Add charsetter project

charsetter/build.gradle

@@ -0,0 +1,14 @@
+plugins {
+    id 'java'
+    id "org.moditect.gradleplugin" version "1.0.0-rc3"
+}
+
+apply from: "$rootDir/deps/java.gradle"
+apply from: "$rootDir/deps/commons.gradle"
+apply from: "$rootDir/deps/junit.gradle"
+apply from: "$rootDir/deps/lombok.gradle"
+
+configurations {
+    compileOnly.extendsFrom(dep)
+}
+

charsetter/src/main/java/io/xpipe/charsetter/Charsettable.java

@@ -0,0 +1,8 @@
+package io.xpipe.charsetter;
+
+import java.nio.charset.Charset;
+
+public interface Charsettable {
+
+    Charset getCharset();
+}

charsetter/src/main/java/io/xpipe/charsetter/Charsetter.java

@@ -0,0 +1,74 @@
+package io.xpipe.charsetter;
+
+import org.apache.commons.io.ByteOrderMark;
+import org.apache.commons.io.input.BOMInputStream;
+import org.apache.commons.lang3.function.FailableBiConsumer;
+import org.apache.commons.lang3.function.FailableSupplier;
+
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.*;
+
+public class Charsetter {
+
+    private static CharsetterUniverse universe;
+    private static final int MAX_BYTES = 8192;
+
+    public static void init(CharsetterContext ctx) {
+        universe = CharsetterUniverse.create(ctx);
+    }
+
+    private static void checkInit() {
+        if (universe == null) {
+            throw new IllegalStateException("Charsetter not initialized");
+        }
+    }
+
+    public static Charset read(FailableSupplier<InputStream, Exception> in, FailableBiConsumer<InputStream, Charset, Exception> con) throws Exception {
+        checkInit();
+
+        try (var is = in.get();
+             var bin = new BOMInputStream(is)) {
+            ByteOrderMark bom = bin.getBOM();
+            String charsetName = bom == null ? null : bom.getCharsetName();
+            var charset = charsetName != null ? Charset.forName(charsetName) : null;
+
+            if (charset == null) {
+                bin.mark(MAX_BYTES);
+                var bytes = bin.readNBytes(MAX_BYTES);
+                bin.reset();
+                charset = inferCharset(bytes);
+            }
+
+            if (con != null) {
+                con.accept(bin, charset);
+            }
+            return charset;
+        }
+    }
+
+    public static Charset inferCharset(byte[] content) {
+        checkInit();
+
+        for (Charset c : universe.getCharsets()) {
+            CharsetDecoder decoder = c.newDecoder();
+            decoder.onMalformedInput(CodingErrorAction.REPORT);
+            decoder.onUnmappableCharacter(CodingErrorAction.REPORT);
+
+            ByteBuffer byteBuf = ByteBuffer.wrap(content);
+            CharBuffer charBuf = CharBuffer.allocate(byteBuf.capacity() * 2);
+
+            CoderResult coderResult = decoder.decode(byteBuf, charBuf, false);
+            if (coderResult != null) {
+                if (coderResult.isError()) {
+                    continue;
+                }
+            }
+
+            return c;
+        }
+
+        return StandardCharsets.UTF_8;
+    }
+}

charsetter/src/main/java/io/xpipe/charsetter/CharsetterContext.java

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+package io.xpipe.charsetter;
+
+import lombok.AllArgsConstructor;
+import lombok.Value;
+
+import java.util.List;
+import java.util.Locale;
+
+@Value
+@AllArgsConstructor
+public class CharsetterContext {
+
+    String systemCharsetName;
+
+    Locale systemLocale;
+
+    Locale appLocale;
+
+    List<String> observedCharsets;
+}

charsetter/src/main/java/io/xpipe/charsetter/CharsetterUniverse.java

@@ -0,0 +1,32 @@
+package io.xpipe.charsetter;
+
+import lombok.AllArgsConstructor;
+import lombok.Value;
+
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+
+@Value
+@AllArgsConstructor
+public class CharsetterUniverse {
+
+    List<Charset> charsets;
+
+    public static CharsetterUniverse create(CharsetterContext ctx) {
+        List<Charset> cs = new ArrayList<>();
+
+        cs.add(StandardCharsets.UTF_8);
+
+        var system = Charset.forName(ctx.getSystemCharsetName());
+        cs.add(system);
+
+        // TODO: Locales
+
+        var observed = ctx.getObservedCharsets().stream().map(Charset::forName).toList();
+        cs.addAll(observed);
+
+        return new CharsetterUniverse(cs);
+    }
+}

charsetter/src/main/java/module-info.java

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+module io.xpipe.charsetter {
+    exports io.xpipe.charsetter;
+
+    requires org.apache.commons.io;
+    requires org.apache.commons.lang3;
+    requires static lombok;
+}