Overgram/src/main/java/io/github/lonamiwebs/overgram/generator/Generator.java

package io.github.lonamiwebs.overgram.generator;

import io.github.lonamiwebs.overgram.parser.TLArg;
import io.github.lonamiwebs.overgram.parser.TLObject;

import java.io.*;
import java.util.*;

public class Generator {

    private static final String VARIABLE_SUFFIX = "$";

    public static void generateJava(
            final List<TLObject> types, final List<TLObject> functions,
            final File abstractsFile, final File typesFile, final File functionsFile) throws IOException {
        makeParents(abstractsFile, typesFile, functionsFile);
        try (final Writer writer = new BufferedWriter(new FileWriter(abstractsFile))) {
            writeAbstract(writer, types);
        }
        try (final Writer writer = new BufferedWriter(new FileWriter(typesFile))) {
            writeCode(writer, "Types", null, types);
        }
        try (final Writer writer = new BufferedWriter(new FileWriter(functionsFile))) {
            writeCode(writer, "Functions", "TLRequest", functions);
        }
    }

    private static void writeAbstract(final Writer writer, final List<TLObject> objects) throws IOException {
        writer.write("package io.github.lonamiwebs.overgram.tl;\n");
        writer.write("@SuppressWarnings(\"unused\")\n");
        writer.write("public class Abstract {\n");
        for (final Map.Entry<String, List<String>> nsNames : stringsByNamespace(uniqueTypes(objects)).entrySet()) {
            if (!nsNames.getKey().isEmpty()) {
                writer.write("public static class ");
                writer.write(nsNames.getKey());
                writer.write(" {\n");
            }
            for (final String name : nsNames.getValue()) {
                writer.write("public static abstract class ");
                writer.write(TLObject.toCamelCase(name));
                writer.write(" extends TLObject {}\n");
            }
            if (!nsNames.getKey().isEmpty()) {
                writer.write("}\n");
            }
        }
        writer.write("}\n");
    }

    private static void writeCode(
            final Writer writer, final String className, final String extendsName,
            final List<TLObject> objects) throws IOException {
        writer.write("package io.github.lonamiwebs.overgram.tl;\n");
        writer.write("import io.github.lonamiwebs.overgram.utils.BinaryReader;\n");
        writer.write("import io.github.lonamiwebs.overgram.utils.BinaryWriter;\n");
        writer.write("import java.util.List;\n");
        writer.write("@SuppressWarnings(\"unused\")\n");
        writer.write("public class ");
        writer.write(className);
        writer.write(" {\n");
        for (final Map.Entry<String, List<TLObject>> nsObjects : byNamespace(objects).entrySet()) {
            if (!nsObjects.getKey().isEmpty()) {
                writer.write("public static class ");
                writer.write(nsObjects.getKey());
                writer.write(" {\n");
            }
            for (final TLObject object : nsObjects.getValue()) {
                writer.write("public static class ");
                writer.write(TLObject.toCamelCase(object.name));
                writer.write(" extends ");
                if (extendsName == null) {
                    writer.write("Abstract.");
                    writer.write(TLObject.toCamelCase(object.type));
                } else {
                    writer.write(extendsName);
                }
                writer.write(" {\n");

                for (int i = 0; i < object.args.size(); ++i) {
                    if (object.args.get(i).flags) {
                        continue;
                    }
                    writer.write("private ");
                    writer.write(object.args.get(i).javaType());
                    writer.write(" " + VARIABLE_SUFFIX + i);
                    writer.write(";\n");
                }

                writer.write("public ");
                writer.write(TLObject.toCamelCase(object.name));
                writer.write("() {}\n");

                // Use the builder pattern because Java is stupid and has no optional named arguments.
                // Objects will be created with nothing set and the arguments set with .argument(value).
                // TODO

                writeSerialize(writer, object);
                writer.write("public void deserialize(final BinaryReader reader) {}\n");

                writer.write("}\n");
            }
            if (!nsObjects.getKey().isEmpty()) {
                writer.write("}\n");
            }
        }
        writer.write("}\n");
    }

    private static void writeSerialize(final Writer writer, final TLObject object) throws IOException {
        writer.write("public void serialize(final BinaryWriter writer) {\n");
        for (final TLArg arg : object.args) {
            if (arg.flags) {
                writer.write("int ");
                writer.write(arg.name);
                writer.write(" = 0;\n");
            }
        }
        for (int i = 0; i < object.args.size(); ++i) {
            final TLArg arg = object.args.get(i);
            if (arg.flag != null) {
                writer.write("if (" + VARIABLE_SUFFIX + i);
                writer.write(arg.javaSetCheck());
                writer.write(") { ");
                writer.write(arg.flag.flagName);
                writer.write(" |= " + (1 << arg.flag.flagIndex));
                writer.write("; }\n");
            }
        }
        for (int i = 0; i < object.args.size(); ++i) {
            final TLArg arg = object.args.get(i);
            if (arg.flag != null) {
                writer.write("if (" + VARIABLE_SUFFIX + i);
                writer.write(arg.javaSetCheck());
                writer.write(") { ");
            }
            if (!arg.flags) {
                writer.write("writer.write(" + VARIABLE_SUFFIX + i + ");");
            } else {
                writer.write("writer.write(");
                writer.write(arg.name);
                writer.write(");");
            }
            if (arg.flag != null) {
                writer.write(" }\n");
            } else {
                writer.write('\n');
            }
        }
        writer.write("}\n");
    }

    private static Map<String, List<TLObject>> byNamespace(final Iterable<TLObject> objects) {
        final Map<String, List<TLObject>> result = new HashMap<>();
        for (final TLObject object : objects) {
            result.computeIfAbsent(object.namespace, k -> new ArrayList<>()).add(object);
        }
        return result;
    }

    private static Map<String, List<String>> stringsByNamespace(final Iterable<String> strings) {
        final Map<String, List<String>> result = new HashMap<>();

        String[] tmp;
        String namespace;
        String name;
        for (final String string : strings) {
            tmp = string.split("\\.");
            if (tmp.length == 1) {
                namespace = "";
                name = tmp[0];
            } else {
                namespace = tmp[0];
                name = tmp[1];
            }
            result.computeIfAbsent(namespace, k -> new ArrayList<>()).add(name);
        }
        return result;
    }

    private static Set<String> uniqueTypes(final List<TLObject> objects) {
        final Set<String> result = new HashSet<>();
        for (final TLObject object : objects) {
            result.add(object.type);
        }
        return result;
    }

    private static void makeParents(final File... files) throws IOException {
        for (File file : files) {
            file = file.getAbsoluteFile().getParentFile();
            if (!file.isDirectory()) {
                if (!file.mkdirs()) {
                    throw new IOException("Failed to create " + file);
                }
            }
        }
    }
}