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A collection of general utilities.
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/*
 * Copyright (c) 2013-2018, João Vitor Verona Biazibetti - All Rights Reserved
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see .
 *
 * https://www.github.com/BloodShura
 */

package com.github.bloodshura.x.utilities.eval;

import com.github.bloodshura.x.object.Base;
import com.github.bloodshura.x.util.XApi;
import com.github.bloodshura.x.utilities.eval.compiler.Compiler;
import com.github.bloodshura.x.utilities.eval.compiler.Tokenizer;
import com.github.bloodshura.x.utilities.eval.exception.EvaluationException;
import com.github.bloodshura.x.utilities.eval.operation.Operation;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.math.BigDecimal;

public class Expression extends Base {
	private Operation compiled;
	private String input;
	private VariableMap variableMap;

	public Expression() {
		this(null);
	}

	public Expression(@Nullable CharSequence input) {
		this(input, new VariableMap());
	}

	public Expression(@Nullable CharSequence input, @Nonnull VariableMap variableMap) {
		setInput(input);
		setVariableMap(variableMap);
	}

	public void addVariables(@Nonnull Object... variables) throws EvaluationException {
		addVariables(variables, 0, variables.length);
	}

	public void addVariables(@Nonnull Object[] variables, int offset, int length) throws EvaluationException {
		XApi.require(length % 2 == 0, "Object array length must be multiple of 2 (key, value, ...)");

		for (int i = offset; i < offset + length; i += 2) {
			Object key = variables[i];
			Object value = variables[i + 1];

			XApi.require(key instanceof String, "Expected argument " + i + " to be a String; received " + key.getClass().getName());

			String string = (String) key;

			if (value instanceof BigDecimal) {
				getVariableMap().set(string, (BigDecimal) value);
			}
			else if (value instanceof Number) {
				Number number = (Number) value;

				if (number instanceof Double || number instanceof Float) {
					getVariableMap().set(string, BigDecimal.valueOf(number.doubleValue()));
				}
				else {
					getVariableMap().set(string, BigDecimal.valueOf(number.longValue()));
				}
			}
			else if (value instanceof String) {
				getVariableMap().set(string, (String) value);
			}
			else {
				XApi.raise("Expected argument " + i + " to be a BigDecimal, Number or String; received " + value.getClass().getName());
			}
		}
	}

	public void compile() throws EvaluationException {
		if (isCompiled()) {
			return;
		}

		XApi.requireState(hasInput(), "No input set");

		Tokenizer tokenizer = new Tokenizer(getInput());

		this.compiled = Compiler.compile(tokenizer);
	}

	@Nonnull
	public BigDecimal evaluate() throws EvaluationException {
		compile();

		return compiled.evaluate(getVariableMap());
	}

	@Nullable
	public String getInput() {
		return input;
	}

	@Nonnull
	public VariableMap getVariableMap() {
		return variableMap;
	}

	public boolean hasInput() {
		return getInput() != null;
	}

	public boolean isCompiled() {
		return compiled != null;
	}

	public void setInput(@Nullable CharSequence input) {
		this.compiled = null;
		this.input = input != null ? input.toString() : null;
	}

	public void setVariableMap(@Nonnull VariableMap variableMap) {
		this.variableMap = variableMap;
	}

	@Nonnull
	@Override
	public String toString() {
		return hasInput() ? getInput() : "";
	}

	@Nonnull
	@Override
	protected Object[] stringValues() {
		return new Object[] { getInput() };
	}
}