package icbc;

import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import static jdk.nashorn.internal.runtime.regexp.joni.Config.DEBUG;

/**
 * @Author: Alawn
 * @Description:
 * @Date: Create in 下午4:52 2021/3/5
 */
public class BeanToJson {


        //需要解决的问题
        //1.怎么获取字段名,怎么获取字段的值
        //2.怎么判断是基本类型,基本类型的值,不需要加隐含
        //3.怎么判断是常用的类型,如果是常用类型里面的集合话,需要递归判断
        //4.如何判断是自定义的bean对象 如果是自定义的bean对象,需要再次进行解析,
        //5.数组的话,需要遍历展示
        //6.将key按照ascii码升序排列


        //修改部分:原文存在bug.当类型为数组类型的时候,会出现问题, 以修正为需要的逻辑

        public static <T> String toJson(T t) {
            if (t == null) {
                return "{}";
            }
            return beanToJson(t);
        }

        public static <T> String beanToJson(T t) {
            //先获取所有字段名
            Field[] fields = t.getClass().getDeclaredFields();
            String[] keys = new String[fields.length];
            for (int i = 0; i < fields.length; i++) {
                keys[i] = fields[i].getName();
            }
            //获取按照Ascii排序之后的顺序
            keys = getUrlParam(keys);

            StringBuilder sb = new StringBuilder();
            sb.append("{");


            Map<String, Field> map = new HashMap<>();
            for (int i = 0; i < keys.length; i++) {
                for (Field field : fields) {
                    if (field.getName().equals(keys[i])) {
                        map.put(keys[i], field);
                        // 当方法名满足键值得时候结束当前层循环
                        continue;
                    }
                }
            }

            for (String name : keys) {
                Field field = map.get(name);

                field.setAccessible(true);
                Class<?> type = field.getType();

                Object value = null;
                try {
                    value = field.get(t);
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                }
                // 内部类的外部类引用(指针)字段
                if (name.contains("this$")) {
                    continue;
                }


                String typeName = type.getName();
                if (typeName.equals("java.lang.String")) {
                    try {
                        sb.append("\"" + name + "\":");
                        sb.append(stringToJson((String) field.get(t)));
                        sb.append(",");
                    } catch (Exception e) {
                        if (DEBUG) {
                            e.printStackTrace();
                        }

                    }
                } else if (typeName.equals("boolean") ||
                        typeName.equals("java.lang.Boolean") ||
                        typeName.equals("int") ||
                        typeName.equals("java.lang.Integer") ||
                        typeName.equals("float") ||
                        typeName.equals("java.lang.Float") ||
                        typeName.equals("double") ||
                        typeName.equals("java.lang.Double") ||
                        typeName.equals("long") ||
                        typeName.equals("java.lang.Long")) {
                    try {
                        sb.append("\"" + name + "\":");
                        sb.append(field.get(t));
                        sb.append(",");
                    } catch (Exception e) {
                        if (DEBUG) {
                            e.printStackTrace();
                        }
                    }
                } else if (typeName.equals("java.util.List") ||
                        typeName.equals("java.util.ArrayList")) {
                    try {
                        List<?> objList = (List<?>) field.get(t);
                        if (null != objList && objList.size() > 0) {
                            sb.append("\"" + name + "\":");
                            sb.append("[");
                            String toJson = listToJson((List<?>) field.get(t));
                            sb.append(toJson);
                            sb.setCharAt(sb.length() - 1, ']');
                            sb.append(",");
                        }
                    } catch (Exception e) {
                        if (DEBUG) {
                            e.printStackTrace();
                        }
                    }
                } else if (value.getClass().isArray()) {

                    Object[] arr = (Object[]) value; // 装换成数组
                    List list =  Arrays.asList(arr);
                    try {
                        if (null != list && list.size() > 0) {
                            sb.append("\"" + name + "\":");
                            sb.append("[");
                            String toJson = listToJson(list);
                            sb.append(toJson);
                            sb.setCharAt(sb.length() - 1, ']');
                            sb.append(",");
                        }
                    } catch (Exception e) {
                        if (DEBUG) {
                            e.printStackTrace();
                        }
                    }
                } else {
                    try {
                        sb.append("\"" + name + "\":");
                        sb.append("{");
                        sb.append(beanToJson(field.get(t)));
                        sb.setCharAt(sb.length() - 1, '}');
                        sb.append(",");
                    } catch (Exception e) {
                        if (DEBUG) {
                            e.printStackTrace();
                        }
                    }
                }

            }

            if (sb.length() == 1) {
                sb.append("}");
            }
            sb.setCharAt(sb.length() - 1, '}');
            return sb.toString();
        }

        /**
         * 将 List 对象编码为 JSON格式
         *
         * @param objList 待封装的对象集合
         * @return String:封装后JSONArray String格式
         * @version 1.0
         */
        private static <T> String listToJson(List<T> objList) {
            final StringBuilder sb = new StringBuilder();
            for (T t : objList) {
                if (t instanceof String) {
                    sb.append(stringToJson((String) t));
                    sb.append(",");
                } else if (t instanceof Boolean ||
                        t instanceof Integer ||
                        t instanceof Float ||
                        t instanceof Double) {
                    sb.append(t);
                    sb.append(",");
                } else {
                    sb.append(beanToJson(t));
                    sb.append(",");
                }
            }
            return sb.toString();
        }

        /**
         * 将 String 对象编码为 JSON格式，只需处理好特殊字符
         *
         * @param str String 对象
         * @return String:JSON格式
         * @version 1.0
         */
        private static String stringToJson(final String str) {
            if (str == null || str.length() == 0) {
                return "\"\"";
            }
            final StringBuilder sb = new StringBuilder();
            sb.append('\"');
            for (int i = 0; i < str.length(); i++) {
                final char c = str.charAt(i);

                sb.append(c == '\"' ? "\\\"" : c == '\\' ? "\\\\"
                        : c == '/' ? "\\/" : c == '\b' ? "\\b" : c == '\f' ? "\\f"
                        : c == '\n' ? "\\n" : c == '\r' ? "\\r"
                        : c == '\t' ? "\\t" : c + "");
            }
            sb.append('\"');
            return sb.toString();
        }


        /**
         * 对字符串数组进行排序
         *
         * @param keys
         * @return
         */
        private static String[] getUrlParam(String[] keys) {

            for (int i = 0; i < keys.length - 1; i++) {
                for (int j = 0; j < keys.length - i - 1; j++) {
                    String pre = keys[j];
                    String next = keys[j + 1];
                    if (isMoreThan(pre, next)) {
                        String temp = pre;
                        keys[j] = next;
                        keys[j + 1] = temp;
                    }
                }
            }
            return keys;
        }

        /**
         * 比较两个字符串的大小，按字母的ASCII码比较
         *
         * @param pre
         * @param next
         * @return
         */
        private static boolean isMoreThan(String pre, String next) {
            if (null == pre || null == next || "".equals(pre) || "".equals(next)) {
                return false;
            }

            char[] c_pre = pre.toCharArray();
            char[] c_next = next.toCharArray();

            int minSize = Math.min(c_pre.length, c_next.length);

            for (int i = 0; i < minSize; i++) {
                if ((int) c_pre[i] > (int) c_next[i]) {
                    return true;
                } else if ((int) c_pre[i] < (int) c_next[i]) {
                    return false;
                }
            }
            if (c_pre.length > c_next.length) {
                return true;
            }

            return false;
        }

}