/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the "Elastic License
 * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
 * Public License v 1"; you may not use this file except in compliance with, at
 * your election, the "Elastic License 2.0", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.ingest;

import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.ElasticsearchParseException;
import org.elasticsearch.ExceptionsHelper;
import org.elasticsearch.cluster.metadata.ProjectId;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.util.Maps;
import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
import org.elasticsearch.common.xcontent.XContentHelper;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.script.Script;
import org.elasticsearch.script.ScriptService;
import org.elasticsearch.script.ScriptType;
import org.elasticsearch.script.TemplateScript;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentType;
import org.elasticsearch.xcontent.json.JsonXContent;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import static org.elasticsearch.script.Script.DEFAULT_TEMPLATE_LANG;

public final class ConfigurationUtils {

    public static final String TAG_KEY = "tag";
    public static final String DESCRIPTION_KEY = "description";
    public static final String[] VALID_MEDIA_TYPES = { "application/json", "text/plain", "application/x-www-form-urlencoded" };

    private ConfigurationUtils() {}

    /**
     * Returns and removes the specified optional property from the specified configuration map.
     *
     * If the property value isn't of type string a {@link ElasticsearchParseException} is thrown.
     */
    public static String readOptionalStringProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        return readString(processorType, processorTag, propertyName, value);
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type string an {@link ElasticsearchParseException} is thrown.
     * If the property is missing an {@link ElasticsearchParseException} is thrown
     */
    public static String readStringProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        return readStringProperty(processorType, processorTag, configuration, propertyName, null);
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type string a {@link ElasticsearchParseException} is thrown.
     * If the property is missing and no default value has been specified a {@link ElasticsearchParseException} is thrown
     */
    public static String readStringProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName,
        String defaultValue
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null && defaultValue != null) {
            return defaultValue;
        } else if (value == null) {
            throw newConfigurationException(processorType, processorTag, propertyName, "required property is missing");
        }
        return readString(processorType, processorTag, propertyName, value);
    }

    private static String readString(String processorType, String processorTag, String propertyName, Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof String string) {
            return string;
        }
        throw newConfigurationException(
            processorType,
            processorTag,
            propertyName,
            "property isn't a string, but of type [" + value.getClass().getName() + "]"
        );
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type string or int a {@link ElasticsearchParseException} is thrown.
     * If the property is missing and no default value has been specified a {@link ElasticsearchParseException} is thrown
     */
    public static String readStringOrIntProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName,
        String defaultValue
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null && defaultValue != null) {
            return defaultValue;
        } else if (value == null) {
            throw newConfigurationException(processorType, processorTag, propertyName, "required property is missing");
        }
        return readStringOrInt(processorType, processorTag, propertyName, value);
    }

    private static String readStringOrInt(String processorType, String processorTag, String propertyName, Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof String string) {
            return string;
        } else if (value instanceof Integer integer) {
            return String.valueOf(integer);
        }
        throw newConfigurationException(
            processorType,
            processorTag,
            propertyName,
            "property isn't a string or int, but of type [" + value.getClass().getName() + "]"
        );
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type string or int a {@link ElasticsearchParseException} is thrown.
     */
    public static String readOptionalStringOrIntProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return null;
        }
        return readStringOrInt(processorType, processorTag, propertyName, value);
    }

    private static String readStringOrLong(String processorType, String processorTag, String propertyName, Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof String string) {
            return string;
        } else if (value instanceof Long || value instanceof Integer) {
            return String.valueOf(value);
        }
        throw newConfigurationException(
            processorType,
            processorTag,
            propertyName,
            "property isn't a string or long, but of type [" + value.getClass().getName() + "]"
        );
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type string or long a {@link ElasticsearchParseException} is thrown.
     */
    public static String readOptionalStringOrLongProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return null;
        }
        return readStringOrLong(processorType, processorTag, propertyName, value);
    }

    public static Boolean readBooleanProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName,
        boolean defaultValue
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return defaultValue;
        } else {
            return readBoolean(processorType, processorTag, propertyName, value).booleanValue();
        }
    }

    @Nullable
    public static Boolean readOptionalBooleanProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        return readBoolean(processorType, processorTag, propertyName, value);
    }

    private static Boolean readBoolean(String processorType, String processorTag, String propertyName, Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof Boolean b) {
            return b;
        }
        throw newConfigurationException(
            processorType,
            processorTag,
            propertyName,
            Strings.format("property isn't a boolean, but of type [%s]", value.getClass().getName())
        );
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type int a {@link ElasticsearchParseException} is thrown.
     * If the property is missing an {@link ElasticsearchParseException} is thrown
     */
    public static Integer readIntProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName,
        Integer defaultValue
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return defaultValue;
        }
        try {
            return Integer.parseInt(value.toString());
        } catch (Exception e) {
            throw newConfigurationException(
                processorType,
                processorTag,
                propertyName,
                "property cannot be converted to an int [" + value.toString() + "]"
            );
        }
    }

    /**
     * Returns and removes the specified property from the specified configuration map.
     *
     * If the property value isn't of type int a {@link ElasticsearchParseException} is thrown.
     * If the property is missing an {@link ElasticsearchParseException} is thrown
     */
    public static Double readDoubleProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            throw newConfigurationException(processorType, processorTag, propertyName, "required property is missing");
        }
        try {
            return Double.parseDouble(value.toString());
        } catch (Exception e) {
            throw newConfigurationException(
                processorType,
                processorTag,
                propertyName,
                "property cannot be converted to a double [" + value.toString() + "]"
            );
        }
    }

    /**
     * Returns and removes the specified property of type list from the specified configuration map.
     *
     * If the property value isn't of type list an {@link ElasticsearchParseException} is thrown.
     */
    public static <T> List<T> readOptionalList(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return null;
        }
        return readList(processorType, processorTag, propertyName, value);
    }

    /**
     * Returns and removes the specified property of type list from the specified configuration map.
     *
     * If the property value isn't of type list or string an {@link ElasticsearchParseException} is thrown.
     */
    public static List<String> readOptionalListOrString(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return List.of();
        }
        if (value instanceof String) {
            return List.of(readString(processorType, processorTag, propertyName, value));
        }
        return readList(processorType, processorTag, propertyName, value);
    }

    /**
     * Returns and removes the specified property of type list from the specified configuration map.
     *
     * If the property value isn't of type list an {@link ElasticsearchParseException} is thrown.
     * If the property is missing an {@link ElasticsearchParseException} is thrown
     */
    public static <T> List<T> readList(String processorType, String processorTag, Map<String, Object> configuration, String propertyName) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            throw newConfigurationException(processorType, processorTag, propertyName, "required property is missing");
        }

        return readList(processorType, processorTag, propertyName, value);
    }

    private static <T> List<T> readList(String processorType, String processorTag, String propertyName, Object value) {
        if (value instanceof List) {
            @SuppressWarnings("unchecked")
            List<T> stringList = (List<T>) value;
            return stringList;
        } else {
            throw newConfigurationException(
                processorType,
                processorTag,
                propertyName,
                "property isn't a list, but of type [" + value.getClass().getName() + "]"
            );
        }
    }

    /**
     * Returns and removes the specified property of type map from the specified configuration map.
     *
     * If the property value isn't of type map an {@link ElasticsearchParseException} is thrown.
     * If the property is missing an {@link ElasticsearchParseException} is thrown
     */
    public static <T> Map<String, T> readMap(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            throw newConfigurationException(processorType, processorTag, propertyName, "required property is missing");
        }

        return readMap(processorType, processorTag, propertyName, value);
    }

    /**
     * Returns and removes the specified property of type map from the specified configuration map.
     *
     * If the property value isn't of type map an {@link ElasticsearchParseException} is thrown.
     */
    public static <T> Map<String, T> readOptionalMap(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName
    ) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            return null;
        }

        return readMap(processorType, processorTag, propertyName, value);
    }

    private static <T> Map<String, T> readMap(String processorType, String processorTag, String propertyName, Object value) {
        if (value instanceof Map) {
            @SuppressWarnings("unchecked")
            Map<String, T> map = (Map<String, T>) value;
            return map;
        } else {
            throw newConfigurationException(
                processorType,
                processorTag,
                propertyName,
                "property isn't a map, but of type [" + value.getClass().getName() + "]"
            );
        }
    }

    /**
     * Returns and removes the specified property as an {@link Object} from the specified configuration map.
     */
    public static Object readObject(String processorType, String processorTag, Map<String, Object> configuration, String propertyName) {
        Object value = configuration.remove(propertyName);
        if (value == null) {
            throw newConfigurationException(processorType, processorTag, propertyName, "required property is missing");
        }
        return value;
    }

    public static String readMediaTypeProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName,
        String defaultValue
    ) {
        String mediaType = readStringProperty(processorType, processorTag, configuration, propertyName, defaultValue);

        if (List.of(VALID_MEDIA_TYPES).contains(mediaType) == false) {
            throw newConfigurationException(
                processorType,
                processorTag,
                propertyName,
                "property does not contain a supported media type [" + mediaType + "]"
            );
        }

        return mediaType;
    }

    public static ElasticsearchException newConfigurationException(
        String processorType,
        String processorTag,
        String propertyName,
        String reason
    ) {
        String msg;
        if (propertyName == null) {
            msg = reason;
        } else {
            msg = "[" + propertyName + "] " + reason;
        }
        ElasticsearchParseException exception = new ElasticsearchParseException(msg);
        addMetadataToException(exception, processorType, processorTag, propertyName);
        return exception;
    }

    public static ElasticsearchException newConfigurationException(
        String processorType,
        String processorTag,
        String propertyName,
        Exception cause
    ) {
        ElasticsearchException exception = ExceptionsHelper.convertToElastic(cause);
        addMetadataToException(exception, processorType, processorTag, propertyName);
        return exception;
    }

    public static List<Processor> readProcessorConfigs(
        List<Map<String, Object>> processorConfigs,
        ScriptService scriptService,
        Map<String, Processor.Factory> processorFactories,
        ProjectId projectId
    ) throws Exception {
        Exception exception = null;
        List<Processor> processors = new ArrayList<>();
        if (processorConfigs != null) {
            for (Map<String, Object> processorConfigWithKey : processorConfigs) {
                for (Map.Entry<String, Object> entry : processorConfigWithKey.entrySet()) {
                    try {
                        if (entry.getValue() == null) {
                            throw newConfigurationException(entry.getKey(), null, null, "processor config cannot be [null]");
                        } else {
                            processors.add(readProcessor(processorFactories, scriptService, entry.getKey(), entry.getValue(), projectId));
                        }
                    } catch (Exception e) {
                        exception = ExceptionsHelper.useOrSuppress(exception, e);
                    }
                }
            }
        }

        if (exception != null) {
            throw exception;
        }

        return Collections.unmodifiableList(processors);
    }

    public static TemplateScript.Factory readTemplateProperty(
        String processorType,
        String processorTag,
        Map<String, Object> configuration,
        String propertyName,
        ScriptService scriptService
    ) {
        String value = readStringProperty(processorType, processorTag, configuration, propertyName, null);
        return compileTemplate(processorType, processorTag, propertyName, value, scriptService);
    }

    public static TemplateScript.Factory compileTemplate(
        String processorType,
        String processorTag,
        String propertyName,
        String propertyValue,
        ScriptService scriptService
    ) {
        try {
            // This check is here because the DEFAULT_TEMPLATE_LANG(mustache) is not
            // installed for use by REST tests. `propertyValue` will not be
            // modified if templating is not available so a script that simply returns an unmodified `propertyValue`
            // is returned.
            if (scriptService.isLangSupported(DEFAULT_TEMPLATE_LANG) && propertyValue.contains("{{")) {
                Script script = new Script(ScriptType.INLINE, DEFAULT_TEMPLATE_LANG, propertyValue, Map.of());
                return scriptService.compile(script, TemplateScript.CONTEXT);
            } else {
                return new ConstantTemplateScriptFactory(propertyValue);
            }
        } catch (Exception e) {
            throw ConfigurationUtils.newConfigurationException(processorType, processorTag, propertyName, e);
        }
    }

    /**
     * A 'template script' that ignores the model to which it is applied and just always returns a constant String.
     * <p>
     * Having a separate named class for this allows for some hot code paths to pre-apply the 'template script' statically,
     * rather than bothering to invoke it per-document. Note that this is probably only useful if something expensive
     * is being done with the result of calling the script, and the code can then avoid doing that thing per-document.
     */
    public static class ConstantTemplateScriptFactory implements TemplateScript.Factory {
        final TemplateScript script;

        private ConstantTemplateScriptFactory(String value) {
            this.script = new TemplateScript(Map.of()) {
                @Override
                public String execute() {
                    return value;
                }
            };
        }

        @Override
        public TemplateScript newInstance(Map<String, Object> params) {
            return script;
        }
    }

    private static void addMetadataToException(
        ElasticsearchException exception,
        String processorType,
        String processorTag,
        String propertyName
    ) {
        if (processorType != null) {
            exception.addMetadata("es.processor_type", processorType);
        }
        if (processorTag != null) {
            exception.addMetadata("es.processor_tag", processorTag);
        }
        if (propertyName != null) {
            exception.addMetadata("es.property_name", propertyName);
        }
    }

    @SuppressWarnings("unchecked")
    public static Processor readProcessor(
        Map<String, Processor.Factory> processorFactories,
        ScriptService scriptService,
        String type,
        Object config,
        ProjectId projectId
    ) throws Exception {
        if (config instanceof Map) {
            return readProcessor(processorFactories, scriptService, type, (Map<String, Object>) config, projectId);
        } else if (config instanceof String && "script".equals(type)) {
            Map<String, Object> normalizedScript = Maps.newMapWithExpectedSize(1);
            normalizedScript.put(ScriptType.INLINE.getParseField().getPreferredName(), config);
            return readProcessor(processorFactories, scriptService, type, normalizedScript, projectId);
        } else {
            throw newConfigurationException(type, null, null, "property isn't a map, but of type [" + config.getClass().getName() + "]");
        }
    }

    public static Processor readProcessor(
        Map<String, Processor.Factory> processorFactories,
        ScriptService scriptService,
        String type,
        Map<String, Object> config,
        ProjectId projectId
    ) throws Exception {
        String tag = ConfigurationUtils.readOptionalStringProperty(null, null, config, TAG_KEY);
        String description = ConfigurationUtils.readOptionalStringProperty(null, tag, config, DESCRIPTION_KEY);
        Script conditionalScript = extractConditional(config);
        Processor.Factory factory = processorFactories.get(type);
        if (factory != null) {
            boolean ignoreFailure = ConfigurationUtils.readBooleanProperty(null, null, config, "ignore_failure", false);
            List<Map<String, Object>> onFailureProcessorConfigs = ConfigurationUtils.readOptionalList(
                null,
                null,
                config,
                Pipeline.ON_FAILURE_KEY
            );

            List<Processor> onFailureProcessors = readProcessorConfigs(
                onFailureProcessorConfigs,
                scriptService,
                processorFactories,
                projectId
            );

            if (onFailureProcessorConfigs != null && onFailureProcessors.isEmpty()) {
                throw newConfigurationException(type, tag, Pipeline.ON_FAILURE_KEY, "processors list cannot be empty");
            }

            try {
                Processor processor = factory.create(processorFactories, tag, description, config, projectId);
                if (config.isEmpty() == false) {
                    throw new ElasticsearchParseException(
                        "processor [{}] doesn't support one or more provided configuration parameters {}",
                        type,
                        Arrays.toString(config.keySet().toArray())
                    );
                }
                if (onFailureProcessors.size() > 0 || ignoreFailure) {
                    processor = new OnFailureProcessor(ignoreFailure, processor, onFailureProcessors);
                }
                if (conditionalScript != null) {
                    processor = new ConditionalProcessor(tag, description, conditionalScript, scriptService, processor);
                }
                return processor;
            } catch (Exception e) {
                throw newConfigurationException(type, tag, null, e);
            }
        }
        throw newConfigurationException(type, tag, null, "No processor type exists with name [" + type + "]");
    }

    private static Script extractConditional(Map<String, Object> config) throws IOException {
        Object scriptSource = config.remove("if");
        if (scriptSource != null) {
            try (
                XContentBuilder builder = XContentBuilder.builder(JsonXContent.jsonXContent).map(normalizeScript(scriptSource));
                XContentParser parser = XContentHelper.createParserNotCompressed(
                    LoggingDeprecationHandler.XCONTENT_PARSER_CONFIG,
                    BytesReference.bytes(builder),
                    XContentType.JSON
                )
            ) {
                return Script.parse(parser);
            }
        }
        return null;
    }

    @SuppressWarnings("unchecked")
    private static Map<String, Object> normalizeScript(Object scriptConfig) {
        if (scriptConfig instanceof Map<?, ?>) {
            return (Map<String, Object>) scriptConfig;
        } else if (scriptConfig instanceof String) {
            return Map.of("source", scriptConfig);
        } else {
            throw newConfigurationException(
                "conditional",
                null,
                "script",
                "property isn't a map or string, but of type [" + scriptConfig.getClass().getName() + "]"
            );
        }
    }
}