package app

import (
	"net/http"
	"strings"
	"time"
)

func executeTransportLifecycleActionLocked(id, action string) (int, TransportClientLifecycleResponse) {
	now := time.Now().UTC()

	transportMu.Lock()
	st := loadTransportClientsState()
	idx := findTransportClientIndex(st.Items, id)
	if idx < 0 {
		transportMu.Unlock()
		return http.StatusNotFound, TransportClientLifecycleResponse{
			OK:      false,
			Message: "not found",
			Code:    "TRANSPORT_CLIENT_NOT_FOUND",
		}
	}
	it := st.Items[idx]
	prev := it.Status
	ifaces, err := syncTransportInterfacesWithClientsLocked(st.Items)
	if err != nil {
		transportMu.Unlock()
		return http.StatusOK, TransportClientLifecycleResponse{
			OK:           false,
			Message:      "interfaces sync failed: " + err.Error(),
			Code:         "TRANSPORT_INTERFACES_SAVE_FAILED",
			ClientID:     id,
			Kind:         it.Kind,
			Action:       action,
			StatusBefore: prev,
			StatusAfter:  it.Status,
			Health:       it.Health,
			Runtime:      transportRuntimeSnapshot(it, now),
		}
	}
	if bound, changed := applyTransportIfaceBinding(it, ifaces, now); changed {
		it = bound
	}
	peerStopPlans := []transportLifecyclePeerStopPlan(nil)
	if action == "start" || action == "restart" {
		peerStopPlans = planTransportSingBoxPeerStops(st.Items, idx, ifaces, now)
	}
	transportMu.Unlock()

	peerStopResults := []transportLifecyclePeerStopExecution(nil)
	peerStopSummary := transportBackendActionResult{OK: true, ExitCode: 0}
	if action == "start" || action == "restart" {
		peerStopResults = executeTransportLifecyclePeerStops(peerStopPlans)
		peerStopSummary = summarizeTransportLifecyclePeerStops(peerStopResults)
	}

	backend := selectTransportBackend(it)
	actionResult := transportBackendActionResult{
		OK:       true,
		ExitCode: 0,
	}
	if action == "start" || action == "restart" {
		if !peerStopSummary.OK {
			transportMu.Lock()
			st = loadTransportClientsState()
			idx = findTransportClientIndex(st.Items, id)
			if idx < 0 {
				transportMu.Unlock()
				return http.StatusNotFound, TransportClientLifecycleResponse{
					OK:      false,
					Message: "not found",
					Code:    "TRANSPORT_CLIENT_NOT_FOUND",
				}
			}
			it = st.Items[idx]
			ifaces, err = syncTransportInterfacesWithClientsLocked(st.Items)
			if err != nil {
				transportMu.Unlock()
				return http.StatusOK, TransportClientLifecycleResponse{
					OK:           false,
					Message:      "interfaces sync failed: " + err.Error(),
					Code:         "TRANSPORT_INTERFACES_SAVE_FAILED",
					ClientID:     id,
					Kind:         it.Kind,
					Action:       action,
					StatusBefore: prev,
					StatusAfter:  it.Status,
					Health:       it.Health,
					Runtime:      transportRuntimeSnapshot(it, now),
				}
			}
			if bound, changed := applyTransportIfaceBinding(it, ifaces, now); changed {
				it = bound
			}
			peerEvents := applyTransportLifecyclePeerStopExecutionsLocked(&st, ifaces, now, peerStopResults)
			if len(peerStopResults) > 0 {
				if err := saveTransportClientsState(st); err != nil {
					transportMu.Unlock()
					return http.StatusOK, TransportClientLifecycleResponse{
						OK:       false,
						Message:  "save failed: " + err.Error(),
						Code:     "TRANSPORT_CLIENT_SAVE_FAILED",
						ClientID: id,
						Kind:     it.Kind,
						Action:   action,
						ExitCode: peerStopSummary.ExitCode,
						Stdout:   peerStopSummary.Stdout,
						Stderr:   peerStopSummary.Stderr,
					}
				}
			}
			for _, peerEvent := range peerEvents {
				events.push("transport_client_state_changed", map[string]any{
					"id":   peerEvent.ClientID,
					"from": peerEvent.From,
					"to":   peerEvent.To,
				})
			}
			transportMu.Unlock()
			if len(peerEvents) > 0 {
				clientIDs := make([]string, 0, len(peerEvents))
				for _, peerEvent := range peerEvents {
					clientIDs = append(clientIDs, peerEvent.ClientID)
				}
				publishTransportRuntimeObservabilitySnapshotChanged(
					"transport_client_state_changed",
					clientIDs,
					nil,
				)
			}

			msg := strings.TrimSpace(peerStopSummary.Message)
			if msg == "" {
				msg = "failed to stop conflicting singbox peers"
			}
			return http.StatusOK, TransportClientLifecycleResponse{
				OK:           false,
				Message:      msg,
				Code:         peerStopSummary.Code,
				ExitCode:     peerStopSummary.ExitCode,
				Stdout:       peerStopSummary.Stdout,
				Stderr:       peerStopSummary.Stderr,
				ClientID:     id,
				Kind:         it.Kind,
				Action:       action,
				StatusBefore: prev,
				StatusAfter:  it.Status,
				Health:       it.Health,
				Runtime:      transportRuntimeSnapshot(it, now),
			}
		}
	}

	if peerStopSummary.OK {
		actionResult = backend.Action(it, action)
		actionResult.Stdout = joinNonEmptyLines(peerStopSummary.Stdout, actionResult.Stdout)
		actionResult.Stderr = joinNonEmptyLines(peerStopSummary.Stderr, actionResult.Stderr)
	}

	transportMu.Lock()
	st = loadTransportClientsState()
	idx = findTransportClientIndex(st.Items, id)
	if idx < 0 {
		transportMu.Unlock()
		return http.StatusNotFound, TransportClientLifecycleResponse{
			OK:      false,
			Message: "not found",
			Code:    "TRANSPORT_CLIENT_NOT_FOUND",
		}
	}
	it = st.Items[idx]
	ifaces, err = syncTransportInterfacesWithClientsLocked(st.Items)
	if err != nil {
		transportMu.Unlock()
		return http.StatusOK, TransportClientLifecycleResponse{
			OK:           false,
			Message:      "interfaces sync failed: " + err.Error(),
			Code:         "TRANSPORT_INTERFACES_SAVE_FAILED",
			ClientID:     id,
			Kind:         it.Kind,
			Action:       action,
			StatusBefore: prev,
			StatusAfter:  it.Status,
			Health:       it.Health,
			Runtime:      transportRuntimeSnapshot(it, now),
		}
	}
	if bound, changed := applyTransportIfaceBinding(it, ifaces, now); changed {
		it = bound
	}
	peerEvents := applyTransportLifecyclePeerStopExecutionsLocked(&st, ifaces, now, peerStopResults)
	if actionResult.OK {
		applyTransportLifecycleAction(&it, action, now)
		it.Runtime.Backend = backend.ID()
	} else {
		applyTransportLifecycleFailure(&it, action, now, backend.ID(), actionResult)
	}
	st.Items[idx] = it
	if err := saveTransportClientsState(st); err != nil {
		transportMu.Unlock()
		return http.StatusOK, TransportClientLifecycleResponse{
			OK:       false,
			Message:  "save failed: " + err.Error(),
			Code:     "TRANSPORT_CLIENT_SAVE_FAILED",
			ClientID: id,
			Kind:     it.Kind,
			Action:   action,
			ExitCode: actionResult.ExitCode,
			Stdout:   actionResult.Stdout,
			Stderr:   actionResult.Stderr,
		}
	}
	for _, peerEvent := range peerEvents {
		events.push("transport_client_state_changed", map[string]any{
			"id":   peerEvent.ClientID,
			"from": peerEvent.From,
			"to":   peerEvent.To,
		})
	}
	events.push("transport_client_state_changed", map[string]any{
		"id":   id,
		"from": prev,
		"to":   it.Status,
	})
	queueRefresh := actionResult.OK && (action == "start" || action == "restart")
	transportMu.Unlock()
	publishClientIDs := make([]string, 0, len(peerEvents)+1)
	publishClientIDs = append(publishClientIDs, id)
	for _, peerEvent := range peerEvents {
		publishClientIDs = append(publishClientIDs, peerEvent.ClientID)
	}
	publishTransportRuntimeObservabilitySnapshotChanged(
		"transport_client_state_changed",
		publishClientIDs,
		nil,
	)

	msg := strings.TrimSpace(actionResult.Message)
	if msg == "" {
		msg = action + " done"
	}
	resp := TransportClientLifecycleResponse{
		OK:           actionResult.OK,
		Message:      msg,
		Code:         actionResult.Code,
		ExitCode:     actionResult.ExitCode,
		Stdout:       actionResult.Stdout,
		Stderr:       actionResult.Stderr,
		ClientID:     id,
		Kind:         it.Kind,
		Action:       action,
		StatusBefore: prev,
		StatusAfter:  it.Status,
		Health:       it.Health,
		Runtime:      transportRuntimeSnapshot(it, now),
	}
	if queueRefresh {
		_, _ = egressIdentitySWR.queueRefresh([]string{"transport:" + id}, true)
	}
	if !actionResult.OK {
		return http.StatusOK, resp
	}
	return http.StatusOK, resp
}