/*
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
*/

use super::rom;
use super::big;
use super::ecp;
use super::fp2::FP2;
use super::big::BIG;
use types::{SexticTwist, CurvePairingType, SignOfX};
use std::str::SplitWhitespace;
use std::fmt;

#[derive(Copy, Clone)]
pub struct ECP2 {
    x: FP2,
    y: FP2,
    z: FP2,
}

impl PartialEq for ECP2 {
	fn eq(&self, other: &ECP2) -> bool {
		self.equals(other)
	}
}

impl fmt::Display for ECP2 {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		write!(f, "ECP2: [ {}, {}, {} ]", self.x, self.y, self.z)
	}
}

impl fmt::Debug for ECP2 {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		write!(f, "ECP2: [ {}, {}, {} ]", self.x, self.y, self.z)
	}
}

#[allow(non_snake_case)]
impl ECP2 {
    pub fn new() -> ECP2 {
        ECP2 {
            x: FP2::new(),
            y: FP2::new_int(1),
            z: FP2::new(),
        }
    }
    #[allow(non_snake_case)]
    /* construct this from (x,y) - but set to O if not on curve */
    pub fn new_fp2s(ix: &FP2, iy: &FP2) -> ECP2 {
        let mut E = ECP2::new();
        E.x.copy(&ix);
        E.y.copy(&iy);
        E.z.one();
        E.x.norm();

        let mut rhs = ECP2::rhs(&E.x);
        let mut y2 = FP2::new_copy(&E.y);
        y2.sqr();
        if !y2.equals(&mut rhs) {
            E.inf();
        }
        return E;
    }

    /* construct this from x - but set to O if not on curve */
    pub fn new_fp2(ix: &FP2) -> ECP2 {
        let mut E = ECP2::new();
        E.x.copy(&ix);
        E.y.one();
        E.z.one();
        E.x.norm();
        let mut rhs = ECP2::rhs(&E.x);
        if rhs.sqrt() {
            E.y.copy(&rhs);
        } else {
            E.inf();
        }
        return E;
    }

    /* Test this=O? */
    pub fn is_infinity(&self) -> bool {
        let xx = FP2::new_copy(&self.x);
        let zz = FP2::new_copy(&self.z);
        return xx.iszilch() && zz.iszilch();
    }

    /* copy self=P */
    pub fn copy(&mut self, P: &ECP2) {
        self.x.copy(&P.x);
        self.y.copy(&P.y);
        self.z.copy(&P.z);
    }

    /* set self=O */
    pub fn inf(&mut self) {
        self.x.zero();
        self.y.one();
        self.z.zero();
    }

    /* set self=-self */
    pub fn neg(&mut self) {
        self.y.norm();
        self.y.neg();
        self.y.norm();
    }

    /* Conditional move of Q to self dependant on d */
    pub fn cmove(&mut self, Q: &ECP2, d: isize) {
        self.x.cmove(&Q.x, d);
        self.y.cmove(&Q.y, d);
        self.z.cmove(&Q.z, d);
    }

    /* return 1 if b==c, no branching */
    fn teq(b: i32, c: i32) -> isize {
        let mut x = b ^ c;
        x -= 1; // if x=0, x now -1
        return ((x >> 31) & 1) as isize;
    }

    /* Constant time select from pre-computed table */
    pub fn selector(&mut self, W: &[ECP2], b: i32) {
        let mut MP = ECP2::new();
        let m = b >> 31;
        let mut babs = (b ^ m) - m;

        babs = (babs - 1) / 2;

        self.cmove(&W[0], ECP2::teq(babs, 0)); // conditional move
        self.cmove(&W[1], ECP2::teq(babs, 1));
        self.cmove(&W[2], ECP2::teq(babs, 2));
        self.cmove(&W[3], ECP2::teq(babs, 3));
        self.cmove(&W[4], ECP2::teq(babs, 4));
        self.cmove(&W[5], ECP2::teq(babs, 5));
        self.cmove(&W[6], ECP2::teq(babs, 6));
        self.cmove(&W[7], ECP2::teq(babs, 7));

        MP.copy(self);
        MP.neg();
        self.cmove(&MP, (m & 1) as isize);
    }

    /* Test if P == Q */
    pub fn equals(&self, Q: &ECP2) -> bool {
        let mut a = FP2::new_copy(&self.x);
        let mut b = FP2::new_copy(&Q.x);

        a.mul(&Q.z);
        b.mul(&self.z);
        if !a.equals(&mut b) {
            return false;
        }
        a.copy(&self.y);
        a.mul(&Q.z);
        b.copy(&Q.y);
        b.mul(&self.z);
        if !a.equals(&mut b) {
            return false;
        }

        return true;
    }

    /* set to Affine - (x,y,z) to (x,y) */
    pub fn affine(&mut self) {
        if self.is_infinity() {
            return;
        }
        let mut one = FP2::new_int(1);
        if self.z.equals(&mut one) {
            return;
        }
        self.z.inverse();

        self.x.mul(&self.z);
        self.x.reduce();
        self.y.mul(&self.z);
        self.y.reduce();
        self.z.copy(&one);
    }

    /* extract affine x as FP2 */
    pub fn getx(&self) -> FP2 {
        let mut W = ECP2::new();
        W.copy(self);
        W.affine();
        return FP2::new_copy(&W.x);
    }

    /* extract affine y as FP2 */
    pub fn gety(&self) -> FP2 {
        let mut W = ECP2::new();
        W.copy(self);
        W.affine();
        return FP2::new_copy(&W.y);
    }

    /* extract projective x */
    pub fn getpx(&self) -> FP2 {
        return FP2::new_copy(&self.x);
    }
    /* extract projective y */
    pub fn getpy(&self) -> FP2 {
        return FP2::new_copy(&self.y);
    }
    /* extract projective z */
    pub fn getpz(&self) -> FP2 {
        return FP2::new_copy(&self.z);
    }

    /* convert to byte array */
    pub fn tobytes(&self, b: &mut [u8]) {
        let mut t: [u8; big::MODBYTES as usize] = [0; big::MODBYTES as usize];
        let mb = big::MODBYTES as usize;
        let mut W = ECP2::new();
        W.copy(self);

        W.affine();
        W.x.geta().tobytes(&mut t);
        for i in 0..mb {
            b[i] = t[i]
        }
        W.x.getb().tobytes(&mut t);
        for i in 0..mb {
            b[i + mb] = t[i]
        }

        W.y.geta().tobytes(&mut t);
        for i in 0..mb {
            b[i + 2 * mb] = t[i]
        }
        W.y.getb().tobytes(&mut t);
        for i in 0..mb {
            b[i + 3 * mb] = t[i]
        }
    }

    /* convert from byte array to point */
    pub fn frombytes(b: &[u8]) -> ECP2 {
        let mut t: [u8; big::MODBYTES as usize] = [0; big::MODBYTES as usize];
        let mb = big::MODBYTES as usize;

        for i in 0..mb {
            t[i] = b[i]
        }
        let mut ra = BIG::frombytes(&t);
        for i in 0..mb {
            t[i] = b[i + mb]
        }
        let mut rb = BIG::frombytes(&t);
        let rx = FP2::new_bigs(&ra, &rb);

        for i in 0..mb {
            t[i] = b[i + 2 * mb]
        }
        ra.copy(&BIG::frombytes(&t));
        for i in 0..mb {
            t[i] = b[i + 3 * mb]
        }
        rb.copy(&BIG::frombytes(&t));
        let ry = FP2::new_bigs(&ra, &rb);

        return ECP2::new_fp2s(&rx, &ry);
    }

    /* convert this to hex string */
    pub fn tostring(&self) -> String {
        let mut W = ECP2::new();
        W.copy(self);
        W.affine();
        if W.is_infinity() {
            return String::from("infinity");
        }
        return format!("({},{})", W.x.tostring(), W.y.tostring());
    }

    pub fn to_hex(&self) -> String {
        format!("{} {} {}", self.x.to_hex(), self.y.to_hex(), self.z.to_hex())
    }

    pub fn from_hex_iter(iter: &mut SplitWhitespace) -> ECP2 {
        ECP2 {
            x: FP2::from_hex_iter(iter),
            y: FP2::from_hex_iter(iter),
            z: FP2::from_hex_iter(iter)
        }
    }

    pub fn from_hex(val: String) -> ECP2 {
        let mut iter = val.split_whitespace();
        return ECP2::from_hex_iter(&mut iter);
    }

    /* Calculate RHS of twisted curve equation x^3+B/i */
    pub fn rhs(x: &FP2) -> FP2 {
        let mut r = FP2::new_copy(x);
        r.sqr();
        let mut b = FP2::new_big(&BIG::new_ints(&rom::CURVE_B));
        if ecp::SEXTIC_TWIST == SexticTwist::D_TYPE {
            b.div_ip();
        }
        if ecp::SEXTIC_TWIST == SexticTwist::M_TYPE {
            b.norm();
            b.mul_ip();
            b.norm();
        }

        r.mul(x);
        r.add(&b);

        r.reduce();
        return r;
    }

    /* self+=self */
    pub fn dbl(&mut self) -> isize {
        let mut iy = FP2::new_copy(&self.y);
        if ecp::SEXTIC_TWIST == SexticTwist::D_TYPE {
            iy.mul_ip();
            iy.norm();
        }

        let mut t0 = FP2::new_copy(&self.y); //***** Change
        t0.sqr();
        if ecp::SEXTIC_TWIST == SexticTwist::D_TYPE {
            t0.mul_ip();
        }
        let mut t1 = FP2::new_copy(&iy);
        t1.mul(&self.z);
        let mut t2 = FP2::new_copy(&self.z);
        t2.sqr();

        self.z.copy(&t0);
        self.z.add(&t0);
        self.z.norm();
        self.z.dbl();
        self.z.dbl();
        self.z.norm();

        t2.imul(3 * rom::CURVE_B_I);
        if ecp::SEXTIC_TWIST == SexticTwist::M_TYPE {
            t2.mul_ip();
            t2.norm();
        }
        let mut x3 = FP2::new_copy(&t2);
        x3.mul(&self.z);

        let mut y3 = FP2::new_copy(&t0);

        y3.add(&t2);
        y3.norm();
        self.z.mul(&t1);
        t1.copy(&t2);
        t1.add(&t2);
        t2.add(&t1);
        t2.norm();
        t0.sub(&t2);
        t0.norm(); //y^2-9bz^2
        y3.mul(&t0);
        y3.add(&x3); //(y^2+3z*2)(y^2-9z^2)+3b.z^2.8y^2
        t1.copy(&self.x);
        t1.mul(&iy); //
        self.x.copy(&t0);
        self.x.norm();
        self.x.mul(&t1);
        self.x.dbl(); //(y^2-9bz^2)xy2

        self.x.norm();
        self.y.copy(&y3);
        self.y.norm();

        return 1;
    }

    /* self+=Q - return 0 for add, 1 for double, -1 for O */
    pub fn add(&mut self, Q: &ECP2) -> isize {
        let b = 3 * rom::CURVE_B_I;
        let mut t0 = FP2::new_copy(&self.x);
        t0.mul(&Q.x); // x.Q.x
        let mut t1 = FP2::new_copy(&self.y);
        t1.mul(&Q.y); // y.Q.y

        let mut t2 = FP2::new_copy(&self.z);
        t2.mul(&Q.z);
        let mut t3 = FP2::new_copy(&self.x);
        t3.add(&self.y);
        t3.norm(); //t3=X1+Y1
        let mut t4 = FP2::new_copy(&Q.x);
        t4.add(&Q.y);
        t4.norm(); //t4=X2+Y2
        t3.mul(&t4); //t3=(X1+Y1)(X2+Y2)
        t4.copy(&t0);
        t4.add(&t1); //t4=X1.X2+Y1.Y2

        t3.sub(&t4);
        t3.norm();
        if ecp::SEXTIC_TWIST == SexticTwist::D_TYPE {
            t3.mul_ip();
            t3.norm(); //t3=(X1+Y1)(X2+Y2)-(X1.X2+Y1.Y2) = X1.Y2+X2.Y1
        }
        t4.copy(&self.y);
        t4.add(&self.z);
        t4.norm(); //t4=Y1+Z1
        let mut x3 = FP2::new_copy(&Q.y);
        x3.add(&Q.z);
        x3.norm(); //x3=Y2+Z2

        t4.mul(&x3); //t4=(Y1+Z1)(Y2+Z2)
        x3.copy(&t1); //
        x3.add(&t2); //X3=Y1.Y2+Z1.Z2

        t4.sub(&x3);
        t4.norm();
        if ecp::SEXTIC_TWIST == SexticTwist::D_TYPE {
            t4.mul_ip();
            t4.norm(); //t4=(Y1+Z1)(Y2+Z2) - (Y1.Y2+Z1.Z2) = Y1.Z2+Y2.Z1
        }
        x3.copy(&self.x);
        x3.add(&self.z);
        x3.norm(); // x3=X1+Z1
        let mut y3 = FP2::new_copy(&Q.x);
        y3.add(&Q.z);
        y3.norm(); // y3=X2+Z2
        x3.mul(&y3); // x3=(X1+Z1)(X2+Z2)
        y3.copy(&t0);
        y3.add(&t2); // y3=X1.X2+Z1+Z2
        y3.rsub(&x3);
        y3.norm(); // y3=(X1+Z1)(X2+Z2) - (X1.X2+Z1.Z2) = X1.Z2+X2.Z1

        if ecp::SEXTIC_TWIST == SexticTwist::D_TYPE {
            t0.mul_ip();
            t0.norm(); // x.Q.x
            t1.mul_ip();
            t1.norm(); // y.Q.y
        }
        x3.copy(&t0);
        x3.add(&t0);
        t0.add(&x3);
        t0.norm();
        t2.imul(b);
        if ecp::SEXTIC_TWIST == SexticTwist::M_TYPE {
            t2.mul_ip();
            t2.norm();
        }
        let mut z3 = FP2::new_copy(&t1);
        z3.add(&t2);
        z3.norm();
        t1.sub(&t2);
        t1.norm();
        y3.imul(b);
        if ecp::SEXTIC_TWIST == SexticTwist::M_TYPE {
            y3.mul_ip();
            y3.norm();
        }
        x3.copy(&y3);
        x3.mul(&t4);
        t2.copy(&t3);
        t2.mul(&t1);
        x3.rsub(&t2);
        y3.mul(&t0);
        t1.mul(&z3);
        y3.add(&t1);
        t0.mul(&t3);
        z3.mul(&t4);
        z3.add(&t0);

        self.x.copy(&x3);
        self.x.norm();
        self.y.copy(&y3);
        self.y.norm();
        self.z.copy(&z3);
        self.z.norm();

        return 0;
    }

    /* set this-=Q */
    pub fn sub(&mut self, Q: &ECP2) -> isize {
        let mut NQ = ECP2::new();
        NQ.copy(Q);
        NQ.neg();
        let d = self.add(&NQ);
        return d;
    }

    /* set this*=q, where q is Modulus, using Frobenius */
    pub fn frob(&mut self, x: &FP2) {
        let mut x2 = FP2::new_copy(x);
        x2.sqr();
        self.x.conj();
        self.y.conj();
        self.z.conj();
        self.z.reduce();
        self.x.mul(&x2);
        self.y.mul(&x2);
        self.y.mul(x);
    }

    /* self*=e */
    pub fn mul(&self, e: &BIG) -> ECP2 {
        /* fixed size windows */
        let mut mt = BIG::new();
        let mut t = BIG::new();
        let mut P = ECP2::new();
        let mut Q = ECP2::new();
        let mut C = ECP2::new();

        if self.is_infinity() {
            return P;
        }

        let mut W: [ECP2; 8] = [
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
        ];

        const CT: usize = 1 + (big::NLEN * (big::BASEBITS as usize) + 3) / 4;
        let mut w: [i8; CT] = [0; CT];

        /* precompute table */
        Q.copy(&self);
        Q.dbl();

        W[0].copy(&self);

        for i in 1..8 {
            C.copy(&W[i - 1]);
            W[i].copy(&C);
            W[i].add(&mut Q);
        }

        /* make exponent odd - add 2P if even, P if odd */
        t.copy(&e);
        let s = t.parity();
        t.inc(1);
        t.norm();
        let ns = t.parity();
        mt.copy(&t);
        mt.inc(1);
        mt.norm();
        t.cmove(&mt, s);
        Q.cmove(&self, ns);
        C.copy(&Q);

        let nb = 1 + (t.nbits() + 3) / 4;

        /* convert exponent to signed 4-bit window */
        for i in 0..nb {
            w[i] = (t.lastbits(5) - 16) as i8;
            t.dec(w[i] as isize);
            t.norm();
            t.fshr(4);
        }
        w[nb] = (t.lastbits(5)) as i8;

        P.copy(&W[((w[nb] as usize) - 1) / 2]);
        for i in (0..nb).rev() {
            Q.selector(&W, w[i] as i32);
            P.dbl();
            P.dbl();
            P.dbl();
            P.dbl();
            P.add(&mut Q);
        }
        P.sub(&mut C);
        P.affine();
        return P;
    }

    /* P=u0.Q0+u1*Q1+u2*Q2+u3*Q3 */
    // Bos & Costello https://eprint.iacr.org/2013/458.pdf
    // Faz-Hernandez & Longa & Sanchez  https://eprint.iacr.org/2013/158.pdf
    // Side channel attack secure

    pub fn mul4(Q: &mut [ECP2], u: &[BIG]) -> ECP2 {
        let mut W = ECP2::new();
        let mut P = ECP2::new();

        let mut T: [ECP2; 8] = [
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
            ECP2::new(),
        ];

        let mut mt = BIG::new();

        let mut t: [BIG; 4] = [
            BIG::new_copy(&u[0]),
            BIG::new_copy(&u[1]),
            BIG::new_copy(&u[2]),
            BIG::new_copy(&u[3]),
        ];

        const CT: usize = 1 + big::NLEN * (big::BASEBITS as usize);
        let mut w: [i8; CT] = [0; CT];
        let mut s: [i8; CT] = [0; CT];

        for i in 0..4 {
            t[i].norm();
        }

        T[0].copy(&Q[0]);
        W.copy(&T[0]);
        T[1].copy(&W);
        T[1].add(&mut Q[1]); // Q[0]+Q[1]
        T[2].copy(&W);
        T[2].add(&mut Q[2]);
        W.copy(&T[1]); // Q[0]+Q[2]
        T[3].copy(&W);
        T[3].add(&mut Q[2]);
        W.copy(&T[0]); // Q[0]+Q[1]+Q[2]
        T[4].copy(&W);
        T[4].add(&mut Q[3]);
        W.copy(&T[1]); // Q[0]+Q[3]
        T[5].copy(&W);
        T[5].add(&mut Q[3]);
        W.copy(&T[2]); // Q[0]+Q[1]+Q[3]
        T[6].copy(&W);
        T[6].add(&mut Q[3]);
        W.copy(&T[3]); // Q[0]+Q[2]+Q[3]
        T[7].copy(&W);
        T[7].add(&mut Q[3]); // Q[0]+Q[1]+Q[2]+Q[3]

        // Make it odd
        let pb = 1 - t[0].parity();
        t[0].inc(pb);
        t[0].norm();

        // Number of bits
        mt.zero();
        for i in 0..4 {
            mt.or(&t[i]);
        }

        let nb = 1 + mt.nbits();

        // Sign pivot

        s[nb - 1] = 1;
        for i in 0..nb - 1 {
            t[0].fshr(1);
            s[i] = (2 * t[0].parity() - 1) as i8;
        }

        // Recoded exponent
        for i in 0..nb {
            w[i] = 0;
            let mut k = 1;
            for j in 1..4 {
                let bt = s[i] * (t[j].parity() as i8);
                t[j].fshr(1);
                t[j].dec((bt >> 1) as isize);
                t[j].norm();
                w[i] += bt * (k as i8);
                k = 2 * k;
            }
        }

        // Main loop
        P.selector(&T, (2 * w[nb - 1] + 1) as i32);
        for i in (0..nb - 1).rev() {
            P.dbl();
            W.selector(&T, (2 * w[i] + s[i]) as i32);
            P.add(&mut W);
        }

        // apply correction
        W.copy(&P);
        W.sub(&mut Q[0]);
        P.cmove(&W, pb);
        P.affine();

        return P;
    }

    #[allow(non_snake_case)]
    pub fn mapit(h: &[u8]) -> ECP2 {
        let mut q = BIG::new_ints(&rom::MODULUS);
        let mut x = BIG::frombytes(h);
        x.rmod(&mut q);
        let mut Q: ECP2;
        let one = BIG::new_int(1);

        loop {
            let X = FP2::new_bigs(&one, &x);
            Q = ECP2::new_fp2(&X);
            if !Q.is_infinity() {
                break;
            }
            x.inc(1);
            x.norm();
        }
        let mut X = FP2::new_bigs(&BIG::new_ints(&rom::FRA), &BIG::new_ints(&rom::FRB));
        if ecp::SEXTIC_TWIST == SexticTwist::M_TYPE {
            X.inverse();
            X.norm();
        }
        x = BIG::new_ints(&rom::CURVE_BNX);

        if ecp::CURVE_PAIRING_TYPE == CurvePairingType::BN {
            let mut T = Q.mul(&mut x);
            if ecp::SIGN_OF_X == SignOfX::NEGATIVEX {
                T.neg();
            }
            let mut K = ECP2::new();
            K.copy(&T);
            K.dbl();
            K.add(&T);

            K.frob(&X);
            Q.frob(&X);
            Q.frob(&X);
            Q.frob(&X);
            Q.add(&T);
            Q.add(&K);
            T.frob(&X);
            T.frob(&X);
            Q.add(&T);
        }
        if ecp::CURVE_PAIRING_TYPE == CurvePairingType::BLS {
            let mut xQ = Q.mul(&mut x);
            let mut x2Q = xQ.mul(&mut x);

            if ecp::SIGN_OF_X == SignOfX::NEGATIVEX {
                xQ.neg();
            }
            x2Q.sub(&xQ);
            x2Q.sub(&Q);

            xQ.sub(&Q);
            xQ.frob(&X);

            Q.dbl();
            Q.frob(&X);
            Q.frob(&X);

            Q.add(&x2Q);
            Q.add(&xQ);
        }

        Q.affine();
        return Q;
    }

    pub fn generator() -> ECP2 {
        return ECP2::new_fp2s(
            &FP2::new_bigs(
                &BIG::new_ints(&rom::CURVE_PXA),
                &BIG::new_ints(&rom::CURVE_PXB),
            ),
            &FP2::new_bigs(
                &BIG::new_ints(&rom::CURVE_PYA),
                &BIG::new_ints(&rom::CURVE_PYB),
            ),
        );
    }
}