/**
    *    Copyright 2009-2019 the original author or authors.
    *
    *    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;
  
  import java.util.HashMap;
  
  /**
   * Inline parameter expression parser. Supported grammar (simplified):
   *
   * <pre>
   * inline-parameter = (propertyName | expression) oldJdbcType attributes
   * propertyName = /expression language's property navigation path/
   * expression = '(' /expression language's expression/ ')'
   * oldJdbcType = ':' /any valid jdbc type/
   * attributes = (',' attribute)*
   * attribute = name '=' value
   * </pre>
   *
   * @author Frank D. Martinez [mnesarco]
   */
  public class ParameterExpression extends HashMap<String, String> {
  
    private static final long serialVersionUID = -2417552199605158680L;
  
    public ParameterExpression(String expression) {
      parse(expression);
    }
  
    private void parse(String expression) {
      int p = skipWS(expression, 0);
      if (expression.charAt(p) == '(') {
        expression(expression, p + 1);
      } else {
        property(expression, p);
      }
    }
  
    private void expression(String expression, int left) {
      int match = 1;
      int right = left + 1;
      while (match > 0) {
        if (expression.charAt(right) == ')') {
          match--;
        } else if (expression.charAt(right) == '(') {
          match++;
        }
        right++;
      }
      put("expression", expression.substring(left, right - 1));
      jdbcTypeOpt(expression, right);
    }
  
    private void property(String expression, int left) {
      if (left < expression.length()) {
        int right = skipUntil(expression, left, ",:");
        put("property", trimmedStr(expression, left, right));
        jdbcTypeOpt(expression, right);
      }
    }
  
    private int skipWS(String expression, int p) {
      for (int i = p; i < expression.length(); i++) {
        if (expression.charAt(i) > 0x20) {
          return i;
        }
      }
      return expression.length();
    }
  
    private int skipUntil(String expression, int p, final String endChars) {
      for (int i = p; i < expression.length(); i++) {
        char c = expression.charAt(i);
        if (endChars.indexOf(c) > -1) {
          return i;
        }
      }
      return expression.length();
    }
  
    private void jdbcTypeOpt(String expression, int p) {
      p = skipWS(expression, p);
      if (p < expression.length()) {
        if (expression.charAt(p) == ':') {
          jdbcType(expression, p + 1);
        } else if (expression.charAt(p) == ',') {
          option(expression, p + 1);
       } else {
         throw new BuilderException("Parsing error in {" + expression + "} in position " + p);
       }
     }
   }
 
   private void jdbcType(String expression, int p) {
     int left = skipWS(expression, p);
     int right = skipUntil(expression, left, ",");
     if (right > left) {
       put("jdbcType", trimmedStr(expression, left, right));
     } else {
       throw new BuilderException("Parsing error in {" + expression + "} in position " + p);
     }
     option(expression, right + 1);
   }
 
   private void option(String expression, int p) {
     int left = skipWS(expression, p);
     if (left < expression.length()) {
       int right = skipUntil(expression, left, "=");
       String name = trimmedStr(expression, left, right);
       left = right + 1;
       right = skipUntil(expression, left, ",");
       String value = trimmedStr(expression, left, right);
       put(name, value);
       option(expression, right + 1);
     }
   }
 
   private String trimmedStr(String str, int start, int end) {
     while (str.charAt(start) <= 0x20) {
       start++;
     }
     while (str.charAt(end - 1) <= 0x20) {
       end--;
     }
     return start >= end ? "" : str.substring(start, end);
   }
 
 }