/*
 * Copyright (C) 2019 Intel Corporation.  All rights reserved.
 * Copyright (C) 2020 TU Bergakademie Freiberg Karl Fessel
 * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 */

#include "platform_api_vmcore.h"
#include "platform_api_extension.h"

#include <panic.h>
#include <sema.h>
#include <ztimer.h>

/* clang-format off */
#define bh_assert(v) do {                                   \
     if (!(v)) {                                            \
       printf("\nASSERTION FAILED: %s, at %s, line %d\n",   \
              #v, __FILE__, __LINE__);                      \
       core_panic(0, 0/*expr_string*/);                     \
       while (1);                                           \
     }                                                      \
} while (0)
/* clang-format on */

struct os_thread_data;
typedef struct os_thread_wait_node {
    sema_t sem;
    void *ret;
    os_thread_wait_list next;
} os_thread_wait_node;

// all information for thread to cleanup it self
typedef struct os_thread_data {
    /* Next thread data */
    struct os_thread_data *next;
    /* thread handle */
    kernel_pid_t tid;
    /* Thread start routine */
    thread_start_routine_t start_routine;
    /* Thread start routine argument */
    void *arg;
    /* thread local root */
    void *tlr;
    /* Lock for waiting list */
    mutex_t wait_list_lock;
    /* Waiting list of other threads who are joining this thread */
    os_thread_wait_list thread_wait_list;
    /* Thread stack size */
    unsigned stack_size;
    /* Thread stack */
    char stack[1];
} os_thread_data;

typedef struct os_thread_obj {
    korp_tid thread;
    /* Whether the thread is terminated and this thread object is to
     be freed in the future. */
    bool to_be_freed;
    struct os_thread_obj *next;
} os_thread_obj;

static bool is_thread_sys_inited = false;

/* Lock for thread data list */
static mutex_t thread_data_lock;

/* Thread data list */
static os_thread_data *thread_data_list = NULL;

static void
thread_data_list_add(os_thread_data *thread_data)
{
    mutex_lock(&thread_data_lock);
    if (!thread_data_list)
        thread_data_list = thread_data;
    else {
        /* If already in list, just return */
        os_thread_data *p = thread_data_list;
        while (p) {
            if (p == thread_data) {
                mutex_unlock(&thread_data_lock);
                return;
            }
            p = p->next;
        }

        /* Set as head of list */
        thread_data->next = thread_data_list;
        thread_data_list = thread_data;
    }
    mutex_unlock(&thread_data_lock);
}

static void
thread_data_list_remove(os_thread_data *thread_data)
{
    mutex_lock(&thread_data_lock);
    if (thread_data_list) {
        if (thread_data_list == thread_data)
            thread_data_list = thread_data_list->next;
        else {
            /* Search and remove it from list */
            os_thread_data *p = thread_data_list;
            while (p && p->next != thread_data)
                p = p->next;
            if (p && p->next == thread_data)
                p->next = p->next->next;
        }
    }
    mutex_unlock(&thread_data_lock);
}

static os_thread_data *
thread_data_list_lookup(korp_tid tid)
{
    mutex_lock(&thread_data_lock);
    if (thread_data_list) {
        os_thread_data *p = thread_data_list;
        while (p) {
            if (p->tid == tid) {
                /* Found */
                mutex_unlock(&thread_data_lock);
                return p;
            }
            p = p->next;
        }
    }
    mutex_unlock(&thread_data_lock);
    return NULL;
}

int
os_thread_sys_init()
{
    if (is_thread_sys_inited)
        return BHT_OK;

    mutex_init(&thread_data_lock);

    is_thread_sys_inited = true;
    return BHT_OK;
}

void
os_thread_sys_destroy()
{
    if (is_thread_sys_inited) {
        is_thread_sys_inited = false;
    }
}

static os_thread_data *
thread_data_current()
{
    kernel_pid_t tid = thread_getpid();
    return thread_data_list_lookup(tid);
}

static void
os_thread_cleanup(void)
{
    // TODO Check this (Join sema trigger, cleanup of thread_data)
    os_thread_data *thread_data = thread_data_current();
    bh_assert(thread_data != NULL);
    mutex_lock(&thread_data->wait_list_lock);
    if (thread_data->thread_wait_list) {
        /* Signal each joining thread */
        os_thread_wait_list head = thread_data->thread_wait_list;
        while (head) {
            os_thread_wait_list next = head->next;
            head->ret = thread_data->arg;
            sema_post(&head->sem);
            head = next;
        }
        thread_data->thread_wait_list = NULL;
    }
    mutex_unlock(&thread_data->wait_list_lock);

    thread_data_list_remove(thread_data);
}

static void *
os_thread_wrapper(void *thread_data)
{
    /* Set thread custom data */
    os_thread_data *t = (os_thread_data *)thread_data;
    t->tid = thread_getpid();
    thread_data_list_add(t);

    // save the return value to arg since it is not need after the call
    t->arg = (t->start_routine)(t->arg);

    os_thread_cleanup(); // internal structures and joiners

    BH_FREE(thread_data);
    sched_task_exit(); // stop thread //clean
    return NULL;       // never reached
}

int
os_thread_create(korp_tid *p_tid, thread_start_routine_t start, void *arg,
                 unsigned int stack_size)
{
    return os_thread_create_with_prio(p_tid, start, arg, stack_size,
                                      BH_THREAD_DEFAULT_PRIORITY);
}

int
os_thread_create_with_prio(korp_tid *p_tid, thread_start_routine_t start,
                           void *arg, unsigned int stack_size, int prio)
{
    kernel_pid_t tid;
    os_thread_data *thread_data;
    unsigned thread_data_size;

    if (!p_tid || !stack_size)
        return BHT_ERROR;

    /* Create and initialize thread data */
    thread_data_size = offsetof(os_thread_data, stack) + stack_size;
    if (!(thread_data = BH_MALLOC(thread_data_size))) {
        return BHT_ERROR;
    }

    memset(thread_data, 0, thread_data_size);
    mutex_init(&thread_data->wait_list_lock);
    thread_data->stack_size = stack_size;
    thread_data->start_routine = start;
    thread_data->arg = arg;

    /* Create the thread &*/
    if (!((tid = thread_create(thread_data->stack, stack_size, prio, 0,
                               os_thread_wrapper, thread_data, "WASM")))) {
        BH_FREE(thread_data);
        return BHT_ERROR;
    }

    thread_data->tid = tid;

    /* Set thread custom data */
    thread_data_list_add(thread_data);
    *p_tid = tid;
    return BHT_OK;
}

korp_tid
os_self_thread()
{
    return (korp_tid)thread_getpid();
}

int
os_thread_join(korp_tid thread, void **value_ptr)
{
    // will test if thread is still working,
    // wait if it is
    os_thread_data *thread_data;
    os_thread_wait_node node;

    sema_create(&node.sem, 0);
    node.next = NULL;

    /* Get thread data */
    thread_data = thread_data_list_lookup(thread);
    if (thread_data == NULL) {
        // thread not found
        sema_destroy(&node.sem);
        return BHT_ERROR;
    }
    bh_assert(thread_data != NULL);

    mutex_lock(&thread_data->wait_list_lock);
    if (!thread_data->thread_wait_list)
        thread_data->thread_wait_list = &node;
    else {
        /* Add to end of waiting list */
        os_thread_wait_node *p = thread_data->thread_wait_list;
        while (p->next)
            p = p->next;
        p->next = &node;
    }
    mutex_unlock(&thread_data->wait_list_lock);

    sema_wait(&node.sem);
    // get the return value pointer conted may not be availible after return
    if (value_ptr)
        (*value_ptr) = node.ret;
    /* Wait some time for the thread to be actually terminated */
    //  TODO:   k_sleep(100);

    // TODO: bump target prio to make it finish and free its resources
    thread_yield();

    // node has done its job
    sema_destroy(&node.sem);

    return BHT_OK;
}

// int vm_mutex_trylock(korp_mutex *mutex)
// {
//     return mutex_trylock(mutex);
// }

int
os_mutex_init(korp_mutex *mutex)
{
    mutex_init(mutex);
    return BHT_OK;
}

int
os_mutex_destroy(korp_mutex *mutex)
{
    (void)mutex;
    return BHT_OK;
}

int
os_mutex_lock(korp_mutex *mutex)
{
    mutex_lock(mutex);
    return 0; // Riot mutexes do not return until success
}

int
os_mutex_unlock(korp_mutex *mutex)
{
    mutex_unlock(mutex);
    return 0; // Riot mutexes do not return until success
}

int
os_cond_init(korp_cond *cond)
{
    mutex_init(&cond->wait_list_lock);
    cond->thread_wait_list = NULL;
    return BHT_OK;
}

int
os_cond_destroy(korp_cond *cond)
{
    (void)cond;
    return BHT_OK;
}

static int
os_cond_wait_internal(korp_cond *cond, korp_mutex *mutex, bool timed,
                      uint64 useconds)
{
    os_thread_wait_node *node;

    /* Create wait node and append it to wait list */
    if (!(node = BH_MALLOC(sizeof(os_thread_wait_node))))
        return BHT_ERROR;

    sema_create(&node->sem, 0);
    node->next = NULL;

    mutex_lock(&cond->wait_list_lock);
    if (!cond->thread_wait_list)
        cond->thread_wait_list = node;
    else {
        /* Add to end of wait list */
        os_thread_wait_node *p = cond->thread_wait_list;
        while (p->next)
            p = p->next;
        p->next = node;
    }
    mutex_unlock(&cond->wait_list_lock);

    /* Unlock mutex, wait sem and lock mutex again */
    mutex_unlock(mutex);
    if (timed)
        sema_wait(&node->sem);
    else
        sema_wait_timed_ztimer(&node->sem, ZTIMER_USEC, useconds);
    mutex_lock(mutex);

    /* Remove wait node from wait list */
    mutex_lock(&cond->wait_list_lock);
    if (cond->thread_wait_list == node)
        cond->thread_wait_list = node->next;
    else {
        /* Remove from the wait list */
        os_thread_wait_node *p = cond->thread_wait_list;
        while (p->next != node)
            p = p->next;
        p->next = node->next;
    }
    BH_FREE(node);
    mutex_unlock(&cond->wait_list_lock);

    return BHT_OK;
}

int
os_cond_wait(korp_cond *cond, korp_mutex *mutex)
{
    return os_cond_wait_internal(cond, mutex, false, 0);
}

int
os_cond_reltimedwait(korp_cond *cond, korp_mutex *mutex, uint64 useconds)
{
    return os_cond_wait_internal(cond, mutex, (useconds != BHT_WAIT_FOREVER),
                                 useconds);
}

int
os_cond_signal(korp_cond *cond)
{
    /* Signal the head wait node of wait list */
    mutex_lock(&cond->wait_list_lock);
    if (cond->thread_wait_list)
        sema_post(&cond->thread_wait_list->sem);
    mutex_unlock(&cond->wait_list_lock);

    return BHT_OK;
}

uint8 *
os_thread_get_stack_boundary()
{
#if defined(DEVELHELP) || defined(SCHED_TEST_STACK) \
    || defined(MODULE_MPU_STACK_GUARD)
    return (uint8 *)thread_get_active()->stack_start;
#else
    return NULL;
#endif
}