/*
 *    Copyright 2009-2011 The MyBatis Team
 *
 *    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 org.apache.ibatis.builder.xml.dynamic;

import org.apache.ibatis.session.Configuration;

import java.util.*;

public class TrimSqlNode implements SqlNode {

  private SqlNode contents;
  private String prefix;
  private String suffix;
  private List<String> prefixesToOverride = new ArrayList<String>();
  private List<String> suffixesToOverride = new ArrayList<String>();
  private Configuration configuration;

  public TrimSqlNode(Configuration configuration, SqlNode contents, String prefix, String prefixesToOverride, String suffix, String suffixesToOverride) {
    this.contents = contents;
    this.prefix = prefix;
    this.prefixesToOverride = parseOverrides(prefixesToOverride);
    this.suffix = suffix;
    this.suffixesToOverride = parseOverrides(suffixesToOverride);
    this.configuration = configuration;
  }

  public boolean apply(DynamicContext context) {
    FilteredDynamicContext filteredDynamicContext = new FilteredDynamicContext(context);
    boolean result = contents.apply(filteredDynamicContext);
    filteredDynamicContext.applyAll();
    return result;
  }

  private List<String> parseOverrides(String overrides) {
    if (overrides != null) {
      final StringTokenizer parser = new StringTokenizer(overrides, "|", false);
      return new ArrayList<String>() {
        private static final long serialVersionUID = -2504816393625384165L;

        {
          while (parser.hasMoreTokens()) {
            add(parser.nextToken().toUpperCase(Locale.ENGLISH));
          }
        }
      };
    }
    return Collections.EMPTY_LIST;
  }

  private class FilteredDynamicContext extends DynamicContext {
    private DynamicContext delegate;
    private boolean prefixApplied;
    private boolean suffixApplied;
    private StringBuilder sqlBuffer;

    public FilteredDynamicContext(DynamicContext delegate) {
      super(configuration, null);
      this.delegate = delegate;
      this.prefixApplied = false;
      this.suffixApplied = false;
      this.sqlBuffer = new StringBuilder();
    }

    public void applyAll() {
      sqlBuffer = new StringBuilder(sqlBuffer.toString().trim());
      String trimmedUppercaseSql = sqlBuffer.toString().toUpperCase(Locale.ENGLISH);
      if (trimmedUppercaseSql.length() > 0) {
        applyPrefix(sqlBuffer, trimmedUppercaseSql);
        applySuffix(sqlBuffer, trimmedUppercaseSql);
      }
      delegate.appendSql(sqlBuffer.toString());
    }

    public Map<String, Object> getBindings() {
      return delegate.getBindings();
    }

    public void bind(String name, Object value) {
      delegate.bind(name, value);
    }

    public int getUniqueNumber() {
      return delegate.getUniqueNumber();
    }

    public void appendSql(String sql) {
      sqlBuffer.append(sql);
    }

    public String getSql() {
      return delegate.getSql();
    }

    private void applyPrefix(StringBuilder sql, String trimmedUppercaseSql) {
      if (!prefixApplied) {
        prefixApplied = true;
        for (String toRemove : prefixesToOverride) {
          if (trimmedUppercaseSql.startsWith(toRemove)) {
            sql.delete(0, toRemove.trim().length());
            break;
          }
        }
        if (prefix != null) {
          sql.insert(0, " ");
          sql.insert(0, prefix);
        }
      }
    }

    private void applySuffix(StringBuilder sql, String trimmedUppercaseSql) {
      if (!suffixApplied) {
        suffixApplied = true;
        for (String toRemove : suffixesToOverride) {
          if (trimmedUppercaseSql.endsWith(toRemove) || trimmedUppercaseSql.endsWith(toRemove.trim())) {
            int start = sql.length() - toRemove.trim().length();
            int end = sql.length();
            sql.delete(start, end);
            break;
          }
        }
        if (suffix != null) {
          sql.append(" ");
          sql.append(suffix);
        }
      }
    }

  }

}
