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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.tomitribe.util;

import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class StringTemplate {

    public static final Pattern PATTERN = Pattern.compile("(\\{)((\\.|\\w)+)(})");
    private final String template;

    public StringTemplate(final String template) {
        this.template = template;
    }

    public String format(final Map map) {
        final Function function = new Function() {
            @Override
            public String apply(final String s) {
                final Object value = map.get(s);
                return value != null ? value.toString() : "";
            }
        };
        return apply(function);
    }

    public String apply(final Function map) {
        final Matcher matcher = PATTERN.matcher(template);
        final StringBuffer buf = new StringBuffer();

        while (matcher.find()) {
            final String key = matcher.group(2);

            if (key == null) {
                throw new IllegalStateException("Key is null. Template '" + template + "'");
            }

            final String value;

            if (key.toLowerCase().endsWith(".lc")) {
                final String key1 = key.substring(0, key.length() - 3);
                value = map.apply(key1).toLowerCase();
            } else if (key.toLowerCase().endsWith(".uc")) {
                final String key1 = key.substring(0, key.length() - 3);
                value = map.apply(key1).toUpperCase();
            } else if (key.toLowerCase().endsWith(".cc")) {
                final String key1 = key.substring(0, key.length() - 3);
                value = Strings.camelCase(map.apply(key1));
            } else {
                value = map.apply(key);
            }

            if (value == null) {
                throw new IllegalStateException("Value is null for key '" + key + "'. Template '" + template + "'.");
            }

            matcher.appendReplacement(buf, value);
        }

        matcher.appendTail(buf);
        return buf.toString();
    }

    public String apply(final Map map) {
        final Matcher matcher = PATTERN.matcher(template);
        final StringBuffer buf = new StringBuffer();

        while (matcher.find()) {
            final String key = matcher.group(2);

            if (key == null) {
                throw new IllegalStateException("Key is null. Template '" + template + "'");
            }

            String value = value(map, key);

            if (key.toLowerCase().endsWith(".lc")) {
                value = value(map, key.substring(0, key.length() - 3)).toLowerCase();
            } else if (key.toLowerCase().endsWith(".uc")) {
                value = value(map, key.substring(0, key.length() - 3)).toUpperCase();
            } else if (key.toLowerCase().endsWith(".cc")) {
                value = Strings.camelCase(value(map, key.substring(0, key.length() - 3)));
            }

            if (value == null) {
                throw new IllegalStateException("Value is null for key '" + key + "'. Template '" + template + "'. " +
                        "Keys: " + Join.join(", ", map.keySet()));
            }
            matcher.appendReplacement(buf, value);
        }

        matcher.appendTail(buf);
        return buf.toString();
    }

    private String value(final Map map, final String key) {
        final Object o = map.get(key);
        if (o == null) throw new IllegalStateException("Missing entry " + key);

        return o.toString();
    }

    public Set keys() {
        final Set keys = new TreeSet();
        final Matcher matcher = PATTERN.matcher(template);

        while (matcher.find()) {
            String key = matcher.group(2);

            final String op = key.toLowerCase();
            if (op.endsWith(".lc") || op.endsWith(".uc") || op.endsWith(".cc")) {
                key = key.substring(0, key.length() - 3);
            }
            keys.add(key);
        }

        return keys;
    }

}