#include "idris_rts.h"
#ifdef IDRIS_GMP
#include <gmp.h>
#else
#include "mini-gmp.h"
#endif
#include <stdlib.h>
#include <string.h>

// TMP HACK! Require this much space in the heap before a GMP operation
// so it doesn't garbage collect in the middle.
// This is highly dodgy and needs to be done better because who knows if
// GMP will need to allocate more than 64k... better to work out how
// much space is needed (or find another way of preventing copying)
#define IDRIS_MAXGMP 65536

void init_gmpalloc(void) {
    mp_set_memory_functions(idris_alloc, idris_realloc, idris_free);
}

VAL MKBIGI(int val) {
    return MKINT((i_int)val);
}

static BigInt * allocBig(VM * vm) {
    idris_requireAlloc(vm, IDRIS_MAXGMP);
    BigInt * cl = iallocate(vm, sizeof(*cl) + sizeof(mpz_t), 0);
    idris_doneAlloc(vm);
    SETTY(cl, CT_BIGINT);
    mpz_init(*getmpz(cl));
    return cl;
}

VAL MKBIGC(VM* vm, char* val) {
    if (*val == '\0') {
        return MKBIGI(0);
    }
    else {
        BigInt * cl = allocBig(vm);
        mpz_set_str(*getmpz(cl), val, 10);
        return (VAL)cl;
    }
}

VAL MKBIGM(VM* vm, void* ibig) {
    BigInt * cl = allocBig(vm);
    mpz_set(*getmpz(cl), *((mpz_t*)ibig));
    return (VAL)cl;
}

VAL MKBIGMc(VM* vm, void* ibig) {
    BigInt * cl = allocBig(vm);
    mpz_init_set(*getmpz(cl), *((mpz_t*)ibig));
    return (VAL)cl;
}

VAL MKBIGUI(VM* vm, unsigned long val) {
    BigInt * cl = allocBig(vm);
    mpz_init_set_ui(*getmpz(cl), val);
    return (VAL)cl;
}

VAL MKBIGSI(VM* vm, signed long val) {
    BigInt * cl = allocBig(vm);
    mpz_init_set_si(*getmpz(cl), val);
    return (VAL)cl;
}

static BigInt * getbig(VM * vm, VAL x) {
    switch(GETTY(x)) {
    case CT_INT:
        {
            BigInt * cl = allocBig(vm);
            mpz_set_si(*getmpz(cl), GETINT(x));
            return cl;
        }
    case CT_FWD:
        return getbig(vm, ((Fwd*)x)->fwd);
    default:
        return (BigInt*)x;
    }
}

#define GETBIG (VAL)getbig

VAL bigAdd(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_add(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigSub(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_sub(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigMul(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_mul(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigDiv(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_tdiv_q(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigMod(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_tdiv_r(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigAnd(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_and(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigOr(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_ior(*getmpz(cl), *getmpz(getbig(vm,x)), *getmpz(getbig(vm,y)));
    return (VAL)cl;
}

VAL bigShiftLeft(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_mul_2exp(*getmpz(cl), *getmpz(getbig(vm,x)), GETINT(y));
    return (VAL)cl;
}


VAL bigLShiftRight(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_fdiv_q_2exp(*getmpz(cl), *getmpz(getbig(vm,x)), GETINT(y));
    return (VAL)cl;
}

VAL bigAShiftRight(VM* vm, VAL x, VAL y) {
    BigInt * cl = allocBig(vm);
    mpz_fdiv_q_2exp(*getmpz(cl), *getmpz(getbig(vm,x)), GETINT(y));
    return (VAL)cl;
}

VAL idris_bigAnd(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(&, x, y);
    } else {
        return bigAnd(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigOr(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(|, x, y);
    } else {
        return bigOr(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigPlus(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        i_int vx = GETINT(x);
        i_int vy = GETINT(y);
        if ((vx <= 0 && vy >=0) || (vx >=0 && vy <=0)) {
            return ADD(x, y);
        }
        i_int res = vx + vy;
        if (res >= 1<<30 || res <= -(1 << 30)) {
            return bigAdd(vm, GETBIG(vm, x), GETBIG(vm, y));
        } else {
            return MKINT(res);
        }
    } else {
        return bigAdd(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigMinus(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        i_int vx = GETINT(x);
        i_int vy = GETINT(y);
        if ((vx <= 0 && vy <=0) || (vx >=0 && vy <=0)) {
            return INTOP(-, x, y);
        }
        i_int res = vx - vy;
        if (res >= 1<<30 || res <= -(1 << 30)) {
            return bigSub(vm, GETBIG(vm, x), GETBIG(vm, y));
        } else {
            return MKINT(res);
        }
    } else {
        return bigSub(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigTimes(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        i_int vx = GETINT(x);
        i_int vy = GETINT(y);
        // we could work out likelihood of overflow by checking the number
        // of necessary bits. Here's a quick conservative hack instead.
        if ((vx < (1<<15) && vy < (1<16)) ||
            (vx < (1<<16) && vy < (1<15)) ||
            (vx < (1<<20) && vy < (1<11)) ||
            (vx < (1<<11) && vy < (1<20)) ||
            (vx < (1<<23) && vy < (1<<8)) ||
            (vx < (1<<8) && vy < (1<<23))) { // ultra-conservative!
            return INTOP(*,x,y);
        } else {
            return bigMul(vm, GETBIG(vm, x), GETBIG(vm, y));
        }
    } else {
        return bigMul(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigShiftLeft(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(<<, x, y);
    } else {
        return bigShiftLeft(vm, GETBIG(vm, x), y);
    }
}

VAL idris_bigAShiftRight(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(>>, x, y);
    } else {
        return bigAShiftRight(vm, GETBIG(vm, x), y);
    }
}

VAL idris_bigLShiftRight(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(>>, x, y);
    } else {
        return bigLShiftRight(vm, GETBIG(vm, x), y);
    }
}

VAL idris_bigDivide(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(/, x, y);
    } else {
        return bigDiv(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigMod(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return INTOP(%, x, y);
    } else {
        return bigMod(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

int bigEqConst(VAL x, int c) {
    if (ISINT(x)) { return (GETINT(x) == c); }
    else {
        int rv = mpz_cmp_si(GETMPZ(x), c);
        return (rv == 0);
    }
}

VAL bigEq(VM* vm, VAL x, VAL y) {
    return MKINT((i_int)(mpz_cmp(GETMPZ(x), GETMPZ(y)) == 0));
}

VAL bigLt(VM* vm, VAL x, VAL y) {
    return MKINT((i_int)(mpz_cmp(GETMPZ(x), GETMPZ(y)) < 0));
}

VAL bigGt(VM* vm, VAL x, VAL y) {
    return MKINT((i_int)(mpz_cmp(GETMPZ(x), GETMPZ(y)) > 0));
}

VAL bigLe(VM* vm, VAL x, VAL y) {
    return MKINT((i_int)(mpz_cmp(GETMPZ(x), GETMPZ(y)) <= 0));
}

VAL bigGe(VM* vm, VAL x, VAL y) {
    return MKINT((i_int)(mpz_cmp(GETMPZ(x), GETMPZ(y)) >= 0));
}

VAL idris_bigEq(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return MKINT((i_int)(GETINT(x) == GETINT(y)));
    } else {
        return bigEq(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigLt(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return MKINT((i_int)(GETINT(x) < GETINT(y)));
    } else {
        return bigLt(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigLe(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return MKINT((i_int)(GETINT(x) <= GETINT(y)));
    } else {
        return bigLe(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigGt(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return MKINT((i_int)(GETINT(x) > GETINT(y)));
    } else {
        return bigGt(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}

VAL idris_bigGe(VM* vm, VAL x, VAL y) {
    if (ISINT(x) && ISINT(y)) {
        return MKINT((i_int)(GETINT(x) >= GETINT(y)));
    } else {
        return bigGe(vm, GETBIG(vm, x), GETBIG(vm, y));
    }
}


VAL idris_castIntBig(VM* vm, VAL i) {
    return i;
}

VAL idris_castBigInt(VM* vm, VAL i) {
    if (ISINT(i)) {
        return i;
    } else {
        return MKINT((i_int)(mpz_get_ui(GETMPZ(i))));
    }
}

VAL idris_castBigFloat(VM* vm, VAL i) {
    if (ISINT(i)) {
        return MKFLOAT(vm, GETINT(i));
    } else {
        return MKFLOAT(vm, mpz_get_d(GETMPZ(i)));
    }
}

VAL idris_castFloatBig(VM* vm, VAL f) {
    double val = GETFLOAT(f);
    BigInt * cl = allocBig(vm);
    mpz_init_set_d(*getmpz(cl), val);
    return (VAL)cl;
}

VAL idris_castStrBig(VM* vm, VAL i) {
    return MKBIGC(vm, GETSTR(i));
}

VAL idris_castBigStr(VM* vm, VAL i) {
    char* str = mpz_get_str(NULL, 10, *getmpz(getbig(vm, i)));
    return MKSTR(vm, str);
}

// Get 64 bits out of a big int with special handling
// for systems that have 32-bit longs which needs two limbs to
// fill that.
uint64_t idris_truncBigB64(const mpz_t bi) {
    if (sizeof(mp_limb_t) == 8) {
        return mpz_get_ui(bi);
    }
    int64_t out = mpz_get_ui(bi);
    if (mpz_size(bi) > 1) {
        out |= ((int64_t)mpz_getlimbn(bi, 1)) << 32;
    }
    return out;
}
