#include "idris_rts.h"
#include <gmp.h>
#include <stdlib.h>
#include <string.h>

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

VAL MKBIGC(VM* vm, char* val) {
    mpz_t* bigint;
    VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
    bigint = allocate(vm, sizeof(mpz_t));

    mpz_init(*bigint);
    mpz_set_str(*bigint, val, 10);

    cl -> ty = BIGINT;
    cl -> info.ptr = (void*)bigint;

    return cl;
}

VAL MKBIGM(VM* vm, void* big) {
    mpz_t* bigint;
    VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
    bigint = allocate(vm, sizeof(mpz_t));

    mpz_init(*bigint);
    mpz_set(*bigint, *((mpz_t*)big));

    cl -> ty = BIGINT;
    cl -> info.ptr = (void*)bigint;

    return cl;
}

VAL GETBIG(VM * vm, VAL x) {
    if (ISINT(x)) {
        mpz_t* bigint;
        VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
        bigint = allocate(vm, sizeof(mpz_t));

        mpz_init(*bigint);
        mpz_set_si(*bigint, GETINT(x));

        cl -> ty = BIGINT;
        cl -> info.ptr = (void*)bigint;

        return cl;
    } else {
        return x;
    }
}

VAL bigAdd(VM* vm, VAL x, VAL y) {
    mpz_t* bigint;
    VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
    bigint = allocate(vm, sizeof(mpz_t));
    mpz_add(*bigint, GETMPZ(x), GETMPZ(y));
    cl -> ty = BIGINT;
    cl -> info.ptr = (void*)bigint;
    return cl;
}

VAL bigSub(VM* vm, VAL x, VAL y) {
    mpz_t* bigint;
    VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
    bigint = allocate(vm, sizeof(mpz_t));
    mpz_sub(*bigint, GETMPZ(x), GETMPZ(y));
    cl -> ty = BIGINT;
    cl -> info.ptr = (void*)bigint;
    return cl;
}

VAL bigMul(VM* vm, VAL x, VAL y) {
    mpz_t* bigint;
    VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
    bigint = allocate(vm, sizeof(mpz_t));
    mpz_mul(*bigint, GETMPZ(x), GETMPZ(y));
    cl -> ty = BIGINT;
    cl -> info.ptr = (void*)bigint;
    return cl;
}

VAL bigDiv(VM* vm, VAL x, VAL y) {
    mpz_t* bigint;
    VAL cl = allocate(vm, sizeof(ClosureType) + sizeof(void*));
    bigint = allocate(vm, sizeof(mpz_t));
    mpz_div(*bigint, GETMPZ(x), GETMPZ(y));
    cl -> ty = BIGINT;
    cl -> info.ptr = (void*)bigint;
    return cl;
}

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_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 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, x, 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, x, 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, x, 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, x, 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, x, 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_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);
}