package gu.sql2java;

import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * 简单日志输出工具类
 * @author guyadong
 *
 */
public class SimpleLog {
        /** 占位符 */
        private static final String DELIM_STR = "(\\{\\}|%s)";
        private static final Object[] EMPTY_ARGS = new Object[0];
        /**
         * 返回格式化的日志信息字符串<br>
         * example:
         * <pre>
         * logString("name : {},age:{}","tom",23);
         * </pre>
         * @param format 格式字符串,采用"{}"或"%s"为占位符
         * @param args 填充占位符的参数列表,如果数量小于占位符个数则多出的占位符填充"null"
         */
        public static String logString(String format, Object ... args){
                if(null == format){
                        return "";
                }
                if(null == args){
                        args = EMPTY_ARGS;
                }
                StringBuilder buffer = new StringBuilder(format.length() + 64);
                int beginIndex = 0,count = 0;
                Pattern pattern = Pattern.compile(DELIM_STR);
                Matcher matcher = pattern.matcher(format);
                while(matcher.find()){
                        buffer.append(format.substring(beginIndex,matcher.start()));
                        try{
                                buffer.append(args[count++]);
                        }catch(IndexOutOfBoundsException e){
                                // 数组越界时对应占位符填null
                                buffer.append("null");
                        }
                        beginIndex = matcher.end();
                }
                buffer.append(format.substring(beginIndex,format.length()));
                return buffer.toString();
        }
        private static void log(PrintStream printStream,int level, String format, Object ... args){
                if(null == printStream){
                        return;
                }
                Thread currentThread = Thread.currentThread();
                StackTraceElement stackTrace = currentThread.getStackTrace()[level];
                printStream.printf("[%s] (%s:%d) %s\n",
                                currentThread.getName(),
                                stackTrace.getFileName(),
                                stackTrace.getLineNumber(),
                                logString(format,args));
        }
        /**
         * 向{@code printStream}输出日志信息<br>
         * example:
         * <pre>
         * log("name : {},age:{}","tom",23);
         * </pre>
         * @param printStream
         * @param format 格式字符串,采用"{}"或"%s"为占位符,占位符个数要与{@code args}数组长度匹配
         * @param args 填充占位符的参数列表,如果数量小于占位符个数则多出的占位符填充"null"
         */
        public static void log(PrintStream printStream,String format, Object ... args){
                log(printStream,3,format,args); 
        }
        /**
         * @param output 是否输出
         * @param printStream
         * @param format 格式字符串
         * @param args 填充占位符的参数列表
         * @see #log(PrintStream, String, Object...)
         */
        public static void log(boolean output,PrintStream printStream,String format, Object ... args){
                if(output){
                        log(printStream,3,format,args);
                }
        }
        private static final String formatByCount(int c){
                StringBuffer buffer = new StringBuffer();
                for(int i=0;i<c;++i){
                        if(i>0){
                                buffer.append(",");
                        }
                        buffer.append("{}");
                }
                return buffer.toString();
        }
        /**
         * 向控制台输出日志信息<br>
         * @param output 是否输出
         * @param arg
         * @see #log(PrintStream, String, Object...)
         */
        public static void logObjects(Object arg){
                log(System.out,3,formatByCount(1),new Object[]{arg});
        }
        /**
         * 向控制台输出日志信息<br>
         * @param output 是否输出
         * @param args
         * @see #log(PrintStream, String, Object...)
         */
        public static void logObjects(Object arg,Object ... args){
                Object[] array = new Object[args.length+1];
                array[0] = arg;
                System.arraycopy(args, 0, array, 1, args.length);
                log(System.out,3,formatByCount(args.length),array);
        }
        /**
         * 向控制台输出日志信息<br>
         * @param format 格式字符串,采用"{}"或"%s"为占位符
         * @param args
         * @see #log(PrintStream, String, Object...)
         */
        public static void log(String format, Object ... args){
                log(System.out,3,format,args);
        }
        /**
         * 向控制台输出日志信息<br>
         * @param output 是否输出
         * @param format 格式字符串,采用"{}"或"%s"为占位符
         * @param args
         * @see #log(PrintStream, String, Object...)
         */
        public static void log(boolean output,String format, Object ... args){
                if(output){
                        log(System.out,3,format,args);
                }
        }
        
        private static final String stackTraceOf(Throwable e){
                if(e == null){                  
                        e = new NullPointerException("e is null");
                }
                
                StringWriter writer = new StringWriter();
                PrintWriter pw = new PrintWriter(writer);
                e.printStackTrace(pw);
                return writer.toString();
        }
        public static void log(String msg,Throwable e){
                log(System.out,3,"{}\n{}",msg,stackTraceOf(e));
        }
        public static void log(Throwable e){
                log(System.out,3,"{}",stackTraceOf(e));
        }
}