fix: ensure GeneratePassword returns password with mixed cases

controllers/apps/cluster/transformer_cluster_sharding_account.go

@@ -164,12 +164,14 @@ func (t *clusterShardingAccountTransformer) buildPassword(transCtx *clusterTrans
 
 func (t *clusterShardingAccountTransformer) generatePassword(account appsv1.SystemAccount) []byte {
 	config := account.PasswordGenerationPolicy
-	passwd, _ := common.GeneratePassword((int)(config.Length), (int)(config.NumDigits), (int)(config.NumSymbols), false, config.Seed)
+	passwd, _ := common.GeneratePassword((int)(config.Length), (int)(config.NumDigits), (int)(config.NumSymbols), config.Seed)
 	switch config.LetterCase {
 	case appsv1.UpperCases:
 		passwd = strings.ToUpper(passwd)
 	case appsv1.LowerCases:
 		passwd = strings.ToLower(passwd)
+	case appsv1.MixedCases:
+		passwd, _ = common.EnsureMixedCase(passwd, config.Seed)
 	}
 	return []byte(passwd)
 }

controllers/apps/component/transformer_component_account.go

@@ -219,12 +219,14 @@ func (t *componentAccountTransformer) buildPassword(ctx *componentTransformConte
 
 func (t *componentAccountTransformer) generatePassword(account synthesizedSystemAccount) []byte {
 	config := account.PasswordGenerationPolicy
-	passwd, _ := common.GeneratePassword((int)(config.Length), (int)(config.NumDigits), (int)(config.NumSymbols), false, config.Seed)
+	passwd, _ := common.GeneratePassword((int)(config.Length), (int)(config.NumDigits), (int)(config.NumSymbols), config.Seed)
 	switch config.LetterCase {
 	case appsv1.UpperCases:
 		passwd = strings.ToUpper(passwd)
 	case appsv1.LowerCases:
 		passwd = strings.ToLower(passwd)
+	case appsv1.MixedCases:
+		passwd, _ = common.EnsureMixedCase(passwd, config.Seed)
 	}
 	return []byte(passwd)
 }

pkg/common/password.go

@@ -24,6 +24,7 @@ import (
 	"encoding/binary"
 	mathrand "math/rand"
 	"time"
+	"unicode"
 
 	"github.com/sethvargo/go-password/password"
 )
@@ -45,19 +46,11 @@ func (r *PasswordReader) Seed(seed int64) {
 	r.rand.Seed(seed)
 }
 
-// GeneratePassword generates a password with the given requirements and seed.
-func GeneratePassword(length, numDigits, numSymbols int, noUpper bool, seed string) (string, error) {
-	var rand *mathrand.Rand
-	if len(seed) == 0 {
-		rand = mathrand.New(mathrand.NewSource(time.Now().UnixNano()))
-	} else {
-		h := sha256.New()
-		_, err := h.Write([]byte(seed))
-		if err != nil {
-			return "", err
-		}
-		uSeed := binary.BigEndian.Uint64(h.Sum(nil))
-		rand = mathrand.New(mathrand.NewSource(int64(uSeed)))
+// GeneratePassword generates a password with the given requirements and seed in lowercase.
+func GeneratePassword(length, numDigits, numSymbols int, seed string) (string, error) {
+	rand, err := newRngFromSeed(seed)
+	if err != nil {
+		return "", err
 	}
 	passwordReader := &PasswordReader{rand: rand}
 	gen, err := password.NewGenerator(&password.GeneratorInput{
@@ -70,5 +63,57 @@ func GeneratePassword(length, numDigits, numSymbols int, noUpper bool, seed stri
 	if err != nil {
 		return "", err
 	}
-	return gen.Generate(length, numDigits, numSymbols, noUpper, true)
+	return gen.Generate(length, numDigits, numSymbols, true, true)
+}
+
+// EnsureMixedCase randomizes the letter casing in the given string, ensuring
+// that the result contains at least one uppercase and one lowercase letter
+func EnsureMixedCase(in, seed string) (string, error) {
+	runes := []rune(in)
+	letterIndices := make([]int, 0, len(runes))
+	for i, r := range runes {
+		if unicode.IsLetter(r) {
+			letterIndices = append(letterIndices, i)
+		}
+	}
+	L := len(letterIndices)
+
+	if L < 2 {
+		return in, nil
+	}
+
+	// Get a random number x in [1, 2^L - 2], whose binary list will be used to determine the letter casing.
+	// avoid the all-0 and all-1 patterns, which cause all-lowercase and all-uppercase password.
+	rng, err := newRngFromSeed(seed)
+	if err != nil {
+		return in, err
+	}
+	x := uint64(rng.Int63n(int64((1<<L)-2))) + 1
+
+	for i := 0; i < L; i++ {
+		bit := (x >> i) & 1
+		idx := letterIndices[i]
+		if bit == 0 {
+			runes[idx] = unicode.ToLower(runes[idx])
+		} else {
+			runes[idx] = unicode.ToUpper(runes[idx])
+		}
+	}
+	return string(runes), nil
+}
+
+// newRngFromSeed initializes a *mathrand.Rand from the given seed. If seed is empty,
+// it uses the current time, making the output non-deterministic.
+func newRngFromSeed(seed string) (*mathrand.Rand, error) {
+	if seed == "" {
+		return mathrand.New(mathrand.NewSource(time.Now().UnixNano())), nil
+	}
+	// Convert seed string to a 64-bit integer via SHA-256
+	h := sha256.New()
+	if _, err := h.Write([]byte(seed)); err != nil {
+		return nil, err
+	}
+	sum := h.Sum(nil)
+	uSeed := binary.BigEndian.Uint64(sum)
+	return mathrand.New(mathrand.NewSource(int64(uSeed))), nil
 }

pkg/common/password_test.go

@@ -34,7 +34,7 @@ func testGeneratorGeneratePasswordWithSeed(t *testing.T) {
 	resultSeedFirstTime := ""
 	resultSeedEachTime := ""
 	for i := 0; i < N; i++ {
-		res, err := GeneratePassword(10, 5, 0, false, seed)
+		res, err := GeneratePassword(10, 5, 0, seed)
 		if err != nil {
 			t.Error(err)
 		}
@@ -52,11 +52,11 @@ func testGeneratorGeneratePassword(t *testing.T) {
 	t.Run("exceeds_length", func(t *testing.T) {
 		t.Parallel()
 
-		if _, err := GeneratePassword(0, 1, 0, false, ""); err != password.ErrExceedsTotalLength {
+		if _, err := GeneratePassword(0, 1, 0, ""); err != password.ErrExceedsTotalLength {
 			t.Errorf("expected %q to be %q", err, password.ErrExceedsTotalLength)
 		}
 
-		if _, err := GeneratePassword(0, 0, 1, false, ""); err != password.ErrExceedsTotalLength {
+		if _, err := GeneratePassword(0, 0, 1, ""); err != password.ErrExceedsTotalLength {
 			t.Errorf("expected %q to be %q", err, password.ErrExceedsTotalLength)
 		}
 	})
@@ -67,7 +67,7 @@ func testGeneratorGeneratePassword(t *testing.T) {
 		resultSeedEachTime := ""
 		hasDiffPassword := false
 		for i := 0; i < N; i++ {
-			res, err := GeneratePassword(i%len(password.LowerLetters), 0, 0, true, "")
+			res, err := GeneratePassword(i%(len(password.LowerLetters)+len(password.UpperLetters)), 0, 0, "")
 			if err != nil {
 				t.Error(err)
 			}
@@ -93,3 +93,74 @@ func TestGeneratorGeneratePassword(t *testing.T) {
 func TestGeneratorGeneratePasswordWithSeed(t *testing.T) {
 	testGeneratorGeneratePasswordWithSeed(t)
 }
+
+// containsUppercase checks if s has at least one uppercase letter (A-Z).
+func containsUppercase(s string) bool {
+	for _, r := range s {
+		if r >= 'A' && r <= 'Z' {
+			return true
+		}
+	}
+	return false
+}
+
+// containsLowercase checks if s has at least one lowercase letter (a-z).
+func containsLowercase(s string) bool {
+	for _, r := range s {
+		if r >= 'a' && r <= 'z' {
+			return true
+		}
+	}
+	return false
+}
+
+// TestGeneratorEnsureMixedCase verifies two requirements:
+// 1) When noUpper = false, the generated password contains uppercase and lowercase letters.
+// 2) Passwords generated with the same seed are identical.
+func TestGeneratorEnsureMixedCase(t *testing.T) {
+	t.Run("should_contain_mixed_case_when_noUpper_false", func(t *testing.T) {
+		length := 12
+		numDigits := 3
+		numSymbols := 2
+		seed := ""
+
+		// Generate multiple passwords and check they have both upper and lower letters.
+		for i := 0; i < 100; i++ {
+			pwd, err := GeneratePassword(length, numDigits, numSymbols, seed)
+			if err != nil {
+				t.Fatalf("unexpected error generating password: %v", err)
+			}
+			pwd, err = EnsureMixedCase(pwd, seed)
+			if err != nil {
+				t.Fatalf("unexpected error Ensuring mixed-case password: %v", err)
+			}
+			if !containsUppercase(pwd) || !containsLowercase(pwd) {
+				t.Errorf("password %q does not contain both uppercase and lowercase letters", pwd)
+			}
+		}
+	})
+
+	t.Run("should_produce_same_result_with_same_seed", func(t *testing.T) {
+		length := 10
+		numDigits := 2
+		numSymbols := 1
+		seed := "fixed-seed-123"
+
+		var firstPwd string
+		for i := 0; i < 50; i++ {
+			pwd, err := GeneratePassword(length, numDigits, numSymbols, seed)
+			if err != nil {
+				t.Fatalf("unexpected error generating password with seed: %v", err)
+			}
+			pwd, err = EnsureMixedCase(pwd, seed)
+			if err != nil {
+				t.Fatalf("unexpected error Ensuring mixed-case password: %v", err)
+			}
+			if i == 0 {
+				firstPwd = pwd
+			} else if pwd != firstPwd {
+				t.Errorf("expected the same password for the same seed, but got %q vs %q", firstPwd, pwd)
+			}
+		}
+	})
+}