diff --git a/index.js b/index.js
index 0fb6c27..d04a823 100644
--- a/index.js
+++ b/index.js
@@ -12,7 +12,7 @@ class EntityMessage {
     // validate params
     if (!text || typeof text !== "string" || !entities || !entities.length) {
       throw new Error(
-        `Expected string in field text - got ${typeof text}, array/object in field entities - got ${typeof entities}`
+          `Expected string in field text - got ${typeof text}, array/object in field entities - got ${typeof entities}`
       );
     }
     this.text = text;
@@ -24,19 +24,7 @@ class EntityMessage {
    * @return {string} HTML formatted text
    */
   get html() {
-    let content = this.text;
-    let totalOffset = 0;
-    for (let entity of this.entities) {
-      let replacement = formatEntity(this.text, entity, "html");
-      content = spliceString(
-        content,
-        totalOffset + entity.offset,
-        entity.length,
-        replacement
-      );
-      totalOffset += replacement.length - entity.length;
-    }
-    return content;
+    return applyEntity(this.text, this.entities, "html");
   }
 
   /**
@@ -44,108 +32,138 @@ class EntityMessage {
    * @return {string} Markdown formatted text
    */
   get markdown() {
-    let content = this.text;
-    let totalOffset = 0;
-    for (let entity of this.entities) {
-      let replacement = formatEntity(this.text, entity, "markdown");
-      content = spliceString(
-        content,
-        entity.offset,
-        entity.length,
-        replacement
-      );
-      totalOffset += replacement.length - entity.length;
-    }
-    return content;
+    return applyEntity(this.text, this.entities, "markdown");
   }
 }
 
 // Helper functions
-function formatEntity(text, entity, format) {
-  let entityText = text.substring(entity.offset, entity.offset + entity.length);
-  let options = {};
-  switch (entity.type) {
-    case "text_link":
-      options.url = entity.url;
-      break;
-    case "text_mention":
-      options.user = entity.user;
-      break;
-    case "pre":
-      options.language = entity.language;
-      break;
-    case "custom_emoji":
-      options.custom_emoji_id = entity.custom_emoji_id;
-      break;
+function applyEntity(mainText = "", entities, markupType = "html") {
+  if (markupType !== "html" || markupType !== "markdown") return mainText;
+  if (!entities.length) return mainText;
+  if (!mainText.length) return mainText;
+
+  let content = mainText;
+  const addedTags = [];
+  for (let entity of entities) {
+    const {
+      type,
+      offset,
+      length,
+      url,
+      user,
+      language,
+      custom_emoji_id
+    } = entity;
+    const text = mainText.slice(offset, offset + length);
+    const [opening, closing] = (entityTypes(text, {
+      url,
+      userId: user?.id,
+      custom_emoji_id,
+      language
+    })[type][markupType] || ["", ""]);
+
+    if (opening !== "" || closing !== "") {
+      const {start: beforeStart, end: beforeEnd} = addedTags.reduce((t, {startAt, tag}) => {
+        let {start, end} = t;
+        if (startAt <= offset) {
+          start += tag.length;
+        }
+        if (startAt < (offset + length)) {
+          end += tag.length
+        }
+        return {start, end};
+      }, {
+        start: 0, end: 0
+      })
+
+      const start = offset + beforeStart;
+      const end = offset + length + beforeEnd;
+      addedTags.push({startAt: offset, tag: opening});
+      addedTags.push({startAt: offset + length, tag: closing});
+      content = content.slice(0, start) + opening + content.slice(start, end) + closing + content.slice(end);
+    }
   }
-  return entityTypes[entity.type][format](entityText, options);
+  return content;
 }
 
-const entityTypes = {
-  mention: { html: (text) => text, markdown: (text) => text },
-
-  hashtag: { html: (text) => text, markdown: (text) => text },
-
-  cashtag: { html: (text) => text, markdown: (text) => text },
-
-  bot_command: { html: (text) => text, markdown: (text) => text },
-
-  url: { html: (text) => text, markdown: (text) => text },
-
-  email: { html: (text) => text, markdown: (text) => text },
-
-  phone_number: { html: (text) => text, markdown: (text) => text },
-
-  bold: { html: (text) => `<b>${text}</b>`, markdown: (text) => `**${text}**` },
+const entityTypes = (text, {url, userId, custom_emoji_id}) => {
 
-  italic: { html: (text) => `<i>${text}</i>`, markdown: (text) => `*${text}*` },
-
-  underline: { html: (text) => `<u>${text}</u>`, markdown: (text) => text },
-
-  strikethrough: {
-    html: (text) => `<strike>${text}</strike>`,
-    markdown: (text) => text,
-  },
-
-  spoiler: { html: (text) => text, markdown: (text) => text },
-
-  code: {
-    html: (text) => `<code>${text}</code>`,
-    markdown: (text) => `\`${text}\``,
-  },
-
-  pre: {
-    html: (text, { language }) => `<pre>${text}</pre>`,
-    markdown: (text, { language }) => `\`\`\`${text}\`\`\``,
-  },
-
-  text_link: {
-    html: (text, { url }) => `<a href="${url}">${text}</a>`,
-    markdown: (text, { url }) => `[${text}](${url})`,
-  },
-
-  text_mention: {
-    html: (text, { user }) => text,
-    markdown: (text, { user }) => text,
-  },
-
-  custom_emoji: {
-    html: (text, { custom_emoji_id }) => "",
-    markdown: (text, { custom_emoji_id }) => "",
-  },
-};
-
-// Utility function
-function spliceString(str, index, count, add) {
-  // We cannot pass negative indexes directly to the 2nd slicing operation.
-  if (index < 0) {
-    index = str.length + index;
-    if (index < 0) {
-      index = 0;
-    }
+  /**
+   * [markUpType]: {
+   *   [markUpName]: [openingTag, closingTag],
+   * },
+   * */
+
+  return {
+    mention: {
+      html: [`<a href="https://t.me/${text.slice(1)}">`, `</a>`],
+      markdown: [`[`, `](https://t.me/${text.slice(1)})`],
+    },
+    hashtag: {
+      html: [``, ``],
+      markdown: [``, ``],
+    },
+    cashtag: {
+      html: [``, ``],
+      markdown: [``, ``],
+    },
+    bot_command: {
+      html: [``, ``],
+      markdown: [``, ``],
+    },
+    url: {
+      html: [`<a href="${text}">`, `</a>`],
+      markdown: [`[`, `](${text})`],
+    },
+    email: {
+      html: [`<a href="mailto:${text}">`, `</a>`],
+      markdown: [`[`, `](mailto:${text})`],
+    },
+    phone_number: {
+      html: [`<a href="tel:${text}">`, `</a>`],
+      markdown: [`[`, `](tel:${text})`],
+    },
+    bold: {
+      html: [`<b>`, `</b>`],
+      markdown: [`**`, `**`],
+    },
+    italic: {
+      html: [`<i>`, `</i>`],
+      markdown: [`*`, `*`],
+    },
+    underline: {
+      html: [`<u>`, `</u>`],
+      markdown: [``, ``],
+    },
+    strikethrough: {
+      html: [`<s>`, `</s>`],
+      markdown: [``, ``],
+    },
+    spoiler: {
+      html: [`<span class="tg-spoiler">`, `</span>`],
+      markdown: [``, ``],
+    },
+    code: {
+      html: [`<code>`, `</code>`],
+      markdown: [``, ``],
+    },
+    pre: {
+      html: [`<pre>`, `</pre>`],
+      markdown: [`\`\`\``, `\`\`\``],
+    },
+    text_link: {
+      html: [`<a href="${url}">`, `</a>`],
+      markdown: [`[`, `](${url})`],
+    },
+    text_mention: {
+      html: [`<a href="tg://user?id=${userId}">`, `</a>`],
+      markdown: [`[`, `](tg://user?id=${userId})`],
+    },
+    custom_emoji: {
+      html: [``, ``],
+      markdown: [``, ``],
+    },
   }
-
-  return str.slice(0, index) + (add || "") + str.slice(index + count);
 }
 
-module.exports = { EntityMessage };
+module.exports = {EntityMessage};