package hw.macro;

typedef JsonKeyPosition = {
  var min:Int;
  var max:Int;
  var file:String;
}

class PositionJsonParser {

  static public inline function parse(str : String, file : String) : Dynamic {
    return new PositionJsonParser(str, file).parseRec();
  }

  var str : String;
  var pos : Int;
  var file : String;

  function new( str : String, file:String ) {
    this.str = str;
    this.pos = 0;
    this.file = file;
  }

  function getKeyPosition():JsonKeyPosition {
    return {
      min: pos,
      max: pos,
      file: file
    }
  }

  function parseRec() : Dynamic {
    while( true ) {
      var c = nextChar();
      switch( c ) {
        case ' '.code, '\r'.code, '\n'.code, '\t'.code:
// loop
        case '{'.code:
          var obj = {}, field = null, comma : Null<Bool> = null;
          var position = null;
          while( true ) {
            var c = nextChar();
            switch( c ) {
              case ' '.code, '\r'.code, '\n'.code, '\t'.code:
// loop
              case '}'.code:
                if( field != null || comma == false )
                  invalidChar();
                return obj;
              case ':'.code:
                if( field == null )
                  invalidChar();
                Reflect.setField(obj,field,parseRec());
                Reflect.setField(obj,"$" + field,position);
                field = null;
                comma = true;
              case ','.code:
                if( comma ) comma = false else invalidChar();
              case '"'.code:
                if( comma ) invalidChar();
                position = getKeyPosition();
                field = parseString();
              default:
                invalidChar();
            }
          }
        case '['.code:
          var arr = [], comma : Null<Bool> = null;
          while( true ) {
            var c = nextChar();
            switch( c ) {
              case ' '.code, '\r'.code, '\n'.code, '\t'.code:
// loop
              case ']'.code:
                if( comma == false ) invalidChar();
                return arr;
              case ','.code:
                if( comma ) comma = false else invalidChar();
              default:
                if( comma ) invalidChar();
                pos--;
                arr.push(parseRec());
                comma = true;
            }
          }
        case 't'.code:
          var save = pos;
          if( nextChar() != 'r'.code || nextChar() != 'u'.code || nextChar() != 'e'.code ) {
            pos = save;
            invalidChar();
          }
          return true;
        case 'f'.code:
          var save = pos;
          if( nextChar() != 'a'.code || nextChar() != 'l'.code || nextChar() != 's'.code || nextChar() != 'e'.code ) {
            pos = save;
            invalidChar();
          }
          return false;
        case 'n'.code:
          var save = pos;
          if( nextChar() != 'u'.code || nextChar() != 'l'.code || nextChar() != 'l'.code ) {
            pos = save;
            invalidChar();
          }
          return null;
        case '"'.code:
          return parseString();
        case '0'.code, '1'.code,'2'.code,'3'.code,'4'.code,'5'.code,'6'.code,'7'.code,'8'.code,'9'.code,'-'.code:
          return parseNumber(c);
        default:
          invalidChar();
      }
    }
  }

  function parseString() {
    var start = pos;
    var buf = null;
    while( true ) {
      var c = nextChar();
      if( c == '"'.code )
        break;
      if( c == '\\'.code ) {
        if (buf == null) {
          buf = new StringBuf();
        }
        buf.addSub(str,start, pos - start - 1);
        c = nextChar();
        switch( c ) {
          case "r".code: buf.addChar("\r".code);
          case "n".code: buf.addChar("\n".code);
          case "t".code: buf.addChar("\t".code);
          case "b".code: buf.addChar(8);
          case "f".code: buf.addChar(12);
          case "/".code, '\\'.code, '"'.code: buf.addChar(c);
          case 'u'.code:
            var uc = Std.parseInt("0x" + str.substr(pos, 4));
            pos += 4;
#if (neko || php || cpp)
            if( uc <= 0x7F )
              buf.addChar(uc);
            else if( uc <= 0x7FF ) {
              buf.addChar(0xC0 | (uc >> 6));
              buf.addChar(0x80 | (uc & 63));
            } else if( uc <= 0xFFFF ) {
              buf.addChar(0xE0 | (uc >> 12));
              buf.addChar(0x80 | ((uc >> 6) & 63));
              buf.addChar(0x80 | (uc & 63));
            } else {
              buf.addChar(0xF0 | (uc >> 18));
              buf.addChar(0x80 | ((uc >> 12) & 63));
              buf.addChar(0x80 | ((uc >> 6) & 63));
              buf.addChar(0x80 | (uc & 63));
            }
#else
            buf.addChar(uc);
#end
          default:
            throw "Invalid escape sequence \\" + String.fromCharCode(c) + " at position " + (pos - 1);
        }
        start = pos;
      }
#if (neko || php || cpp)
// ensure utf8 chars are not cut
      else if( c >= 0x80 ) {
        pos++;
        if( c >= 0xFC ) pos += 4;
        else if( c >= 0xF8 ) pos += 3;
        else if( c >= 0xF0 ) pos += 2;
        else if( c >= 0xE0 ) pos++;
      }
#end
      else if( StringTools.isEof(c) )
        throw "Unclosed string";
    }
    if (buf == null) {
      return str.substr(start, pos - start - 1);
    }
    else {
      buf.addSub(str,start, pos - start - 1);
      return buf.toString();
    }
  }

  inline function parseNumber( c : Int ) : Dynamic {
    var start = pos - 1;
    var minus = c == '-'.code, digit = !minus, zero = c == '0'.code;
    var point = false, e = false, pm = false, end = false;
    while( true ) {
      c = nextChar();
      switch( c ) {
        case '0'.code :
          if (zero && !point) invalidNumber(start);
          if (minus) {
            minus = false; zero = true;
          }
          digit = true;
        case '1'.code,'2'.code,'3'.code,'4'.code,'5'.code,'6'.code,'7'.code,'8'.code,'9'.code :
          if (zero && !point) invalidNumber(start);
          if (minus) minus = false;
          digit = true; zero = false;
        case '.'.code :
          if (minus || point) invalidNumber(start);
          digit = false; point = true;
        case 'e'.code, 'E'.code :
          if (minus || zero || e) invalidNumber(start);
          digit = false; e = true;
        case '+'.code, '-'.code :
          if (!e || pm) invalidNumber(start);
          digit = false; pm = true;
        default :
          if (!digit) invalidNumber(start);
          pos--;
          end = true;
      }
      if (end) break;
    }
    var f = Std.parseFloat(str.substr(start, pos - start));
    var i = Std.int(f);
    return if( i == f ) i else f;
  }

  inline function nextChar() {
    return StringTools.fastCodeAt(str,pos++);
  }

  function invalidChar() {
    pos--; // rewind
    throw "Invalid char "+StringTools.fastCodeAt(str,pos)+" at position "+pos;
  }

  function invalidNumber( start : Int ) {
    throw "Invalid number at position "+start+": " + str.substr(start, pos - start);
  }
}