diff --git a/src/validateRegisterForm.js b/src/validateRegisterForm.js
index 751cb14..b8f147b 100644
--- a/src/validateRegisterForm.js
+++ b/src/validateRegisterForm.js
@@ -1,40 +1,63 @@
 'use strict';
 
 /**
- * @param {string} email
- *
  * @param {string} password
- *
+ * @param {string} email
  * @returns {object}
  */
-function validateRegisterForm(email, password) {
-  // eslint-disable-next-line max-len
-  const validPassword = /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9])(?!.*\s).{8,16}$/;
+function validateRegisterForm(password, email) {
+  // Password regex
+  const n = '(?=.*\\d)';
+  const l = '(?=.*[a-zA-Z\u0400-\u04FF])';
+  const u = '(?=.*[A-Z\u0400-\u04FF])';
+  const s = '(?=.*[^\\da-zA-Z\u0400-\u04FF])';
+  const ns = '(?!.*\\s)';
+  const len = '.{8,16}';
+
+  const pwdPattern = '^' + n + l + u + s + ns + len + '$';
+  const validPassword = new RegExp(pwdPattern, 'u');
+
+  // Email regex (local-part + domain)
+  const localChars = "[A-Za-z0-9!#$%&'*+/=?^_`{|}~-]+";
+  const loc = '(' + localChars + '(?:\\.' + localChars + ')*)';
+  const domLabel = '[A-Za-z0-9-]+';
+  const dom = '(' + domLabel + '(?:\\.' + domLabel + ')+)';
+  const at = '@';
+  const validEmailMask = new RegExp('^' + loc + at + dom + '$', 'i');
 
-  // eslint-disable-next-line max-len
-  const validEmailMask = new RegExp(/^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\./i);
+  const isEmailValid = validEmailMask.test(email);
+  const isPasswordValid = validPassword.test(password);
 
-  if (!email.match(validEmailMask) && password.match(validPassword)) {
-    return {
-      code: 422, message: 'Email is invalid.',
-    };
+  // Extra dot rules
+  let emailExtraValid = true;
+  if (isEmailValid) {
+    const parts = email.split('@');
+    const local = parts[0];
+    const domain = parts[1];
+
+    const localInvalid = local.startsWith('.');
+    const domainInvalid = domain.startsWith('.');
+    const dotsInvalid = email.includes('..');
+
+    if (localInvalid || domainInvalid || dotsInvalid) {
+      emailExtraValid = false;
+    }
   }
 
-  if (email.match(validEmailMask) && !password.match(validPassword)) {
-    return {
-      code: 422, message: 'Password is invalid.',
-    };
+  // Result mapping
+  if (!isEmailValid || !emailExtraValid) {
+    if (isPasswordValid) {
+      return { code: 422, message: 'Email is invalid.' };
+    }
+    return { code: 500, message: 'Password and email are invalid.' };
   }
 
-  if (!email.match(validEmailMask) && !password.match(validPassword)) {
-    return {
-      code: 500, message: 'Password and email are invalid.',
-    };
+  if (!isPasswordValid) {
+    return { code: 422, message: 'Password is invalid.' };
   }
 
-  return {
-    code: 200, message: 'Email and password are valid.',
-  };
+  return { code: 200, message: 'Email and password are valid.' };
 }
 
 module.exports = validateRegisterForm;
+
diff --git a/src/validateRegisterForm.test.js b/src/validateRegisterForm.test.js
index 6d86ab9..e0a047e 100644
--- a/src/validateRegisterForm.test.js
+++ b/src/validateRegisterForm.test.js
@@ -8,23 +8,72 @@ describe(`Function 'validateRegisterForm':`, () => {
   });
 
   it(`should return object`, () => {
-    expect(typeof validateRegisterForm('test@mail.com', 'P@ssword1!'))
-      .toBe('object');
+    const pwd = 'P@ssword1!';
+    const email = 'test@mail.com';
+    const result = validateRegisterForm(pwd, email);
+    expect(typeof result).toBe('object');
   });
 
-  it(`should return success message for the valid input`, () => {
-    const isValid = validateRegisterForm('test@mail.com', 'P@ssword1!');
+  it(`should return 200 for valid password and email`, () => {
+    const result = validateRegisterForm('P@ssword1!', 'test@mail.com');
+    expect(result.code).toBe(200);
+    expect(result.message).toBe('Email and password are valid.');
+  });
+
+  it(`should return 422 for valid email but password missing digit`, () => {
+    const result = validateRegisterForm('P@ssword', 'test@mail.com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Password is invalid.');
+  });
+
+  it(`should return 422 for invalid email and valid password`, () => {
+    const result = validateRegisterForm('P@ssword1!', 'test@com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Email is invalid.');
+  });
+
+  it(`should return 500 for invalid password and email`, () => {
+    const result = validateRegisterForm('ssword1', 'test@com');
+    expect(result.code).toBe(500);
+    expect(result.message)
+      .toBe('Password and email are invalid.');
+  });
 
-    expect(isValid.code).toBe(200);
-    expect(isValid.message).toBe('Email and password are valid.');
+  it(`should return 422 if password too short`, () => {
+    const result = validateRegisterForm('Aa1!', 'valid@mail.com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Password is invalid.');
   });
 
-  it(`should return error for valid email and password without number`, () => {
-    const invalidPassword = validateRegisterForm('test@mail.com', 'P@ssword');
+  it(`should return 422 if password too long`, () => {
+    const longPwd = 'A1!aaaaaaaaaaaaaaa';
+    const result = validateRegisterForm(longPwd, 'valid@mail.com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Password is invalid.');
+  });
+
+  it(`should return 422 if email missing '@' symbol`, () => {
+    const result = validateRegisterForm('P@ssword1!', 'invalidmail.com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Email is invalid.');
+  });
 
-    expect(invalidPassword.code).toBe(422);
-    expect(invalidPassword.message).toBe('Password is invalid.');
+  it(`should return 422 if email starts with dot`, () => {
+    const result = validateRegisterForm('P@ssword1!', '.test@mail.com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Email is invalid.');
   });
 
-  // write more tests here
+  it(`should return 422 if email has double dots`, () => {
+    const result = validateRegisterForm('P@ssword1!', 'test..mail@mail.com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Email is invalid.');
+  });
+
+  it(`should return 422 if top-level domain starts with dot`, () => {
+    const result = validateRegisterForm('P@ssword1!', 'test@mail..com');
+    expect(result.code).toBe(422);
+    expect(result.message).toBe('Email is invalid.');
+  });
 });
+