#include <string.h>

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "cJSON.h"
#include "driver/gpio.h"
#include "esp_system.h"
#include "esp_log.h"
#include "esp_http_client.h"
#include "esp_https_ota.h"

#include "wifi_functions.h"

#define FIRMWARE_VERSION	0.1
#define UPDATE_JSON_URL		"https://esp32.sk/firmware.json"
#define BLINK_GPIO 			GPIO_NUM_13

// server certificates
extern const char server_cert_pem_start[] asm("_binary_certs_pem_start");
extern const char server_cert_pem_end[] asm("_binary_certs_pem_end");

// receive buffer
char rcv_buffer[200];

// esp_http_client event handler
esp_err_t _http_event_handler(esp_http_client_event_t *evt) {
    
	switch(evt->event_id) {
        case HTTP_EVENT_ERROR:
            break;
        case HTTP_EVENT_ON_CONNECTED:
            break;
        case HTTP_EVENT_HEADER_SENT:
            break;
        case HTTP_EVENT_ON_HEADER:
            break;
        case HTTP_EVENT_ON_DATA:
            if (!esp_http_client_is_chunked_response(evt->client)) {
				strncpy(rcv_buffer, (char*)evt->data, evt->data_len);
            }
            break;
        case HTTP_EVENT_ON_FINISH:
            break;
        case HTTP_EVENT_DISCONNECTED:
            break;
    }
    return ESP_OK;
}

// Blink task
void blink_task(void *pvParameter) {
	
    gpio_pad_select_gpio(BLINK_GPIO);
    gpio_set_direction(BLINK_GPIO, GPIO_MODE_OUTPUT);
    while(1) {
        gpio_set_level(BLINK_GPIO, 0);
        vTaskDelay(1000 / portTICK_PERIOD_MS);
        gpio_set_level(BLINK_GPIO, 1);
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}


// Check update task
// downloads every 30sec the json file with the latest firmware
void check_update_task(void *pvParameter) {
	
	while(1) {
        
		printf("Looking for a new firmware...\n");
	
		// configure the esp_http_client
		esp_http_client_config_t config = {
        .url = UPDATE_JSON_URL,
        .event_handler = _http_event_handler,
		};
		esp_http_client_handle_t client = esp_http_client_init(&config);
	
		// downloading the json file
		esp_err_t err = esp_http_client_perform(client);
		if(err == ESP_OK) {
			
			// parse the json file	
			cJSON *json = cJSON_Parse(rcv_buffer);
			if(json == NULL) printf("downloaded file is not a valid json, aborting...\n");
			else {	
				cJSON *version = cJSON_GetObjectItemCaseSensitive(json, "version");
				cJSON *file = cJSON_GetObjectItemCaseSensitive(json, "file");
				
				// check the version
				if(!cJSON_IsNumber(version)) printf("unable to read new version, aborting...\n");
				else {
					
					double new_version = version->valuedouble;
					if(new_version > FIRMWARE_VERSION) {
						
						printf("current firmware version (%.1f) is lower than the available one (%.1f), upgrading...\n", FIRMWARE_VERSION, new_version);
						if(cJSON_IsString(file) && (file->valuestring != NULL)) {
							printf("downloading and installing new firmware (%s)...\n", file->valuestring);
							
							esp_http_client_config_t ota_client_config = {
								.url = file->valuestring,
								.cert_pem = server_cert_pem_start,
							};
							esp_err_t ret = esp_https_ota(&ota_client_config);
							if (ret == ESP_OK) {
								printf("OTA OK, restarting...\n");
								esp_restart();
							} else {
								printf("OTA failed...\n");
							}
						}
						else printf("unable to read the new file name, aborting...\n");
					}
					else printf("current firmware version (%.1f) is greater or equal to the available one (%.1f), nothing to do...\n", FIRMWARE_VERSION, new_version);
				}
			}
		}
		else printf("unable to download the json file, aborting...\n");
		
		// cleanup
		esp_http_client_cleanup(client);
		
		printf("\n");
        vTaskDelay(30000 / portTICK_PERIOD_MS);
    }
}

void app_main() {
	
	printf("HTTPS OTA, firmware %.1f\n\n", FIRMWARE_VERSION);
	
	// start the blink task
	xTaskCreate(&blink_task, "blink_task", configMINIMAL_STACK_SIZE, NULL, 5, NULL);
	
	// connect to the wifi network
	wifi_initialise();
	wifi_wait_connected();
	printf("Connected to wifi network\n");
	
	// start the check update task
	xTaskCreate(&check_update_task, "check_update_task", 8192, NULL, 5, NULL);
}