#include "gpu.h"
#include "common/io.h"
#include "common/strutil.h"

#include <fcntl.h>

static double parseTZDir(int dfd, FFstrbuf* buffer) {
    if (!ffReadFileBufferRelative(dfd, "type", buffer) || !ffStrbufStartsWithS(buffer, "gpu")) {
        return FF_GPU_TEMP_UNSET;
    }

    if (!ffReadFileBufferRelative(dfd, "temp", buffer)) {
        return FF_GPU_TEMP_UNSET;
    }

    double value = ffStrbufToDouble(buffer, FF_GPU_TEMP_UNSET); // millidegree Celsius
    if (value == FF_GPU_TEMP_UNSET) {
        return FF_GPU_TEMP_UNSET;
    }

    return value / 1000.;
}

double ffGPUDetectTempFromTZ(void) {
    FF_AUTO_CLOSE_DIR DIR* dirp = opendir("/sys/class/thermal/");
    if (dirp) {
        FF_STRBUF_AUTO_DESTROY buffer = ffStrbufCreate();
        int dfd = dirfd(dirp);
        struct dirent* entry;
        while ((entry = readdir(dirp)) != nullptr) {
            if (entry->d_name[0] == '.') {
                continue;
            }
            if (!ffStrStartsWith(entry->d_name, "thermal_zone")) {
                continue;
            }

            FF_AUTO_CLOSE_FD int subfd = openat(dfd, entry->d_name, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
            if (subfd < 0) {
                continue;
            }

            double result = parseTZDir(subfd, &buffer);
            if (result != FF_GPU_TEMP_UNSET) {
                return result;
            }
        }
    }
    return FF_GPU_TEMP_UNSET;
}

const char* ffDetectGPUImpl(const FFGPUOptions* options, FFlist* gpus) {
    FF_UNUSED(options, gpus);
    return "No permission. Fallbacks to Vulkan, OpenCL or OpenGL instead";
}
