package kdbx

import (
	"bytes"
	"strings"
	"testing"
	"time"
)

// fastKDF keeps the tests quick; the format does not care about the cost.
var fastKDF = KDFParams{MemoryKiB: 64, Iterations: 1, Lanes: 1}

func TestRoundTripPreservesEverything(t *testing.T) {
	db := New("Team Vault", fastKDF)
	entry := NewEntry("Router", "admin", "s3cret-pw", "https://router.lan", "line one\nline two")
	db.RootGroup().Nodes = append(db.RootGroup().Nodes, entry)

	// An element this package knows nothing about must survive the trip.
	db.RootGroup().Nodes = append(db.RootGroup().Nodes,
		&Node{Name: "FutureKeePassElement", Attrs: []Attr{{Name: "Mode", Value: "odd"}},
			Nodes: []*Node{{Name: "Inner", Text: "keep me"}}})

	data, err := db.Marshal("vault-password")
	if err != nil {
		t.Fatal(err)
	}
	if len(data) < 100 {
		t.Fatalf("file is only %d bytes", len(data))
	}

	back, err := Open(data, "vault-password")
	if err != nil {
		t.Fatal(err)
	}
	if back.Name() != "Team Vault" {
		t.Fatalf("name = %q", back.Name())
	}
	e := back.RootGroup().Find("Entry")
	if e == nil {
		t.Fatal("entry missing after round trip")
	}
	if got := entryValue(e, "Password"); got != "s3cret-pw" {
		t.Fatalf("password = %q", got)
	}
	if got := entryValue(e, "Notes"); got != "line one\nline two" {
		t.Fatalf("notes = %q", got)
	}
	fut := back.RootGroup().Find("FutureKeePassElement")
	if fut == nil || fut.Attr("Mode") != "odd" || fut.Value("Inner") != "keep me" {
		t.Fatalf("unknown element was not preserved: %+v", fut)
	}
}

func TestPasswordIsNotStoredInTheClear(t *testing.T) {
	db := New("V", fastKDF)
	db.RootGroup().Nodes = append(db.RootGroup().Nodes,
		NewEntry("T", "u", "needle-in-the-haystack", "", ""))
	data, err := db.Marshal("vault-password")
	if err != nil {
		t.Fatal(err)
	}
	if bytes.Contains(data, []byte("needle-in-the-haystack")) {
		t.Fatal("the entry password appears in the encrypted file")
	}
	// Nor in the compressed-but-decrypted XML: it is under the inner stream.
	db.Compression = 0
	plain, err := db.Marshal("vault-password")
	if err != nil {
		t.Fatal(err)
	}
	if bytes.Contains(plain, []byte("needle-in-the-haystack")) {
		t.Fatal("the entry password survives as plaintext inside the payload")
	}
}

func TestWrongPasswordIsRejected(t *testing.T) {
	db := New("V", fastKDF)
	data, err := db.Marshal("right-password")
	if err != nil {
		t.Fatal(err)
	}
	if _, err := Open(data, "wrong-password"); err != ErrWrongPassword {
		t.Fatalf("err = %v, want ErrWrongPassword", err)
	}
}

func TestTamperingIsDetected(t *testing.T) {
	db := New("V", fastKDF)
	data, err := db.Marshal("pw")
	if err != nil {
		t.Fatal(err)
	}
	// Flip a byte in the encrypted payload, past the header and hashes.
	bad := append([]byte(nil), data...)
	bad[len(bad)-10] ^= 0xFF
	if _, err := Open(bad, "pw"); err == nil {
		t.Fatal("a modified payload was accepted")
	}
	// And one in the header.
	bad = append([]byte(nil), data...)
	bad[20] ^= 0xFF
	if _, err := Open(bad, "pw"); err == nil {
		t.Fatal("a modified header was accepted")
	}
}

func TestAESKDFFileOpens(t *testing.T) {
	db := New("V", fastKDF)
	// Switch the file to the older AES work factor and check both paths.
	db.KDF = variantDict{}
	db.KDF.set(vdByteArray, "$UUID", kdfAES)
	db.KDF.set(vdByteArray, "S", make([]byte, 32))
	db.KDF.setUint64("R", 64)
	data, err := db.Marshal("pw")
	if err != nil {
		t.Fatal(err)
	}
	if _, err := Open(data, "pw"); err != nil {
		t.Fatalf("AES-KDF round trip: %v", err)
	}
}

func TestKDBX3IsReportedNotGuessed(t *testing.T) {
	db := New("V", fastKDF)
	data, _ := db.Marshal("pw")
	data[8], data[9], data[10], data[11] = 0x01, 0x00, 0x03, 0x00 // version 3.1
	_, err := Open(data, "pw")
	var un *ErrUnsupported
	if err == nil || !strings.Contains(err.Error(), "KDBX 3") {
		t.Fatalf("err = %v, want an unsupported-KDBX-3 report", err)
	}
	if !asUnsupported(err, &un) {
		t.Fatalf("err %T is not ErrUnsupported", err)
	}
}

func TestTimeRoundTrip(t *testing.T) {
	now := time.Now().UTC().Truncate(time.Second)
	got, ok := DecodeTime(EncodeTime(now))
	if !ok || !got.Equal(now) {
		t.Fatalf("decode(encode(%v)) = %v, %v", now, got, ok)
	}
	// KDBX 3's text form must still be readable.
	got, ok = DecodeTime("2026-10-29T12:00:00Z")
	if !ok || got.Year() != 2026 || got.Hour() != 12 {
		t.Fatalf("iso time = %v, %v", got, ok)
	}
}

// entryValue reads one string field out of an entry node.
func entryValue(entry *Node, key string) string {
	for _, s := range entry.FindAll("String") {
		if s.Value("Key") == key {
			return s.Value("Value")
		}
	}
	return ""
}

func asUnsupported(err error, target **ErrUnsupported) bool {
	u, ok := err.(*ErrUnsupported)
	if ok {
		*target = u
	}
	return ok
}