/*
 * 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.apache.logging.log4j.jackson.layout;

import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonRootName;
import com.fasterxml.jackson.annotation.JsonUnwrapped;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectWriter;
import java.io.IOException;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.LinkedHashMap;
import java.util.Map;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.impl.Log4jLogEvent;
import org.apache.logging.log4j.core.layout.AbstractStringLayout;
import org.apache.logging.log4j.core.lookup.StrSubstitutor;
import org.apache.logging.log4j.core.util.KeyValuePair;
import org.apache.logging.log4j.core.util.StringBuilderWriter;
import org.apache.logging.log4j.jackson.XmlConstants;
import org.apache.logging.log4j.plugins.PluginBuilderAttribute;
import org.apache.logging.log4j.plugins.PluginElement;
import org.apache.logging.log4j.util.Strings;

abstract class AbstractJacksonLayout extends AbstractStringLayout {

    public abstract static class Builder<B extends Builder<B>> extends AbstractStringLayout.Builder<B> {

        @PluginBuilderAttribute
        private boolean eventEol;

        @PluginBuilderAttribute
        private String endOfLine;

        @PluginBuilderAttribute
        private boolean compact;

        @PluginBuilderAttribute
        private boolean complete;

        @PluginBuilderAttribute
        private boolean locationInfo;

        @PluginBuilderAttribute
        private boolean properties;

        @PluginBuilderAttribute
        private boolean includeStacktrace = true;

        @PluginBuilderAttribute
        private boolean stacktraceAsString = false;

        @PluginBuilderAttribute
        private boolean includeNullDelimiter = false;

        @PluginElement("AdditionalField")
        private KeyValuePair[] additionalFields;

        public KeyValuePair[] getAdditionalFields() {
            return additionalFields;
        }

        public boolean getEventEol() {
            return eventEol;
        }

        public String getEndOfLine() {
            return endOfLine;
        }

        public boolean isCompact() {
            return compact;
        }

        public boolean isComplete() {
            return complete;
        }

        public boolean isIncludeNullDelimiter() {
            return includeNullDelimiter;
        }

        /**
         * If "true", includes the stacktrace of any Throwable in the generated data, defaults to "true".
         *
         * @return If "true", includes the stacktrace of any Throwable in the generated data, defaults to "true".
         */
        public boolean isIncludeStacktrace() {
            return includeStacktrace;
        }

        public boolean isLocationInfo() {
            return locationInfo;
        }

        public boolean isProperties() {
            return properties;
        }

        public boolean isStacktraceAsString() {
            return stacktraceAsString;
        }

        /**
         * Additional fields to set on each log event.
         *
         * @return this builder
         */
        public B setAdditionalFields(final KeyValuePair[] additionalFields) {
            this.additionalFields = additionalFields;
            return asBuilder();
        }

        public B setCompact(final boolean compact) {
            this.compact = compact;
            return asBuilder();
        }

        public B setComplete(final boolean complete) {
            this.complete = complete;
            return asBuilder();
        }

        public B setEventEol(final boolean eventEol) {
            this.eventEol = eventEol;
            return asBuilder();
        }

        public B setEndOfLine(final String endOfLine) {
            this.endOfLine = endOfLine;
            return asBuilder();
        }

        /**
         * Whether to include NULL byte as delimiter after each event (optional, default to false).
         *
         * @return this builder
         */
        public B setIncludeNullDelimiter(final boolean includeNullDelimiter) {
            this.includeNullDelimiter = includeNullDelimiter;
            return asBuilder();
        }

        /**
         * If "true", includes the stacktrace of any Throwable in the generated JSON, defaults to "true".
         *
         * @param includeStacktrace
         *            If "true", includes the stacktrace of any Throwable in the generated JSON, defaults to "true".
         * @return this builder
         */
        public B setIncludeStacktrace(final boolean includeStacktrace) {
            this.includeStacktrace = includeStacktrace;
            return asBuilder();
        }

        public B setLocationInfo(final boolean locationInfo) {
            this.locationInfo = locationInfo;
            return asBuilder();
        }

        public B setProperties(final boolean properties) {
            this.properties = properties;
            return asBuilder();
        }

        /**
         * Whether to format the stacktrace as a string, and not a nested object (optional, defaults to false).
         *
         * @return this builder
         */
        public B setStacktraceAsString(final boolean stacktraceAsString) {
            this.stacktraceAsString = stacktraceAsString;
            return asBuilder();
        }

        protected String toStringOrNull(final byte[] header) {
            return header == null ? null : new String(header, Charset.defaultCharset());
        }
    }

    @JsonRootName(XmlConstants.ELT_EVENT)
    public static class LogEventWrapperWithAdditionalFields {

        private final Object logEvent;
        private final Map<String, String> additionalFields;

        public LogEventWrapperWithAdditionalFields(final Object logEvent, final Map<String, String> additionalFields) {
            this.logEvent = logEvent;
            this.additionalFields = additionalFields;
        }

        @JsonAnyGetter
        @SuppressWarnings("unused")
        public Map<String, String> getAdditionalFields() {
            return additionalFields;
        }

        @JsonUnwrapped
        public Object getLogEvent() {
            return logEvent;
        }
    }

    protected static class ResolvableKeyValuePair {

        final String key;
        final String value;
        final boolean valueNeedsLookup;

        ResolvableKeyValuePair(final KeyValuePair pair) {
            this.key = pair.getKey();
            this.value = pair.getValue();
            this.valueNeedsLookup = AbstractJacksonLayout.valueNeedsLookup(this.value);
        }
    }

    protected static final String DEFAULT_EOL = "\r\n";

    protected static final String COMPACT_EOL = Strings.EMPTY;

    private static LogEvent convertMutableToLog4jEvent(final LogEvent event) {
        // TODO Jackson-based layouts have certain filters set up for Log4jLogEvent.
        // TODO Need to set up the same filters for MutableLogEvent but don't know how...
        // This is a workaround.
        return event instanceof Log4jLogEvent ? event : event.toMemento();
    }

    private static ResolvableKeyValuePair[] prepareAdditionalFields(
            final Configuration config, final KeyValuePair[] additionalFields) {
        if (additionalFields == null || additionalFields.length == 0) {
            // No fields set
            return new ResolvableKeyValuePair[0];
        }

        // Convert to specific class which already determines whether values needs lookup during serialization
        final ResolvableKeyValuePair[] resolvableFields = new ResolvableKeyValuePair[additionalFields.length];

        for (int i = 0; i < additionalFields.length; i++) {
            final ResolvableKeyValuePair resolvable =
                    resolvableFields[i] = new ResolvableKeyValuePair(additionalFields[i]);

            // Validate
            if (config == null && resolvable.valueNeedsLookup) {
                throw new IllegalArgumentException(
                        "configuration needs to be set when there are additional fields with variables");
            }
        }

        return resolvableFields;
    }

    protected static boolean valueNeedsLookup(final String value) {
        return value != null && value.contains("${");
    }

    protected final String eol;
    protected final ObjectWriter objectWriter;

    protected final boolean compact;

    protected final boolean complete;

    protected final boolean includeNullDelimiter;

    protected final ResolvableKeyValuePair[] additionalFields;

    protected AbstractJacksonLayout(
            final Configuration config,
            final ObjectWriter objectWriter,
            final Charset charset,
            final boolean compact,
            final boolean complete,
            final boolean eventEol,
            final Serializer headerSerializer,
            final Serializer footerSerializer,
            final boolean includeNullDelimiter,
            final KeyValuePair[] additionalFields) {
        this(
                config,
                objectWriter,
                charset,
                compact,
                complete,
                eventEol,
                null,
                headerSerializer,
                footerSerializer,
                includeNullDelimiter,
                additionalFields);
    }

    protected AbstractJacksonLayout(
            final Configuration config,
            final ObjectWriter objectWriter,
            final Charset charset,
            final boolean compact,
            final boolean complete,
            final boolean eventEol,
            final String endOfLine,
            final Serializer headerSerializer,
            final Serializer footerSerializer,
            final boolean includeNullDelimiter,
            final KeyValuePair[] additionalFields) {
        super(config, charset, headerSerializer, footerSerializer);
        this.objectWriter = objectWriter;
        this.compact = compact;
        this.complete = complete;
        this.eol = endOfLine != null ? endOfLine : compact && !eventEol ? COMPACT_EOL : DEFAULT_EOL;
        this.includeNullDelimiter = includeNullDelimiter;
        this.additionalFields = prepareAdditionalFields(config, additionalFields);
    }

    protected LogEventWrapperWithAdditionalFields createLogEventWrapperWithAdditionalFields(
            final LogEvent event, final Map<String, String> additionalFieldsMap) {
        return new LogEventWrapperWithAdditionalFields(event, additionalFieldsMap);
    }

    private Map<String, String> resolveAdditionalFields(final LogEvent logEvent) {
        // Note: LinkedHashMap retains order
        final Map<String, String> additionalFieldsMap = new LinkedHashMap<>(additionalFields.length);
        final StrSubstitutor strSubstitutor = configuration.getStrSubstitutor();

        // Go over each field
        for (final ResolvableKeyValuePair pair : additionalFields) {
            if (pair.valueNeedsLookup) {
                // Resolve value
                additionalFieldsMap.put(pair.key, strSubstitutor.replace(logEvent, pair.value));
            } else {
                // Plain text value
                additionalFieldsMap.put(pair.key, pair.value);
            }
        }

        return additionalFieldsMap;
    }

    /**
     * Formats a {@link org.apache.logging.log4j.core.LogEvent}.
     *
     * @param event The LogEvent.
     * @return The XML representation of the LogEvent.
     */
    @Override
    public String toSerializable(final LogEvent event) {
        final StringBuilderWriter writer = new StringBuilderWriter();
        try {
            toSerializable(event, writer);
            return writer.toString();
        } catch (final IOException e) {
            // Should this be an ISE or IAE?
            LOGGER.error(e);
            return Strings.EMPTY;
        }
    }

    public void toSerializable(final LogEvent event, final Writer writer)
            throws JsonGenerationException, JsonMappingException, IOException {
        objectWriter.writeValue(writer, wrapLogEvent(convertMutableToLog4jEvent(event)));
        writer.write(eol);
        if (includeNullDelimiter) {
            writer.write('\0');
        }
        markEvent();
    }

    protected Object wrapLogEvent(final LogEvent event) {
        if (additionalFields.length > 0) {
            // Construct map for serialization - note that we are intentionally using original LogEvent
            final Map<String, String> additionalFieldsMap = resolveAdditionalFields(event);
            // This class combines LogEvent with AdditionalFields during serialization
            return createLogEventWrapperWithAdditionalFields(event, additionalFieldsMap);
        }
        // No additional fields, return original object
        return event;
    }
}
