package tudelft.mentalhealth.motivatepersisting;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Random;

import tudelft.utilities.statistic.WeightedSet;

/**
 * contains Table 1/ Statements-nl-NL.csv or Statements=en.csv: the Statements
 * table with all available statements. The .csv files contain rows with 4
 * columns of data:
 * <ol>
 * <li>New Category
 * <li>New subcat
 * <li>Count
 * <li>Statement (correct language)
 * </ol>
 */
class Statements {

	// contains for each Category and Subcategory a set of statements.
	private final Map<Category, Map<Subcategory, WeightedSet<String>>> statements;
	private static final Random random = new Random();

	public Statements(Locale locale) {
		statements = readTable(locale);
	}

	/**
	 * 
	 * @param cat    required {@link Category}
	 * @param subcat required {@link Subcategory}
	 * @return all statements for given category and subcategory.
	 */
	public WeightedSet<String> getStatements(Category cat, Subcategory subcat) {
		return statements.get(cat).get(subcat);
	}

	/**
	 * read in the CSV table
	 * 
	 * @return map containing the CSV file contents.
	 * @throws IOException
	 */
	private Map<Category, Map<Subcategory, WeightedSet<String>>> readTable(
			Locale locale) {
		Map<Category, Map<Subcategory, WeightedSet<String>>> table = new HashMap<>();
		String filename = "Statements-" + locale.toLanguageTag() + ".csv";
		InputStream is = getClass().getResourceAsStream(filename);
		if (is == null) {
			throw new IllegalStateException("Resource not found: " + filename);
		}

		BufferedReader reader = new BufferedReader(new InputStreamReader(is));
		reader.lines().forEach(line -> addLine(line, table));
		return table;

	}

	/**
	 * Add one line of comma-separated text (typically from csv file) to given
	 * table.
	 * 
	 * @param line  the line of text, containing Category, Subcategory, text.
	 * @param table the table to add the info in the line to
	 */
	private void addLine(String line,
			Map<Category, Map<Subcategory, WeightedSet<String>>> table) {
		String[] values = line.split(",", 4);
		Category cat = Category.valueOf(values[0]);

		Subcategory subcat;
		if (values[1].isEmpty()) {
			subcat = Subcategory.ALL;
			if (!cat.getSubCategories().isEmpty()) {
				throw new IllegalArgumentException("Category " + cat
						+ " has subcategories, so ALL is not allowed in this table here:"
						+ line);
			}
		} else {
			subcat = Subcategory.valueOf(values[1]);
			if (!cat.isSubcategoryAllowed(subcat)) {
				throw new IllegalArgumentException(
						"" + subcat + " is not allowed as subcategory of " + cat
								+ " here :" + line);
			}
		}

		if (!table.containsKey(cat)) {
			table.put(cat, new HashMap<>());
		}
		WeightedSet<String> map = table.get(cat).get(subcat);
		Double count;
		try {
			count = Double.valueOf(values[2]);
		} catch (NumberFormatException e) {
			throw new IllegalArgumentException("'" + values[2]
					+ "' is not a good line count value here :" + line);

		}

		if (map != null) {
			map = map.add(values[3].trim(), count);
		} else {
			Map<String, Double> first = new HashMap<>();
			first.put(values[3].trim(), count);
			map = new WeightedSet<String>(first);
		}
		table.get(cat).put(subcat, map);
	}

	/**
	 * @param category    the {@link Category} required
	 * @param subcategory the subcategory, or {@link Subcategory#ALL} if the
	 *                    category has no subcategory.
	 * @return text string that matches the Category and Subcategory as
	 *         specified. Thee chosen text is weighted according to the count
	 *         field of the text lines. Subsequent calls may return different
	 *         results.
	 */
	public String getText(Category category, Subcategory subcategory) {
		return getStatements(category, subcategory).getRandom();
	}

}