GenEmojiKt.kt

import com.google.gson.JsonObject
import com.google.gson.JsonParser
import com.google.gson.JsonPrimitive
import java.net.HttpURLConnection
import java.net.URL
import kotlin.io.path.Path
import kotlin.io.path.writer

val prefix = "https://github.githubassets.com/images/icons/emoji/unicode/"
val suffix = ".png?v8"

fun main() {
    val json = (URL("https://api.github.com/emojis").openConnection() as HttpURLConnection)
        .inputStream.use { it.reader().readText() }
    val obj = JsonParser.parseString(json) as JsonObject
    
    Path("Emoji.kt").writer().use { writer ->
        writer.appendLine("package org.kodein.pres.ui")
        writer.appendLine()
        writer.appendLine("// Generated from https://api.github.com/emojis")
        writer.appendLine("// with https://gist.github.com/SalomonBrys/f1c21beefd9150bfd659ff8c59030c48")
        writer.appendLine("public object Emoji {")
        val map = LinkedHashMap<String, String>()
        obj.keySet().forEach { id ->
            val url = (obj[id] as JsonPrimitive).asString
            if (!url.startsWith(prefix)) return@forEach
            require(url.endsWith(suffix)) { url }
            val codePointsStr = url.removeSurrounding(prefix, suffix)
            val name = when {
                id[0] == '+' -> "plus${id.substring(1)}"
                id[0] == '-' -> "minus${id.substring(1)}"
                id[0] in "0123456789" -> "_$id"
                id == "package" -> "_package"
                else -> id
            } .replace('-', '_')
            map[id] = name
            val utf16Str = codePointsStr.split("-")
                .map { codePointStr ->
                    val codePoint = codePointStr.toIntOrNull(16) ?: error("Not Int: $codePointStr")
                    Character.toChars(codePoint).joinToString("") { "\\u${it.code.toString(16).padStart(4, '0')}" }
                }
                .joinToString("\\u200d")
            writer.appendLine("    public val $name: String = \"$utf16Str\" // U+$codePointsStr")
        }
        writer.appendLine("    private val map: Map<String, String> by lazy {")
        writer.appendLine("        mapOf(")
        map.forEach { id, name ->
            writer.appendLine("            \"$id\" to $name,")
        }
        writer.appendLine("        )")
        writer.appendLine("    }")
        writer.appendLine("    public operator fun get(id: String): String? = map[id]")
        writer.appendLine("}")
    }
}