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package com.oracle.truffle.js.nodes.array;

import java.util.Objects;

import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.object.DynamicObject;
import com.oracle.truffle.api.profiles.BranchProfile;
import com.oracle.truffle.js.nodes.JavaScriptBaseNode;
import com.oracle.truffle.js.nodes.access.ReadElementNode;
import com.oracle.truffle.js.runtime.JSContext;
import com.oracle.truffle.js.runtime.JSRuntime;
import com.oracle.truffle.js.runtime.array.ScriptArray;
import com.oracle.truffle.js.runtime.util.SimpleArrayList;

Converts a JS array to an Object[]. If the array is sparse or has holes, it is compacted to a dense array that consists of only actual elements. Used by Array.prototype.sort. /**
 * Converts a JS array to an Object[]. If the array is sparse or has holes, it is compacted to a
 * dense array that consists of only actual elements.
 *
 * Used by {@code Array.prototype.sort}.
 */
public abstract class JSArrayToDenseObjectArrayNode extends JavaScriptBaseNode {

    protected final JSContext context;

    protected JSArrayToDenseObjectArrayNode(JSContext context) {
        this.context = Objects.requireNonNull(context);
    }

    public static JSArrayToDenseObjectArrayNode create(JSContext context) {
        return JSArrayToDenseObjectArrayNodeGen.create(context);
    }

    public abstract Object[] executeObjectArray(DynamicObject array, ScriptArray arrayType, long length);

    @Specialization(guards = {"cachedArrayType.isInstance(arrayType)", "!cachedArrayType.isHolesType()", "!cachedArrayType.hasHoles(array)"}, limit = "5")
    protected Object[] fromDenseArray(DynamicObject array, @SuppressWarnings("unused") ScriptArray arrayType, long length,
                    @Cached("arrayType") @SuppressWarnings("unused") ScriptArray cachedArrayType,
                    @Cached("create(context)") ReadElementNode readNode) {
        assert JSRuntime.longIsRepresentableAsInt(length);
        int iLen = (int) length;

        Object[] arr = new Object[iLen];
        for (int index = 0; index < iLen; index++) {
            Object value = readNode.executeWithTargetAndIndex(array, index);
            arr[index] = value;
        }
        return arr;
    }

    @Specialization(guards = {"cachedArrayType.isInstance(arrayType)", "cachedArrayType.isHolesType() || cachedArrayType.hasHoles(array)"}, limit = "5")
    protected Object[] fromSparseArray(DynamicObject array, @SuppressWarnings("unused") ScriptArray arrayType, long length,
                    @Cached("arrayType") @SuppressWarnings("unused") ScriptArray cachedArrayType,
                    @Cached("create(context)") JSArrayNextElementIndexNode nextElementIndexNode,
                    @Cached BranchProfile growProfile) {
        long pos = cachedArrayType.firstElementIndex(array);
        SimpleArrayList<Object> list = new SimpleArrayList<>();
        while (pos <= cachedArrayType.lastElementIndex(array)) {
            assert cachedArrayType.hasElement(array, pos);
            list.add(cachedArrayType.getElement(array, pos), growProfile);
            pos = nextElementIndexNode.executeLong(array, pos, length);
        }
        return list.toArray(new Object[list.size()]);
    }

    @Specialization(replaces = {"fromDenseArray", "fromSparseArray"})
    protected Object[] doUncached(DynamicObject array, ScriptArray arrayType, long length,
                    @Cached("create(context)") JSArrayNextElementIndexNode nextElementIndexNode,
                    @Cached("create(context)") ReadElementNode readNode,
                    @Cached BranchProfile growProfile) {
        if (arrayType.isHolesType() || arrayType.hasHoles(array)) {
            return fromSparseArray(array, arrayType, length, arrayType, nextElementIndexNode, growProfile);
        } else {
            return fromDenseArray(array, arrayType, length, arrayType, readNode);
        }
    }
}