// Package tracker 是 tracker 模块：变更追踪（overlayfs）。
//
// 依赖 config + AgentWorkDir（后者由 Group 0 的 ensureDataDirs 产出）。
package tracker

import (
	"log"
	"time"

	"github.com/JianFeeeee/HomeAgent/internal/kernelboot"
	"github.com/JianFeeeee/HomeAgent/internal/kernelmod"
	"github.com/JianFeeeee/HomeAgent/internal/tracker"
)

// Module 提供变更追踪。
type Module struct{}

func (Module) Name() string       { return "tracker" }
func (Module) Requires() []string { return []string{kernelmod.FacConfig} }
func (Module) Provides() []string { return []string{kernelmod.FacTracker} }

func (Module) Init(ks *kernelboot.KernelState) error {
	trk := tracker.NewTracker(ks.Cfg.Daemon.DataDir, ks.AgentWorkDir,
		tracker.WithKeepChangesets(100),
		tracker.WithMaxChangesetAge(30*24*time.Hour),
	)
	if err := trk.Init(); err != nil {
		log.Printf("[homed] warning: tracker init: %v", err)
	} else if err := trk.Start(); err != nil {
		log.Printf("[homed] warning: tracker mount overlay: %v (non-fatal: no overlayfs support?)", err)
	} else {
		log.Printf("[homed] change tracker active at %s", trk.MergeDir())
	}
	ks.Tracker = trk
	return nil
}

func init() { kernelmod.Register(Module{}) }