var first *Registry
	for resolved := range results {
		if first == nil {
			first = resolved
		} else if resolved != first {
			t.Fatalf("concurrent resolved registry %p differs from cached %p", resolved, first)
		}
	}
}

func TestNewResolverAllowsGeneratedDeclarationButRejectsMalformedStaticItem(t *testing.T) {
	placeholder := contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{
		ReferenceSlot: {Slot: contracts.ReferenceSlot{Name: ReferenceSlot, AcceptedArtifactKinds: []contracts.ArtifactKind{dnd.NPCListKind}}},
	}}
	if _, err := NewResolver(placeholder); err != nil {
		t.Fatalf("NewResolver(generated declaration) error = %v, want nil", err)
	}
	malformed := registryReference([]byte(`{"npcs":[`), "file:///runtime.json")
	if _, err := NewResolver(malformed); err == nil || !strings.Contains(err.Error(), "invalid approved NPC JSON") {
		t.Fatalf("NewResolver(malformed) error = %v, want bounded decode failure", err)
	}
}

func validRegistryList() dnd.NPCList {
	return dnd.NPCList{NPCs: []dnd.NPC{{
		ID:          identity.DeriveID("Mira Thorn"),
		Name:        "Mira Thorn",
		Aliases:     []string{"The Greencloak"},
		Description: "A guarded ranger who watches the northern road.",
		Relationships: []dnd.NPCRelationship{{
			Target: "Captain Vale", Relationship: "reports to",
		}},
		SourceRefs: []source.SourceRef{{SourceID: "npc-session", StartUnitID: 41, EndUnitID: 43}},
	}}}
}

func encodeRegistry(t *testing.T, value dnd.NPCList) []byte {
	t.Helper()
	content, err := npccodec.New().Encode(value)
	if err != nil {
		t.Fatalf("encode NPC registry: %v", err)
	}
	return content
}

func marshalRegistry(t *testing.T, value dnd.NPCList) []byte {
	t.Helper()
	content, err := json.Marshal(value)
	if err != nil {
		t.Fatalf("marshal NPC registry: %v", err)
	}
	return content
}

func registryReference(content []byte, origin string) contracts.ReferenceSet {
	references := registryReferenceWithMedia(content, "application/json; charset=utf-8")
	item := references.Slots[ReferenceSlot].Items[0]
	item.Origin.URI = origin
	slot := references.Slots[ReferenceSlot]
	slot.Items[0] = item
	references.Slots[ReferenceSlot] = slot
	return references
}

func registryReferenceWithMedia(content []byte, mediaType string) contracts.ReferenceSet {
	return contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{
		ReferenceSlot: {
			Slot: contracts.ReferenceSlot{Name: ReferenceSlot, AcceptedMediaTypes: []string{npccodec.MediaType}, MaxBytes: MaxBytes},
			Items: []contracts.ReferenceItem{{
				SlotName:  ReferenceSlot,
				MediaType: mediaType,
				Content:   append([]byte(nil), content...),
				Origin:    contracts.ReferenceOrigin{Type: "file", URI: "file:///npc-registry.json"},
			}},
		},
	}}
}