/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.
 */
/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.script.mustache;

import com.github.mustachejava.MustacheFactory;

import org.opensearch.core.xcontent.XContentParser;
import org.opensearch.common.xcontent.json.JsonXContent;
import org.opensearch.script.TemplateScript;
import org.opensearch.script.Script;
import org.opensearch.test.OpenSearchTestCase;
import org.junit.Before;

import java.io.IOException;
import java.io.StringWriter;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import static org.hamcrest.Matchers.equalTo;

/**
 * Mustache based templating test
 */
public class MustacheScriptEngineTests extends OpenSearchTestCase {
    private MustacheScriptEngine qe;
    private MustacheFactory factory;

    @Before
    public void setup() {
        qe = new MustacheScriptEngine();
        factory = new CustomMustacheFactory();
    }

    public void testSimpleParameterReplace() {
        Map<String, String> compileParams = Collections.singletonMap("content_type", "application/json");
        {
            String template = "GET _search {\"query\": "
                + "{\"boosting\": {"
                + "\"positive\": {\"match\": {\"body\": \"gift\"}},"
                + "\"negative\": {\"term\": {\"body\": {\"value\": \"solr\"}"
                + "}}, \"negative_boost\": {{boost_val}} } }}";
            Map<String, Object> vars = new HashMap<>();
            vars.put("boost_val", "0.3");
            String o = qe.compile(null, template, TemplateScript.CONTEXT, compileParams).newInstance(vars).execute();
            assertEquals(
                "GET _search {\"query\": {\"boosting\": {\"positive\": {\"match\": {\"body\": \"gift\"}},"
                    + "\"negative\": {\"term\": {\"body\": {\"value\": \"solr\"}}}, \"negative_boost\": 0.3 } }}",
                o
            );
        }
        {
            String template = "GET _search {\"query\": "
                + "{\"boosting\": {"
                + "\"positive\": {\"match\": {\"body\": \"gift\"}},"
                + "\"negative\": {\"term\": {\"body\": {\"value\": \"{{body_val}}\"}"
                + "}}, \"negative_boost\": {{boost_val}} } }}";
            Map<String, Object> vars = new HashMap<>();
            vars.put("boost_val", "0.3");
            vars.put("body_val", "\"quick brown\"");
            String o = qe.compile(null, template, TemplateScript.CONTEXT, compileParams).newInstance(vars).execute();
            assertEquals(
                "GET _search {\"query\": {\"boosting\": {\"positive\": {\"match\": {\"body\": \"gift\"}},"
                    + "\"negative\": {\"term\": {\"body\": {\"value\": \"\\\"quick brown\\\"\"}}}, \"negative_boost\": 0.3 } }}",
                o
            );
        }
    }

    public void testSimple() throws IOException {
        String templateString = "{" + "\"source\":{\"match_{{template}}\": {}}," + "\"params\":{\"template\":\"all\"}" + "}";
        XContentParser parser = createParser(JsonXContent.jsonXContent, templateString);
        Script script = Script.parse(parser);
        TemplateScript.Factory compiled = qe.compile(null, script.getIdOrCode(), TemplateScript.CONTEXT, Collections.emptyMap());
        TemplateScript TemplateScript = compiled.newInstance(script.getParams());
        assertThat(TemplateScript.execute(), equalTo("{\"match_all\":{}}"));
    }

    public void testParseTemplateAsSingleStringWithConditionalClause() throws IOException {
        String templateString = "{"
            + "  \"source\" : \"{ \\\"match_{{#use_it}}{{template}}{{/use_it}}\\\":{} }\","
            + "  \"params\":{"
            + "    \"template\":\"all\","
            + "    \"use_it\": true"
            + "  }"
            + "}";
        XContentParser parser = createParser(JsonXContent.jsonXContent, templateString);
        Script script = Script.parse(parser);
        TemplateScript.Factory compiled = qe.compile(null, script.getIdOrCode(), TemplateScript.CONTEXT, Collections.emptyMap());
        TemplateScript TemplateScript = compiled.newInstance(script.getParams());
        assertThat(TemplateScript.execute(), equalTo("{ \"match_all\":{} }"));
    }

    public void testEscapeJson() throws IOException {
        {
            StringWriter writer = new StringWriter();
            factory.encode("hello \n world", writer);
            assertThat(writer.toString(), equalTo("hello \\n world"));
        }
        {
            StringWriter writer = new StringWriter();
            factory.encode("\n", writer);
            assertThat(writer.toString(), equalTo("\\n"));
        }

        Character[] specialChars = new Character[] {
            '\"',
            '\\',
            '\u0000',
            '\u0001',
            '\u0002',
            '\u0003',
            '\u0004',
            '\u0005',
            '\u0006',
            '\u0007',
            '\u0008',
            '\u0009',
            '\u000B',
            '\u000C',
            '\u000E',
            '\u000F',
            '\u001F' };
        String[] escapedChars = new String[] {
            "\\\"",
            "\\\\",
            "\\u0000",
            "\\u0001",
            "\\u0002",
            "\\u0003",
            "\\u0004",
            "\\u0005",
            "\\u0006",
            "\\u0007",
            "\\u0008",
            "\\u0009",
            "\\u000B",
            "\\u000C",
            "\\u000E",
            "\\u000F",
            "\\u001F" };
        int iters = scaledRandomIntBetween(100, 1000);
        for (int i = 0; i < iters; i++) {
            int rounds = scaledRandomIntBetween(1, 20);
            StringWriter expect = new StringWriter();
            StringWriter writer = new StringWriter();
            for (int j = 0; j < rounds; j++) {
                String s = getChars();
                writer.write(s);
                expect.write(s);

                int charIndex = randomInt(7);
                writer.append(specialChars[charIndex]);
                expect.append(escapedChars[charIndex]);
            }
            StringWriter target = new StringWriter();
            factory.encode(writer.toString(), target);
            assertThat(expect.toString(), equalTo(target.toString()));
        }
    }

    private String getChars() {
        String string = randomRealisticUnicodeOfCodepointLengthBetween(0, 10);
        for (int i = 0; i < string.length(); i++) {
            if (isEscapeChar(string.charAt(i))) {
                return string.substring(0, i);
            }
        }
        return string;
    }

    /**
     * From https://www.ietf.org/rfc/rfc4627.txt:
     *
     * All Unicode characters may be placed within the
     * quotation marks except for the characters that must be escaped:
     * quotation mark, reverse solidus, and the control characters (U+0000
     * through U+001F).
     * */
    private static boolean isEscapeChar(char c) {
        switch (c) {
            case '"':
            case '\\':
                return true;
        }

        if (c < '\u002F') return true;
        return false;
    }
}