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

#include "evga-card.h"
#include "icx3.h"

/* Search all i2c device files for ones are on a PCI device of a supported GPU,
   and respond with the correct iCX3 version information */
int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus, int i2c_bus)
{
	char i2c_devices_path[NAME_MAX];
	char device_path[NAME_MAX];
	char dev_file[NAME_MAX];
	char *pci_addr;

	FILE *test_fd;
	DIR *dir;
	struct dirent *ent;
	
	int num_gpus = 0;
	int current_i2c_bus = -1;
	unsigned short pci_vendor, pci_device, pci_subsystem_vendor, pci_subsystem_device = 0;
	
	/* Start looking for I2C adapters in /sys/bus/i2c/devices/ */
	strcpy(i2c_devices_path, "/sys/bus/i2c/devices/");
	dir = opendir(i2c_devices_path);
	
	/* make sure we can open the i2c device */
	if(dir == NULL)
		return -1;
	
	/* loop over all i2c devices */
	while((ent = readdir(dir)) != NULL)
	{
		/* Don't check any non-i2c devices */
		if(strncmp(ent->d_name, "i2c-", 4) != 0) 
			continue;
		
		/* Only probe the specific device given (if provided) */
		if (i2c_bus >= 0) {
			sscanf(ent->d_name, "i2c-%i", &current_i2c_bus);
			if (current_i2c_bus != i2c_bus)
				continue;
		}
		
		
		strcpy(device_path, i2c_devices_path);
		strcat(device_path, ent->d_name);
		
		/* Only check Nvidia devices */
		pci_addr = read_nvidia_pci_address(device_path);
		if (pci_addr == NULL)
			continue;
		
		/* Read the PCI info for the underlying device */
		pci_vendor           = read_pci_id(device_path, "/device/vendor");
		pci_device           = read_pci_id(device_path, "/device/device");
		pci_subsystem_vendor = read_pci_id(device_path, "/device/subsystem_vendor");
		pci_subsystem_device = read_pci_id(device_path, "/device/subsystem_device");
		
		/* See if it's a matching device for a supported EVGA card */
		for (int i = 0; i < (sizeof(evga_pci_ids) / sizeof(struct gpu_pci_info)); i++) {
			
			if (pci_vendor           == evga_pci_ids[i].vendor_id &&
			    pci_device           == evga_pci_ids[i].device_id &&
			    pci_subsystem_vendor == evga_pci_ids[i].subvendor_id && 
			    pci_subsystem_device == evga_pci_ids[i].subdevice_id) {
				
				/* Matched all PCI IDs, check for good firmware read */
				strcpy(dev_file, "/dev/");
				strcat(dev_file, ent->d_name);
				infos[num_gpus].i2c_dev_path = dev_file;
				if (icx3_init(&infos[num_gpus]) > 0) {
					/* Write our card info into the provided struct array */
					infos[num_gpus].card_name = evga_pci_ids[i].card_name;
					infos[num_gpus].pci_id = pci_addr;
					infos[num_gpus].pci_device_id = pci_device;
					infos[num_gpus].i2c_dev_path = calloc(strlen(dev_file) + 1, sizeof(char));
					strcpy(infos[num_gpus].i2c_dev_path, dev_file);
					num_gpus++;
					break;
				}
			}
		}
		
		if (num_gpus == max_gpus)
			break;
		
	}
	
	return num_gpus;
}

/* Read a 16-bit unsigned int from a pci id file */
unsigned short read_pci_id(char *device_path, char *field)
{
	char buf[16];
	char file_path[NAME_MAX];
	
	strcpy(file_path, device_path);
	strcat(file_path, field);
	
	FILE *fp = fopen(file_path, "r");
	
	if (fp == NULL)
		return 0;
		
	if (fgets(buf, sizeof(buf), fp) == NULL) {
		fclose(fp);
		return 0;
	}
	
	fclose(fp);
	
	return (unsigned short)strtoul(buf, NULL, 16);
}

char *read_nvidia_pci_address(char *device_path)
{
	char file_path[NAME_MAX];
	
	char *ret = calloc(16 + 1, sizeof(char)); /* assuming pci ids could look as large as 00000000:0C:00.0 */
	
	strcpy(file_path, device_path);
	strcat(file_path, "/name");
	
	FILE *fp = fopen(file_path, "r");
	
	if (fp == NULL) {
		free(ret);
		return NULL;
	}
	
	fscanf(fp, "NVIDIA i2c adapter %*u at %16s", ret);
	fclose(fp);
	
	if (strlen(ret) == 0) {
		free(ret);
		return NULL;
	}
	
	return ret;
}