package drivers

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
)

type SysDriver struct{}

func NewSysDriver() *SysDriver {
	return &SysDriver{}
}

func (r *SysDriver) ReadClockSensors() ([]ClockSensor, error) {
	// Glob directly targets scaling_cur_freq for all numerical CPU core paths
	freqFiles, err := filepath.Glob("/sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_cur_freq")
	if err != nil {
		return nil, fmt.Errorf("failed to glob cpufreq files: %w", err)
	}

	clockSensors := []ClockSensor{}

	for _, path := range freqFiles {
		// Example path: /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
		// Extract core ID from path segments
		parts := strings.Split(path, "/")
		if len(parts) < 6 {
			continue
		}

		// Parse "cpu0" -> 0
		cpuDir := parts[5]
		coreIDStr := strings.TrimPrefix(cpuDir, "cpu")
		coreID, err := strconv.Atoi(coreIDStr)
		if err != nil {
			continue
		}

		// Read frequency in kHz directly from the matched file path
		data, err := os.ReadFile(path)
		if err != nil {
			continue
		}

		khz, err := strconv.ParseFloat(strings.TrimSpace(string(data)), 64)
		if err != nil {
			continue
		}

		clockSensors = append(clockSensors, ClockSensor{
			path:         path,
			Name:         coreID,
			FrequencyGHz: khz / 1000000.0, // Convert KHz to GHz
		})
	}

	// Guarantee numerical order by core ID
	sort.Slice(clockSensors, func(i, j int) bool {
		return clockSensors[i].Name < clockSensors[j].Name
	})

	return clockSensors, nil
}