package autotrack

import (
	"encoding/json"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
)

// Sample is one OS observation handed to the segmentation loop.
type Sample struct {
	Idle   int  // HID idle seconds
	Raw    *Ctx // foreground context; nil when no foreground app
	Locked bool // screen locked (hard, immediate away signal)
}

// parseHIDIdle extracts HIDIdleTime (nanoseconds) from `ioreg -c IOHIDSystem`
// output and returns whole seconds. 0 when absent or malformed.
func parseHIDIdle(out string) int {
	for _, line := range strings.Split(out, "\n") {
		if !strings.Contains(line, "HIDIdleTime") {
			continue
		}
		i := strings.LastIndex(line, "=")
		if i < 0 {
			continue
		}
		ns, err := strconv.ParseInt(strings.TrimSpace(line[i+1:]), 10, 64)
		if err != nil {
			continue
		}
		return int(ns / 1_000_000_000)
	}
	return 0
}

// parseLocked reports whether ioreg output shows the lock flag. The
// CGSSessionScreenIsLocked key is present only while the screen is locked.
func parseLocked(out string) bool {
	return strings.Contains(strings.ReplaceAll(out, " ", ""), `"CGSSessionScreenIsLocked"=Yes`)
}

// parseWinctx decodes the winctx helper's {"app","title"} JSON. Empty on error.
func parseWinctx(b []byte) (app, title string) {
	var v struct {
		App   string `json:"app"`
		Title string `json:"title"`
	}
	if err := json.Unmarshal(b, &v); err != nil {
		return "", ""
	}
	return v.App, v.Title
}

// HelperPath finds a bundled native helper (winctx, cal-events): first next
// to the symlink-resolved tt binary (make install symlinks ~/.local/bin/tt →
// <repo>/bin/tt, and the helpers build into <repo>/bin), then on $PATH.
// "" when not found — callers degrade gracefully.
func HelperPath(name string) string {
	if exe, err := os.Executable(); err == nil {
		if resolved, rerr := filepath.EvalSymlinks(exe); rerr == nil {
			p := filepath.Join(filepath.Dir(resolved), name)
			if st, serr := os.Stat(p); serr == nil && !st.IsDir() {
				return p
			}
		}
	}
	if p, err := exec.LookPath(name); err == nil {
		return p
	}
	return ""
}