/************************************************************************
 ************************************************************************
    FAUST compiler
    Copyright (C) 2003-2018 GRAME, Centre National de Creation Musicale
    ---------------------------------------------------------------------
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 ************************************************************************
 ************************************************************************/

#include "mterm.hh"
#include "exception.hh"
#include "global.hh"
#include "ppsig.hh"
#include "signals.hh"
#include "xtended.hh"

using namespace std;

typedef map<Tree, int> MP;

mterm::mterm() : fCoef(sigInt(0))
{
}
mterm::mterm(int k) : fCoef(sigInt(k))
{
}
mterm::mterm(double k) : fCoef(sigReal(k))
{
}
mterm::mterm(const mterm& m) : fCoef(m.fCoef), fFactors(m.fFactors)
{
}

/**
 * Create a mterm from a tree expression
 */
mterm::mterm(Tree t) : fCoef(sigInt(1))
{
#ifdef TRACE
    cerr << "mterm::mterm (Tree t) : " << ppsig(t) << endl;
#endif
    *this *= t;
#ifdef TRACE
    cerr << "MTERM(" << ppsig(t) << ") -> " << *this << endl;
#endif
}

/**
 * true if mterm doesn't represent number 0
 */
bool mterm::isNotZero() const
{
    return !isZero(fCoef);
}

/**
 * true if mterm is strictly negative
 */
bool mterm::isNegative() const
{
    return !isGEZero(fCoef);
}

/**
 * Print a mterm in a human readable format
 */
ostream& mterm::print(ostream& dst) const
{
    const char* sep = "";
    if (!isOne(fCoef) || fFactors.empty()) {
        dst << ppsig(fCoef);
        sep = " * ";
    }
    // if (true) { dst << ppsig(fCoef); sep = " * "; }
    for (const auto& p : fFactors) {
        dst << sep << ppsig(p.first);
        if (p.second != 1) {
            dst << "**" << p.second;
        }
        sep = " * ";
    }
    return dst;
}

/**
 * Compute the "complexity" of a mterm, that is the number of
 * factors it contains (weighted by the importance of these factors)
 */
int mterm::complexity() const
{
    int c = isOne(fCoef) ? 0 : (isMinusOne(fCoef) ? 0 : 1);
    for (const auto& p : fFactors) {
        c += (1 + getSigOrder(p.first)) * abs(p.second);
    }
    // cerr << __LINE__ << ":" << __FUNCTION__ << "(" << *this << ") --> " << c << endl;
    return c;
}

/**
 * Match x^p with p:int
 */
static bool isSigPow(Tree sig, Tree& x, int& n)
{
    // cerr << "isSigPow("<< *sig << ')' << endl;
    xtended* p = (xtended*)getUserData(sig);
    if (p == gGlobal->gPowPrim) {
        if (isSigInt(sig->branch(1), &n)) {
            x = sig->branch(0);
            // cerr << "factor of isSigPow " << *x << endl;
            return true;
        }
    }
    return false;
}

/**
 * Produce x^p with p:int
 */
static Tree sigPow(Tree x, int p)
{
    return tree(gGlobal->gPowPrim->symbol(), x, sigInt(p));
}

/**
 * Multiply a mterm by an expression tree. Go down recursively looking
 * for multiplications and divisions
 */
const mterm& mterm::operator*=(Tree t)
{
    int  op, n;
    Tree x, y;

    faustassert(t);

    if (isNum(t)) {
        fCoef = mulNums(fCoef, t);

    } else if (isSigBinOp(t, &op, x, y) && (op == kMul)) {
        *this *= x;
        *this *= y;

    } else if (isSigBinOp(t, &op, x, y) && (op == kDiv)) {
        *this *= x;
        *this /= y;

    } else {
        if (isSigPow(t, x, n)) {
            fFactors[x] += n;
        } else {
            fFactors[t] += 1;
        }
    }
    return *this;
}

/**
 * Divide a mterm by an expression tree t. Go down recursively looking
 * for multiplications and divisions
 */
const mterm& mterm::operator/=(Tree t)
{
    // cerr << "division in place : " << *this << " / " << ppsig(t) << endl;
    int  op, n;
    Tree x, y;

    faustassert(t);

    if (isNum(t)) {
        if (isZero(t)) {
            stringstream error;
            error << "ERROR : division by 0 in " << *this << " / " << ppsig(t) << endl;
            throw faustexception(error.str());
        }
        fCoef = divExtendedNums(fCoef, t);

    } else if (isSigBinOp(t, &op, x, y) && (op == kMul)) {
        *this /= x;
        *this /= y;

    } else if (isSigBinOp(t, &op, x, y) && (op == kDiv)) {
        *this /= x;
        *this *= y;

    } else {
        if (isSigPow(t, x, n)) {
            fFactors[x] -= n;
        } else {
            fFactors[t] -= 1;
        }
    }
    return *this;
}

/**
 * Replace the content with a copy of m
 */
const mterm& mterm::operator=(const mterm& m)
{
    fCoef    = m.fCoef;
    fFactors = m.fFactors;
    return *this;
}

/**
 * Clean a mterm by removing x**0 factors
 */
void mterm::cleanup()
{
    if (isZero(fCoef)) {
        fFactors.clear();
    } else {
        for (MP::iterator p = fFactors.begin(); p != fFactors.end();) {
            if (p->second == 0) {
                fFactors.erase(p++);
            } else {
                p++;
            }
        }
    }
}

/**
 * Add in place an mterm. As we want the result to be
 * a mterm therefore essentially mterms of same signature can be added
 */
const mterm& mterm::operator+=(const mterm& m)
{
    if (isZero(m.fCoef)) {
        // nothing to do
    } else if (isZero(fCoef)) {
        // copy of m
        fCoef    = m.fCoef;
        fFactors = m.fFactors;
    } else {
        // only add mterms of same signature
        faustassert(signatureTree() == m.signatureTree());
        fCoef = addNums(fCoef, m.fCoef);
    }
    cleanup();
    return *this;
}

/**
 * Substract in place an mterm. As we want the result to be
 * a mterm therefore essentially mterms of same signature can be substracted
 */
const mterm& mterm::operator-=(const mterm& m)
{
    if (isZero(m.fCoef)) {
        // nothing to do
    } else if (isZero(fCoef)) {
        // minus of m
        fCoef    = minusNum(m.fCoef);
        fFactors = m.fFactors;
    } else {
        // only add mterms of same signature
        faustassert(signatureTree() == m.signatureTree());
        fCoef = subNums(fCoef, m.fCoef);
    }
    cleanup();
    return *this;
}

/**
 * Multiply a mterm by the content of another mterm
 */
const mterm& mterm::operator*=(const mterm& m)
{
    fCoef = mulNums(fCoef, m.fCoef);
    for (const auto& p : m.fFactors) {
        fFactors[p.first] += p.second;
    }
    cleanup();
    return *this;
}

/**
 * Divide a mterm by the content of another mterm
 */
const mterm& mterm::operator/=(const mterm& m)
{
    // cerr << "division en place : " << *this << " / " << m << endl;
    if (m.fCoef == nullptr) {
        stringstream error;
        error << "ERROR : division by 0 in " << *this << " / " << m << endl;
        throw faustexception(error.str());
    }
    fCoef = divExtendedNums(fCoef, m.fCoef);
    for (const auto& p : m.fFactors) {
        fFactors[p.first] -= p.second;
    }
    cleanup();
    return *this;
}

/**
 * Multiply two mterms
 */
mterm mterm::operator*(const mterm& m) const
{
    mterm r(*this);
    r *= m;
    return r;
}

/**
 * Divide two mterms
 */
mterm mterm::operator/(const mterm& m) const
{
    mterm r(*this);
    r /= m;
    return r;
}

/**
 * Return the "common quantity" of two numbers
 */
static int common(int a, int b)
{
    if ((a > 0) & (b > 0)) {
        return std::min(a, b);
    } else if ((a < 0) & (b < 0)) {
        return std::max(a, b);
    } else {
        return 0;
    }
}

/**
 * Return a mterm that is the greatest common divisor of two mterms
 */
mterm gcd(const mterm& m1, const mterm& m2)
{
    // cerr << "GCD of " << m1 << " and " << m2 << endl;

    Tree  c = (sameMagnitude(m1.fCoef, m2.fCoef))
                  ? m1.fCoef
                  : tree(1);  // common coefficient (real gcd not needed)
    mterm R(c);
    for (const auto& p1 : m1.fFactors) {
        Tree               t  = p1.first;
        MP::const_iterator p2 = m2.fFactors.find(t);
        if (p2 != m2.fFactors.end()) {
            int v1 = p1.second;
            int v2 = p2->second;
            int c1 = common(v1, v2);
            if (c1 != 0) {
                R.fFactors[t] = c1;
            }
        }
    }
    // cerr << "GCD of " << m1 << " and " << m2 << " is : " << R << endl;
    return R;
}

/**
 * We say that a "contains" b if a/b > 0. For example 3 contains 2 and
 * -4 contains -2, but 3 doesn't contains -2 and -3 doesn't contains 1
 */
static bool contains(int a, int b)
{
    return (b == 0) || (a / b > 0);
}

/**
 * Check if M accept N has a divisor. We can say that N is
 * a divisor of M if M = N*Q and the complexity is preserved :
 * complexity(M) = complexity(N)+complexity(Q)
 * x**u has divisor x**v if u >= v
 * x**-u has divisor x**-v if -u <= -v
 */
bool mterm::hasDivisor(const mterm& n) const
{
    if (n.fFactors.size() == 0) {
        // n is a pure number
        return sameMagnitude(fCoef, n.fCoef);
    }
    for (const auto& p1 : n.fFactors) {
        // for each factor f**q of m
        Tree f = p1.first;
        int  v = p1.second;

        // check that f is also a factor of *this
        MP::const_iterator p2 = fFactors.find(f);
        if (p2 == fFactors.end()) {
            return false;
        }

        // analyze quantities
        int u = p2->second;
        if (!contains(u, v)) {
            return false;
        }
    }
    // cerr << __LINE__ << ":" << __func__ << *this << " is divisible by " << n << endl;
    return true;
}

/**
 * Produce the canonical tree corresponding to a mterm
 */

/**
 * Build a power term of type f**q -> (((f.f).f)..f) with q>0
 */
static Tree buildPowTerm(Tree f, int q)
{
    faustassert(f);
    faustassert(q > 0);
    if (q > 1) {
        return sigPow(f, q);
    } else {
        return f;
    }
}

/**
 * Combine R and A doing R = R*A or R = A
 */
static void combineMulLeft(Tree& R, Tree A)
{
    if (R && A) {
        R = sigMul(R, A);
    } else if (A) {
        R = A;
    } else {
        cerr << "ERROR : combineMulLeft\n";
        faustassert(false);
    }
}

/**
 * Combine R and A doing R = R/A or R = A
 */
static void combineDivLeft(Tree& R, Tree A)
{
    if (R && A) {
        R = sigDiv(R, A);
    } else if (A) {
        R = sigDiv(tree(1.0f), A);
    } else {
        cerr << "ERROR : combineDivLeft\n";
        faustassert(false);
    }
}

/**
 * Do M = M * f**q or D = D * f**-q
 */
static void combineMulDiv(Tree& M, Tree& D, Tree f, int q)
{
#ifdef TRACE
    cerr << "combineMulDiv (" << M << "/" << D << "*" << ppsig(f) << "**" << q << endl;
#endif
    if (f) {
        faustassert(q != 0);
        if (q > 0) {
            combineMulLeft(M, buildPowTerm(f, q));
        } else if (q < 0) {
            combineMulLeft(D, buildPowTerm(f, -q));
        }
    }
}

/**
 * Returns a normalized (canonical) tree expression of structure :
 * 		((v1/v2)*(c1/c2))*(s1/s2)
 */
Tree mterm::signatureTree() const
{
    return normalizedTree(true);
}

/**
 * Returns a normalized (canonical) tree expression of structure :
 * 		((k*(v1/v2))*(c1/c2))*(s1/s2)
 * In signature mode the fCoef factor is ommited
 * In negativeMode the sign of the fCoef factor is inverted
 */
Tree mterm::normalizedTree(bool signatureMode, bool negativeMode) const
{
#ifdef TRACE
    cout << "normalizedTree " << *this << endl;
#endif

    if (fFactors.empty() || isZero(fCoef)) {
        // it's a pure number
        if (signatureMode) {
            return tree(1);
        }
        if (negativeMode) {
            return minusNum(fCoef);
        } else {
            return fCoef;
        }
    } else {
        // it's not a pure number, it has factors
        Tree A[4], B[4];

        // group by order
        for (int order = 0; order < 4; order++) {
            A[order] = 0;
            B[order] = 0;
            for (const auto& p : fFactors) {
                Tree f = p.first;   // f = factor
                int  q = p.second;  // q = power of f
                if (f && q && getSigOrder(f) == order) {
                    combineMulDiv(A[order], B[order], f, q);
                }
            }
        }
#if 1
        if (A[0] != 0) {
            cerr << "A[0] == " << *A[0] << endl;
        }
        if (B[0] != 0) {
            cerr << "B[0] == " << *B[0] << endl;
        }
        // in principle here zero order is empty because it corresponds to the numerical coef
        faustassert(A[0] == nullptr);
        faustassert(B[0] == nullptr);
#endif

        // we only use a coeficient if it differs from 1 and if we are not in signature mode
        if (!(signatureMode || isOne(fCoef))) {
            A[0] = (negativeMode) ? minusNum(fCoef) : fCoef;
        }

        if (signatureMode) {
            A[0] = 0;
        } else if (negativeMode) {
            if (isMinusOne(fCoef)) {
                A[0] = 0;
            } else {
                A[0] = minusNum(fCoef);
            }
        } else if (isOne(fCoef)) {
            A[0] = 0;
        } else {
            A[0] = fCoef;
        }

        // combine each order separately : R[i] = A[i]/B[i]
        Tree RR = 0;
        for (int order = 0; order < 4; order++) {
            if (A[order] && B[order]) {
                combineMulLeft(RR, sigDiv(A[order], B[order]));
            } else if (A[order]) {
                combineMulLeft(RR, A[order]);
            } else if (B[order]) {
                combineDivLeft(RR, B[order]);
            }
        }
        if (RR == nullptr) {
            RR = tree(1);  // to check *******************
        }

        faustassert(RR);
#ifdef TRACE
        cout << "Normalized Tree of " << *this << " is " << ppsig(RR) << endl;
#endif
        return RR;
    }
}