#include "metrics/Collector.h"

#include <sstream>
#include <fstream>
#include <filesystem>
#include <sys/statvfs.h>
#include <unistd.h>
#include <limits.h>
#include <cerrno>
#include <cstring>
#include <algorithm>

namespace metrics
{

    Collector::Collector(const std::vector<std::vector<std::string>> &disks) : disks(disks)
    {
        std::vector<int> cpuLogicalIds;
        for (const auto &cpuDir : std::filesystem::directory_iterator("/sys/devices/system/cpu"))
        {
            std::string name = cpuDir.path().filename().string();
            if (name.find("cpu") != 0)
                continue;
            std::string suffix = name.substr(3);
            if (!std::all_of(suffix.begin(), suffix.end(), ::isdigit))
                continue;
            cpuLogicalIds.push_back(std::stoi(suffix));
        }

        std::sort(cpuLogicalIds.begin(), cpuLogicalIds.end());

        // строим логическое → физическое
        logicalToPhysical.resize(cpuLogicalIds.size());
        for (size_t i = 0; i < cpuLogicalIds.size(); ++i)
        {
            int cpu = cpuLogicalIds[i];
            std::ifstream f("/sys/devices/system/cpu/cpu" + std::to_string(cpu) + "/topology/core_id");
            if (!f)
                throw std::runtime_error("Cannot read core_id for cpu" + std::to_string(cpu));
            int coreId;
            f >> coreId;
            logicalToPhysical[i] = coreId;
        }
    }

    Host Collector::collect()
    {
        Host host;

        auto curCpu = readCpuTimes();

        if (prevCpu.second.empty())
            prevCpu = curCpu;

        host.cpu.coreLoads.resize(curCpu.second.size());

        host.cpu.totalLoad = cpuLoad(prevCpu.first, curCpu.first);
        for (size_t i = 0; i < curCpu.second.size(); ++i)
            host.cpu.coreLoads[i] = cpuLoad(prevCpu.second[i], curCpu.second[i]);

        prevCpu = curCpu;

        host.cpu.coreTemps = readCpuCoreTemps();
        host.memory = readMemory();
        for (const std::vector<std::string> &disk : disks)
            host.disks.push_back(readDisk(disk));
        readLoad(host.load1, host.load5, host.load15);
        host.uptime = readUptime();
        host.hostname = readHostname();

        return host;
    }

    std::pair<Collector::CpuTimes, std::vector<Collector::CpuTimes>> Collector::readCpuTimes()
    {
        std::ifstream f("/proc/stat");
        std::pair<CpuTimes, std::vector<CpuTimes>> out;

        std::string line;
        while (std::getline(f, line))
        {
            if (!line.starts_with("cpu"))
                break;

            std::istringstream ss(line);
            std::string cpu;
            CpuTimes t;

            ss >> cpu >> t.user >> t.nice >> t.system >> t.idle >> t.iowait >> t.irq >> t.softirq >> t.steal;

            if (cpu == "cpu")
            {
                out.first = t;
            }
            else
            {
                out.second.push_back(t);
            }
        }

        return out;
    }

    std::vector<CpuTemperature> Collector::readCpuCoreTemps()
    {
        std::vector<CpuTemperature> physical;
        std::vector<CpuTemperature> logical(logicalToPhysical.size());

        for (const auto &hwmon : std::filesystem::directory_iterator("/sys/class/hwmon"))
        {
            std::string name;
            std::ifstream nameFile(hwmon.path() / "name");
            if (nameFile)
                std::getline(nameFile, name);

            // проверяем на CPU
            if (name != "coretemp" && name != "k10temp")
                continue;

            for (const auto &f : std::filesystem::directory_iterator(hwmon))
            {
                std::string fname = f.path().filename().string();
                if (fname.find("temp") != 0)
                    continue;

                // определяем, какой тип файла
                std::string suffix;
                if (fname.find("_input") != std::string::npos)
                    suffix = "_input";
                else if (fname.find("_max") != std::string::npos)
                    suffix = "_max";
                else
                    continue;

                int millideg = 0;
                std::ifstream tempFile(f.path());
                tempFile >> millideg;
                float value = millideg / 1000.0f;

                // находим индекс ядра в temps по tempN
                std::string numStr = fname.substr(4, fname.find('_') - 4);
                int n = std::stoi(numStr);

                // если _input — создаём новый объект
                if (suffix == "_input")
                {
                    if (n >= static_cast<int>(physical.size()))
                        physical.resize(n + 1);
                    physical[n].current = value;
                }
                else
                {
                    // _max/_crit: если temps[n] ещё нет, создаём объект
                    if (n >= static_cast<int>(physical.size()))
                        physical.resize(n + 1);
                    if (suffix == "_max")
                        physical[n].max = value;
                }
            }

            // Убираем пропуски: оставшиеся нули → копируем предыдущий или последующий?
            // Можно фильтровать нулевые ядра, если нужно
            physical.erase(std::remove_if(physical.begin(), physical.end(),
                                          [](const CpuTemperature &t)
                                          { return t.current == 0 && t.max == 0; }),
                           physical.end());

            for (size_t i = 0; i < logicalToPhysical.size(); ++i)
            {
                int phys = logicalToPhysical[i];
                if (phys >= static_cast<int>(physical.size()))
                    phys = physical.size() - 1; // safety
                logical[i] = physical[phys];
            }
        }

        return logical;
    }

    float Collector::cpuLoad(const Collector::CpuTimes &prev,
                             const Collector::CpuTimes &cur)
    {
        uint64_t prevIdle = prev.idle + prev.iowait;
        uint64_t curIdle = cur.idle + cur.iowait;

        uint64_t prevTotal =
            prev.user + prev.nice + prev.system +
            prevIdle + prev.irq + prev.softirq + prev.steal;

        uint64_t curTotal =
            cur.user + cur.nice + cur.system +
            curIdle + cur.irq + cur.softirq + cur.steal;

        uint64_t totalDiff = curTotal - prevTotal;
        uint64_t idleDiff = curIdle - prevIdle;

        if (totalDiff == 0)
            return 0.f;

        return 100.f * (totalDiff - idleDiff) / totalDiff;
    }

    Memory Collector::readMemory()
    {
        std::ifstream f("/proc/meminfo");
        std::string key;
        uint64_t value;
        std::string unit;

        uint64_t mem_total = 0, mem_available = 0, swap_total = 0, swap_available = 0;

        while (f >> key >> value >> unit)
        {
            if (key == "MemTotal:")
                mem_total = value * 1024;
            else if (key == "MemAvailable:")
                mem_available = value * 1024;
            else if (key == "SwapTotal:")
                swap_total = value * 1024;
            else if (key == "SwapFree:")
                swap_available = value * 1024;
        }

        Memory memory;
        memory.memory.total = mem_total;
        memory.memory.available = mem_available;
        memory.memory.used = mem_total - mem_available;
        memory.swap.total = swap_total;
        memory.swap.available = swap_available;
        memory.swap.used = swap_total - swap_available;
        return memory;
    }

    Disk Collector::readDisk(const std::vector<std::string> &disk)
    {
        struct statvfs vfs;
        if (statvfs(disk.at(1).c_str(), &vfs) != 0)
        {
            throw std::runtime_error(
                std::string("statvfs failed for ") + disk.at(1).c_str() + ": " +
                std::strerror(errno));
        }

        uint64_t total = static_cast<uint64_t>(vfs.f_blocks) * vfs.f_frsize;
        uint64_t available = static_cast<uint64_t>(vfs.f_bavail) * vfs.f_frsize;
        uint64_t used = total - available;

        Disk d;
        d.name = disk.at(0);
        d.path = disk.at(1);
        d.metrics.total = total;
        d.metrics.available = available;
        d.metrics.used = used;
        return d;
    }

    void Collector::readLoad(float &l1, float &l5, float &l15)
    {
        std::ifstream f("/proc/loadavg");
        f >> l1 >> l5 >> l15;
    }

    uint64_t Collector::readUptime()
    {
        std::ifstream f("/proc/uptime");
        double up;
        f >> up;
        return static_cast<uint64_t>(up);
    }

    std::string Collector::readHostname()
    {
        char buf[HOST_NAME_MAX + 1] = {};
        if (gethostname(buf, sizeof(buf)) == 0)
            return std::string(buf);

        return "Unknown";
    }

}