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 * Licensed under the Apache License, Version 2.0 (the "License");
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package org.jooq.tools.jdbc;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;

import org.jooq.DSLContext;
import org.jooq.Query;
import org.jooq.Record;
import org.jooq.ResultQuery;

/**
 * A data provider for mock query executions.
 * <p>
 * Supply this data provider to your {@link MockConnection} in order to globally
 * provide data for SQL statements.
 * <p>
 * <strong>Disclaimer: The general idea of mocking a JDBC connection with this
 * jOOQ API is to provide quick workarounds, injection points, etc. using a very
 * simple JDBC abstraction. It is NOT RECOMMENDED to emulate an entire database
 * (including complex state transitions, transactions, locking, etc.) using this
 * mock API. Once you have this requirement, please consider using an actual
 * database instead for integration testing (e.g. using
 * <a href="https://www.testcontainers.org">https://www.testcontainers.org</a>),
 * rather than implementing your test database inside of a
 * MockDataProvider.</strong>
 * <p>
 * See {@link #execute(MockExecuteContext)} for more details.
 *
 * @author Lukas Eder
 * @see MockConnection
 */
@FunctionalInterface
public interface MockDataProvider {

    /**
     * Execution callback for a JDBC query execution.
     * <p>
     * This callback will be called by {@link MockStatement} upon the various
     * statement execution methods. These include:
     * <p>
     * <ul>
     * <li>{@link Statement#execute(String)}</li>
     * <li>{@link Statement#execute(String, int)}</li>
     * <li>{@link Statement#execute(String, int[])}</li>
     * <li>{@link Statement#execute(String, String[])}</li>
     * <li>{@link Statement#executeBatch()}</li>
     * <li>{@link Statement#executeQuery(String)}</li>
     * <li>{@link Statement#executeUpdate(String)}</li>
     * <li>{@link Statement#executeUpdate(String, int)}</li>
     * <li>{@link Statement#executeUpdate(String, int[])}</li>
     * <li>{@link Statement#executeUpdate(String, String[])}</li>
     * <li>{@link PreparedStatement#execute()}</li>
     * <li>{@link PreparedStatement#executeQuery()}</li>
     * <li>{@link PreparedStatement#executeUpdate()}</li>
     * </ul>
     * <p>
     * The various execution modes are unified into this simple method.
     * Implementations should adhere to this contract:
     * <p>
     * <ul>
     * <li><code>MockStatement</code> does not distinguish between "static" and
     * "prepared" statements. However, a non-empty
     * {@link MockExecuteContext#bindings()} is a strong indicator for a
     * {@link PreparedStatement}.</li>
     * <li><code>MockStatement</code> does not distinguish between "batch" and
     * "single" statements. However...
     * <ul>
     * <li>A {@link MockExecuteContext#batchSQL()} with more than one SQL string
     * is a strong indicator for a "multi-batch statement", as understood by
     * jOOQ's {@link DSLContext#batch(Query...)}.</li>
     * <li>A {@link MockExecuteContext#batchBindings()} with more than one bind
     * variable array is a strong indicator for a "single-batch statement", as
     * understood by jOOQ's {@link DSLContext#batch(Query)}.</li>
     * </ul>
     * </li>
     * <li>It is recommended to return as many <code>MockResult</code> objects
     * as batch executions. In other words, you should guarantee that:
     * <p>
     * <pre><code>
     * int multiSize = context.getBatchSQL().length;
     * int singleSize = context.getBatchBindings().length;
     * assertEquals(result.length, Math.max(multiSize, singleSize))
     * </code></pre>
     * <p>
     * This holds true also for non-batch executions (where both sizes are equal
     * to <code>1</code>)</li>
     * <li>You may also return more than one result for non-batch executions.
     * This is useful for procedure calls with several result sets.
     * <ul>
     * <li>In JDBC, such additional result sets can be obtained with
     * {@link Statement#getMoreResults()}.</li>
     * <li>In jOOQ, such additional result sets can be obtained with
     * {@link ResultQuery#fetchMany()}</li>
     * </ul>
     * </li>
     * <li>If generated keys ({@link Statement#RETURN_GENERATED_KEYS}) are
     * requested from this execution, you can also add {@link MockResult#data}
     * to your first result, in addition to the affected
     * {@link MockResult#rows}. The relevant flag is passed from
     * <code>MockStatement</code> to any of these properties:
     * <ul>
     * <li>{@link MockExecuteContext#autoGeneratedKeys()}</li>
     * <li>{@link MockExecuteContext#columnIndexes()}</li>
     * <li>{@link MockExecuteContext#columnNames()}</li>
     * </ul>
     * </li>
     * <li>OUT parameters from stored procedures are generated from the first
     * {@link MockResult}'s first {@link Record}. If OUT parameters are
     * requested, implementors must ensure the presence of such a
     * <code>Record</code>.</li>
     * </ul>
     *
     * @param ctx The execution context.
     * @return The execution results. If a <code>null</code> or an empty
     *         <code>MockResult[]</code> is returned, this has the same effect
     *         as returning
     *         <code>new MockResult[] { new MockResult(-1, null) }</code>
     * @throws SQLException A <code>SQLException</code> that is passed through
     *             to jOOQ.
     */
    MockResult[] execute(MockExecuteContext ctx) throws SQLException;
}
