import { type ParseMode } from "https://dotland.deno.dev/x/grammy@v1.18.3/types.ts";

The Bot API supports basic formatting for messages. You can use bold, italic, underlined, strikethrough, and spoiler text, as well as inline links and pre-formatted code in your bots' messages. Telegram clients will render them accordingly. You can use either markdown-style or HTML-style formatting.

Note that Telegram clients will display an*alert** to the user before opening an inline link ('Open this link?' together with the full URL).

Message entities can be nested, providing following restrictions are met:

• If two entities have common characters, then one of them is fully contained inside another.
• bold, italic, underline, strikethrough, and spoiler entities can contain and can be part of any other entities, except pre and code.
• All other entities can't contain each other.

Links tg://user?id=<user_id> can be used to mention a user by their ID without using a username. Please note:

• These links will work only if they are used inside an inline link or in an inline keyboard button. For example, they will not work, when used in a message text.
• Unless the user is a member of the chat where they were mentioned, these mentions are only guaranteed to work if the user has contacted the bot in private in the past or has sent a callback query to the bot via an inline button and doesn't have Forwarded Messages privacy enabled for the bot.

MarkdownV2 style

To use this mode, passMarkdownV2* in the parse_mode field. Use the following syntax in your message:

bold \*text*
_italic \text_
__underline__
~strikethrough~
||spoiler||
bold _italic bold ~italic bold strikethrough ||italic bold strikethrough spoiler||~ __underline italic bold___ bold*
[inline URL](http://www.example.com/)
[inline mention of a user](tg://user?id=123456789)
![👍](tg://emoji?id=5368324170671202286)
`inline fixed-width code`
`​`​`
pre-formatted fixed-width code block
`​`​`
`​`​`python
pre-formatted fixed-width code block written in the Python programming language
`​`​`

Please note:

• Any character with code between 1 and 126 inclusively can be escaped anywhere with a preceding '' character, in which case it is treated as an ordinary character and not a part of the markup. This implies that '' character usually must be escaped with a preceding '' character.
• Inside pre and code entities, all '`' and '' characters must be escaped with a preceding '' character.
• Inside the (...) part of the inline link and custom emoji definition, all ')' and '' must be escaped with a preceding '' character.
• In all other places characters '_', '', '[', ']', '(', ')', '~', '`', '>', '#', '+', '-', '=', '|', '{', '}', '.', '!' must be escaped with the preceding character ''.
• In case of ambiguity between italic and underline entities __ is always greadily treated from left to right as beginning or end of underline entity, so instead of ___italic underline___ use ___italic underline_\r__, where \r is a character with code 13, which will be ignored.
• A valid emoji must be provided as an alternative value for the custom emoji. The emoji will be shown instead of the custom emoji in places where a custom emoji cannot be displayed (e.g., system notifications) or if the message is forwarded by a non-premium user. It is recommended to use the emoji from the emoji field of the custom emoji sticker.
• Custom emoji entities can only be used by bots that purchased additional usernames on Fragment.

HTML style

To use this mode, passHTML* in the parse_mode field. The following tags are currently supported:

<b>bold</b>, <strong>bold</strong>
<i>italic</i>, <em>italic</em>
<u>underline</u>, <ins>underline</ins>
<s>strikethrough</s>, <strike>strikethrough</strike>, <del>strikethrough</del>
<span class="tg-spoiler">spoiler</span>, <tg-spoiler>spoiler</tg-spoiler>
<b>bold <i>italic bold <s>italic bold strikethrough <span class="tg-spoiler">italic bold strikethrough spoiler</span></s> <u>underline italic bold</u></i> bold</b>
<a href="http://www.example.com/">inline URL</a>
<a href="tg://user?id=123456789">inline mention of a user</a>
<tg-emoji emoji-id="5368324170671202286">👍</tg-emoji>
<code>inline fixed-width code</code>
<pre>pre-formatted fixed-width code block</pre>
<pre><code class="language-python">pre-formatted fixed-width code block written in the Python programming language</code></pre>

Please note:

• Only the tags mentioned above are currently supported.
• All <, > and & symbols that are not a part of a tag or an HTML entity must be replaced with the corresponding HTML entities (< with <, > with > and & with &).
• All numerical HTML entities are supported.
• The API currently supports only the following named HTML entities: <, >, & and ".
• Use nested pre and code tags, to define programming language for pre entity.
• Programming language can't be specified for standalone code tags.
• A valid emoji must be used as the content of the tg-emoji tag. The emoji will be shown instead of the custom emoji in places where a custom emoji cannot be displayed (e.g., system notifications) or if the message is forwarded by a non-premium user. It is recommended to use the emoji from the emoji field of the custom emoji sticker.
• Custom emoji entities can only be used by bots that purchased additional usernames on Fragment.

Markdown style

This is a legacy mode, retained for backward compatibility. To use this mode, passMarkdown* in the parse_mode field. Use the following syntax in your message:

bold text*
_italic text_
[inline URL](http://www.example.com/)
[inline mention of a user](tg://user?id=123456789)
`inline fixed-width code`
`​`​`
pre-formatted fixed-width code block
`​`​`
`​`​`python
pre-formatted fixed-width code block written in the Python programming language
`​`​`

Please note:

• Entities must not be nested, use parse mode MarkdownV2 instead.
• There is no way to specify underline and strikethrough entities, use parse mode MarkdownV2 instead.
• To escape characters '_', '', '`', '[' outside of an entity, prepend the characters '' before them.
• Escaping inside entities is not allowed, so entity must be closed first and reopened again: use _snake_\__case_ for italic snake_case and 2*\**2=4* for bold 2*2=4.