/********************************************************************************
 * Copyright (c) 2015-2019 Contributors to the Eclipse Foundation
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 ********************************************************************************/

package org.eclipse.mdm.api.base.model;

import java.time.LocalDateTime;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import java.util.function.Function;

import org.eclipse.mdm.api.base.adapter.Core;

/**
 * Implementation of an abstract parameter which holds a value with one of the
 * supported {@link ValueType}s listed below. The value is internally stored in
 * its {@code String} representation. Any modeled entity with such a use case
 * should extends this class. API consumers should never use this class in any
 * way, instead the implementations of this class have to be used.
 *
 * <ul>
 * <li>{@link ValueType#STRING}</li>
 * <li>{@link ValueType#DATE}</li>
 * <li>{@link ValueType#BOOLEAN}</li>
 * <li>{@link ValueType#BYTE}</li>
 * <li>{@link ValueType#SHORT}</li>
 * <li>{@link ValueType#INTEGER}</li>
 * <li>{@link ValueType#LONG}</li>
 * <li>{@link ValueType#FLOAT}</li>
 * <li>{@link ValueType#DOUBLE}</li>
 * <li>{@link ValueType#FLOAT_COMPLEX}</li>
 * <li>{@link ValueType#DOUBLE_COMPLEX}</li>
 * </ul>
 *
 * @since 1.0.0
 * @author Viktor Stoehr, Gigatronik Ingolstadt GmbH
 * @author Sebastian Dirsch, Gigatronik Ingolstadt GmbH
 * @see #getVirtualValue()
 * @see #setObjectValue(Object, Unit)
 * @see #setStringValue(String)
 * @see #setDateValue(LocalDateTime)
 * @see #setBooleanValue(Boolean)
 * @see #setByteValue(Byte, Unit)
 * @see #setShortValue(Short, Unit)
 * @see #setIntegerValue(Integer, Unit)
 * @see #setLongValue(Long, Unit)
 * @see #setFloatValue(Float, Unit)
 * @see #setDoubleValue(Double, Unit)
 * @see #setFloatComplexValue(FloatComplex, Unit)
 * @see #setDoubleComplexValue(DoubleComplex, Unit)
 */
public abstract class BaseParameter extends BaseEntity implements Deletable {

	private static final Map<ScalarType, Function<String, Object>> SCALARTYPE_FUNCTION_MAP = new HashMap<>();
	// ======================================================================
	// Instance variables
	// ======================================================================

	private final String attrScalarType;
	private final String attrValue;

	static {
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.STRING, v -> v);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.DATE, v -> LocalDateTime.parse(v, Value.LOCAL_DATE_TIME_FORMATTER));
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.BOOLEAN, Boolean::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.BYTE, Byte::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.SHORT, Short::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.INTEGER, Integer::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.LONG, Long::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.FLOAT, Float::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.DOUBLE, Double::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.FLOAT_COMPLEX, FloatComplex::valueOf);
		SCALARTYPE_FUNCTION_MAP.put(ScalarType.DOUBLE_COMPLEX, DoubleComplex::valueOf);
	}
	// ======================================================================
	// Constructors
	// ======================================================================

	/**
	 * Constructor.
	 *
	 * @param attrScalarType Name of the {@link ScalarType} attribute.
	 * @param attrValue      Name of the {@code String} value attribute.
	 * @param core           The {@link Core}.
	 */
	protected BaseParameter(String attrScalarType, String attrValue, Core core) {
		super(core);
		this.attrScalarType = attrScalarType;
		this.attrValue = attrValue;
	}

	// ======================================================================
	// Public methods
	// ======================================================================

	/**
	 * Creates a virtual representation of this parameter's value. This is done by
	 * converting the internally stored {@code String} value to type specified by
	 * this parameter's {@link ValueType} (the allowed types are listed below). The
	 * name of the returned virtual {@link Value} is the name of this parameter.
	 *
	 * <ul>
	 * <li>{@link ValueType#STRING}</li>
	 * <li>{@link ValueType#DATE}</li>
	 * <li>{@link ValueType#BOOLEAN}</li>
	 * <li>{@link ValueType#BYTE}</li>
	 * <li>{@link ValueType#SHORT}</li>
	 * <li>{@link ValueType#INTEGER}</li>
	 * <li>{@link ValueType#LONG}</li>
	 * <li>{@link ValueType#FLOAT}</li>
	 * <li>{@link ValueType#DOUBLE}</li>
	 * <li>{@link ValueType#FLOAT_COMPLEX}</li>
	 * <li>{@link ValueType#DOUBLE_COMPLEX}</li>
	 * </ul>
	 *
	 * <p>
	 * <b>Note:</b> The returned value is a virtual one and hence intended for
	 * displaying purposes only. To change this parameter's value one of its
	 * {@code setXYValue} methods has to be used.
	 *
	 * @return The created {@code Value} with the converted value is returned.
	 */
	public Value getVirtualValue() {
		ScalarType scalarType = getScalarType();
		Function<String, Object> typeConverter = SCALARTYPE_FUNCTION_MAP.get(scalarType);

		if (typeConverter == null) {
			return ValueType.UNKNOWN.create(getName());
		}

		Value parameterValue = getParameterValue();
		Object value = parameterValue.isValid() ? typeConverter.apply(parameterValue.extract()) : null;
		return scalarType.toSingleValueType().create(getName(), getUnitName(), parameterValue.isValid(), value);
	}

	/**
	 * Takes given value and determines its type. Finally value and the optional
	 * {@code Unit} are passed to the corresponding {@code setXYValue(XY)} method as
	 * listed below. The value is allowed to be an instance of the following types:
	 * {@code String}, {@code LocalDateTime}, {@code Boolean}, {@code Byte},
	 * {@code Short}, {@code Integer}, {@code Long}, {@code Float}, {@code Double},
	 * {@code FloatComplex} and {@code DoubleComplex}.
	 *
	 * <p>
	 * <b>Note:</b> If the given value is an instance of {@code String}, {@code
	 * LocalDateTime} or a {@code Boolean}, then the given unit is ignored.
	 *
	 * @param value The new value for this parameter is not allowed to be null.
	 * @param unit  The optionally related {@code Unit}.
	 * @throws IllegalArgumentException Thrown if the given value is not supported.
	 * @see #setStringValue(String)
	 * @see #setDateValue(LocalDateTime)
	 * @see #setBooleanValue(Boolean)
	 * @see #setByteValue(Byte, Unit)
	 * @see #setShortValue(Short, Unit)
	 * @see #setIntegerValue(Integer, Unit)
	 * @see #setLongValue(Long, Unit)
	 * @see #setFloatValue(Float, Unit)
	 * @see #setDoubleValue(Double, Unit)
	 * @see #setFloatComplexValue(FloatComplex, Unit)
	 * @see #setDoubleComplexValue(DoubleComplex, Unit)
	 */
	public void setObjectValue(Object value, Unit unit) {
		if (value instanceof String) {
			setStringValue((String) value);
		} else if (value instanceof LocalDateTime) {
			setDateValue((LocalDateTime) value);
		} else if (value instanceof Boolean) {
			setBooleanValue((Boolean) value);
		} else if (value instanceof Byte) {
			setByteValue((Byte) value, unit);
		} else if (value instanceof Short) {
			setShortValue((Short) value, unit);
		} else if (value instanceof Integer) {
			setIntegerValue((Integer) value, unit);
		} else if (value instanceof Long) {
			setLongValue((Long) value, unit);
		} else if (value instanceof Float) {
			setFloatValue((Float) value, unit);
		} else if (value instanceof Double) {
			setDoubleValue((Double) value, unit);
		} else if (value instanceof FloatComplex) {
			setFloatComplexValue((FloatComplex) value, unit);
		} else if (value instanceof DoubleComplex) {
			setDoubleComplexValue((DoubleComplex) value, unit);
		} else {
			throw new IllegalArgumentException(
					"Value '" + value + "' of type '" + value.getClass().getSimpleName() + "' is not supported.");
		}
	}

	/**
	 * Replaces current value with given {@code String} value. Any existing relation
	 * to a {@link Unit} will be removed.
	 *
	 * @param value The new value for this parameter.
	 */
	public void setStringValue(String value) {
		setScalarType(ScalarType.STRING);
		getParameterValue().set(value);
		setUnit(null);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code LocalDateTime}. Any existing relation to a {@link Unit} will be
	 * removed.
	 *
	 * @param value The new value for this parameter.
	 */
	public void setDateValue(LocalDateTime value) {
		setScalarType(ScalarType.DATE);
		getParameterValue().set(value.format(Value.LOCAL_DATE_TIME_FORMATTER));
		setUnit(null);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Boolean}. Any existing relation to a {@link Unit} will be removed.
	 *
	 * @param value The new value for this parameter.
	 */
	public void setBooleanValue(Boolean value) {
		setScalarType(ScalarType.BOOLEAN);
		getParameterValue().set(value.toString());
		setUnit(null);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Byte}. Any existing relation to a {@link Unit} will be replaced with
	 * the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setByteValue(Byte value, Unit unit) {
		setScalarType(ScalarType.BYTE);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Short}. Any existing relation to a {@link Unit} will be replaced with
	 * the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setShortValue(Short value, Unit unit) {
		setScalarType(ScalarType.SHORT);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Integer}. Any existing relation to a {@link Unit} will be replaced
	 * with the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setIntegerValue(Integer value, Unit unit) {
		setScalarType(ScalarType.INTEGER);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Long}. Any existing relation to a {@link Unit} will be replaced with
	 * the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setLongValue(Long value, Unit unit) {
		setScalarType(ScalarType.LONG);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Float}. Any existing relation to a {@link Unit} will be replaced with
	 * the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setFloatValue(Float value, Unit unit) {
		setScalarType(ScalarType.FLOAT);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code Double}. Any existing relation to a {@link Unit} will be replaced with
	 * the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setDoubleValue(Double value, Unit unit) {
		setScalarType(ScalarType.DOUBLE);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code FloatComplex}. Any existing relation to a {@link Unit} will be
	 * replaced with the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setFloatComplexValue(FloatComplex value, Unit unit) {
		setScalarType(ScalarType.FLOAT_COMPLEX);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * Replaces current value with the {@code String} representation of given
	 * {@code DoubleComplex}. Any existing relation to a {@link Unit} will be
	 * replaced with the given one.
	 *
	 * @param value The new value for this parameter.
	 * @param unit  The relation to a unit is optional.
	 */
	public void setDoubleComplexValue(DoubleComplex value, Unit unit) {
		setScalarType(ScalarType.DOUBLE_COMPLEX);
		getParameterValue().set(value.toString());
		setUnit(unit);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder(getClass().getSimpleName()).append("(Name = ").append(getName());

		sb.append(", Value = ");
		Value parameterValue = getParameterValue();
		if (parameterValue.isValid()) {
			sb.append((String) getParameterValue().extract());
		}

		Optional<Unit> unit = getUnit();
		if (unit.isPresent()) {
			sb.append(" [").append(unit.get().getName()).append(']');
		}

		return sb.append(')').toString();
	}

	// ======================================================================
	// Private methods
	// ======================================================================

	/**
	 * Returns the {@link Value} of this parameter.
	 *
	 * @return This parameter's {@code Value} is returned.
	 */
	private Value getParameterValue() {
		return getValue(attrValue);
	}

	/**
	 * Returns the scalar value type of this parameter.
	 *
	 * @return This parameter's scalar type is returned.
	 */
	private ScalarType getScalarType() {
		return getValue(attrScalarType).extract();
	}

	/**
	 * Sets new scalar type for this parameter.
	 *
	 * @param scalarType The new {@code ScalarType}.
	 */
	private void setScalarType(ScalarType scalarType) {
		getValue(attrScalarType).set(scalarType);
	}

	/**
	 * Returns the name of the related {@link Unit}. If no {@code Unit} is related,
	 * an empty {@code String} is returned instead.
	 *
	 * @return The name of the related {@code Unit} is returned or an empty
	 *         {@code String}.
	 */
	private String getUnitName() {
		Optional<Unit> unit = getUnit();
		if (unit.isPresent()) {
			return unit.get().getName();
		}

		return "";
	}

	/**
	 * Returns an optionally related {@link Unit}.
	 *
	 * @return The returned {@code Optional} is empty if no {@code Unit} is related.
	 */
	private Optional<Unit> getUnit() {
		return Optional.ofNullable(getCore().getMutableStore().get(Unit.class));
	}

	/**
	 * Replaces current {@link Unit} relation with the given one, if the {@code
	 * Optional} is not empty. Otherwise any current relations is removed.
	 *
	 * @param unit The new {@code Unit} may be {@code null}.
	 */
	private void setUnit(Unit unit) {
		if (unit == null) {
			getCore().getMutableStore().remove(Unit.class);
		} else {
			getCore().getMutableStore().set(unit);
		}
	}

}