#include "nvml_gpu.h"
#include <nvml.h>
#include <stdio.h>
#include <string.h>

// Thread-local error buffer
static __thread char last_error_buffer[256] = {0};

static void set_error(const char* msg) {
    strncpy(last_error_buffer, msg, sizeof(last_error_buffer) - 1);
    last_error_buffer[sizeof(last_error_buffer) - 1] = '\0';
}

int gpu_init(void) {
    nvmlReturn_t result = nvmlInit();
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }
    return 0;
}

void gpu_shutdown(void) {
    nvmlShutdown();
}

int gpu_get_count(void) {
    unsigned int count = 0;
    nvmlReturn_t result = nvmlDeviceGetCount(&count);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }
    return (int)count;
}

int gpu_get_info(uint32_t index, gpu_info_t* info) {
    if (!info) {
        set_error("null info pointer");
        return -1;
    }

    memset(info, 0, sizeof(gpu_info_t));
    info->index = index;

    nvmlDevice_t device;
    nvmlReturn_t result = nvmlDeviceGetHandleByIndex(index, &device);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    // Get name
    result = nvmlDeviceGetName(device, info->name, sizeof(info->name));
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    // Get UUID
    result = nvmlDeviceGetUUID(device, info->uuid, sizeof(info->uuid));
    if (result != NVML_SUCCESS) {
        // Non-critical, continue
        strcpy(info->uuid, "unknown");
    }

    // Get VBIOS version
    result = nvmlDeviceGetVbiosVersion(device, info->vbios_version, sizeof(info->vbios_version));
    if (result != NVML_SUCCESS) {
        strcpy(info->vbios_version, "unknown");
    }

    // Get utilization
    nvmlUtilization_t utilization;
    result = nvmlDeviceGetUtilizationRates(device, &utilization);
    if (result == NVML_SUCCESS) {
        info->utilization = utilization.gpu;
    }

    // Get memory info
    nvmlMemory_t memory;
    result = nvmlDeviceGetMemoryInfo(device, &memory);
    if (result == NVML_SUCCESS) {
        info->memory_used = memory.used;
        info->memory_total = memory.total;
    }

    // Get temperature
    result = nvmlDeviceGetTemperature(device, NVML_TEMPERATURE_GPU, &info->temperature);
    if (result != NVML_SUCCESS) {
        info->temperature = 0;  // Not available
    }

    // Get power draw
    unsigned int power_mw;
    result = nvmlDeviceGetPowerUsage(device, &power_mw);
    if (result == NVML_SUCCESS) {
        info->power_draw = power_mw;
    }

    // Get clocks
    unsigned int clock;
    result = nvmlDeviceGetClock(device, NVML_CLOCK_SM, NVML_CLOCK_ID_CURRENT, &clock);
    if (result == NVML_SUCCESS) {
        info->clock_sm = clock;
    }
    result = nvmlDeviceGetClock(device, NVML_CLOCK_MEM, NVML_CLOCK_ID_CURRENT, &clock);
    if (result == NVML_SUCCESS) {
        info->clock_memory = clock;
    }

    // Get PCIe info
    nvmlPciInfo_t pciInfo;
    result = nvmlDeviceGetPciInfo(device, &pciInfo);
    if (result == NVML_SUCCESS) {
        // PCIe generation and width require NVML 11.0+
        // For now, we leave them as 0
        info->pcie_gen = 0;
        info->pcie_width = 0;
    }

    return 0;
}

int gpu_get_utilization(uint32_t index, uint32_t* utilization) {
    if (!utilization) {
        set_error("null utilization pointer");
        return -1;
    }

    nvmlDevice_t device;
    nvmlReturn_t result = nvmlDeviceGetHandleByIndex(index, &device);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    nvmlUtilization_t util;
    result = nvmlDeviceGetUtilizationRates(device, &util);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    *utilization = util.gpu;
    return 0;
}

int gpu_get_memory(uint32_t index, uint64_t* used, uint64_t* total) {
    if (!used || !total) {
        set_error("null pointer");
        return -1;
    }

    nvmlDevice_t device;
    nvmlReturn_t result = nvmlDeviceGetHandleByIndex(index, &device);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    nvmlMemory_t memory;
    result = nvmlDeviceGetMemoryInfo(device, &memory);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    *used = memory.used;
    *total = memory.total;
    return 0;
}

int gpu_get_temperature(uint32_t index, uint32_t* temp) {
    if (!temp) {
        set_error("null temp pointer");
        return -1;
    }

    nvmlDevice_t device;
    nvmlReturn_t result = nvmlDeviceGetHandleByIndex(index, &device);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    unsigned int temperature;
    result = nvmlDeviceGetTemperature(device, NVML_TEMPERATURE_GPU, &temperature);
    if (result != NVML_SUCCESS) {
        set_error(nvmlErrorString(result));
        return -1;
    }

    *temp = temperature;
    return 0;
}

int gpu_is_available(void) {
    nvmlReturn_t result = nvmlInit();
    if (result == NVML_SUCCESS) {
        nvmlShutdown();
        return 1;
    }
    return 0;
}

const char* gpu_last_error(void) {
    return last_error_buffer;
}