87 lines
3.1 KiB
Kotlin
87 lines
3.1 KiB
Kotlin
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package moe.nea.firmament.util
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import java.util.*
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import kotlinx.serialization.DeserializationStrategy
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import kotlinx.serialization.SerializationStrategy
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import kotlinx.serialization.json.Json
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import kotlinx.serialization.serializer
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import moe.nea.firmament.Firmament
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object TemplateUtil {
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@JvmStatic
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fun getTemplatePrefix(data: String): String? {
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val decoded = maybeFromBase64Encoded(data) ?: return null
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return decoded.replaceAfter("/", "", "").ifBlank { null }
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}
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@JvmStatic
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fun intoBase64Encoded(raw: String): String {
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return Base64.getEncoder().encodeToString(raw.encodeToByteArray())
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}
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private val base64Alphabet = charArrayOf(
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
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'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', '='
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)
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@JvmStatic
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fun maybeFromBase64Encoded(raw: String): String? {
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val raw = raw.trim()
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if (raw.any { it !in base64Alphabet }) {
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return null
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}
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return try {
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Base64.getDecoder().decode(raw).decodeToString()
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} catch (ex: Exception) {
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null
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}
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}
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/**
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* Returns a base64 encoded string, truncated such that for all `x`, `x.startsWith(prefix)` implies
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* `base64Encoded(x).startsWith(getPrefixComparisonSafeBase64Encoding(prefix))`
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* (however, the inverse may not always be true).
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*/
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@JvmStatic
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fun getPrefixComparisonSafeBase64Encoding(prefix: String): String {
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val rawEncoded =
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Base64.getEncoder().encodeToString(prefix.encodeToByteArray())
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.replace("=", "")
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return rawEncoded.substring(0, rawEncoded.length - rawEncoded.length % 4)
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}
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inline fun <reified T> encodeTemplate(sharePrefix: String, data: T): String =
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encodeTemplate(sharePrefix, data, serializer())
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fun <T> encodeTemplate(sharePrefix: String, data: T, serializer: SerializationStrategy<T>): String {
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require(sharePrefix.endsWith("/"))
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return intoBase64Encoded(sharePrefix + Firmament.tightJson.encodeToString(serializer, data))
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}
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inline fun <reified T : Any> maybeDecodeTemplate(sharePrefix: String, data: String): T? =
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maybeDecodeTemplate(sharePrefix, data, serializer())
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fun <T : Any> maybeDecodeTemplate(sharePrefix: String, data: String, serializer: DeserializationStrategy<T>): T? {
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require(sharePrefix.endsWith("/"))
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val data = data.trim()
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if (!data.startsWith(getPrefixComparisonSafeBase64Encoding(sharePrefix)))
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return null
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val decoded = maybeFromBase64Encoded(data) ?: return null
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if (!decoded.startsWith(sharePrefix))
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return null
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return try {
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Firmament.json.decodeFromString<T>(serializer, decoded.substring(sharePrefix.length))
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} catch (e: Exception) {
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null
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}
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}
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}
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