package liquibase.sqlgenerator.core;

import liquibase.change.ColumnConfig;
import liquibase.database.Database;
import liquibase.database.core.*;
import liquibase.exception.ValidationErrors;
import liquibase.sql.Sql;
import liquibase.sql.UnparsedSql;
import liquibase.sqlgenerator.SqlGenerator;
import liquibase.sqlgenerator.SqlGeneratorChain;
import liquibase.statement.core.DropUniqueConstraintStatement;
import liquibase.structure.core.Column;
import liquibase.structure.core.Table;
import liquibase.structure.core.UniqueConstraint;
import liquibase.util.StringUtils;

public class DropUniqueConstraintGenerator extends AbstractSqlGenerator<DropUniqueConstraintStatement> {

    @Override
    public boolean supports(DropUniqueConstraintStatement statement, Database database) {
        return !(database instanceof SQLiteDatabase);
    }

    @Override
    public ValidationErrors validate(DropUniqueConstraintStatement dropUniqueConstraintStatement, Database database, SqlGeneratorChain sqlGeneratorChain) {
        ValidationErrors validationErrors = new ValidationErrors();
        validationErrors.checkRequiredField("tableName", dropUniqueConstraintStatement.getTableName());
        validationErrors.checkRequiredField("constraintName", dropUniqueConstraintStatement.getConstraintName());
        return validationErrors;
    }

    @Override
    public Sql[] generateSql(DropUniqueConstraintStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
        String sql;
        if (database instanceof MySQLDatabase) {
            sql = "ALTER TABLE " + database.escapeTableName(statement.getCatalogName(), statement.getSchemaName(), statement.getTableName()) + " DROP KEY " + database.escapeConstraintName(statement.getConstraintName());
        } else if (database instanceof OracleDatabase) {
            sql = "ALTER TABLE " + database.escapeTableName(statement.getCatalogName(), statement.getSchemaName(), statement.getTableName()) + " DROP CONSTRAINT " + database.escapeConstraintName(statement.getConstraintName()) + " DROP INDEX";
        } else if (database instanceof SybaseASADatabase) {
            sql = "ALTER TABLE " + database.escapeTableName(statement.getCatalogName(), statement.getSchemaName(), statement.getTableName()) + " DROP UNIQUE (" + StringUtils.join(statement.getUniqueColumns(), ", ", new StringUtils.StringUtilsFormatter<ColumnConfig>() {
                @Override
                public String toString(ColumnConfig obj) {
                    return obj.getName();
                }
            }) + ")";
        } else {
            sql = "ALTER TABLE " + database.escapeTableName(statement.getCatalogName(), statement.getSchemaName(), statement.getTableName()) + " DROP CONSTRAINT " + database.escapeConstraintName(statement.getConstraintName());
        }

        return new Sql[] {
                new UnparsedSql(sql, getAffectedUniqueConstraint(statement))
        };
    }

    protected UniqueConstraint getAffectedUniqueConstraint(DropUniqueConstraintStatement statement) {
        UniqueConstraint constraint = new UniqueConstraint().setName(statement.getConstraintName()).setTable((Table) new Table().setName(statement.getTableName()).setSchema(statement.getCatalogName(), statement.getSchemaName()));
        if (statement.getUniqueColumns() != null) {
            int i = 0;
            for (ColumnConfig column : statement.getUniqueColumns()) {
                constraint.addColumn(i++, new Column(column));
            }
        }
        return constraint;
    }
}