extern crate bn;
extern crate rand;
extern crate bincode;
extern crate sodiumoxide;

use std::fmt;
use std::str;
use std::default;
use bn::{Group, Fr, G1, G2, pairing};
use bincode::SizeLimit::Infinite;
use bincode::rustc_serialize::{encode, decode};
use sodiumoxide::crypto::hash::sha512;

// Begin CL Signature scheme data structures

// End CL Signature scheme data structures

//pub fn hash_string(s: &str) -> String {
//    let digest = sha256::hash(s.as_bytes());
//    format!("{:X}", HexSlice::new(&digest))
//}

pub fn debug_elem_in_hex(prefix: &str, r: &Fr) {
    let encoded: Vec<u8> = encode(&r, Infinite).unwrap();
    print!("{} (hex) = 0x", prefix);
    for e in encoded.iter() {
        print!("{:x}", e);
    }
    print!("\n");
}

struct HexSlice<'a>(&'a [u8]);

impl<'a> HexSlice<'a> {
    fn new<T>(data: &'a T) -> HexSlice<'a>
        where T: ?Sized + AsRef<[u8]> + 'a
    {
        HexSlice(data.as_ref())
    }
}

impl<'a> fmt::LowerHex for HexSlice<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        for byte in self.0 {
            // Decide if you want upper- or lowercase results,
            // padding the values to two characters, spaces
            // between bytes, etc.
            write!(f, "{:x}", byte)?;
        }
        Ok(())
    }
}

impl<'a> fmt::UpperHex for HexSlice<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        for byte in self.0 {
            // Decide if you want upper- or lowercase results,
            // padding the values to two characters, spaces
            // between bytes, etc.
            write!(f, "{:X}", byte)?;
        }
        Ok(())
    }
}
// To hash this message structure, encode each element in the tuple
// as a byte stream, then apply a hash on it. Then, convert the output value into
// a Fr element.

pub fn misc_tests() {
    let rng = &mut rand::thread_rng();
    let a = Fr::random(rng);
    // println!("crs = {}", stringify!(a));
    // let limit = bincode::SizeLimit::Bounded(256);
    let encoded: Vec<u8> = encode(&a, Infinite).unwrap();
    println!("a length = {}", encoded.len());
    println!("a = {:?}", encoded);
    print!("a (hex) = 0x");
    for x in encoded.iter() {
        print!("{:x}", x);
    }
    print!("\n");

}

////////////////////////////////// SymKeyEnc ///////////////////////////////////
/*
    Symmetric Key Encryption Scheme.
*/
pub mod sym {
    use std::fmt;
    use sodiumoxide;
    use sodiumoxide::crypto::secretbox;

    pub struct SymCT {
        nonce: secretbox::Nonce,
        ciphertext: Vec<u8>
    }


    impl fmt::Display for SymCT {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            let mut y_s = String::new();
            for y in self.ciphertext.iter() {
                y_s = format!("{}{:x}", y_s, y);
            }

            write!(f, "CT : (ct=0x{})", y_s)
        }
    }

    #[derive(Clone)]
    pub struct SymKey {
        key: secretbox::Key,
        l: i32
    }

    pub fn init() {
        sodiumoxide::init();
    }

    pub fn keygen(l: i32) -> SymKey {
        // TODO: make sure key is a l-bit key
        return SymKey { key: secretbox::gen_key(), l: l };
    }

    pub fn encrypt(key: &SymKey, plaintext: &String) -> SymCT {
        let nonce = secretbox::gen_nonce();
        let pt = plaintext.as_bytes();
        let ct = secretbox::seal(pt, &nonce, &key.key);
        return SymCT { nonce: nonce, ciphertext: ct };
    }

    pub fn decrypt(key: &SymKey, ciphertext: &SymCT) -> String {
        let nonce = ciphertext.nonce;
        let pt = secretbox::open(&ciphertext.ciphertext, &nonce, &key.key).unwrap();
        // TODO: investigate better error handling here
        let plaintext = String::from_utf8(pt).expect("Found invalid UTF-8");
        return plaintext;
    }
}

////////////////////////////////// SymKeyEnc ///////////////////////////////////

////////////////////////////////// OTEnc ///////////////////////////////////////

// TODO: implement this next
pub mod ot {

}

////////////////////////////////// OTEnc ///////////////////////////////////////

////////////////////////////////// CL Sigs /////////////////////////////////////

pub mod clsigs;
pub mod commit_scheme;
//pub mod clsigs {
//    use std::fmt;
//    use std::str;
//    //use std::default;
//    use rand;
//    use bn::{Group, Fr, G1, G2, pairing};
//    //use debug_elem_in_hex;
//    use bincode::SizeLimit::Infinite;
//    use bincode::rustc_serialize::encode;
//    use sodiumoxide::crypto::hash::sha512;
//
//    pub struct PublicParams {
//        g: G1
//    }
//
//    pub struct PublicKey {
//        X: G1,
//        Y: G1
//    }
//
//    impl fmt::Display for PublicKey {
//        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
//            let x_vec: Vec<u8> = encode(&self.X, Infinite).unwrap();
//            let y_vec: Vec<u8> = encode(&self.Y, Infinite).unwrap();
//            let mut x_s = String::new();
//            for x in x_vec.iter() {
//                x_s = format!("{}{:x}", x_s, x);
//            }
//
//            let mut y_s = String::new();
//            for y in y_vec.iter() {
//                y_s = format!("{}{:x}", y_s, y);
//            }
//
//            write!(f, "PK : (X=0x{}, Y=0x{})", x_s, y_s)
//        }
//    }
//
//    #[derive(Copy, Clone)]
//    pub struct SecretKey {
//        x: Fr,
//        y: Fr
//    }
//
//    impl SecretKey {
//        pub fn encode(&self) -> Vec<u8> {
//            let mut output_buf = Vec::new();
//            let x_vec: Vec<u8> = encode(&self.x, Infinite).unwrap();
//            let y_vec: Vec<u8> = encode(&self.y, Infinite).unwrap();
//            output_buf.extend(x_vec);
//            output_buf.extend(y_vec);
//            return output_buf;
//        }
//    }
//
//    pub struct KeyPair {
//        pub sk: SecretKey,
//        pub pk: PublicKey
//    }
//
//    pub struct Signature {
//        a: G2,
//        b: G2,
//        c: G2
//    }
//
//    impl fmt::Display for Signature {
//        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
//            let a_vec: Vec<u8> = encode(&self.a, Infinite).unwrap();
//            let b_vec: Vec<u8> = encode(&self.b, Infinite).unwrap();
//            let c_vec: Vec<u8> = encode(&self.c, Infinite).unwrap();
//            let mut a_s = String::new();
//            for x in a_vec.iter() {
//                a_s = format!("{}{:x}", a_s, x);
//            }
//
//            let mut b_s = String::new();
//            for y in b_vec.iter() {
//                b_s = format!("{}{:x}", b_s, y);
//            }
//
//            let mut c_s = String::new();
//            for y in c_vec.iter() {
//                c_s = format!("{}{:x}", c_s, y);
//            }
//
//            write!(f, "Signature : (\na = 0x{},\nb = 0x{},\nc = 0x{}\n)", a_s, b_s, c_s)
//        }
//    }
//
//    #[derive(Clone)]
//    pub struct Message<'a> {
//        prefix: &'a str, // string prefix for the prefix
//        c_id: Fr, // uniquely identifies the
//        index: i32, // index
//        // ck: Fr, // TODO: l-bit key (from SymKeyEnc)
//    }
//
//    impl<'a> Message<'a> {
//        pub fn new(_prefix: &str, _c_id: Fr, _index: i32) -> Message {
//            Message {
//                prefix: _prefix, c_id: _c_id, index: _index,
//            }
//        }
//
//        fn hash(&self) -> Fr {
//            let mut input_buf = Vec::new();
//            input_buf.extend_from_slice(self.prefix.as_bytes());
//            let c_id_vec: Vec<u8> = encode(&self.c_id, Infinite).unwrap();
//            // encode cId in the vector
//            input_buf.extend(c_id_vec);
//            // encoee the balance as a hex string
//            let b = format!("{:x}", self.index);
//            input_buf.extend_from_slice(b.as_bytes());
//            // TODO: add the ck vector (l-bit key)
//    //        let mut in_str = String::new();
//    //        for y in input_buf.iter() {
//    //            in_str = format!("{}{:x}", in_str, y);
//    //        }
//    //        println!("input_buf: {}", in_str);
//
//            // hash the inputs via SHA256
//            let sha2_digest = sha512::hash(input_buf.as_slice());
//            // println!("hash: {:?}", sha2_digest);
//            // let h = format!("{:x}", HexSlice::new(&sha2_digest));
//            let mut hash_buf: [u8; 64] = [0; 64];
//            hash_buf.copy_from_slice(&sha2_digest[0..64]);
//            return Fr::interpret(&hash_buf);
//        }
//    }
//
//
//    pub fn setup() -> PublicParams {
//        let rng = &mut rand::thread_rng();
//        let g = G1::random(rng);
//        let mpk = PublicParams { g: g };
//        return mpk;
//    }
//
//    pub fn keygen(mpk : &PublicParams) -> KeyPair {
//        let rng = &mut rand::thread_rng();
//        let x = Fr::random(rng);
//        let y = Fr::random(rng);
//        let sk = SecretKey { x: x, y: y };
//        let pk = PublicKey { X: mpk.g * x,
//                             Y: mpk.g * y
//                            };
//        return KeyPair { sk: sk, pk: pk }
//    }
//
//    pub fn sign(sk: &SecretKey, msg: &Message) -> Signature {
//        let rng = &mut rand::thread_rng();
//        let a = G2::random(rng);
//        let m = msg.hash();
//        let b = a * sk.y;
//        let c = a * (sk.x + (m * sk.x * sk.y));
//        let sig = Signature { a: a, b: b, c: c };
//        return sig;
//    }
//
//    pub fn verify(mpk: &PublicParams, pk: &PublicKey, msg: &Message, sig: &Signature) -> bool {
//        let m = msg.hash();
//        let lhs1 = pairing(pk.Y, sig.a);
//        let rhs1 = pairing(mpk.g, sig.b);
//        let lhs2 = pairing(pk.X, sig.a) * (pairing(pk.X, sig.b).pow(m));
//        let rhs2 = pairing(mpk.g, sig.c);
//        return (lhs1 == rhs1) && (lhs2 == rhs2);
//    }
//
//}

#[derive(Clone)]
pub struct RefundMessage<'a> {
    prefix: &'a str, // string prefix for the prefix
    c_id: Fr, // uniquely identifies the
    index: i32, // index
    // ck: Fr, // TODO: l-bit key (from SymKeyEnc)
}

impl<'a> RefundMessage<'a> {
    pub fn new(_c_id: Fr, _index: i32) -> RefundMessage<'a> {
        RefundMessage {
            prefix: "refund", c_id: _c_id, index: _index,
        }
    }

    pub fn hash(&self) -> Fr {
        let mut input_buf = Vec::new();
        input_buf.extend_from_slice(self.prefix.as_bytes());
        let c_id_vec: Vec<u8> = encode(&self.c_id, Infinite).unwrap();
        // encode cId in the vector
        input_buf.extend(c_id_vec);
        // encoee the balance as a hex string
        let b = format!("{:x}", self.index);
        input_buf.extend_from_slice(b.as_bytes());
        // TODO: add the ck vector (l-bit key)
//        let mut in_str = String::new();
//        for y in input_buf.iter() {
//            in_str = format!("{}{:x}", in_str, y);
//        }
//        println!("input_buf: {}", in_str);

        // hash the inputs via SHA256
        let sha2_digest = sha512::hash(input_buf.as_slice());
        // println!("hash: {:?}", sha2_digest);
        // let h = format!("{:x}", HexSlice::new(&sha2_digest));
        let mut hash_buf: [u8; 64] = [0; 64];
        hash_buf.copy_from_slice(&sha2_digest[0..64]);
        return Fr::interpret(&hash_buf);
    }
}

////////////////////////////////// CL Sigs /////////////////////////////////////

////////////////////////////////// COMMITMENT //////////////////////////////////

#[derive(Copy, Clone)]
pub struct Message {
    sk: clsigs::SecretKey, // the secret key for the signature scheme (Is it possible to make this a generic field?)
    k1: Fr, // seed 1 for PRF
    k2: Fr, // seed 2 for PRF
    balance: i32 // the balance for the user
}

impl Message {
    pub fn new(_sk: clsigs::SecretKey, _k1: Fr, _k2: Fr, _balance: i32) -> Message {
        Message {
            sk: _sk, k1: _k1, k2: _k2, balance: _balance,
        }
    }

    fn hash(&self) -> Fr {
        let mut input_buf = self.sk.encode();
        // TODO: add sk_sigs to encode it
        let k1_vec: Vec<u8> = encode(&self.k1, Infinite).unwrap();
        let k2_vec: Vec<u8> = encode(&self.k2, Infinite).unwrap();
        // encode k1 in the vector
        input_buf.extend(k1_vec);
        // encode k2 in the vector
        input_buf.extend(k2_vec);
        // encoee the balance as a hex string
        let b = format!("{:x}", self.balance);
//        println!("Balance: {}", b);
        input_buf.extend_from_slice(b.as_bytes());
//        let mut in_str = String::new();
//        for y in input_buf.iter() {
//            in_str = format!("{}{:x}", in_str, y);
//        }
//        println!("input_buf: {}", in_str);

        // hash the inputs via SHA256
        let sha2_digest = sha512::hash(input_buf.as_slice());
        // println!("hash: {:?}", sha2_digest);
        // let h = format!("{:x}", HexSlice::new(&sha2_digest));
        let mut hash_buf: [u8; 64] = [0; 64];
        hash_buf.copy_from_slice(&sha2_digest[0..64]);
        return Fr::interpret(&hash_buf);
    }
}


//pub mod commit_scheme {
//    use std::fmt;
//    use rand;
//    //use std::str;
//    //use std::default;
//    use bn::{Group, Fr, G1};
//    use debug_elem_in_hex;
//    use bincode::SizeLimit::Infinite;
//    use bincode::rustc_serialize::encode;
//    use sodiumoxide::crypto::hash::sha512;
//    use clsigs;
//    // define some structures here
//    #[derive(Copy, Clone)]
//    pub struct PublicKey {
//        g: G1,
//        h: G1
//    }
//
//    #[derive(Copy, Clone)]
//    pub struct Commitment {
//        c: G1,
//        d: Fr
//    }
//
//    impl fmt::Display for PublicKey {
//        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
//            let g_vec: Vec<u8> = encode(&self.g, Infinite).unwrap();
//            let h_vec: Vec<u8> = encode(&self.h, Infinite).unwrap();
//            let mut g_s = String::new();
//            for x in g_vec.iter() {
//                g_s = format!("{}{:x}", g_s, x);
//            }
//
//            let mut h_s = String::new();
//            for y in h_vec.iter() {
//                h_s = format!("{}{:x}", h_s, y);
//            }
//
//            write!(f, "PK : (g=0x{}, h=0x{})", g_s, h_s)
//        }
//    }
//
//
//    impl fmt::Display for Commitment {
//        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
//            let c_vec: Vec<u8> = encode(&self.c, Infinite).unwrap();
//            let mut c_s = String::new();
//            for x in c_vec.iter() {
//                c_s = format!("{}{:x}", c_s, x);
//            }
//
//            let d_vec: Vec<u8> = encode(&self.d, Infinite).unwrap();
//            let mut d_s = String::new();
//            for x in d_vec.iter() {
//                d_s = format!("{}{:x}", d_s, x);
//            }
//            write!(f, "Commitment : (c=0x{}, d=0x{})", c_s, d_s)
//        }
//    }
//
//    #[derive(Copy, Clone)]
//    pub struct Message {
//        sk: clsigs::SecretKey, // the secret key for the signature scheme (Is it possible to make this a generic field?)
//        k1: Fr, // seed 1 for PRF
//        k2: Fr, // seed 2 for PRF
//        balance: i32 // the balance for the user
//    }
//
//    impl Message {
//        pub fn new(_sk: clsigs::SecretKey, _k1: Fr, _k2: Fr, _balance: i32) -> Message {
//            Message {
//                sk: _sk, k1: _k1, k2: _k2, balance: _balance,
//            }
//        }
//
//        fn hash(&self) -> Fr {
//            let mut input_buf = self.sk.encode();
//            // TODO: add sk_sigs to encode it
//            let k1_vec: Vec<u8> = encode(&self.k1, Infinite).unwrap();
//            let k2_vec: Vec<u8> = encode(&self.k2, Infinite).unwrap();
//            // encode k1 in the vector
//            input_buf.extend(k1_vec);
//            // encode k2 in the vector
//            input_buf.extend(k2_vec);
//            // encoee the balance as a hex string
//            let b = format!("{:x}", self.balance);
//    //        println!("Balance: {}", b);
//            input_buf.extend_from_slice(b.as_bytes());
//    //        let mut in_str = String::new();
//    //        for y in input_buf.iter() {
//    //            in_str = format!("{}{:x}", in_str, y);
//    //        }
//    //        println!("input_buf: {}", in_str);
//
//            // hash the inputs via SHA256
//            let sha2_digest = sha512::hash(input_buf.as_slice());
//            // println!("hash: {:?}", sha2_digest);
//            // let h = format!("{:x}", HexSlice::new(&sha2_digest));
//            let mut hash_buf: [u8; 64] = [0; 64];
//            hash_buf.copy_from_slice(&sha2_digest[0..64]);
//            return Fr::interpret(&hash_buf);
//        }
//    }
//
//
//    /*
//    Implements the setup algorithm for the Pedersen92 commitment scheme
//    */
//    pub fn setup() -> PublicKey {
//        println!("Run Setup...");
//        let rng = &mut rand::thread_rng();
//        let g = G1::random(rng);
//        let h = G1::random(rng);
//        let pk = PublicKey { g: g, h: h };
//        println!("{}", pk);
//        return pk;
//    }
//
//    /*
//    commit(pk, msg) -> cm where
//    - pk is the public key generated from setup()
//    - msg is the message structure for the commitment scheme
//    - cm is the output commitment message for the given message
//    */
//    pub fn commit(pk: &PublicKey, msg: &Message) -> Commitment {
//        let rng = &mut rand::thread_rng();
//
//        let r = Fr::random(rng);
//
//        let m = msg.hash();
//        let p = "commit -> m";
//        debug_elem_in_hex(p, &m);
//
//        let c = (pk.g * m) + (pk.h * r);
//        // return (c, r) <- d=r
//        let commitment = Commitment { c: c, d: r };
//
//        // debugging
//        println!("{}", commitment);
//        return commitment;
//    }
//
//    /*
//    decommit(pk, cm, msg) -> bool where
//    - pk is the public key generated from setup()
//    - cm is the commitment
//    - msg is the message to validate
//    - outputs T/F for whether the cm is a valid commitmentt to the msg
//    */
//    pub fn decommit(pk: &PublicKey, cm: &Commitment, msg: &Message) -> bool {
//        let m = msg.hash();
//        let p = "decommit -> m";
//        debug_elem_in_hex(p, &m);
//
//        let dm = (pk.g * m) + (pk.h * cm.d);
//        return dm == cm.c;
//    }
//
//}
////////////////////////////////// COMMITMENT //////////////////////////////////

//pub fn keygen() {
//    println!("Run Keygen...");
//}
//
//pub fn init() {
//    println!("Run Init...");
//
//}
//
//pub fn refund() {
//    println!("Run Refund...");
//
//}
//
//pub fn refute() {
//    println!("Run Refute...");
//
//}
//
//pub fn resolve() {
//    println!("Run Resolve...");
//
//}