package nwsync

import (
	"bytes"
	"crypto/sha1"
	"crypto/sha256"
	"encoding/binary"
	"encoding/hex"
	"encoding/json"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/erf"
)

func restype(t *testing.T, extension string) uint16 {
	t.Helper()
	value, ok := erf.ResourceTypeForExtension(extension)
	if !ok {
		t.Fatalf("unknown restype %q", extension)
	}
	return value
}

// writeHak builds a HAK fixture from resref.ext => body pairs.
func writeHak(t *testing.T, path string, contents map[string][]byte) {
	t.Helper()
	resources := make([]erf.Resource, 0, len(contents))
	for name, body := range contents {
		stem, extension, _ := strings.Cut(name, ".")
		resources = append(resources, erf.Resource{
			Name: stem,
			Type: restype(t, extension),
			Data: body,
			Size: int64(len(body)),
		})
	}
	var out bytes.Buffer
	if err := erf.Write(&out, erf.New("HAK", resources)); err != nil {
		t.Fatalf("write hak: %v", err)
	}
	if err := os.WriteFile(path, out.Bytes(), 0o644); err != nil {
		t.Fatalf("write hak file: %v", err)
	}
}

// artifactKey is the depot key a file would be published under: the sha256 of
// its bytes, hash-tree depth 2, keeping the extension.
func artifactKey(t *testing.T, path string) string {
	t.Helper()
	body, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	sum := sha256.Sum256(body)
	digest := hex.EncodeToString(sum[:])
	return "artifacts/haks/sha256/" + digest[0:2] + "/" + digest[2:4] + "/" + digest + filepath.Ext(path)
}

// emitLocal emits one artifact into a local tree, the conformance path.
func emitLocal(t *testing.T, path, out string) (EmitResult, error) {
	t.Helper()
	return Emit(EmitOptions{
		ArtifactKey:  artifactKey(t, path),
		ArtifactPath: path,
		As:           filepath.Base(path),
		OutDir:       out,
	})
}

func TestBlobFramingRoundTrips(t *testing.T) {
	data := []byte("the quick brown fox jumps over the lazy dog, repeatedly and at length")
	blob := compressBlob(data)

	header := make([]uint32, 6)
	if err := binary.Read(bytes.NewReader(blob[:blobHeaderBytes]), binary.LittleEndian, header); err != nil {
		t.Fatalf("read header: %v", err)
	}
	want := []uint32{blobMagic, 3, 2, uint32(len(data)), 1, 0}
	for i := range want {
		if header[i] != want[i] {
			t.Errorf("header field %d = %d, want %d", i, header[i], want[i])
		}
	}
	if string(blob[:4]) != "NSYC" {
		t.Errorf("magic bytes = %q, want NSYC", blob[:4])
	}

	got, err := decompressBlob(blob)
	if err != nil {
		t.Fatalf("decompress: %v", err)
	}
	if !bytes.Equal(got, data) {
		t.Errorf("round trip mismatch: %q", got)
	}
}

func TestManifestBytesMatchUpstreamLayout(t *testing.T) {
	shared := sha1.Sum([]byte("shared"))
	other := sha1.Sum([]byte("other"))
	// Deliberately out of order, and with two resrefs sharing one sha1: the
	// second one must become a mapping, not a second entry.
	entries := []Entry{
		{SHA1: other, Size: 5, ResRef: "zzz", ResType: 1},
		{SHA1: shared, Size: 6, ResRef: "bbb", ResType: 2},
		{SHA1: shared, Size: 6, ResRef: "aaa", ResType: 3},
	}
	data, err := writeManifest(entries)
	if err != nil {
		t.Fatalf("write manifest: %v", err)
	}

	if string(data[:4]) != "NSYM" {
		t.Fatalf("magic = %q", data[:4])
	}
	var version, entryCount, mappingCount uint32
	reader := bytes.NewReader(data[4:16])
	for _, field := range []*uint32{&version, &entryCount, &mappingCount} {
		_ = binary.Read(reader, binary.LittleEndian, field)
	}
	if version != 3 || entryCount != 2 || mappingCount != 1 {
		t.Fatalf("header = version %d, %d entries, %d mappings; want 3/2/1", version, entryCount, mappingCount)
	}
	wantSize := 16 + int(entryCount)*(20+4+16+2) + int(mappingCount)*(4+16+2)
	if len(data) != wantSize {
		t.Fatalf("manifest is %d bytes, want %d", len(data), wantSize)
	}

	// Sorted by sha1 hex then resref, so the shared hash's "aaa" is the entry
	// and "bbb" is demoted to a mapping.
	round, err := readManifest(data)
	if err != nil {
		t.Fatalf("read manifest: %v", err)
	}
	if len(round) != 3 {
		t.Fatalf("round trip returned %d entries, want 3", len(round))
	}
	byResRef := map[string]Entry{}
	for _, entry := range round {
		byResRef[entry.ResRef] = entry
	}
	for _, entry := range entries {
		got, ok := byResRef[entry.ResRef]
		if !ok {
			t.Fatalf("resref %q lost in round trip", entry.ResRef)
		}
		if got != entry {
			t.Errorf("resref %q = %+v, want %+v", entry.ResRef, got, entry)
		}
	}
	if round[0].ResRef != "aaa" && round[1].ResRef != "aaa" {
		t.Errorf("entries are not sorted by sha1 then resref: %+v", round)
	}
}

func TestEmitWritesBlobsAndManifest(t *testing.T) {
	dir := t.TempDir()
	hak := filepath.Join(dir, "sow_test_01.hak")
	body := []byte("texture bytes")
	writeHak(t, hak, map[string][]byte{
		"bloodstain1.tga": body,
		"copy1.txi":       body, // same content, different resref: one blob
		"script1.nss":     []byte("void main() {}"),
		"debug1.ndb":      []byte("debug"),
		"comment1.gic":    []byte("comment"),
	})

	out := filepath.Join(dir, "out")
	result, err := emitLocal(t, hak, out)
	if err != nil {
		t.Fatalf("emit: %v", err)
	}
	if result.Entries != 2 {
		t.Errorf("emitted %d entries, want 2 (nss/ndb/gic are always skipped)", result.Entries)
	}
	if result.BlobsWritten != 1 {
		t.Errorf("wrote %d blobs, want 1 (identical content shares a blob)", result.BlobsWritten)
	}

	// The blob is named by the sha1 of the uncompressed bytes, under a depth-2
	// hash tree, and decompresses back to exactly those bytes.
	sum := sha1.Sum(body)
	name := hex.EncodeToString(sum[:])
	path := filepath.Join(out, "data", "sha1", name[0:2], name[2:4], name)
	blob, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("blob missing at %s: %v", path, err)
	}
	got, err := decompressBlob(blob)
	if err != nil {
		t.Fatalf("decompress blob: %v", err)
	}
	if !bytes.Equal(got, body) {
		t.Errorf("blob decompressed to %q, want %q", got, body)
	}

	entries := readEmitted(t, result.ManifestPath)
	for _, entry := range entries {
		if entry.ResType == restype(t, "nss") || entry.ResType == restype(t, "ndb") || entry.ResType == restype(t, "gic") {
			t.Errorf("skipped restype leaked into the manifest: %+v", entry)
		}
	}

	var sidecar Sidecar
	body2, err := os.ReadFile(result.ManifestPath + ".json")
	if err != nil {
		t.Fatalf("sidecar missing: %v", err)
	}
	if err := json.Unmarshal(body2, &sidecar); err != nil {
		t.Fatalf("sidecar json: %v", err)
	}
	if sidecar.TotalFiles != 2 || sidecar.HashTreeDepth != 2 || sidecar.Version != 3 {
		t.Errorf("sidecar = %+v", sidecar)
	}
	if sidecar.IncludesModuleContents {
		t.Error("sidecar claims module contents; a published manifest never has them")
	}
	if strings.Contains(string(body2), "group_id") {
		t.Error("per-artifact sidecar should omit group_id (0 means absent)")
	}
	if _, err := os.Stat(filepath.Join(out, "latest")); err == nil {
		t.Error("a latest file was written; there must never be one")
	}
}

func readEmitted(t *testing.T, indexPath string) []Entry {
	t.Helper()
	data, err := os.ReadFile(indexPath)
	if err != nil {
		t.Fatalf("read emitted manifest: %v", err)
	}
	entries, err := readManifest(data)
	if err != nil {
		t.Fatalf("parse emitted manifest: %v", err)
	}
	return entries
}

func TestEmitFailsClosedOnOversizeResource(t *testing.T) {
	dir := t.TempDir()
	hak := filepath.Join(dir, "big.hak")
	writeHak(t, hak, map[string][]byte{"huge1.tga": make([]byte, fileSizeLimit+1)})

	if _, err := emitLocal(t, hak, filepath.Join(dir, "out")); err == nil {
		t.Fatal("emit accepted a resource over the 15 MB limit")
	}
}

func TestEmitLooseFile(t *testing.T) {
	dir := t.TempDir()
	tlk := filepath.Join(dir, "sow_tlk.tlk")
	if err := os.WriteFile(tlk, []byte("TLK V3.0 payload"), 0o644); err != nil {
		t.Fatal(err)
	}
	out := filepath.Join(dir, "out")
	result, err := emitLocal(t, tlk, out)
	if err != nil {
		t.Fatalf("emit tlk: %v", err)
	}
	entries := readEmitted(t, result.ManifestPath)
	if len(entries) != 1 || entries[0].ResRef != "sow_tlk" || entries[0].ResType != restype(t, "tlk") {
		t.Fatalf("tlk emitted as %+v", entries)
	}
	if result.BlobsWritten != 1 {
		t.Errorf("wrote %d blobs, want 1", result.BlobsWritten)
	}
}

// emitFixture emits two haks that share a resref, so the merge rule is
// observable: "top" holds the winning body, "assets" the shadowed one.
func emitFixture(t *testing.T) (out string, keys map[string]string, topBody, assetBody []byte) {
	t.Helper()
	dir := t.TempDir()
	topBody = []byte("2da from sow_top")
	assetBody = []byte("2da from the asset hak")
	writeHak(t, filepath.Join(dir, "sow_top.hak"), map[string][]byte{"appearance.2da": topBody})
	writeHak(t, filepath.Join(dir, "sow_core_01.hak"), map[string][]byte{
		"appearance.2da":  assetBody,
		"bloodstain1.tga": []byte("blood"),
	})
	out = filepath.Join(dir, "out")
	keys = map[string]string{}
	for _, name := range []string{"sow_top", "sow_core_01"} {
		path := filepath.Join(dir, name+".hak")
		keys[name] = artifactKey(t, path)
		if _, err := emitLocal(t, path, out); err != nil {
			t.Fatalf("emit %s: %v", name, err)
		}
	}
	return out, keys, topBody, assetBody
}

func TestAssembleShadowsByOrder(t *testing.T) {
	entriesDir, keys, topBody, assetBody := emitFixture(t)

	result, err := Assemble(AssembleOptions{
		ArtifactKeys: []string{keys["sow_top"], keys["sow_core_01"]},
		OutDir:       entriesDir,
		GroupID:      2,
	})
	if err != nil {
		t.Fatalf("assemble: %v", err)
	}
	if result.Entries != 2 {
		t.Fatalf("merged %d entries, want 2 (appearance.2da is shadowed, not duplicated)", result.Entries)
	}

	data, err := os.ReadFile(result.ManifestPath)
	if err != nil {
		t.Fatalf("read merged manifest: %v", err)
	}
	merged := sha1.Sum(data)
	if hex.EncodeToString(merged[:]) != result.SHA1 || filepath.Base(result.ManifestPath) != result.SHA1 {
		t.Errorf("manifest is not named by its own sha1: %s", result.ManifestPath)
	}
	entries, err := readManifest(data)
	if err != nil {
		t.Fatalf("parse merged manifest: %v", err)
	}
	for _, entry := range entries {
		if entry.ResRef != "appearance" {
			continue
		}
		if entry.SHA1 != sha1.Sum(topBody) {
			t.Errorf("appearance.2da resolved to the wrong hak; want the earliest in --order")
		}
		if entry.SHA1 == sha1.Sum(assetBody) {
			t.Error("appearance.2da resolved to the shadowed hak")
		}
	}

	sidecar := Sidecar{}
	body, err := os.ReadFile(result.ManifestPath + ".json")
	if err != nil {
		t.Fatalf("merged sidecar missing: %v", err)
	}
	if err := json.Unmarshal(body, &sidecar); err != nil {
		t.Fatalf("merged sidecar json: %v", err)
	}
	if sidecar.GroupID != 2 {
		t.Errorf("group_id = %d, want 2 (testing)", sidecar.GroupID)
	}
	if sidecar.SHA1 != result.SHA1 {
		t.Errorf("sidecar sha1 = %s, want %s", sidecar.SHA1, result.SHA1)
	}
	if sidecar.TotalFiles != 2 {
		t.Errorf("total_files = %d, want 2", sidecar.TotalFiles)
	}
}

func TestAssembleReversedOrderPicksTheOtherHak(t *testing.T) {
	entriesDir, keys, topBody, assetBody := emitFixture(t)

	result, err := Assemble(AssembleOptions{
		ArtifactKeys: []string{keys["sow_core_01"], keys["sow_top"]},
		OutDir:       entriesDir,
	})
	if err != nil {
		t.Fatalf("assemble: %v", err)
	}
	data, _ := os.ReadFile(result.ManifestPath)
	entries, err := readManifest(data)
	if err != nil {
		t.Fatalf("parse merged manifest: %v", err)
	}
	for _, entry := range entries {
		if entry.ResRef == "appearance" && entry.SHA1 != sha1.Sum(assetBody) {
			t.Errorf("appearance.2da did not follow --order; still resolves to %x", entry.SHA1)
		}
	}
	_ = topBody
}

func TestAssembleRefusesMismatchedEmitterVersions(t *testing.T) {
	entriesDir, keys, _, _ := emitFixture(t)

	index, err := resolveIndexKey(keys["sow_core_01"], entriesDir)
	if err != nil {
		t.Fatal(err)
	}
	path := filepath.Join(entriesDir, index+".json")
	var sidecar Sidecar
	body, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if err := json.Unmarshal(body, &sidecar); err != nil {
		t.Fatal(err)
	}
	sidecar.EmitterVersion = "0"
	patched, err := marshalSidecar(sidecar)
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, patched, 0o644); err != nil {
		t.Fatal(err)
	}

	_, err = Assemble(AssembleOptions{
		ArtifactKeys: []string{keys["sow_top"], keys["sow_core_01"]},
		OutDir:       entriesDir,
	})
	if err == nil || !strings.Contains(err.Error(), "emitter version mismatch") {
		t.Fatalf("assemble merged across emitter versions: %v", err)
	}
}

func TestEmitHonoursSourceDateEpoch(t *testing.T) {
	t.Setenv("SOURCE_DATE_EPOCH", "1700000000")
	dir := t.TempDir()
	hak := filepath.Join(dir, "pinned.hak")
	writeHak(t, hak, map[string][]byte{"one1.tga": []byte("body")})
	result, err := emitLocal(t, hak, filepath.Join(dir, "out"))
	if err != nil {
		t.Fatalf("emit: %v", err)
	}
	body, err := os.ReadFile(result.ManifestPath + ".json")
	if err != nil {
		t.Fatal(err)
	}
	var sidecar Sidecar
	if err := json.Unmarshal(body, &sidecar); err != nil {
		t.Fatal(err)
	}
	if sidecar.Created != 1700000000 {
		t.Errorf("created = %d, want the pinned SOURCE_DATE_EPOCH", sidecar.Created)
	}
}

func TestEmitRejectsAModule(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "sow.mod")
	var out bytes.Buffer
	if err := erf.Write(&out, erf.New("MOD", []erf.Resource{
		{Name: "module", Type: restype(t, "ifo"), Data: []byte("ifo"), Size: 3},
	})); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, out.Bytes(), 0o644); err != nil {
		t.Fatal(err)
	}
	if _, err := emitLocal(t, path, filepath.Join(dir, "out")); err == nil {
		t.Fatal("emit accepted a .mod; a manifest never carries module contents")
	}
}

func TestAssembleFailsClosedOnMissingIndex(t *testing.T) {
	entriesDir, keys, _, _ := emitFixture(t)
	missing := "artifacts/haks/sha256/00/11/" + strings.Repeat("0", 64) + ".hak"
	_, err := Assemble(AssembleOptions{
		ArtifactKeys: []string{keys["sow_top"], missing},
		OutDir:       entriesDir,
	})
	if err == nil || !strings.Contains(err.Error(), missing) {
		t.Fatalf("assemble did not fail closed and name the missing artifact: %v", err)
	}
}

func TestRunUsageErrors(t *testing.T) {
	cases := [][]string{
		nil,
		{"nope"},
		{"emit"},
		{"emit", "artifact-key.hak"},
		{"emit", "a", "b", "c"},
		{"assemble", "--out", "y"},
	}
	for _, args := range cases {
		var out, errw bytes.Buffer
		if code := Run(args, &out, &errw); code != exitUsage {
			t.Errorf("Run(%v) exit=%d, want %d", args, code, exitUsage)
		}
	}
}