/*
 * This file is part of vospace-rest
 * Copyright (C) 2021 Istituto Nazionale di Astrofisica
 * SPDX-License-Identifier: GPL-3.0-or-later
 */
package it.inaf.oats.vospace.parent.persistence;

import com.opentable.db.postgres.embedded.EmbeddedPostgres;
import com.opentable.db.postgres.embedded.PgBinaryResolver;
import com.opentable.db.postgres.embedded.UncompressBundleDirectoryResolver;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.sql.DataSource;
import static org.junit.jupiter.api.Assertions.assertTrue;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Primary;
import org.springframework.context.annotation.Scope;
import org.springframework.core.io.ClassPathResource;

/**
 * Generates a DataSource that can be used for testing DAO classes. It loads an
 * embedded Postgres database and fills it using the data from
 * vospace-transfer-service repository (folder must exists; it location can be
 * configured using the init_database_scripts_path in test.properties).
 */
@TestConfiguration
public class DataSourceConfig {

    @Value("${init_database_scripts_path}")
    private String scriptPath;

    /**
     * Using the prototype scope we are generating a different database in each
     * test.
     */
    @Bean
    @Scope("prototype")
    @Primary
    public DataSource dataSource() throws Exception {
        DataSource embeddedPostgresDS = EmbeddedPostgres.builder()
                .setPgDirectoryResolver(new UncompressBundleDirectoryResolver(new CustomPostgresBinaryResolver()))
                .start().getPostgresDatabase();

        initDatabase(embeddedPostgresDS);

        return embeddedPostgresDS;
    }

    private class CustomPostgresBinaryResolver implements PgBinaryResolver {

        /**
         * Loads specific embedded Postgres version.
         */
        @Override
        public InputStream getPgBinary(String system, String architecture) throws IOException {
            ClassPathResource resource = new ClassPathResource(String.format("postgres-%s-%s.txz", system.toLowerCase(), architecture));
            return resource.getInputStream();
        }
    }

    /**
     * Loads SQL scripts for database initialization from
     * vospace-transfer-service repo directory.
     */
    private void initDatabase(DataSource dataSource) throws Exception {
        try ( Connection conn = dataSource.getConnection()) {

            File currentDir = new File(DataSourceConfig.class.getClassLoader().getResource(".").getFile());
            File scriptDir = currentDir.toPath().resolve(scriptPath).toFile().getCanonicalFile();

            assertTrue(scriptDir.exists(), "DAO tests require " + scriptDir.getAbsolutePath() + " to exists.\n"
                    + "Please clone the repository from https://www.ict.inaf.it/gitlab/vospace/vospace-file-catalog.git");

            // load all sql files in vospace-file-catalog repo
            File[] repoScripts = scriptDir.listFiles(f -> f.getName().endsWith(".sql"));
            Arrays.sort(repoScripts); // sort alphabetically

            // add test-data.sql
            List<File> scripts = new ArrayList<>(Arrays.asList(repoScripts));
            scripts.add(new ClassPathResource("test-data.sql").getFile());

            for (File script : scripts) {
                String scriptContent = Files.readString(script.toPath());
                for (String sql : splitScript(scriptContent)) {
                    executeSql(conn, replaceDollarQuoting(sql));
                }
            }
        }
    }

    /**
     * Spring ScriptUtils is not able to correctly split the SQL statements if a
     * function definition contains semicolon characters, so this method is used
     * instead of it.
     */
    private List<String> splitScript(String script) {

        List<String> parts = new ArrayList<>();

        StringBuilder sb = new StringBuilder();

        boolean insideFunc = false;
        for (int i = 0; i < script.length(); i++) {
            char c = script.charAt(i);
            sb.append(c);

            if (insideFunc) {
                if (i > 6 && "$func$".equals(script.substring(i - 6, i))) {
                    insideFunc = false;
                }
            } else {
                if (i > 6 && "$func$".equals(script.substring(i - 6, i))) {
                    insideFunc = true;
                } else if (c == ';') {
                    parts.add(sb.toString());
                    sb = new StringBuilder();
                }
            }
        }

        return parts;
    }

    private void executeSql(Connection conn, String sqlStatement) throws SQLException {
        try ( Statement stat = conn.createStatement()) {
            stat.execute(sqlStatement);
        }
    }

    /**
     * It seems that dollar quoting (used in UDF) is broken in JDBC. Replacing
     * it with single quotes solves the problem. We replace the quoting here
     * instead of inside the original files because dollar quoting provides a
     * better visibility.
     */
    private String replaceDollarQuoting(String scriptContent) {

        if (scriptContent.contains("$func$")) {

            String func = extractFunctionDefinition(scriptContent);

            String originalFunction = "$func$" + func + "$func$";
            String newFunction = "'" + func.replaceAll("'", "''") + "'";

            scriptContent = scriptContent.replace(originalFunction, newFunction);
        }

        return scriptContent;
    }

    private String extractFunctionDefinition(String scriptContent) {
        Pattern pattern = Pattern.compile("\\$func\\$(.*?)\\$func\\$", Pattern.DOTALL);
        Matcher matcher = pattern.matcher(scriptContent);
        if (matcher.find()) {
            return matcher.group(1);
        }
        throw new IllegalArgumentException(scriptContent + " doesn't contain $func$");
    }
}