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

#include "py/runtime.h"
#include "py/bc0.h"
#include "py/bc.h"

#if MICROPY_DEBUG_VERBOSE // print debugging info
#define DEBUG_PRINT (1)
#else // don't print debugging info
#define DEBUG_PRINT (0)
#define DEBUG_printf(...) (void)0
#endif

#if !MICROPY_PERSISTENT_CODE

mp_uint_t mp_decode_uint(const byte **ptr) {
 mp_uint_t unum = 0;
 byte val;
 const byte *p = *ptr;
 do {
 val = *p++;
 unum = (unum << 7) | (val & 0x7f);
 } while ((val & 0x80) != 0);
 *ptr = p;
 return unum;
}

// This function is used to help reduce stack usage at the caller, for the case when
// the caller doesn't need to increase the ptr argument. If ptr is a local variable
// and the caller uses mp_decode_uint(&ptr) instead of this function, then the compiler
// must allocate a slot on the stack for ptr, and this slot cannot be reused for
// anything else in the function because the pointer may have been stored in a global
// and reused later in the function.
mp_uint_t mp_decode_uint_value(const byte *ptr) {
 return mp_decode_uint(&ptr);
}

// This function is used to help reduce stack usage at the caller, for the case when
// the caller doesn't need the actual value and just wants to skip over it.
const byte *mp_decode_uint_skip(const byte *ptr) {
 while ((*ptr++) & 0x80) {
 }
 return ptr;
}

#endif

STATIC NORETURN void fun_pos_args_mismatch(mp_obj_fun_bc_t *f, size_t expected, size_t given) {
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE
 // generic message, used also for other argument issues
 (void)f;
 (void)expected;
 (void)given;
 mp_arg_error_terse_mismatch();
 #elif MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NORMAL
 (void)f;
 mp_raise_msg_varg(&mp_type_TypeError,
 MP_ERROR_TEXT("function takes %d positional arguments but %d were given"), expected, given);
 #elif MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_DETAILED
 mp_raise_msg_varg(&mp_type_TypeError,
 MP_ERROR_TEXT("%q() takes %d positional arguments but %d were given"),
 mp_obj_fun_get_name(MP_OBJ_FROM_PTR(f)), expected, given);
 #endif
}

#if DEBUG_PRINT
STATIC void dump_args(const mp_obj_t *a, size_t sz) {
 DEBUG_printf("%p: ", a);
 for (size_t i = 0; i < sz; i++) {
 DEBUG_printf("%p ", a[i]);
 }
 DEBUG_printf("\n");
}
#else
#define dump_args(...) (void)0
#endif

// On entry code_state should be allocated somewhere (stack/heap) and
// contain the following valid entries:
// - code_state->fun_bc should contain a pointer to the function object
// - code_state->ip should contain the offset in bytes from the pointer
// code_state->fun_bc->bytecode to the entry n_state (0 for bytecode, non-zero for native)
void mp_setup_code_state(mp_code_state_t *code_state, size_t n_args, size_t n_kw, const mp_obj_t *args) {
 // This function is pretty complicated. It's main aim is to be efficient in speed and RAM
 // usage for the common case of positional only args.

 // get the function object that we want to set up (could be bytecode or native code)
 mp_obj_fun_bc_t *self = code_state->fun_bc;

 // ip comes in as an offset into bytecode, so turn it into a true pointer
 code_state->ip = self->bytecode + (size_t)code_state->ip;

 #if MICROPY_STACKLESS
 code_state->prev = NULL;
 #endif

 #if MICROPY_PY_SYS_SETTRACE
 code_state->prev_state = NULL;
 code_state->frame = NULL;
 #endif

 // Get cached n_state (rather than decode it again)
 size_t n_state = code_state->n_state;

 // Decode prelude
 size_t n_state_unused, n_exc_stack_unused, scope_flags, n_pos_args, n_kwonly_args, n_def_pos_args;
 MP_BC_PRELUDE_SIG_DECODE_INTO(code_state->ip, n_state_unused, n_exc_stack_unused, scope_flags, n_pos_args, n_kwonly_args, n_def_pos_args);
 (void)n_state_unused;
 (void)n_exc_stack_unused;

 code_state->sp = &code_state->state[0] - 1;
 code_state->exc_sp_idx = 0;

 // zero out the local stack to begin with
 memset(code_state->state, 0, n_state * sizeof(*code_state->state));

 const mp_obj_t *kwargs = args + n_args;

 // var_pos_kw_args points to the stack where the var-args tuple, and var-kw dict, should go (if they are needed)
 mp_obj_t *var_pos_kw_args = &code_state->state[n_state - 1 - n_pos_args - n_kwonly_args];

 // check positional arguments

 if (n_args > n_pos_args) {
 // given more than enough arguments
 if ((scope_flags & MP_SCOPE_FLAG_VARARGS) == 0) {
 fun_pos_args_mismatch(self, n_pos_args, n_args);
 }
 // put extra arguments in varargs tuple
 *var_pos_kw_args-- = mp_obj_new_tuple(n_args - n_pos_args, args + n_pos_args);
 n_args = n_pos_args;
 } else {
 if ((scope_flags & MP_SCOPE_FLAG_VARARGS) != 0) {
 DEBUG_printf("passing empty tuple as *args\n");
 *var_pos_kw_args-- = mp_const_empty_tuple;
 }
 // Apply processing and check below only if we don't have kwargs,
 // otherwise, kw handling code below has own extensive checks.
 if (n_kw == 0 && (scope_flags & MP_SCOPE_FLAG_DEFKWARGS) == 0) {
 if (n_args >= (size_t)(n_pos_args - n_def_pos_args)) {
 // given enough arguments, but may need to use some default arguments
 for (size_t i = n_args; i < n_pos_args; i++) {
 code_state->state[n_state - 1 - i] = self->extra_args[i - (n_pos_args - n_def_pos_args)];
 }
 } else {
 fun_pos_args_mismatch(self, n_pos_args - n_def_pos_args, n_args);
 }
 }
 }

 // copy positional args into state
 for (size_t i = 0; i < n_args; i++) {
 code_state->state[n_state - 1 - i] = args[i];
 }

 // check keyword arguments

 if (n_kw != 0 || (scope_flags & MP_SCOPE_FLAG_DEFKWARGS) != 0) {
 DEBUG_printf("Initial args: ");
 dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);

 mp_obj_t dict = MP_OBJ_NULL;
 if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0) {
 dict = mp_obj_new_dict(n_kw); // TODO: better go conservative with 0?
 *var_pos_kw_args = dict;
 }

 // get pointer to arg_names array
 const mp_obj_t *arg_names = (const mp_obj_t *)self->const_table;

 for (size_t i = 0; i < n_kw; i++) {
 // the keys in kwargs are expected to be qstr objects
 mp_obj_t wanted_arg_name = kwargs[2 * i];
 for (size_t j = 0; j < n_pos_args + n_kwonly_args; j++) {
 if (wanted_arg_name == arg_names[j]) {
 if (code_state->state[n_state - 1 - j] != MP_OBJ_NULL) {
 mp_raise_msg_varg(&mp_type_TypeError,
 MP_ERROR_TEXT("function got multiple values for argument '%q'"), MP_OBJ_QSTR_VALUE(wanted_arg_name));
 }
 code_state->state[n_state - 1 - j] = kwargs[2 * i + 1];
 goto continue2;
 }
 }
 // Didn't find name match with positional args
 if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) == 0) {
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE
 mp_raise_TypeError(MP_ERROR_TEXT("unexpected keyword argument"));
 #else
 mp_raise_msg_varg(&mp_type_TypeError,
 MP_ERROR_TEXT("unexpected keyword argument '%q'"), MP_OBJ_QSTR_VALUE(wanted_arg_name));
 #endif
 }
 mp_obj_dict_store(dict, kwargs[2 * i], kwargs[2 * i + 1]);
 continue2:;
 }

 DEBUG_printf("Args with kws flattened: ");
 dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);

 // fill in defaults for positional args
 mp_obj_t *d = &code_state->state[n_state - n_pos_args];
 mp_obj_t *s = &self->extra_args[n_def_pos_args - 1];
 for (size_t i = n_def_pos_args; i > 0; i--, d++, s--) {
 if (*d == MP_OBJ_NULL) {
 *d = *s;
 }
 }

 DEBUG_printf("Args after filling default positional: ");
 dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);

 // Check that all mandatory positional args are specified
 while (d < &code_state->state[n_state]) {
 if (*d++ == MP_OBJ_NULL) {
 mp_raise_msg_varg(&mp_type_TypeError,
 MP_ERROR_TEXT("function missing required positional argument #%d"), &code_state->state[n_state] - d);
 }
 }

 // Check that all mandatory keyword args are specified
 // Fill in default kw args if we have them
 for (size_t i = 0; i < n_kwonly_args; i++) {
 if (code_state->state[n_state - 1 - n_pos_args - i] == MP_OBJ_NULL) {
 mp_map_elem_t *elem = NULL;
 if ((scope_flags & MP_SCOPE_FLAG_DEFKWARGS) != 0) {
 elem = mp_map_lookup(&((mp_obj_dict_t *)MP_OBJ_TO_PTR(self->extra_args[n_def_pos_args]))->map, arg_names[n_pos_args + i], MP_MAP_LOOKUP);
 }
 if (elem != NULL) {
 code_state->state[n_state - 1 - n_pos_args - i] = elem->value;
 } else {
 mp_raise_msg_varg(&mp_type_TypeError,
 MP_ERROR_TEXT("function missing required keyword argument '%q'"), MP_OBJ_QSTR_VALUE(arg_names[n_pos_args + i]));
 }
 }
 }

 } else {
 // no keyword arguments given
 if (n_kwonly_args != 0) {
 mp_raise_TypeError(MP_ERROR_TEXT("function missing keyword-only argument"));
 }
 if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0) {
 *var_pos_kw_args = mp_obj_new_dict(0);
 }
 }

 // read the size part of the prelude
 const byte *ip = code_state->ip;
 MP_BC_PRELUDE_SIZE_DECODE(ip);

 // jump over code info (source file and line-number mapping)
 ip += n_info;

 // bytecode prelude: initialise closed over variables
 for (; n_cell; --n_cell) {
 size_t local_num = *ip++;
 code_state->state[n_state - 1 - local_num] =
 mp_obj_new_cell(code_state->state[n_state - 1 - local_num]);
 }

 #if !MICROPY_PERSISTENT_CODE
 // so bytecode is aligned
 ip = MP_ALIGN(ip, sizeof(mp_uint_t));
 #endif

 // now that we skipped over the prelude, set the ip for the VM
 code_state->ip = ip;

 DEBUG_printf("Calling: n_pos_args=%d, n_kwonly_args=%d\n", n_pos_args, n_kwonly_args);
 dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);
 dump_args(code_state->state, n_state);
}

#if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE

// The following table encodes the number of bytes that a specific opcode
// takes up. Some opcodes have an extra byte, defined by MP_BC_MASK_EXTRA_BYTE.
// There are 4 special opcodes that have an extra byte only when
// MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE is enabled (and they take a qstr):
// MP_BC_LOAD_NAME
// MP_BC_LOAD_GLOBAL
// MP_BC_LOAD_ATTR
// MP_BC_STORE_ATTR
uint mp_opcode_format(const byte *ip, size_t *opcode_size, bool count_var_uint) {
 uint f = MP_BC_FORMAT(*ip);
 const byte *ip_start = ip;
 if (f == MP_BC_FORMAT_QSTR) {
 if (MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE_DYNAMIC) {
 if (*ip == MP_BC_LOAD_NAME
 || *ip == MP_BC_LOAD_GLOBAL
 || *ip == MP_BC_LOAD_ATTR
 || *ip == MP_BC_STORE_ATTR) {
 ip += 1;
 }
 }
 ip += 3;
 } else {
 int extra_byte = (*ip & MP_BC_MASK_EXTRA_BYTE) == 0;
 ip += 1;
 if (f == MP_BC_FORMAT_VAR_UINT) {
 if (count_var_uint) {
 while ((*ip++ & 0x80) != 0) {
 }
 }
 } else if (f == MP_BC_FORMAT_OFFSET) {
 ip += 2;
 }
 ip += extra_byte;
 }
 *opcode_size = ip - ip_start;
 return f;
}

#endif // MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE