/*
 * Copyright (C) 2019 Intel Corporation.  All rights reserved.
 * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 */

#include "bh_platform.h"
#include "app_manager_export.h"
#include "../app-manager/module_wasm_app.h"
#include "timer_native_api.h"

typedef struct {
    bh_list_link l;
    timer_ctx_t timer_ctx;
} timer_ctx_node_t;

static bool timer_thread_run = true;

static bh_list g_timer_ctx_list;
static korp_cond g_timer_ctx_list_cond;
static korp_mutex g_timer_ctx_list_mutex;

void
wasm_timer_callback(timer_id_t id, unsigned int mod_id)
{
    module_data* module = module_data_list_lookup_id(mod_id);
    if (module == NULL)
        return;

    // !!! the length parameter must be 0, so the receiver will
    //     not free the payload pointer.
    bh_post_msg(module->queue, TIMER_EVENT_WASM, (char *)(uintptr_t)id, 0);
}

/**
 * why we create a separate link for module timer contexts
 * rather than traverse the module list?
 * It helps to reduce the lock frequency for the module list.
 * Also when we lock the module list and then call the callback for
 * timer expire, the callback is request the list lock again for lookup
 * the module from module id. It is for avoiding that situation.
 */

void * thread_modulers_timer_check(void * arg)
{
    uint32 ms_to_expiry;
    uint64 us_to_wait;

    while (timer_thread_run) {
        ms_to_expiry = (uint32)-1;
        os_mutex_lock(&g_timer_ctx_list_mutex);
        timer_ctx_node_t* elem = (timer_ctx_node_t*)
                                 bh_list_first_elem(&g_timer_ctx_list);
        while (elem) {
            uint32 next = check_app_timers(elem->timer_ctx);
            if (next != (uint32)-1) {
                if (ms_to_expiry == (uint32)-1 || ms_to_expiry > next)
                    ms_to_expiry = next;
            }

            elem = (timer_ctx_node_t*) bh_list_elem_next(elem);
        }
        os_mutex_unlock(&g_timer_ctx_list_mutex);

        if (ms_to_expiry == (uint32)-1)
            us_to_wait = BHT_WAIT_FOREVER;
        else
            us_to_wait = (uint64)ms_to_expiry * 1000;
        os_mutex_lock(&g_timer_ctx_list_mutex);
        os_cond_reltimedwait(&g_timer_ctx_list_cond, &g_timer_ctx_list_mutex,
                             us_to_wait);
        os_mutex_unlock(&g_timer_ctx_list_mutex);
    }

    return NULL;
}

void
wakeup_modules_timer_thread(timer_ctx_t ctx)
{
    os_mutex_lock(&g_timer_ctx_list_mutex);
    os_cond_signal(&g_timer_ctx_list_cond);
    os_mutex_unlock(&g_timer_ctx_list_mutex);
}

void
init_wasm_timer()
{
    korp_tid tm_tid;
    bh_list_init(&g_timer_ctx_list);

    os_cond_init(&g_timer_ctx_list_cond);
    /* temp solution for: thread_modulers_timer_check thread
       would recursive lock the mutex */
    os_recursive_mutex_init(&g_timer_ctx_list_mutex);

    os_thread_create(&tm_tid, thread_modulers_timer_check,
                     NULL, BH_APPLET_PRESERVED_STACK_SIZE);
}

void
exit_wasm_timer()
{
    timer_thread_run = false;
}

timer_ctx_t
create_wasm_timer_ctx(unsigned int module_id, int prealloc_num)
{
    timer_ctx_t ctx = create_timer_ctx(wasm_timer_callback,
                                       wakeup_modules_timer_thread,
                                       prealloc_num, module_id);

    if (ctx == NULL)
        return NULL;

    timer_ctx_node_t * node = (timer_ctx_node_t*)
                              wasm_runtime_malloc(sizeof(timer_ctx_node_t));
    if (node == NULL) {
        destroy_timer_ctx(ctx);
        return NULL;
    }
    memset(node, 0, sizeof(*node));
    node->timer_ctx = ctx;

    os_mutex_lock(&g_timer_ctx_list_mutex);
    bh_list_insert(&g_timer_ctx_list, node);
    os_mutex_unlock(&g_timer_ctx_list_mutex);

    return ctx;
}

void
destroy_module_timer_ctx(unsigned int module_id)
{
    timer_ctx_node_t* elem;

    os_mutex_lock(&g_timer_ctx_list_mutex);
    elem = (timer_ctx_node_t*)
           bh_list_first_elem(&g_timer_ctx_list);
    while (elem) {
        if (timer_ctx_get_owner(elem->timer_ctx) == module_id) {
            bh_list_remove(&g_timer_ctx_list, elem);
            destroy_timer_ctx(elem->timer_ctx);
            wasm_runtime_free(elem);
            break;
        }

        elem = (timer_ctx_node_t*) bh_list_elem_next(elem);
    }
    os_mutex_unlock(&g_timer_ctx_list_mutex);
}

timer_ctx_t
get_wasm_timer_ctx(wasm_module_inst_t module_inst)
{
    module_data * m = app_manager_get_module_data(Module_WASM_App,
                                                  module_inst);
    if (m == NULL)
        return NULL;
    return m->timer_ctx;
}

timer_id_t
wasm_create_timer(wasm_exec_env_t exec_env,
                  int interval, bool is_period, bool auto_start)
{
    wasm_module_inst_t module_inst = get_module_inst(exec_env);
    timer_ctx_t timer_ctx = get_wasm_timer_ctx(module_inst);
    bh_assert(timer_ctx);
    return sys_create_timer(timer_ctx, interval, is_period, auto_start);
}

void
wasm_timer_destroy(wasm_exec_env_t exec_env, timer_id_t timer_id)
{
    wasm_module_inst_t module_inst = get_module_inst(exec_env);
    timer_ctx_t timer_ctx = get_wasm_timer_ctx(module_inst);
    bh_assert(timer_ctx);
    sys_timer_destroy(timer_ctx, timer_id);
}

void
wasm_timer_cancel(wasm_exec_env_t exec_env, timer_id_t timer_id)
{
    wasm_module_inst_t module_inst = get_module_inst(exec_env);
    timer_ctx_t timer_ctx = get_wasm_timer_ctx(module_inst);
    bh_assert(timer_ctx);
    sys_timer_cancel(timer_ctx, timer_id);
}

void
wasm_timer_restart(wasm_exec_env_t exec_env,
                   timer_id_t timer_id, int interval)
{
    wasm_module_inst_t module_inst = get_module_inst(exec_env);
    timer_ctx_t timer_ctx = get_wasm_timer_ctx(module_inst);
    bh_assert(timer_ctx);
    sys_timer_restart(timer_ctx, timer_id, interval);
}

uint32
wasm_get_sys_tick_ms(wasm_exec_env_t exec_env)
{
    return (uint32)bh_get_tick_ms();
}