/*
 * 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.cluster.metadata;

import org.elasticsearch.common.io.stream.BytesStreamOutput;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.test.AbstractXContentTestCase;
import org.elasticsearch.xcontent.XContentParser;

import java.io.IOException;
import java.util.Map;
import java.util.function.Predicate;

import static org.elasticsearch.cluster.metadata.InferenceFieldMetadata.CHUNKING_SETTINGS_FIELD;
import static org.hamcrest.Matchers.equalTo;

public class InferenceFieldMetadataTests extends AbstractXContentTestCase<InferenceFieldMetadata> {

    public void testSerialization() throws IOException {
        final InferenceFieldMetadata before = createTestItem();
        final BytesStreamOutput out = new BytesStreamOutput();
        before.writeTo(out);

        final StreamInput in = out.bytes().streamInput();
        final InferenceFieldMetadata after = new InferenceFieldMetadata(in);

        assertThat(after, equalTo(before));
    }

    @Override
    protected InferenceFieldMetadata createTestInstance() {
        return createTestItem();
    }

    @Override
    protected InferenceFieldMetadata doParseInstance(XContentParser parser) throws IOException {
        if (parser.nextToken() == XContentParser.Token.START_OBJECT) {
            parser.nextToken();
        }
        assertEquals(XContentParser.Token.FIELD_NAME, parser.currentToken());
        InferenceFieldMetadata inferenceMetadata = InferenceFieldMetadata.fromXContent(parser);
        assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
        return inferenceMetadata;
    }

    @Override
    protected boolean supportsUnknownFields() {
        return true;
    }

    @Override
    protected Predicate<String> getRandomFieldsExcludeFilter() {
        // do not add elements at the top-level as any element at this level is parsed as a new inference field,
        // and do not add additional elements to chunking maps as they will fail parsing with extra data
        return field -> field.equals("") || field.contains(CHUNKING_SETTINGS_FIELD);
    }

    private static InferenceFieldMetadata createTestItem() {
        String name = randomAlphaOfLengthBetween(3, 10);
        String inferenceId = randomIdentifier();
        String searchInferenceId = randomIdentifier();
        String[] inputFields = generateRandomStringArray(5, 10, false, false);
        Map<String, Object> chunkingSettings = generateRandomChunkingSettings();
        return new InferenceFieldMetadata(name, inferenceId, searchInferenceId, inputFields, chunkingSettings);
    }

    public static Map<String, Object> generateRandomChunkingSettings() {
        if (randomBoolean()) {
            return null; // Defaults to model chunking settings
        }
        return randomBoolean() ? generateRandomWordBoundaryChunkingSettings() : generateRandomSentenceBoundaryChunkingSettings();
    }

    private static Map<String, Object> generateRandomWordBoundaryChunkingSettings() {
        return Map.of("strategy", "word_boundary", "max_chunk_size", randomIntBetween(20, 100), "overlap", randomIntBetween(1, 50));
    }

    private static Map<String, Object> generateRandomSentenceBoundaryChunkingSettings() {
        return Map.of(
            "strategy",
            "sentence_boundary",
            "max_chunk_size",
            randomIntBetween(20, 100),
            "sentence_overlap",
            randomIntBetween(0, 1)
        );
    }

    public void testNullCtorArgsThrowException() {
        assertThrows(
            NullPointerException.class,
            () -> new InferenceFieldMetadata(null, "inferenceId", "searchInferenceId", new String[0], Map.of())
        );
        assertThrows(
            NullPointerException.class,
            () -> new InferenceFieldMetadata("name", null, "searchInferenceId", new String[0], Map.of())
        );
        assertThrows(NullPointerException.class, () -> new InferenceFieldMetadata("name", "inferenceId", null, new String[0], Map.of()));
        assertThrows(
            NullPointerException.class,
            () -> new InferenceFieldMetadata("name", "inferenceId", "searchInferenceId", null, Map.of())
        );
    }
}