var Stream = require('stream').Stream,
    utillib = require('util'),
    mimelib = require("mimelib"),
    encodinglib = require("encoding"),
    crypto = require("crypto");

module.exports.Base64Stream = Base64Stream;
module.exports.QPStream = QPStream;
module.exports.BinaryStream = BinaryStream;

function Base64Stream(){
    Stream.call(this);
    this.writable = true;

    this.checksum = crypto.createHash("md5");
    this.length = 0;

    this.current = "";
}
utillib.inherits(Base64Stream, Stream);

Base64Stream.prototype.write = function(data){
    this.handleInput(data);
    return true;
};

Base64Stream.prototype.end = function(data){
    this.handleInput(data);
    this.emit("end");
    return {
        length: this.length,
        checksum: this.checksum.digest("hex")
    };
};

Base64Stream.prototype.handleInput = function(data){
    if(!data || !data.length){
        return;
    }

    data = (data || "").toString("utf-8");

    var remainder = 0;
    this.current += data.replace(/[^\w\+\/=]/g,'');
    var buffer = new Buffer(this.current.substr(0, this.current.length - this.current.length % 4),"base64");
    if(buffer.length){
        this.length += buffer.length;
        this.checksum.update(buffer);
        this.emit("data", buffer);
    }
    this.current = (remainder=this.current.length % 4)?this.current.substr(- remainder):"";
};

function QPStream(charset){
    Stream.call(this);
    this.writable = true;

    this.checksum = crypto.createHash("md5");
    this.length = 0;

    this.charset = charset || "UTF-8";
    this.current = undefined;
}
utillib.inherits(QPStream, Stream);

QPStream.prototype.write = function(data){
    this.handleInput(data);
    return true;
};

QPStream.prototype.end = function(data){
    this.handleInput(data);
    this.flush();
    this.emit("end");
    return {
        length: this.length,
        checksum: this.checksum.digest("hex")
    };
};

QPStream.prototype.handleInput = function(data){
    if(!data || !data.length){
        return;
    }

    data = (data || "").toString("utf-8");
    if(data.match(/^\r\n/)){
        data = data.substr(2);
    }

    if(typeof this.current !="string"){
        this.current = data;
    }else{
        this.current += "\r\n" + data;
    }
};

QPStream.prototype.flush = function(){
    var buffer = mimelib.decodeQuotedPrintable(this.current, false, this.charset);

    if(this.charset.toLowerCase() == "binary"){
        // do nothing
    }else if(this.charset.toLowerCase() != "utf-8"){
        buffer = encodinglib.convert(buffer, "utf-8", this.charset);
    }else{
        buffer = new Buffer(buffer, "utf-8");
    }

    this.length += buffer.length;
    this.checksum.update(buffer);

    this.emit("data", buffer);
};

function BinaryStream(charset){
    Stream.call(this);
    this.writable = true;

    this.checksum = crypto.createHash("md5");
    this.length = 0;

    this.charset = charset || "UTF-8";
    this.current = "";
}
utillib.inherits(BinaryStream, Stream);

BinaryStream.prototype.write = function(data){
    if(data && data.length){
        this.length += data.length;
        this.checksum.update(data);
        this.emit("data", data);
    }
    return true;
};

BinaryStream.prototype.end = function(data){
    if(data && data.length){
        this.emit("data", data);
    }
    this.emit("end");
    return {
        length: this.length,
        checksum: this.checksum.digest("hex")
    };
};