package probes

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

// ThermalSample is one reading from /sys/class/hwmon. Kind is "temp",
// Key is the label (or chip-relative name) and Value is degrees C.
type ThermalSample struct {
	Kind  string
	Key   string
	Value float64
	Unit  string
}

// Thermals walks /sys/class/hwmon looking for temp*_input files. The
// kernel reports millidegrees C; we divide by 1000. Labels come from
// temp*_label (preferred) or a chip-relative fallback.
//
// This is also used by the thermal sidecar; it re-reads on each tick
// rather than holding open handles so hot-plugged sensors (e.g. a PCIe
// card enumerating late) get picked up.
func Thermals() []ThermalSample {
	root := "/sys/class/hwmon"
	chips, err := os.ReadDir(root)
	if err != nil {
		return nil
	}
	var out []ThermalSample
	for _, c := range chips {
		base := filepath.Join(root, c.Name())
		chipName := strings.TrimSpace(readFileStr(filepath.Join(base, "name")))
		files, err := os.ReadDir(base)
		if err != nil {
			continue
		}
		for _, f := range files {
			name := f.Name()
			if !strings.HasPrefix(name, "temp") || !strings.HasSuffix(name, "_input") {
				continue
			}
			idx := strings.TrimSuffix(strings.TrimPrefix(name, "temp"), "_input")
			label := strings.TrimSpace(readFileStr(filepath.Join(base, "temp"+idx+"_label")))
			if label == "" {
				label = chipName + "/temp" + idx
			}
			raw := strings.TrimSpace(readFileStr(filepath.Join(base, name)))
			milli, err := strconv.Atoi(raw)
			if err != nil {
				continue
			}
			out = append(out, ThermalSample{Kind: "temp", Key: label, Value: float64(milli) / 1000, Unit: "C"})
		}
	}
	return out
}

func readFileStr(p string) string {
	b, err := os.ReadFile(p)
	if err != nil {
		return ""
	}
	return string(b)
}