Add posterHelper for null posters

library/src/commonMain/kotlin/com/lagradost/cloudstream3/utils/PosterHelper.kt

@@ -0,0 +1,42 @@
+package com.lagradost.cloudstream3.utils
+
+/**
+ * Generates a placeholder poster image URL using placehold.co.
+ *
+ * @param title The text to display on the poster.
+ *              You can add a newline using `\n`.
+ * @param width Poster width in pixels. Default is 2400.
+ * @param height Poster height in pixels. Default is 400.
+ * @param backgroundColor Background color.
+ *        Supports hex values (with or without `#`) and CSS color names
+ *        like orange or white. Use "transparent" for transparency.
+ * @param textColor Text color.
+ *        Supports hex values (with or without `#`) and CSS color names.
+ * @param font Font name.
+ *        Spaces are automatically replaced with `-`.
+ *
+ * Available fonts:
+ * lato, lora, montserrat, noto-sans, open-sans,
+ * oswald, playfair-display, poppins, pt-sans,
+ * raleway, roboto, source-sans-pro
+ *
+ * @return A URL string pointing to the generated placeholder image.
+ */
+fun posterHelper(
+    title: String,
+    width: Int? = null,
+    height: Int? = null,
+    backgroundColor: String? = null,
+    textColor: String? = null,
+    font: String? = null,
+): String {
+    // Check the documentation on the official website.
+    val domain    = "https://placehold.co"
+    val imgWidth  = width ?: 2400
+    val imgHeight = height ?: 400
+    val bgColor   = backgroundColor?.removePrefix("#") ?: "EEE"
+    val txtColor  = textColor?.removePrefix("#") ?: "31343C"
+    val txtFont   = font?.lowercase()?.replace(" ","-") ?: "lato"
+
+    return "$domain/${imgWidth}x${imgHeight}/$bgColor/$txtColor.png?text=$title&font=$txtFont"
+}