feat(client): bot keyboard builder

packages/client/src/types/bots/index.ts

@@ -5,3 +5,4 @@ export * from './inline-query'
 export * from './callback-query'
 export * from './game-high-score'
 export * from './command-scope'
+export * from './keyboard-builder'

packages/client/src/types/bots/keyboard-builder.ts

@@ -0,0 +1,105 @@
+import type { InlineKeyboardMarkup, ReplyKeyboardMarkup } from './keyboards'
+import { tl } from '@mtcute/tl'
+
+type ButtonLike = tl.TypeKeyboardButton | false | null | undefined | void
+
+/**
+ * Builder for bot keyboards
+ */
+export class BotKeyboardBuilder {
+    private _buttons: tl.TypeKeyboardButton[][] = []
+
+    constructor(readonly maxRowWidth: number | null = 3) {}
+
+    /**
+     * Add buttons, wrapping them once {@link maxRowWidth} is reached
+     *
+     * @param buttons  Buttons to add
+     */
+    push(...buttons: (ButtonLike | (() => ButtonLike))[]): this {
+        if (!buttons.length) return this
+
+        let row: tl.TypeKeyboardButton[] = []
+        buttons.forEach((btn) => {
+            if (typeof btn === 'function') btn = btn()
+            if (!btn) return
+
+            row.push(btn)
+            if (row.length === this.maxRowWidth) {
+                this._buttons.push(row)
+                row = []
+            }
+        })
+
+        if (row.length) {
+            this._buttons.push(row)
+        }
+
+        return this
+    }
+
+    /**
+     * Add a row of buttons. Will not be wrapped.
+     *
+     * @param row  Row or a function that will populate it
+     */
+    row(row: ButtonLike[] | ((arr: ButtonLike[]) => void)): this {
+        if (typeof row === 'function') {
+            const fn = row
+            row = []
+            fn(row)
+        }
+
+        const normal = row.filter(Boolean) as tl.TypeKeyboardButton[]
+        if (normal.length) this._buttons.push(normal)
+
+        return this
+    }
+
+    /**
+     * Append a button to the last row, wrapping if needed.
+     *
+     * @param btn  Button to add
+     * @param force  Whether to forcefully add the button (i.e. do not wrap)
+     */
+    append(btn: ButtonLike | (() => ButtonLike), force = false): this {
+        if (typeof btn === 'function') btn = btn()
+        if (!btn) return this
+
+        if (
+            this._buttons.length &&
+            (this.maxRowWidth === null ||
+                force ||
+                this._buttons[this._buttons.length - 1].length <
+                    this.maxRowWidth)
+        ) {
+            this._buttons[this._buttons.length - 1].push()
+        } else {
+            this._buttons.push([btn])
+        }
+
+        return this
+    }
+
+    /**
+     * Return contents of this builder as an inline keyboard
+     */
+    asInline(): InlineKeyboardMarkup {
+        return {
+            type: 'inline',
+            buttons: this._buttons,
+        }
+    }
+
+    /**
+     * Return contents of this builder as a reply keyboard
+     */
+    asReply(
+        params: Omit<ReplyKeyboardMarkup, 'type' | 'buttons'> = {}
+    ): ReplyKeyboardMarkup {
+        const ret = params as tl.Mutable<ReplyKeyboardMarkup>
+        ret.type = 'reply'
+        ret.buttons = this._buttons
+        return ret
+    }
+}

packages/client/src/types/bots/keyboards.ts

@@ -1,4 +1,5 @@
 import { tl } from '@mtcute/tl'
+import { BotKeyboardBuilder } from './keyboard-builder'
 
 /**
  * Reply keyboard markup
@@ -57,6 +58,10 @@ export type ReplyMarkup =
  * > in the description.
  */
 export namespace BotKeyboard {
+    export function builder(maxRowWidth?: number | null): BotKeyboardBuilder {
+        return new BotKeyboardBuilder(maxRowWidth)
+    }
+
     /**
      * Create an inline keyboard markup
      *