/*
   * 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("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 agross 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) {
      nlr_raise(mp_obj_new_exception(&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