// Copyright 2016-2018 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <stdlib.h>
#include <ctype.h>
#include "sdkconfig.h"
#include "esp_types.h"
#include "esp_log.h"
#include "soc/rtc_periph.h"
#include "soc/syscon_periph.h"
#include "soc/rtc.h"
#include "soc/periph_defs.h"
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "freertos/timers.h"
#include "esp_intr_alloc.h"
#include "sys/lock.h"
#include "driver/rtc_cntl.h"

#ifndef NDEBUG
// Enable built-in checks in queue.h in debug builds
#define INVARIANTS
#endif
#include "sys/queue.h"

portMUX_TYPE rtc_spinlock = portMUX_INITIALIZER_UNLOCKED;

/*---------------------------------------------------------------
                        INTERRUPT HANDLER
---------------------------------------------------------------*/


typedef struct rtc_isr_handler_ {
    uint32_t mask;
    intr_handler_t handler;
    void* handler_arg;
    SLIST_ENTRY(rtc_isr_handler_) next;
} rtc_isr_handler_t;

static SLIST_HEAD(rtc_isr_handler_list_, rtc_isr_handler_) s_rtc_isr_handler_list =
        SLIST_HEAD_INITIALIZER(s_rtc_isr_handler_list);
portMUX_TYPE s_rtc_isr_handler_list_lock = portMUX_INITIALIZER_UNLOCKED;
static intr_handle_t s_rtc_isr_handle;

static void rtc_isr(void* arg)
{
    uint32_t status = REG_READ(RTC_CNTL_INT_ST_REG);
    rtc_isr_handler_t* it;
    portENTER_CRITICAL_ISR(&s_rtc_isr_handler_list_lock);
    SLIST_FOREACH(it, &s_rtc_isr_handler_list, next) {
        if (it->mask & status) {
            portEXIT_CRITICAL_ISR(&s_rtc_isr_handler_list_lock);
            (*it->handler)(it->handler_arg);
            portENTER_CRITICAL_ISR(&s_rtc_isr_handler_list_lock);
        }
    }
    portEXIT_CRITICAL_ISR(&s_rtc_isr_handler_list_lock);
    REG_WRITE(RTC_CNTL_INT_CLR_REG, status);
}

static esp_err_t rtc_isr_ensure_installed(void)
{
    esp_err_t err = ESP_OK;
    portENTER_CRITICAL(&s_rtc_isr_handler_list_lock);
    if (s_rtc_isr_handle) {
        goto out;
    }

    REG_WRITE(RTC_CNTL_INT_ENA_REG, 0);
    REG_WRITE(RTC_CNTL_INT_CLR_REG, UINT32_MAX);
    err = esp_intr_alloc(ETS_RTC_CORE_INTR_SOURCE, 0, &rtc_isr, NULL, &s_rtc_isr_handle);
    if (err != ESP_OK) {
        goto out;
    }

out:
    portEXIT_CRITICAL(&s_rtc_isr_handler_list_lock);
    return err;
}


esp_err_t rtc_isr_register(intr_handler_t handler, void* handler_arg, uint32_t rtc_intr_mask)
{
    esp_err_t err = rtc_isr_ensure_installed();
    if (err != ESP_OK) {
        return err;
    }

    rtc_isr_handler_t* item = malloc(sizeof(*item));
    if (item == NULL) {
        return ESP_ERR_NO_MEM;
    }
    item->handler = handler;
    item->handler_arg = handler_arg;
    item->mask = rtc_intr_mask;
    portENTER_CRITICAL(&s_rtc_isr_handler_list_lock);
    SLIST_INSERT_HEAD(&s_rtc_isr_handler_list, item, next);
    portEXIT_CRITICAL(&s_rtc_isr_handler_list_lock);
    return ESP_OK;
}

esp_err_t rtc_isr_deregister(intr_handler_t handler, void* handler_arg)
{
    rtc_isr_handler_t* it;
    rtc_isr_handler_t* prev = NULL;
    bool found = false;
    portENTER_CRITICAL(&s_rtc_isr_handler_list_lock);
    SLIST_FOREACH(it, &s_rtc_isr_handler_list, next) {
        if (it->handler == handler && it->handler_arg == handler_arg) {
            if (it == SLIST_FIRST(&s_rtc_isr_handler_list)) {
                SLIST_REMOVE_HEAD(&s_rtc_isr_handler_list, next);
            } else {
                SLIST_REMOVE_AFTER(prev, next);
            }
            found = true;
            free(it);
            break;
        }
        prev = it;
    }
    portEXIT_CRITICAL(&s_rtc_isr_handler_list_lock);
    return found ? ESP_OK : ESP_ERR_INVALID_STATE;
}