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/*
 * Code licensed under new-style BSD (see LICENSE).
 * All code up to tags/original: Copyright (c) 2006, Wojciech Gradkowski
 * All code after tags/original: Copyright (c) 2015, DiffPlug
 */
package com.jmatio.common.util;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.jmatio.types.MLArray;
import com.jmatio.types.MLCell;
import com.jmatio.types.MLChar;
import com.jmatio.types.MLNumericArray;
import com.jmatio.types.MLObject;
import com.jmatio.types.MLStructure;

/**
 * The JMatIO query parser. Allows to use Matlab-like syntax to access {@link MLArray} objects. 
 * 
 * 
 * @author wgradkowski
 *
 */
public class MLArrayQuery {
	private String queryString;

	private static final String regexp = "([a-zA-Z0-9]+)(\\(([0-9]+|:)(,([0-9:]+|:))?\\))?\\.?";
	private static final Pattern pat = Pattern.compile(regexp);

	public MLArrayQuery(String queryString) {
		if (!Pattern.matches("^(" + regexp + ")+$", queryString)) {
			throw new IllegalArgumentException();
		}

		this.queryString = queryString;
	}

	/**
	 * 
	 * 
	 * @param array
	 * @param query
	 * @return
	 */
	public static Object q(MLArray array, String query) {
		MLArrayQuery q = new MLArrayQuery(query);

		return q.query(array);
	}

	/**
	 * Parses the query string and returns the object it refers to.
	 * 
	 * @param array
	 *            source {@link MLArray}
	 * @return query result
	 */
	public Object query(MLArray array) {
		Matcher mat = pat.matcher(queryString);

		MLArray current = null;

		int prevM = 0;
		int prevN = 0;

		while (mat.find()) {
			String name = mat.group(1);
			String rangeM = mat.group(3);
			String rangeN = mat.group(5);

			int m = rangeM != null ? Integer.parseInt(rangeM) - 1 : -1;
			int n = rangeN != null ? Integer.parseInt(rangeN) - 1 : -1;

			if (current == null) {
				current = array;

				if (!current.getName().equals(name) && !current.getName().equals(MLArray.DEFAULT_NAME)) {
					throw new RuntimeException("No such array or field <" + name + "> in <" + current.getName() + ">");
				}

				prevM = m;
				prevN = n;

				continue;
			}

			int type = current.getType();

			switch (type) {
			case MLArray.mxOBJECT_CLASS: {
				MLObject object = cast(current, MLObject.class);
				MLArray field = object.getField(name);
				if (field == null) {
					throw new RuntimeException("no such field: " + name);
				}
				current = field;
			}
				break;
			case MLArray.mxSTRUCT_CLASS: {
				MLStructure struct = cast(current, MLStructure.class);
				MLArray field = struct.getField(name, prevM > 0 ? prevM : 0, prevN > 0 ? prevN : 0);
				if (field == null) {
					throw new RuntimeException("no such field: " + name);
				}
				current = field;
			}
				break;
			case MLArray.mxCELL_CLASS: {
				MLCell mlcell = cast(current, MLCell.class);
				if (m > -1 && n > -1) {
					current = mlcell.get(m, n);
				} else if (m > -1) {
					current = mlcell.get(m);
				} else {
					throw new RuntimeException();
				}
			}
				break;
			default:
			}
			prevM = m;
			prevN = n;
		}

		return getContent(current, prevM, prevN);
	}

	/**
	 * Returns the content of the field/cell/object.
	 * 
	 * @param array
	 *            the parent structure/cell
	 * @param m
	 *            column or -1
	 * @param n
	 *            row or -1
	 * @return if both m and n are -1, returns {@link MLArray}, if n is -1, returns
	 *         content under index m, if both m and n are not-negative, returns
	 *         content of (m,n)
	 */
	public Object getContent(MLArray array, int m, int n) {
		int type = array.getType();

		Object result = null;

		switch (type) {
		case MLArray.mxINT8_CLASS:
		case MLArray.mxINT16_CLASS:
		case MLArray.mxINT32_CLASS:
		case MLArray.mxINT64_CLASS:
		case MLArray.mxUINT8_CLASS:
		case MLArray.mxUINT16_CLASS:
		case MLArray.mxUINT32_CLASS:
		case MLArray.mxUINT64_CLASS:
		case MLArray.mxSINGLE_CLASS:
		case MLArray.mxDOUBLE_CLASS:
			MLNumericArray numeric = cast(array, MLNumericArray.class);
			if (m > -1 && n > -1) {
				result = numeric.get(m, n);
			} else if (m > -1) {
				result = numeric.get(m);
			} else {
				result = array;
			}
			break;
		case MLArray.mxCHAR_CLASS:
			MLChar mlchar = cast(array, MLChar.class);
			if (m > -1 && n > -1) {
				result = mlchar.getChar(m, n);
			} else if (m > -1) {
				result = mlchar.getString(m);
			} else {
				result = mlchar;
			}
			break;
		case MLArray.mxCELL_CLASS:
			MLCell mlcell = cast(array, MLCell.class);
			if (m > -1 && n > -1) {
				result = getContent(mlcell.get(m, n), 0, -1);
			} else if (m > -1) {
				result = getContent(mlcell.get(m), 0, -1);
			} else {
				result = getContent(mlcell.get(0), -1, -1);
			}
			break;
		default:
			result = array;
		}
		return result;
	}

	/** Performs a checked cast to keep FindBugs happy. */
	@SuppressWarnings("unchecked")
	private static  T cast(Object o, Class clazz) {
		if (o.getClass().isAssignableFrom(clazz)) {
			return (T) o;
		} else {
			throw new ClassCastException(o.getClass().toString());
		}
	}
}