/*
 * SPDX-FileCopyrightText: 2022 Helmut Pozimski <helmut@pozimski.eu>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 */
 
#include <string.h>

#include <esp_http_server.h>
#include <esp_event.h>
#include <esp_log.h>
#include <esp_err.h>
#include <cJSON.h>
 
#include "storage.h"

#define TAG "api"
#define BUF_LEN 1000

static TaskHandle_t* alarm_task_handle = NULL;

static char* extract_wakeup(const char* uri) {
	return strrchr(uri, '/') +1;
}

static uint8_t contains_weekday(char* param) {
	uint8_t result = 0;
	for (int i = 1; i<=NUM_WEEK_DAYS; i++) {
		if (strcmp(WEEK_DAYS[i], param) == 0) {
			result = 1;
			break;		
		}
	}
	return result;
}

static uint8_t day_is_valid(char* day) {
	return strlen(day) == 8 || contains_weekday(day);
}

static esp_err_t wakeup_get_handler(httpd_req_t *req) {
	httpd_resp_set_hdr(req, "Access-Control-Allow-Origin", "*");
	char* wakeup_str = extract_wakeup(req->uri);
	
	if (!day_is_valid(wakeup_str)) {
		httpd_resp_send_err(req, HTTPD_400_BAD_REQUEST, "Invalid day requested");
		return ESP_OK;	
	}
	
	int16_t wakeup_minutes;
	esp_err_t ret = read_wakeup_time_str(wakeup_str, &wakeup_minutes);
	
	if (ret == ESP_OK) {
		httpd_resp_set_type(req, "application/json");
		cJSON *root = cJSON_CreateObject();
		if (wakeup_minutes >= 0) {
			cJSON_AddNumberToObject(root, "hour", wakeup_minutes / 60);
			cJSON_AddNumberToObject(root, "minute", wakeup_minutes % 60);
		}
		const char *response = cJSON_Print(root);
		httpd_resp_sendstr(req, response);
	} else if (ret == ESP_ERR_NVS_NOT_FOUND) {
		httpd_resp_send_err(req, HTTPD_404_NOT_FOUND, "Requested entry not found");
	} else {
		httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "Request could not be processed");
	}
	
	return ESP_OK;
}

static const httpd_uri_t wakeup_get = {
    .uri       = "/v1/wakeup/*",
    .method    = HTTP_GET,
    .handler   = wakeup_get_handler
};

static uint8_t validate_time(int hour, int minute) {
	return (hour >= 0 && hour < 24) && (minute >= 0 && minute < 60);
}

static void notify_alarm_task() {
	if (alarm_task_handle != NULL) {
		xTaskNotify(*alarm_task_handle, 0, eNoAction);	
	}
}

static esp_err_t wakeup_put_handler(httpd_req_t *req) {
	httpd_resp_set_hdr(req, "Access-Control-Allow-Origin", "*");
	char* wakeup_str = extract_wakeup(req->uri);
	char buf[BUF_LEN];
	if (!day_is_valid(wakeup_str)) {
		httpd_resp_send_err(req, HTTPD_400_BAD_REQUEST, "Invalid day requested");
		return ESP_OK;	
	}
	
	if (req->content_len >= BUF_LEN) {
		httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "Maximum content length exceeded");
		return ESP_OK;	
	}
	
	int bytes_received = httpd_req_recv(req, buf, BUF_LEN);
	
	if (bytes_received == 0) {
		httpd_resp_send_err(req, HTTPD_400_BAD_REQUEST, "No content received");
		return ESP_OK;
	} else if (bytes_received < 0) {
		httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "Request could not be processed");
		return ESP_OK;
	}
	buf[req->content_len] = '\0';
	
	cJSON *root = cJSON_Parse(buf);
	if (root == NULL) {
		httpd_resp_send_err(req, HTTPD_400_BAD_REQUEST, "Could not parse object");
		return ESP_OK;
	}
	
	int16_t minute_of_day;
	
	if (cJSON_GetArraySize(root) == 0) {
		minute_of_day = -1;
	} else {
		int16_t hour = cJSON_GetObjectItem(root, "hour")->valueint;
		int16_t minute = cJSON_GetObjectItem(root, "minute")->valueint;
		if (validate_time(hour, minute)) {
			minute_of_day = hour * 60 + minute;
		} else {
			httpd_resp_send_err(req, HTTPD_400_BAD_REQUEST, "Time values outside allowed range");
			cJSON_Delete(root);
			return ESP_OK;
		}
	}

	esp_err_t ret = write_wakeup_time_str(wakeup_str, minute_of_day);
	if (ret == ESP_OK) {
		httpd_resp_sendstr(req, "");
		notify_alarm_task();
	} else {
		httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "Error while writing data");		
	}
	cJSON_Delete(root);
	return ESP_OK;
}

static const httpd_uri_t wakeup_put = {
    .uri       = "/v1/wakeup/*",
    .method    = HTTP_PUT,
    .handler   = wakeup_put_handler
};

static esp_err_t wakeup_delete_handler(httpd_req_t *req) {
	httpd_resp_set_hdr(req, "Access-Control-Allow-Origin", "*");
	char* wakeup_str = extract_wakeup(req->uri);
	if (!day_is_valid(wakeup_str)) {
		httpd_resp_send_err(req, HTTPD_400_BAD_REQUEST, "Invalid day requested");
		return ESP_OK;	
	}
	
	esp_err_t ret = delete_wakeup_time_str(wakeup_str);
	if (ret == ESP_OK) {
		httpd_resp_sendstr(req, "");
		return ret;
	} else if (ret == ESP_ERR_NVS_NOT_FOUND) {
		httpd_resp_send_err(req, HTTPD_404_NOT_FOUND, "Entry does not exist");
	}
	
	httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "Error while deleting data");
	return ESP_OK;
}

static const httpd_uri_t wakeup_delete = {
    .uri       = "/v1/wakeup/*",
    .method    = HTTP_DELETE,
    .handler   = wakeup_delete_handler
};

static esp_err_t wakeup_options_handler(httpd_req_t *req) {
	httpd_resp_set_hdr(req, "Access-Control-Allow-Origin", "*");
	httpd_resp_set_hdr(req, "Access-Control-Allow-Methods", "GET, PUT, DELETE, OPTIONS");
	httpd_resp_set_hdr(req, "Access-Control-Max-Age", "86400");
	httpd_resp_set_hdr(req, "Access-Control-Allow-Headers", "Content-Type");
	httpd_resp_sendstr(req, "");
	return ESP_OK;
}

static const httpd_uri_t wakeup_options = {
    .uri       = "/v1/wakeup/*",
    .method    = HTTP_OPTIONS,
    .handler   = wakeup_options_handler
};


httpd_handle_t start_webserver(TaskHandle_t* task_handle) {
   httpd_handle_t server;
   httpd_config_t config = HTTPD_DEFAULT_CONFIG();
   config.lru_purge_enable = true;
   config.uri_match_fn = httpd_uri_match_wildcard;
   if (task_handle != NULL) {
    	alarm_task_handle = task_handle;
 	}
    
    ESP_LOGI(TAG, "Starting server on port: '%d'", config.server_port);
    if (httpd_start(&server, &config) == ESP_OK) {
      ESP_LOGI(TAG, "Registering URI handlers");
      httpd_register_uri_handler(server, &wakeup_get);
     	httpd_register_uri_handler(server, &wakeup_put);
		httpd_register_uri_handler(server, &wakeup_delete);
		httpd_register_uri_handler(server, &wakeup_options);
      return server;
    }

    ESP_LOGI(TAG, "Error starting server!");
    return NULL;
}

esp_err_t stop_webserver(httpd_handle_t server) {
    return httpd_stop(server);
}

void disconnect_handler(void* arg, esp_event_base_t event_base,
                        int32_t event_id, void* event_data) {
    httpd_handle_t* server = (httpd_handle_t*) arg;
    if (*server) {
        ESP_LOGI(TAG, "Stopping webserver");
        if (stop_webserver(*server) == ESP_OK) {
            *server = NULL;
        } else {
            ESP_LOGE(TAG, "Failed to stop http server");
        }
    }
}

void connect_handler(void* arg, esp_event_base_t event_base,
                     int32_t event_id, void* event_data) {
    httpd_handle_t* server = (httpd_handle_t*) arg;
    if (*server == NULL) {
        ESP_LOGI(TAG, "Starting webserver");
        *server = start_webserver(NULL);
    }
}