use base64;
use byteorder::{BigEndian, ByteOrder};
use crypto;
use crypto::aes;
use crypto::digest::Digest;
use crypto::hmac::Hmac;
use crypto::pbkdf2::pbkdf2;
use crypto::sha1::Sha1;
use protobuf::ProtobufEnum;
use rpassword;
use serde;
use serde_json;
use std::io::{self, stderr, Read, Write};
use std::fs::File;
use std::path::Path;

use protocol::authentication::AuthenticationType;

#[derive(Debug, Clone)]
#[derive(Serialize, Deserialize)]
pub struct Credentials {
    pub username: String,

    #[serde(serialize_with="serialize_protobuf_enum")]
    #[serde(deserialize_with="deserialize_protobuf_enum")]
    pub auth_type: AuthenticationType,

    #[serde(serialize_with="serialize_base64")]
    #[serde(deserialize_with="deserialize_base64")]
    pub auth_data: Vec<u8>,
}

impl Credentials {
    pub fn with_password(username: String, password: String) -> Credentials {
        Credentials {
            username: username,
            auth_type: AuthenticationType::AUTHENTICATION_USER_PASS,
            auth_data: password.into_bytes(),
        }
    }

    pub fn with_blob(username: String, encrypted_blob: &str, device_id: &str) -> Credentials {
        fn read_u8<R: Read>(stream: &mut R) -> io::Result<u8> {
            let mut data = [0u8];
            try!(stream.read_exact(&mut data));
            Ok(data[0])
        }

        fn read_int<R: Read>(stream: &mut R) -> io::Result<u32> {
            let lo = try!(read_u8(stream)) as u32;
            if lo & 0x80 == 0 {
                return Ok(lo);
            }

            let hi = try!(read_u8(stream)) as u32;
            Ok(lo & 0x7f | hi << 7)
        }

        fn read_bytes<R: Read>(stream: &mut R) -> io::Result<Vec<u8>> {
            let length = try!(read_int(stream));
            let mut data = vec![0u8; length as usize];
            try!(stream.read_exact(&mut data));

            Ok(data)
        }

        let encrypted_blob = base64::decode(encrypted_blob).unwrap();

        let secret = {
            let mut data = [0u8; 20];
            let mut h = crypto::sha1::Sha1::new();
            h.input(device_id.as_bytes());
            h.result(&mut data);
            data
        };

        let key = {
            let mut data = [0u8; 24];
            let mut mac = Hmac::new(Sha1::new(), &secret);
            pbkdf2(&mut mac, username.as_bytes(), 0x100, &mut data[0..20]);

            let mut hash = Sha1::new();
            hash.input(&data[0..20]);
            hash.result(&mut data[0..20]);
            BigEndian::write_u32(&mut data[20..], 20);
            data
        };

        let blob = {
            // Anyone know what this block mode is ?
            let mut data = vec![0u8; encrypted_blob.len()];
            let mut cipher = aes::ecb_decryptor(aes::KeySize::KeySize192,
                                                &key,
                                                crypto::blockmodes::NoPadding);
            cipher.decrypt(&mut crypto::buffer::RefReadBuffer::new(&encrypted_blob),
                           &mut crypto::buffer::RefWriteBuffer::new(&mut data),
                           true)
                  .unwrap();

            let l = encrypted_blob.len();
            for i in 0..l - 0x10 {
                data[l - i - 1] ^= data[l - i - 0x11];
            }

            data
        };

        let mut cursor = io::Cursor::new(&blob);
        read_u8(&mut cursor).unwrap();
        read_bytes(&mut cursor).unwrap();
        read_u8(&mut cursor).unwrap();
        let auth_type = read_int(&mut cursor).unwrap();
        let auth_type = AuthenticationType::from_i32(auth_type as i32).unwrap();
        read_u8(&mut cursor).unwrap();
        let auth_data = read_bytes(&mut cursor).unwrap();;

        Credentials {
            username: username,
            auth_type: auth_type,
            auth_data: auth_data,
        }
    }

    pub fn from_reader<R: Read>(mut reader: R) -> Credentials {
        let mut contents = String::new();
        reader.read_to_string(&mut contents).unwrap();

        serde_json::from_str(&contents).unwrap()
    }

    pub fn from_file<P: AsRef<Path>>(path: P) -> Option<Credentials> {
        File::open(path).ok().map(Credentials::from_reader)
    }

    pub fn save_to_writer<W: Write>(&self, writer: &mut W) {
        let contents = serde_json::to_string(&self.clone()).unwrap();
        writer.write_all(contents.as_bytes()).unwrap();
    }

    pub fn save_to_file<P: AsRef<Path>>(&self, path: P) {
        let mut file = File::create(path).unwrap();
        self.save_to_writer(&mut file)
    }
}

fn serialize_protobuf_enum<T, S>(v: &T, ser: S) -> Result<S::Ok, S::Error>
    where T: ProtobufEnum, S: serde::Serializer {

    serde::Serialize::serialize(&v.value(), ser)
}

fn deserialize_protobuf_enum<T, D>(de: D) -> Result<T, D::Error>
    where T: ProtobufEnum, D: serde::Deserializer {

    let v : i32 = try!(serde::Deserialize::deserialize(de));
    T::from_i32(v).ok_or_else(|| serde::de::Error::custom("Invalid enum value"))
}

fn serialize_base64<T, S>(v: &T, ser: S) -> Result<S::Ok, S::Error>
    where T: AsRef<[u8]>, S: serde::Serializer {

    serde::Serialize::serialize(&base64::encode(v.as_ref()), ser)
}

fn deserialize_base64<D>(de: D) -> Result<Vec<u8>, D::Error>
    where D: serde::Deserializer {

    let v : String = try!(serde::Deserialize::deserialize(de));
    base64::decode(&v).map_err(|e| serde::de::Error::custom(e.to_string()))
}

pub fn get_credentials(username: Option<String>, password: Option<String>,
                       cached_credentials: Option<Credentials>)
    -> Option<Credentials>
{
    match (username, password, cached_credentials) {

        (Some(username), Some(password), _)
            => Some(Credentials::with_password(username, password)),

        (Some(ref username), _, Some(ref credentials))
            if *username == credentials.username => Some(credentials.clone()),

        (Some(username), None, _) => {
            write!(stderr(), "Password for {}: ", username).unwrap();
            stderr().flush().unwrap();
            let password = rpassword::read_password().unwrap();
            Some(Credentials::with_password(username.clone(), password))
        }

        (None, _, Some(credentials))
            => Some(credentials),

        (None, _, None) => None,
    }
}