#include <os_mutex.h>
#include "os_critical.h"


void os_mutex_init(os_mutex_t* self){
    self->owner = 0;
    os_waitobject_init(&self->wait_obj);
}

void os_mutex_destroy(os_mutex_t* self){
    OS_ASSERT(self->owner==0);
}

os_err_t os_mutex_trylock(os_mutex_t* self){
    os_critical_enter();
    os_task_t* p_thread =  os_task_self();

    if(self->owner!=0){ // 已经被锁定了
        if(self->owner==p_thread){ // 是当前任务锁定的
            os_critical_leave();
            return OS_ERR_OK;
        }

        // 当前任务不是 owner，判断优先级是否反转
        if(os_priority_cmp(p_thread->curr_priority, self->owner->curr_priority)==OS_PRIORITY_CMP_HIGH){
            // 当前任务的优先级更高，优先级反转了，提升 owner 优先级
            self->owner->curr_priority = p_thread->curr_priority;
        }

        os_critical_leave();
        return OS_ERR_FAIL;
    }

    // 到这里说明没有owner
    self->owner = (os_task_t*)p_thread;
    os_critical_leave();
    return OS_ERR_OK;
}

os_err_t os_mutex_lock(os_mutex_t* self){

    while(os_mutex_trylock(self)!=OS_ERR_OK){
        os_task_yield();        // 未获得锁，主动让出
    }

    return OS_ERR_OK;
}

os_err_t os_mutex_timed_lock(os_mutex_t* self, os_tick_t ticks){
    if(os_mutex_trylock(self)!=OS_ERR_OK){
        os_critical_enter();
        os_task_t* p_task = os_task_self();
        os_critical_leave();
        return os_waitobject_timed_wait(&self->wait_obj, p_task, ticks);
    }
    return OS_ERR_OK;
}

void os_mutex_unlock(os_mutex_t* self){
    os_critical_enter();

    os_task_t* p_task = os_task_self();

    if(self->owner != p_task){
        // 只有 owner 才能 unlock
        os_critical_leave();
        os_task_yield();
        return;
    }

    if(self->owner->curr_priority!=self->owner->init_priority) {
        self->owner->curr_priority = self->owner->init_priority; /* 恢复优先级 */
    }
    self->owner = 0;

    os_critical_leave();

    os_waitobject_notify_all(&self->wait_obj);
}

void os_mutex_unlock_one(os_mutex_t* self){
    os_critical_enter();

    os_task_t* p_task = os_task_self();

    if(self->owner != p_task){
        // 只有 owner 才能 unlock
        os_critical_leave();
        os_task_yield();
        return;
    }

    if(self->owner->curr_priority!=self->owner->init_priority) {
        self->owner->curr_priority = self->owner->init_priority; /* 恢复优先级 */
    }
    self->owner = 0;

    // 将所有等待任务加入就绪表，等待当前任务用时完成后进行调度

    os_critical_leave();

    os_waitobject_notify_one(&self->wait_obj);
}