/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 *
 * 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 <stdio.h>
#include <string.h>

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

#if MICROPY_PY_THREAD

#include "py/mpthread.h"

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

/****************************************************************/
// Lock object

STATIC const mp_obj_type_t mp_type_thread_lock;

typedef struct _mp_obj_thread_lock_t {
 mp_obj_base_t base;
 mp_thread_mutex_t mutex;
 volatile bool locked;
} mp_obj_thread_lock_t;

STATIC mp_obj_thread_lock_t *mp_obj_new_thread_lock(void) {
 mp_obj_thread_lock_t *self = m_new_obj(mp_obj_thread_lock_t);
 self->base.type = &mp_type_thread_lock;
 mp_thread_mutex_init(&self->mutex);
 self->locked = false;
 return self;
}

STATIC mp_obj_t thread_lock_acquire(size_t n_args, const mp_obj_t *args) {
 mp_obj_thread_lock_t *self = MP_OBJ_TO_PTR(args[0]);
 bool wait = true;
 if (n_args > 1) {
 wait = mp_obj_get_int(args[1]);
 // TODO support timeout arg
 }
 MP_THREAD_GIL_EXIT();
 int ret = mp_thread_mutex_lock(&self->mutex, wait);
 MP_THREAD_GIL_ENTER();
 if (ret == 0) {
 return mp_const_false;
 } else if (ret == 1) {
 self->locked = true;
 return mp_const_true;
 } else {
 mp_raise_OSError(-ret);
 }
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(thread_lock_acquire_obj, 1, 3, thread_lock_acquire);

STATIC mp_obj_t thread_lock_release(mp_obj_t self_in) {
 mp_obj_thread_lock_t *self = MP_OBJ_TO_PTR(self_in);
 if (!self->locked) {
 mp_raise_msg(&mp_type_RuntimeError, NULL);
 }
 self->locked = false;
 MP_THREAD_GIL_EXIT();
 mp_thread_mutex_unlock(&self->mutex);
 MP_THREAD_GIL_ENTER();
 return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(thread_lock_release_obj, thread_lock_release);

STATIC mp_obj_t thread_lock_locked(mp_obj_t self_in) {
 mp_obj_thread_lock_t *self = MP_OBJ_TO_PTR(self_in);
 return mp_obj_new_bool(self->locked);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(thread_lock_locked_obj, thread_lock_locked);

STATIC mp_obj_t thread_lock___exit__(size_t n_args, const mp_obj_t *args) {
 (void)n_args; // unused
 return thread_lock_release(args[0]);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(thread_lock___exit___obj, 4, 4, thread_lock___exit__);

STATIC const mp_rom_map_elem_t thread_lock_locals_dict_table[] = {
 { MP_ROM_QSTR(MP_QSTR_acquire), MP_ROM_PTR(&thread_lock_acquire_obj) },
 { MP_ROM_QSTR(MP_QSTR_release), MP_ROM_PTR(&thread_lock_release_obj) },
 { MP_ROM_QSTR(MP_QSTR_locked), MP_ROM_PTR(&thread_lock_locked_obj) },
 { MP_ROM_QSTR(MP_QSTR___enter__), MP_ROM_PTR(&thread_lock_acquire_obj) },
 { MP_ROM_QSTR(MP_QSTR___exit__), MP_ROM_PTR(&thread_lock___exit___obj) },
};

STATIC MP_DEFINE_CONST_DICT(thread_lock_locals_dict, thread_lock_locals_dict_table);

STATIC const mp_obj_type_t mp_type_thread_lock = {
 { &mp_type_type },
 .name = MP_QSTR_lock,
 .locals_dict = (mp_obj_dict_t *)&thread_lock_locals_dict,
};

/****************************************************************/
// _thread module

STATIC size_t thread_stack_size = 0;

STATIC mp_obj_t mod_thread_get_ident(void) {
 return mp_obj_new_int_from_uint((uintptr_t)mp_thread_get_state());
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_thread_get_ident_obj, mod_thread_get_ident);

STATIC mp_obj_t mod_thread_stack_size(size_t n_args, const mp_obj_t *args) {
 mp_obj_t ret = mp_obj_new_int_from_uint(thread_stack_size);
 if (n_args == 0) {
 thread_stack_size = 0;
 } else {
 thread_stack_size = mp_obj_get_int(args[0]);
 }
 return ret;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_thread_stack_size_obj, 0, 1, mod_thread_stack_size);

typedef struct _thread_entry_args_t {
 mp_obj_dict_t *dict_locals;
 mp_obj_dict_t *dict_globals;
 size_t stack_size;
 mp_obj_t fun;
 size_t n_args;
 size_t n_kw;
 mp_obj_t args[];
} thread_entry_args_t;

STATIC void *thread_entry(void *args_in) {
 // Execution begins here for a new thread. We do not have the GIL.

 thread_entry_args_t *args = (thread_entry_args_t *)args_in;

 mp_state_thread_t ts;
 mp_thread_set_state(&ts);

 mp_stack_set_top(&ts + 1); // need to include ts in root-pointer scan
 mp_stack_set_limit(args->stack_size);

 #if MICROPY_ENABLE_PYSTACK
 // TODO threading and pystack is not fully supported, for now just make a small stack
 mp_obj_t mini_pystack[128];
 mp_pystack_init(mini_pystack, &mini_pystack[128]);
 #endif

 // set locals and globals from the calling context
 mp_locals_set(args->dict_locals);
 mp_globals_set(args->dict_globals);

 MP_THREAD_GIL_ENTER();

 // signal that we are set up and running
 mp_thread_start();

 // TODO set more thread-specific state here:
 // mp_pending_exception? (root pointer)
 // cur_exception (root pointer)

 DEBUG_printf("[thread] start ts=%p args=%p stack=%p\n", &ts, &args, MP_STATE_THREAD(stack_top));

 nlr_buf_t nlr;
 if (nlr_push(&nlr) == 0) {
 mp_call_function_n_kw(args->fun, args->n_args, args->n_kw, args->args);
 nlr_pop();
 } else {
 // uncaught exception
 // check for SystemExit
 mp_obj_base_t *exc = (mp_obj_base_t *)nlr.ret_val;
 if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(exc->type), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) {
 // swallow exception silently
 } else {
 // print exception out
 mp_printf(MICROPY_ERROR_PRINTER, "Unhandled exception in thread started by ");
 mp_obj_print_helper(MICROPY_ERROR_PRINTER, args->fun, PRINT_REPR);
 mp_printf(MICROPY_ERROR_PRINTER, "\n");
 mp_obj_print_exception(MICROPY_ERROR_PRINTER, MP_OBJ_FROM_PTR(exc));
 }
 }

 DEBUG_printf("[thread] finish ts=%p\n", &ts);

 // signal that we are finished
 mp_thread_finish();

 MP_THREAD_GIL_EXIT();

 return NULL;
}

STATIC mp_obj_t mod_thread_start_new_thread(size_t n_args, const mp_obj_t *args) {
 // This structure holds the Python function and arguments for thread entry.
 // We copy all arguments into this structure to keep ownership of them.
 // We must be very careful about root pointers because this pointer may
 // disappear from our address space before the thread is created.
 thread_entry_args_t *th_args;

 // get positional arguments
 size_t pos_args_len;
 mp_obj_t *pos_args_items;
 mp_obj_get_array(args[1], &pos_args_len, &pos_args_items);

 // check for keyword arguments
 if (n_args == 2) {
 // just position arguments
 th_args = m_new_obj_var(thread_entry_args_t, mp_obj_t, pos_args_len);
 th_args->n_kw = 0;
 } else {
 // positional and keyword arguments
 if (mp_obj_get_type(args[2]) != &mp_type_dict) {
 mp_raise_TypeError(MP_ERROR_TEXT("expecting a dict for keyword args"));
 }
 mp_map_t *map = &((mp_obj_dict_t *)MP_OBJ_TO_PTR(args[2]))->map;
 th_args = m_new_obj_var(thread_entry_args_t, mp_obj_t, pos_args_len + 2 * map->used);
 th_args->n_kw = map->used;
 // copy across the keyword arguments
 for (size_t i = 0, n = pos_args_len; i < map->alloc; ++i) {
 if (mp_map_slot_is_filled(map, i)) {
 th_args->args[n++] = map->table[i].key;
 th_args->args[n++] = map->table[i].value;
 }
 }
 }

 // copy across the positional arguments
 th_args->n_args = pos_args_len;
 memcpy(th_args->args, pos_args_items, pos_args_len * sizeof(mp_obj_t));

 // pass our locals and globals into the new thread
 th_args->dict_locals = mp_locals_get();
 th_args->dict_globals = mp_globals_get();

 // set the stack size to use
 th_args->stack_size = thread_stack_size;

 // set the function for thread entry
 th_args->fun = args[0];

 // spawn the thread!
 mp_thread_create(thread_entry, th_args, &th_args->stack_size);

 return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_thread_start_new_thread_obj, 2, 3, mod_thread_start_new_thread);

STATIC mp_obj_t mod_thread_exit(void) {
 mp_raise_type(&mp_type_SystemExit);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_thread_exit_obj, mod_thread_exit);

STATIC mp_obj_t mod_thread_allocate_lock(void) {
 return MP_OBJ_FROM_PTR(mp_obj_new_thread_lock());
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_thread_allocate_lock_obj, mod_thread_allocate_lock);

STATIC const mp_rom_map_elem_t mp_module_thread_globals_table[] = {
 { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR__thread) },
 { MP_ROM_QSTR(MP_QSTR_LockType), MP_ROM_PTR(&mp_type_thread_lock) },
 { MP_ROM_QSTR(MP_QSTR_get_ident), MP_ROM_PTR(&mod_thread_get_ident_obj) },
 { MP_ROM_QSTR(MP_QSTR_stack_size), MP_ROM_PTR(&mod_thread_stack_size_obj) },
 { MP_ROM_QSTR(MP_QSTR_start_new_thread), MP_ROM_PTR(&mod_thread_start_new_thread_obj) },
 { MP_ROM_QSTR(MP_QSTR_exit), MP_ROM_PTR(&mod_thread_exit_obj) },
 { MP_ROM_QSTR(MP_QSTR_allocate_lock), MP_ROM_PTR(&mod_thread_allocate_lock_obj) },
};

STATIC MP_DEFINE_CONST_DICT(mp_module_thread_globals, mp_module_thread_globals_table);

const mp_obj_module_t mp_module_thread = {
 .base = { &mp_type_module },
 .globals = (mp_obj_dict_t *)&mp_module_thread_globals,
};

#endif // MICROPY_PY_THREAD