#include <dirent.h>
#include <string.h>
#include <stdlib.h>

#include "board-sensors.h"

int find_board_sensors(struct hwmon_avail_sensor *board_sensors, int max_sensors)
{
	const char *hwmon_path = "/sys/class/hwmon/";
	char device_path[NAME_MAX];
	char sensor_path[NAME_MAX];
	
	char driver_name[256];
	
	FILE *file;
	DIR *dir;
	struct dirent *ent;
	
	int num_sensors = 0;
	
	/* Start looking for hwmon devices in /sys/class/hwmon/ */
	dir = opendir(hwmon_path);
	
	/* make sure we can open the device directory */
	if(dir == NULL)
		return 0;
	
	/* loop over all hwmon devices */
	while((ent = readdir(dir)) != NULL)
	{
		/* Ignore any non-hwmon dirs */
		if(strncmp(ent->d_name, "hwmon", 5) != 0) 
			continue;
		
		strcpy(device_path, hwmon_path);
		strcat(device_path, ent->d_name);
		
		/* Read in the name of the device */
		strcpy(sensor_path, device_path);
		strcat(sensor_path, "/name");
		
		file = fopen(sensor_path, "r");
		if (file == NULL)
			continue;
		
		if (fgets(driver_name, sizeof(driver_name), file) == NULL) {
			fclose(file);
			continue;
		}
		
		fclose(file);

		/* Driver names have a linebreak at the end so let's remove that for comparison*/
		driver_name[strlen(driver_name) - 1] = '\0';
		
		/* Loop through all supported sensors and see if any are present in this device */
		for (int i = 0; i < (sizeof(hwmon_sensor_info) / sizeof(struct hwmon_sensor)); i++) {
			if (strcmp(driver_name, hwmon_sensor_info[i].driver_name) == 0) {
				/* We matched the driver name, try to open the files */
				strcpy(sensor_path, device_path);
				strcat(sensor_path, "/");
				strcat(sensor_path, hwmon_sensor_info[i].sensor_file_name);
				strcat(sensor_path, "_input");
				
				file = fopen(sensor_path, "r");
				if (file != NULL) {
					fclose(file);
					/* Good open of the sensor file */
					board_sensors[num_sensors].file = calloc(NAME_MAX, sizeof(char));
					strcpy(board_sensors[num_sensors].file, sensor_path);
					board_sensors[num_sensors].sort_index = i;
					board_sensors[num_sensors].sensor_info = &hwmon_sensor_info[i];
					
					/* Read in the sensor name */
					board_sensors[num_sensors].sensor_name = calloc(MAX_SENSOR_NAME_LENGTH, sizeof(char));
					strcpy(sensor_path, device_path);
					strcat(sensor_path, "/");
					strcat(sensor_path, hwmon_sensor_info[i].sensor_file_name);
					strcat(sensor_path, "_label");
					
					file = fopen(sensor_path, "r");
					if (file != NULL)
						fgets(board_sensors[num_sensors].sensor_name, MAX_SENSOR_NAME_LENGTH, file);

					/* Sensor name seems to always have a trailing newline we don't want */
					size_t len_without_newline = strcspn(board_sensors[num_sensors].sensor_name, "\n");
					board_sensors[num_sensors].sensor_name[len_without_newline] = '\0';
					
					if (num_sensors == max_sensors)
						return num_sensors;
					num_sensors++;
				}
			}
		}
		
	}
	
	return num_sensors;
}

/* Returns 0 on a bad read or missing sensor, 1 on OK */
int get_sensor_reading(struct hwmon_avail_sensor *sensor, float *reading) {
	char buf[256] = {0};
	long int raw;
	FILE *file;
	
	file = fopen(sensor->file, "r");
	if (file == NULL)
		return 0;

	fgets(buf, 256, file);
	raw = strtol(buf, NULL, 10);
	
	fclose(file);
	
	*reading = (float)raw / sensor->sensor_info->divisor;

	if (*reading == sensor->sensor_info->bad_value)
		return 0;
	
	return 1;
}