// SPDX-License-Identifier: GPL-3.0-or-later

// Package system captures one cached, injectable view of live host state.
package system

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

	"codeberg.org/anassaeneroi/enodia-sentinal/go-agent/internal/model"
)

// Capture reads process state once from procRoot. Transient per-process read
// failures degrade to empty fields, matching Python's fail-open Process view.
func Capture(procRoot string) (model.State, error) {
	if procRoot == "" {
		procRoot = "/proc"
	}
	entries, err := os.ReadDir(procRoot)
	if err != nil {
		return model.State{}, err
	}
	processes := make([]model.Process, 0, len(entries))
	for _, entry := range entries {
		pid, err := strconv.Atoi(entry.Name())
		if err != nil || !entry.IsDir() {
			continue
		}
		base := filepath.Join(procRoot, entry.Name())
		processes = append(processes, model.Process{
			PID:     pid,
			Comm:    strings.TrimSpace(readText(filepath.Join(base, "comm"))),
			Cmdline: strings.TrimSpace(strings.ReplaceAll(readText(filepath.Join(base, "cmdline")), "\x00", " ")),
			Exe:     readLink(filepath.Join(base, "exe")),
		})
	}
	sort.Slice(processes, func(i, j int) bool { return processes[i].PID < processes[j].PID })
	return model.State{Processes: processes}, nil
}

func readText(path string) string {
	raw, err := os.ReadFile(path)
	if err != nil {
		return ""
	}
	return string(raw)
}

func readLink(path string) string {
	target, err := os.Readlink(path)
	if err != nil {
		return ""
	}
	return target
}