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

package rootcheck

import (
	"context"
	"sync"
	"time"

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

const runTimeout = 30 * time.Second

// Manager schedules the expensive cross-view collection independently from
// polling. One bounded check may run at a time; completed alerts return to the
// Agent's existing cooldown, incident, and snapshot path on the next sweep.
type Manager struct {
	Config config.Config
	Now    func() time.Time
	Run    func(context.Context, model.State) []model.Alert

	mu      sync.Mutex
	lastRun time.Time
	running bool
	pending []model.Alert
}

func New(cfg config.Config) *Manager {
	manager := &Manager{Config: cfg, Now: time.Now}
	manager.Run = func(ctx context.Context, state model.State) []model.Alert {
		return Run(ctx, state, cfg.RootcheckPIDCap, cfg.RootcheckModuleAllow)
	}
	return manager
}

func (m *Manager) MaybeStart(now time.Time, state model.State) {
	if !m.Config.RootcheckEnabled {
		return
	}
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.running || (!m.lastRun.IsZero() && now.Sub(m.lastRun) < m.Config.RootcheckInterval) {
		return
	}
	// Record the start before launching the goroutine. This prevents a fast
	// polling loop from scheduling duplicates while collection is still running
	// or while a timed-out external command unwinds.
	m.running, m.lastRun = true, now
	go m.run(state)
}

func (m *Manager) run(state model.State) {
	// Rootcheck compares several host views and may invoke ps; its deadline
	// makes that diagnostic work bounded even on a degraded host.
	ctx, cancel := context.WithTimeout(context.Background(), runTimeout)
	defer cancel()
	alerts := m.Run(ctx, state)
	m.mu.Lock()
	m.pending = append(m.pending, alerts...)
	m.running = false
	m.mu.Unlock()
}

func (m *Manager) Drain() []model.Alert {
	m.mu.Lock()
	defer m.mu.Unlock()
	alerts := append([]model.Alert(nil), m.pending...)
	m.pending = nil
	return alerts
}