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 * The Universal Permissive License (UPL), Version 1.0
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 * person obtaining a copy of this software, associated documentation and/or
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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
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package org.graalvm.wasm.api;

import org.graalvm.wasm.exception.Failure;
import org.graalvm.wasm.exception.WasmException;
import org.graalvm.wasm.exception.WasmJsApiException;
import org.graalvm.wasm.memory.UnsafeWasmMemory;
import org.graalvm.wasm.memory.WasmMemory;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.interop.InteropLibrary;
import com.oracle.truffle.api.interop.UnknownIdentifierException;
import com.oracle.truffle.api.interop.UnsupportedMessageException;

public class Memory extends Dictionary {
    private final MemoryDescriptor descriptor;
    private final WasmMemory memory;

    public Memory(WasmMemory memory) {
        this.descriptor = new MemoryDescriptor(memory.pageSize(), memory.maxPageSize());
        this.memory = memory;
        addMembers(new Object[]{
                        "descriptor", this.descriptor,
                        "grow", new Executable(args -> grow((Integer) args[0])),
                        "buffer", new Executable(args -> new MemoryArrayBuffer(memory)),
        });
    }

    public Memory(Object descriptor) {
        this(new UnsafeWasmMemory(initial(descriptor), maximum(descriptor)));
    }

    private static int initial(Object descriptor) {
        try {
            return (int) InteropLibrary.getUncached().readMember(descriptor, "initial");
        } catch (UnsupportedMessageException | UnknownIdentifierException e) {
            throw new WasmJsApiException(WasmJsApiException.Kind.TypeError, "Invalid memory descriptor " + descriptor);
        }
    }

    private static int maximum(Object descriptor) {
        try {
            return (int) InteropLibrary.getUncached().readMember(descriptor, "maximum");
        } catch (UnsupportedMessageException | UnknownIdentifierException e) {
            throw new WasmJsApiException(WasmJsApiException.Kind.TypeError, "Invalid memory descriptor " + descriptor);
        }
    }

    public WasmMemory wasmMemory() {
        return memory;
    }

    @TruffleBoundary
    private static WasmException rangeError() {
        return WasmException.create(Failure.UNSPECIFIED_INTERNAL, "Range error.");
    }

    private long grow(int delta) {
        final long pageSize = memory.pageSize();
        if (!memory.grow(delta)) {
            throw rangeError();
        }
        return pageSize;
    }
}