package com.redhat.thermostat.tools.eclipse.plugin.editor;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.eclipse.core.databinding.conversion.Converter;

public class Converters {

    /**
     * Converts a {@link List}{@code <String>} to a single {@code String} by
     * joining all the items in the list with a single space.
     */
    public static class ListToStringConverter extends Converter {

        public ListToStringConverter() {
            super(List.class, String.class);
        }

        @Override
        public String convert(Object fromObject) {
            if (!(fromObject instanceof List)) {
                throw new AssertionError("Only List objects can be converted");
            }
            List<String> list = (List<String>) fromObject;

            if (list.size() == 0) {
                return "";
            }

            StringBuilder result = new StringBuilder();
            for (String item : list) {
                result.append(item).append(" ");
            }
            // return everything except the last " "
            return result.substring(0, result.length() - 1);
        }
    }

    /**
     * Converts a {@link String} to a {@link List}{@code <String>} by splitting
     * the {@code String} along spaces.
     */
    public static class StringToListConverter extends Converter {

        public StringToListConverter() {
            super(String.class, List.class);
        }

        @Override
        public List<String> convert(Object fromObject) {
            if (!(fromObject instanceof String)) {
                throw new AssertionError("Only String objects can be converted");
            }
            String from = (String) fromObject;
            if (from.trim().isEmpty()) {
                return Collections.emptyList();
            }
            String[] parts = from.trim().split(" +");
            List<String> result = Arrays.asList(parts);
            return result;
        }

    }

    /** Converts an empty String to {@code null}. */
    public static class EmptyStringToNullConverter extends Converter {
        public EmptyStringToNullConverter() {
            super(String.class, String.class);
        }

        @Override
        public String convert(Object fromObject) {
            if (!(fromObject instanceof String)) {
                throw new IllegalArgumentException("Only strings can be converted. Got a " + fromObject.getClass() + " type");
            }
            String in = (String) fromObject;
            if (in == null || in.trim().isEmpty()) {
                return null;
            }
            return in;
        }
    }
}