Keep fractional numbers when saving JSON array subscriptions (#6293)

* Keep fractional numbers when saving JSON array subscriptions

toJsonPretty wrote every Double through toInt(), so 0.4 became 0 and
values above Int.MAX_VALUE were clamped. Write whole numbers as Long
and leave other values as Double.

Fixes #6291

* Add a JsonUtil test for numbers in config arrays

* Update JsonUtil.kt

---------

Co-authored-by: 2dust <31833384+2dust@users.noreply.github.com>

V2rayNG/app/src/main/java/com/v2ray/ang/util/JsonUtil.kt

@@ -7,6 +7,7 @@ import com.google.gson.JsonParser
 import com.google.gson.JsonPrimitive
 import com.google.gson.JsonSerializationContext
 import com.google.gson.JsonSerializer
+import com.google.gson.ToNumberPolicy
 import com.google.gson.reflect.TypeToken
 import com.v2ray.ang.AppConfig
 import java.lang.reflect.Type
@@ -64,12 +65,15 @@ object JsonUtil {
         val gsonPre = GsonBuilder()
             .setPrettyPrinting()
             .disableHtmlEscaping()
+            .setObjectToNumberStrategy(ToNumberPolicy.LONG_OR_DOUBLE)
             .registerTypeAdapter( // custom serializer is needed here since JSON by default parse number as Double, core will fail to start
                 object : TypeToken<Double>() {}.type,
                 JsonSerializer { src: Double?, _: Type?, _: JsonSerializationContext? ->
-                    JsonPrimitive(
-                        src?.toInt()
-                    )
+                    when (src) {
+                        null -> null
+                        src.toLong().toDouble() -> JsonPrimitive(src.toLong())
+                        else -> JsonPrimitive(src)
+                    }
                 }
             )
             .create()

V2rayNG/app/src/test/java/com/v2ray/ang/util/JsonUtilTest.kt

@@ -0,0 +1,24 @@
+package com.v2ray.ang.util
+
+import com.google.gson.JsonParser
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class JsonUtilTest {
+
+    @Test
+    fun toJsonPrettyKeepsNumbersOfConfigArrayElements() {
+        val configs = JsonUtil.fromJson(
+            """[{"port":443,"tolerance":0.4,"offset":-0.5,"timestamp":1700000000000,"name":"0.4"}]""",
+            Array<Any>::class.java
+        )
+
+        val output = JsonParser.parseString(JsonUtil.toJsonPretty(configs!![0])).asJsonObject
+
+        assertEquals("443", output["port"].asString)
+        assertEquals("0.4", output["tolerance"].asString)
+        assertEquals("-0.5", output["offset"].asString)
+        assertEquals("1700000000000", output["timestamp"].asString)
+        assertEquals("0.4", output["name"].asString)
+    }
+}