/*
 * QuickJS Javascript Engine
 *
 * Copyright (c) 2017-2021 Fabrice Bellard
 * Copyright (c) 2017-2021 Charlie Gordon
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "libc/calls/struct/timeval.h"
#include "libc/time/time.h"
#include "third_party/quickjs/internal.h"

asm(".ident\t\"\\n\\n\
QuickJS (MIT License)\\n\
Copyright (c) 2017-2021 Fabrice Bellard\\n\
Copyright (c) 2017-2021 Charlie Gordon\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */

/* precondition: a and b are not NaN */
static double js_fmin(double a, double b)
{
    if (a == 0 && b == 0) {
        JSFloat64Union a1, b1;
        a1.d = a;
        b1.d = b;
        a1.u64 |= b1.u64;
        return a1.d;
    } else {
        return fmin(a, b);
    }
}

/* precondition: a and b are not NaN */
static double js_fmax(double a, double b)
{
    if (a == 0 && b == 0) {
        JSFloat64Union a1, b1;
        a1.d = a;
        b1.d = b;
        a1.u64 &= b1.u64;
        return a1.d;
    } else {
        return fmax(a, b);
    }
}

static JSValue js_math_min_max(JSContext *ctx, JSValueConst this_val,
                               int argc, JSValueConst *argv, int magic)
{
    BOOL is_max = magic;
    double r, a;
    int i;
    uint32_t tag;
    if (UNLIKELY(argc == 0)) {
        return __JS_NewFloat64(ctx, is_max ? -1.0 / 0.0 : 1.0 / 0.0);
    }
    tag = JS_VALUE_GET_TAG(argv[0]);
    if (tag == JS_TAG_INT) {
        int a1, r1 = JS_VALUE_GET_INT(argv[0]);
        for(i = 1; i < argc; i++) {
            tag = JS_VALUE_GET_TAG(argv[i]);
            if (tag != JS_TAG_INT) {
                r = r1;
                goto generic_case;
            }
            a1 = JS_VALUE_GET_INT(argv[i]);
            if (is_max)
                r1 = max_int(r1, a1);
            else
                r1 = min_int(r1, a1);
        }
        return JS_NewInt32(ctx, r1);
    } else {
        if (JS_ToFloat64(ctx, &r, argv[0]))
            return JS_EXCEPTION;
        i = 1;
    generic_case:
        while (i < argc) {
            if (JS_ToFloat64(ctx, &a, argv[i]))
                return JS_EXCEPTION;
            if (!isnan(r)) {
                if (isnan(a)) {
                    r = a;
                } else {
                    if (is_max)
                        r = js_fmax(r, a);
                    else
                        r = js_fmin(r, a);
                }
            }
            i++;
        }
        return JS_NewFloat64(ctx, r);
    }
}

static double js_math_sign(double a)
{
    if (isnan(a) || a == 0.0)
        return a;
    if (a < 0)
        return -1;
    else
        return 1;
}

static double js_math_round(double a)
{
    JSFloat64Union u;
    uint64_t frac_mask, one;
    unsigned int e, s;
    u.d = a;
    e = (u.u64 >> 52) & 0x7ff;
    if (e < 1023) {
        /* abs(a) < 1 */
        if (e == (1023 - 1) && u.u64 != 0xbfe0000000000000) {
            /* abs(a) > 0.5 or a = 0.5: return +/-1.0 */
            u.u64 = (u.u64 & ((uint64_t)1 << 63)) | ((uint64_t)1023 << 52);
        } else {
            /* return +/-0.0 */
            u.u64 &= (uint64_t)1 << 63;
        }
    } else if (e < (1023 + 52)) {
        s = u.u64 >> 63;
        one = (uint64_t)1 << (52 - (e - 1023));
        frac_mask = one - 1;
        u.u64 += (one >> 1) - s;
        u.u64 &= ~frac_mask; /* truncate to an integer */
    }
    /* otherwise: abs(a) >= 2^52, or NaN, +/-Infinity: no change */
    return u.d;
}

static JSValue js_math_hypot(JSContext *ctx, JSValueConst this_val,
                             int argc, JSValueConst *argv)
{
    double r, a;
    int i;
    r = 0;
    if (argc > 0) {
        if (JS_ToFloat64(ctx, &r, argv[0]))
            return JS_EXCEPTION;
        if (argc == 1) {
            r = fabs(r);
        } else {
            /* use the built-in function to minimize precision loss */
            for (i = 1; i < argc; i++) {
                if (JS_ToFloat64(ctx, &a, argv[i]))
                    return JS_EXCEPTION;
                r = hypot(r, a);
            }
        }
    }
    return JS_NewFloat64(ctx, r);
}

static double js_math_fround(double a)
{
    return (float)a;
}

static JSValue js_math_imul(JSContext *ctx, JSValueConst this_val,
                            int argc, JSValueConst *argv)
{
    int a, b;
    if (JS_ToInt32(ctx, &a, argv[0]))
        return JS_EXCEPTION;
    if (JS_ToInt32(ctx, &b, argv[1]))
        return JS_EXCEPTION;
    /* purposely ignoring overflow */
    return JS_NewInt32(ctx, a * b);
}

static JSValue js_math_clz32(JSContext *ctx, JSValueConst this_val,
                             int argc, JSValueConst *argv)
{
    uint32_t a, r;
    if (JS_ToUint32(ctx, &a, argv[0]))
        return JS_EXCEPTION;
    if (a == 0)
        r = 32;
    else
        r = clz32(a);
    return JS_NewInt32(ctx, r);
}

/* xorshift* random number generator by Marsaglia */
static uint64_t xorshift64star(uint64_t *pstate)
{
    uint64_t x;
    x = *pstate;
    x ^= x >> 12;
    x ^= x << 25;
    x ^= x >> 27;
    *pstate = x;
    return x * 0x2545F4914F6CDD1D;
}

static void js_random_init(JSContext *ctx)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    ctx->random_state = ((int64_t)tv.tv_sec * 1000000) + tv.tv_usec;
    /* the state must be non zero */
    if (ctx->random_state == 0)
        ctx->random_state = 1;
}

static JSValue js_math_random(JSContext *ctx, JSValueConst this_val,
                              int argc, JSValueConst *argv)
{
    JSFloat64Union u;
    uint64_t v;

    v = xorshift64star(&ctx->random_state);
    /* 1.0 <= u.d < 2 */
    u.u64 = ((uint64_t)0x3ff << 52) | (v >> 12);
    return __JS_NewFloat64(ctx, u.d - 1.0);
}

double js_pow(double a, double b)
{
    if (UNLIKELY(!isfinite(b)) && fabs(a) == 1) {
        /* not compatible with IEEE 754 */
        return JS_FLOAT64_NAN;
    } else {
        return pow(a, b);
    }
}

static const JSCFunctionListEntry js_math_funcs[] = {
    JS_CFUNC_MAGIC_DEF("min", 2, js_math_min_max, 0 ),
    JS_CFUNC_MAGIC_DEF("max", 2, js_math_min_max, 1 ),
    JS_CFUNC_SPECIAL_DEF("abs", 1, f_f, fabs ),
    JS_CFUNC_SPECIAL_DEF("floor", 1, f_f, floor ),
    JS_CFUNC_SPECIAL_DEF("ceil", 1, f_f, ceil ),
    JS_CFUNC_SPECIAL_DEF("round", 1, f_f, js_math_round ),
    JS_CFUNC_SPECIAL_DEF("sqrt", 1, f_f, sqrt ),
    JS_CFUNC_SPECIAL_DEF("acos", 1, f_f, acos ),
    JS_CFUNC_SPECIAL_DEF("asin", 1, f_f, asin ),
    JS_CFUNC_SPECIAL_DEF("atan", 1, f_f, atan ),
    JS_CFUNC_SPECIAL_DEF("atan2", 2, f_f_f, atan2 ),
    JS_CFUNC_SPECIAL_DEF("cos", 1, f_f, cos ),
    JS_CFUNC_SPECIAL_DEF("exp", 1, f_f, exp ),
    JS_CFUNC_SPECIAL_DEF("log", 1, f_f, log ),
    JS_CFUNC_SPECIAL_DEF("pow", 2, f_f_f, js_pow ),
    JS_CFUNC_SPECIAL_DEF("sin", 1, f_f, sin ),
    JS_CFUNC_SPECIAL_DEF("tan", 1, f_f, tan ),
    /* ES6 */
    JS_CFUNC_SPECIAL_DEF("trunc", 1, f_f, trunc ),
    JS_CFUNC_SPECIAL_DEF("sign", 1, f_f, js_math_sign ),
    JS_CFUNC_SPECIAL_DEF("cosh", 1, f_f, cosh ),
    JS_CFUNC_SPECIAL_DEF("sinh", 1, f_f, sinh ),
    JS_CFUNC_SPECIAL_DEF("tanh", 1, f_f, tanh ),
    JS_CFUNC_SPECIAL_DEF("acosh", 1, f_f, acosh ),
    JS_CFUNC_SPECIAL_DEF("asinh", 1, f_f, asinh ),
    JS_CFUNC_SPECIAL_DEF("atanh", 1, f_f, atanh ),
    JS_CFUNC_SPECIAL_DEF("expm1", 1, f_f, expm1 ),
    JS_CFUNC_SPECIAL_DEF("log1p", 1, f_f, log1p ),
    JS_CFUNC_SPECIAL_DEF("log2", 1, f_f, log2 ),
    JS_CFUNC_SPECIAL_DEF("log10", 1, f_f, log10 ),
    JS_CFUNC_SPECIAL_DEF("cbrt", 1, f_f, cbrt ),
    JS_CFUNC_DEF("hypot", 2, js_math_hypot ),
    JS_CFUNC_DEF("random", 0, js_math_random ),
    JS_CFUNC_SPECIAL_DEF("fround", 1, f_f, js_math_fround ),
    JS_CFUNC_DEF("imul", 2, js_math_imul ),
    JS_CFUNC_DEF("clz32", 1, js_math_clz32 ),
    JS_PROP_STRING_DEF("[Symbol.toStringTag]", "Math", JS_PROP_CONFIGURABLE ),
    JS_PROP_DOUBLE_DEF("E", 2.718281828459045, 0 ),
    JS_PROP_DOUBLE_DEF("LN10", 2.302585092994046, 0 ),
    JS_PROP_DOUBLE_DEF("LN2", 0.6931471805599453, 0 ),
    JS_PROP_DOUBLE_DEF("LOG2E", 1.4426950408889634, 0 ),
    JS_PROP_DOUBLE_DEF("LOG10E", 0.4342944819032518, 0 ),
    JS_PROP_DOUBLE_DEF("PI", 3.141592653589793, 0 ),
    JS_PROP_DOUBLE_DEF("SQRT1_2", 0.7071067811865476, 0 ),
    JS_PROP_DOUBLE_DEF("SQRT2", 1.4142135623730951, 0 ),
};

static const JSCFunctionListEntry js_math_obj[] = {
    JS_OBJECT_DEF("Math", js_math_funcs, countof(js_math_funcs), JS_PROP_WRITABLE | JS_PROP_CONFIGURABLE ),
};

void JS_AddIntrinsicMath(JSContext *ctx) {
    /* Math: create as autoinit object */
    js_random_init(ctx);
    JS_SetPropertyFunctionList(ctx, ctx->global_obj, js_math_obj, countof(js_math_obj));
}