/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 *
 * 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 <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>

#include "py/parsenum.h"
#include "py/runtime.h"

#if MICROPY_PY_BUILTINS_FLOAT

#include <math.h>
#include "py/formatfloat.h"

#if MICROPY_OBJ_REPR != MICROPY_OBJ_REPR_C && MICROPY_OBJ_REPR != MICROPY_OBJ_REPR_D

// M_E and M_PI are not part of the math.h standard and may not be defined
#ifndef M_E
#define M_E (2.7182818284590452354)
#endif
#ifndef M_PI
#define M_PI (3.14159265358979323846)
#endif

typedef struct _mp_obj_float_t {
 mp_obj_base_t base;
 mp_float_t value;
} mp_obj_float_t;

const mp_obj_float_t mp_const_float_e_obj = {{&mp_type_float}, M_E};
const mp_obj_float_t mp_const_float_pi_obj = {{&mp_type_float}, M_PI};

#endif

#if MICROPY_FLOAT_HIGH_QUALITY_HASH
// must return actual integer value if it fits in mp_int_t
mp_int_t mp_float_hash(mp_float_t src) {
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
typedef uint64_t mp_float_uint_t;
#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
typedef uint32_t mp_float_uint_t;
#endif
 union {
 mp_float_t f;
 #if MP_ENDIANNESS_LITTLE
 struct { mp_float_uint_t frc:MP_FLOAT_FRAC_BITS, exp:MP_FLOAT_EXP_BITS, sgn:1; } p;
 #else
 struct { mp_float_uint_t sgn:1, exp:MP_FLOAT_EXP_BITS, frc:MP_FLOAT_FRAC_BITS; } p;
 #endif
 mp_float_uint_t i;
 } u = {.f = src};

 mp_int_t val;
 const int adj_exp = (int)u.p.exp - MP_FLOAT_EXP_BIAS;
 if (adj_exp < 0) {
 // value < 1; must be sure to handle 0.0 correctly (ie return 0)
 val = u.i;
 } else {
 // if adj_exp is max then: u.p.frc==0 indicates inf, else NaN
 // else: 1 <= value
 mp_float_uint_t frc = u.p.frc | ((mp_float_uint_t)1 << MP_FLOAT_FRAC_BITS);

 if (adj_exp <= MP_FLOAT_FRAC_BITS) {
 // number may have a fraction; xor the integer part with the fractional part
 val = (frc >> (MP_FLOAT_FRAC_BITS - adj_exp))
 ^ (frc & ((1 << (MP_FLOAT_FRAC_BITS - adj_exp)) - 1));
 } else if ((unsigned int)adj_exp < BITS_PER_BYTE * sizeof(mp_int_t) - 1) {
 // the number is a (big) whole integer and will fit in val's signed-width
 val = (mp_int_t)frc << (adj_exp - MP_FLOAT_FRAC_BITS);
 } else {
 // integer part will overflow val's width so just use what bits we can
 val = frc;
 }
 }

 if (u.p.sgn) {
 val = -val;
 }

 return val;
}
#endif

STATIC void float_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
 (void)kind;
 mp_float_t o_val = mp_obj_float_get(o_in);
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
 char buf[16];
 #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_C
 const int precision = 6;
 #else
 const int precision = 7;
 #endif
#else
 char buf[32];
 const int precision = 16;
#endif
 mp_format_float(o_val, buf, sizeof(buf), 'g', precision, '0円');
 mp_print_str(print, buf);
 if (strchr(buf, '.') == NULL && strchr(buf, 'e') == NULL && strchr(buf, 'n') == NULL) {
 // Python floats always have decimal point (unless inf or nan)
 mp_print_str(print, ".0");
 }
}

STATIC mp_obj_t float_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
 (void)type_in;
 mp_arg_check_num(n_args, n_kw, 0, 1, false);

 switch (n_args) {
 case 0:
 return mp_obj_new_float(0);

 case 1:
 default: {
 mp_buffer_info_t bufinfo;
 if (mp_get_buffer(args[0], &bufinfo, MP_BUFFER_READ)) {
 // a textual representation, parse it
 return mp_parse_num_decimal(bufinfo.buf, bufinfo.len, false, false, NULL);
 } else if (mp_obj_is_float(args[0])) {
 // a float, just return it
 return args[0];
 } else {
 // something else, try to cast it to a float
 return mp_obj_new_float(mp_obj_get_float(args[0]));
 }
 }
 }
}

STATIC mp_obj_t float_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
 mp_float_t val = mp_obj_float_get(o_in);
 switch (op) {
 case MP_UNARY_OP_BOOL: return mp_obj_new_bool(val != 0);
 case MP_UNARY_OP_HASH: return MP_OBJ_NEW_SMALL_INT(mp_float_hash(val));
 case MP_UNARY_OP_POSITIVE: return o_in;
 case MP_UNARY_OP_NEGATIVE: return mp_obj_new_float(-val);
 case MP_UNARY_OP_ABS: {
 // TODO check for NaN etc
 if (val < 0) {
 return mp_obj_new_float(-val);
 } else {
 return o_in;
 }
 }
 default: return MP_OBJ_NULL; // op not supported
 }
}

STATIC mp_obj_t float_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
 mp_float_t lhs_val = mp_obj_float_get(lhs_in);
#if MICROPY_PY_BUILTINS_COMPLEX
 if (MP_OBJ_IS_TYPE(rhs_in, &mp_type_complex)) {
 return mp_obj_complex_binary_op(op, lhs_val, 0, rhs_in);
 } else
#endif
 {
 return mp_obj_float_binary_op(op, lhs_val, rhs_in);
 }
}

const mp_obj_type_t mp_type_float = {
 { &mp_type_type },
 .name = MP_QSTR_float,
 .print = float_print,
 .make_new = float_make_new,
 .unary_op = float_unary_op,
 .binary_op = float_binary_op,
};

#if MICROPY_OBJ_REPR != MICROPY_OBJ_REPR_C && MICROPY_OBJ_REPR != MICROPY_OBJ_REPR_D

mp_obj_t mp_obj_new_float(mp_float_t value) {
 mp_obj_float_t *o = m_new(mp_obj_float_t, 1);
 o->base.type = &mp_type_float;
 o->value = value;
 return MP_OBJ_FROM_PTR(o);
}

mp_float_t mp_obj_float_get(mp_obj_t self_in) {
 assert(mp_obj_is_float(self_in));
 mp_obj_float_t *self = MP_OBJ_TO_PTR(self_in);
 return self->value;
}

#endif

STATIC void mp_obj_float_divmod(mp_float_t *x, mp_float_t *y) {
 // logic here follows that of CPython
 // https://docs.python.org/3/reference/expressions.html#binary-arithmetic-operations
 // x == (x//y)*y + (x%y)
 // divmod(x, y) == (x//y, x%y)
 mp_float_t mod = MICROPY_FLOAT_C_FUN(fmod)(*x, *y);
 mp_float_t div = (*x - mod) / *y;

 // Python specs require that mod has same sign as second operand
 if (mod == 0.0) {
 mod = MICROPY_FLOAT_C_FUN(copysign)(0.0, *y);
 } else {
 if ((mod < 0.0) != (*y < 0.0)) {
 mod += *y;
 div -= 1.0;
 }
 }

 mp_float_t floordiv;
 if (div == 0.0) {
 // if division is zero, take the correct sign of zero
 floordiv = MICROPY_FLOAT_C_FUN(copysign)(0.0, *x / *y);
 } else {
 // Python specs require that x == (x//y)*y + (x%y)
 floordiv = MICROPY_FLOAT_C_FUN(floor)(div);
 if (div - floordiv > 0.5) {
 floordiv += 1.0;
 }
 }

 // return results
 *x = floordiv;
 *y = mod;
}

mp_obj_t mp_obj_float_binary_op(mp_binary_op_t op, mp_float_t lhs_val, mp_obj_t rhs_in) {
 mp_float_t rhs_val;
 if (!mp_obj_get_float_maybe(rhs_in, &rhs_val)) {
 return MP_OBJ_NULL; // op not supported
 }

 switch (op) {
 case MP_BINARY_OP_ADD:
 case MP_BINARY_OP_INPLACE_ADD: lhs_val += rhs_val; break;
 case MP_BINARY_OP_SUBTRACT:
 case MP_BINARY_OP_INPLACE_SUBTRACT: lhs_val -= rhs_val; break;
 case MP_BINARY_OP_MULTIPLY:
 case MP_BINARY_OP_INPLACE_MULTIPLY: lhs_val *= rhs_val; break;
 case MP_BINARY_OP_FLOOR_DIVIDE:
 case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE:
 if (rhs_val == 0) {
 zero_division_error:
 mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
 }
 // Python specs require that x == (x//y)*y + (x%y) so we must
 // call divmod to compute the correct floor division, which
 // returns the floor divide in lhs_val.
 mp_obj_float_divmod(&lhs_val, &rhs_val);
 break;
 case MP_BINARY_OP_TRUE_DIVIDE:
 case MP_BINARY_OP_INPLACE_TRUE_DIVIDE:
 if (rhs_val == 0) {
 goto zero_division_error;
 }
 lhs_val /= rhs_val;
 break;
 case MP_BINARY_OP_MODULO:
 case MP_BINARY_OP_INPLACE_MODULO:
 if (rhs_val == 0) {
 goto zero_division_error;
 }
 lhs_val = MICROPY_FLOAT_C_FUN(fmod)(lhs_val, rhs_val);
 // Python specs require that mod has same sign as second operand
 if (lhs_val == 0.0) {
 lhs_val = MICROPY_FLOAT_C_FUN(copysign)(0.0, rhs_val);
 } else {
 if ((lhs_val < 0.0) != (rhs_val < 0.0)) {
 lhs_val += rhs_val;
 }
 }
 break;
 case MP_BINARY_OP_POWER:
 case MP_BINARY_OP_INPLACE_POWER:
 if (lhs_val == 0 && rhs_val < 0 && !isinf(rhs_val)) {
 goto zero_division_error;
 }
 if (lhs_val < 0 && rhs_val != MICROPY_FLOAT_C_FUN(floor)(rhs_val)) {
 #if MICROPY_PY_BUILTINS_COMPLEX
 return mp_obj_complex_binary_op(MP_BINARY_OP_POWER, lhs_val, 0, rhs_in);
 #else
 mp_raise_ValueError("complex values not supported");
 #endif
 }
 lhs_val = MICROPY_FLOAT_C_FUN(pow)(lhs_val, rhs_val);
 break;
 case MP_BINARY_OP_DIVMOD: {
 if (rhs_val == 0) {
 goto zero_division_error;
 }
 mp_obj_float_divmod(&lhs_val, &rhs_val);
 mp_obj_t tuple[2] = {
 mp_obj_new_float(lhs_val),
 mp_obj_new_float(rhs_val),
 };
 return mp_obj_new_tuple(2, tuple);
 }
 case MP_BINARY_OP_LESS: return mp_obj_new_bool(lhs_val < rhs_val);
 case MP_BINARY_OP_MORE: return mp_obj_new_bool(lhs_val > rhs_val);
 case MP_BINARY_OP_EQUAL: return mp_obj_new_bool(lhs_val == rhs_val);
 case MP_BINARY_OP_LESS_EQUAL: return mp_obj_new_bool(lhs_val <= rhs_val);
 case MP_BINARY_OP_MORE_EQUAL: return mp_obj_new_bool(lhs_val >= rhs_val);

 default:
 return MP_OBJ_NULL; // op not supported
 }
 return mp_obj_new_float(lhs_val);
}

#endif // MICROPY_PY_BUILTINS_FLOAT