/*
 * 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;

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.config.plugins.PluginBuilderAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
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.util.Strings;

import com.fasterxml.jackson.databind.ObjectWriter;

public abstract class AbstractJacksonLayout extends AbstractStringLayout {

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

        @PluginBuilderAttribute
        private boolean eventEol;

        @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 boolean isCompact() {
            return compact;
        }

        public boolean isComplete() {
            return complete;
        }

        public boolean isIncludeNullDelimiter() {
            return includeNullDelimiter;
        }

        /**
         * If "true", includes the stack trace of any Throwable in the generated data, defaults to "true".
         *
         * @return If "true", includes the stack trace 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();
        }

        /**
         * 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());
        }
    }
    /**
     * Subclasses can annotate with Jackson annotations for JSON example.
     */
    public static class LogEventWithAdditionalFields {

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

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

        public Map<String, String> getAdditionalFields() {
            return additionalFields;
        }

        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 : Log4jLogEvent.createMemento(event);
    }
    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;

    @Deprecated
    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) {
        this(config, objectWriter, charset, compact, complete, eventEol, headerSerializer, footerSerializer, false);
    }

    @Deprecated
    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) {
        this(config, objectWriter, charset, compact, complete, eventEol, headerSerializer, footerSerializer,
                includeNullDelimiter, null);
    }

    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) {
        super(config, charset, headerSerializer, footerSerializer);
        this.objectWriter = objectWriter;
        this.compact = compact;
        this.complete = complete;
        this.eol = compact && !eventEol ? COMPACT_EOL : DEFAULT_EOL;
        this.includeNullDelimiter = includeNullDelimiter;
        this.additionalFields = prepareAdditionalFields(config, additionalFields);
    }

    protected LogEventWithAdditionalFields createLogEventWithAdditionalFields(final LogEvent event,
            final Map<String, String> additionalFieldsMap) {
        return new LogEventWithAdditionalFields(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) {
        try (final StringBuilderWriter writer = new StringBuilderWriter()) {
            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 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 createLogEventWithAdditionalFields(event, additionalFieldsMap);
        }
        // No additional fields, return original object
        return event;
    }
}