/*
 * Copyright DataStax, Inc.
 *
 * Licensed 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 com.datastax.driver.core.schemabuilder;

import com.datastax.driver.core.CodecRegistry;
import com.datastax.driver.core.Metadata;
import com.datastax.driver.core.ProtocolVersion;
import com.datastax.driver.core.RegularStatement;
import com.google.common.base.Strings;

import java.nio.ByteBuffer;
import java.util.Map;

/**
 * A DDL statement generated by {@link SchemaBuilder}.
 */
public abstract class SchemaStatement extends RegularStatement {

    static final String STATEMENT_START = "\n\t";
    static final String COLUMN_FORMATTING = "\n\t\t";

    private volatile String cache;

    abstract String buildInternal();

    @Override
    public String getQueryString(CodecRegistry codecRegistry) {
        if (cache == null) {
            cache = buildInternal();
        }
        return cache;
    }

    @Override
    public ByteBuffer[] getValues(ProtocolVersion protocolVersion, CodecRegistry codecRegistry) {
        // DDL statements never have values
        return new ByteBuffer[0];
    }

    @Override
    public boolean hasValues(CodecRegistry codecRegistry) {
        return false;
    }

    @Override
    public Map<String, ByteBuffer> getNamedValues(ProtocolVersion protocolVersion, CodecRegistry codecRegistry) {
        // DDL statements never have values
        return null;
    }

    @Override
    public boolean usesNamedValues() {
        return false;
    }

    @Override
    public String getKeyspace() {
        // This is exposed for token-aware routing. Since there is no token awareness for DDL statements, we don't need to
        // return anything here (even if a keyspace has been explicitly set in the statement).
        return null;
    }

    /**
     * {@inheritDoc}
     *
     * @param protocolVersion unused by this implementation (the key is always null for schema statements).
     * @param codecRegistry   unused by this implementation (the key is always null for schema statements).
     */
    @Override
    public ByteBuffer getRoutingKey(ProtocolVersion protocolVersion, CodecRegistry codecRegistry) {
        return null; // there is no token awareness for DDL statements
    }

    static void validateNotEmpty(String columnName, String label) {
        if (Strings.isNullOrEmpty(columnName)) {
            throw new IllegalArgumentException(label + " should not be null or blank");
        }
    }

    static void validateNotNull(Object value, String label) {
        if (value == null) {
            throw new IllegalArgumentException(label + " should not be null");
        }
    }

    static void validateNotKeyWord(String label, String message) {
        if (Metadata.isReservedCqlKeyword(label)) {
            throw new IllegalArgumentException(message);
        }
    }

    static SchemaStatement fromQueryString(final String queryString) {
        return new SchemaStatement() {
            @Override
            public String buildInternal() {
                return queryString;
            }
        };
    }

    StatementStart asStatementStart() {
        return new StatementStart() {
            @Override
            public String buildInternal() {
                return SchemaStatement.this.buildInternal();
            }
        };
    }
}
