package app

import (
	"fmt"
	"strings"
	"time"
)

type transportNetnsToggleClientPlan struct {
	Item           TransportNetnsToggleItem
	NeedsProvision bool
	NeedsRestart   bool
}

func prepareTransportNetnsToggleClientLocked(
	it TransportClient,
	ifaces transportInterfacesState,
	targetEnabled bool,
	now time.Time,
) (TransportNetnsToggleItem, TransportClient) {
	item := TransportNetnsToggleItem{
		OK:           true,
		ClientID:     it.ID,
		Kind:         it.Kind,
		StatusBefore: it.Status,
		StatusAfter:  it.Status,
		NetnsEnabled: targetEnabled,
	}
	if it.Kind != TransportClientSingBox {
		item.OK = false
		item.Code = "TRANSPORT_NETNS_KIND_UNSUPPORTED"
		item.Message = "netns toggle is supported only for singbox clients"
		return item, it
	}

	cfg := cloneMap(it.Config)
	if cfg == nil {
		cfg = map[string]any{}
	}
	changed := false
	prevEnabled := transportConfigBool(cfg, "netns_enabled")
	if prevEnabled != targetEnabled {
		changed = true
	}
	cfg["netns_enabled"] = targetEnabled
	if targetEnabled && strings.TrimSpace(transportConfigString(cfg, "netns_name")) == "" {
		probe := it
		probe.Config = cfg
		binding := resolveTransportIfaceBinding(probe, ifaces)
		if strings.TrimSpace(binding.NetnsName) != "" {
			cfg["netns_name"] = binding.NetnsName
			changed = true
		}
	}
	item.ConfigUpdated = changed
	if changed {
		it.Config = cfg
		it.UpdatedAt = now.Format(time.RFC3339)
	}
	if rebound, reboundChanged := applyTransportIfaceBinding(it, ifaces, now); reboundChanged {
		it = rebound
		item.ConfigUpdated = true
	}
	return item, it
}

func applyTransportNetnsToggleClientPlanLocked(plan transportNetnsToggleClientPlan) TransportNetnsToggleItem {
	item := plan.Item
	if !item.OK {
		return item
	}

	if plan.NeedsProvision {
		_, provisionResp := executeTransportClientProvisionActionLocked(item.ClientID)
		mergeTransportNetnsToggleProvisionResponse(&item, provisionResp)
		if !item.OK {
			return item
		}
	}

	if plan.NeedsRestart {
		_, restartResp := executeTransportLifecycleActionWithPreflightLocked(item.ClientID, "restart")
		mergeTransportNetnsToggleRestartResponse(&item, restartResp)
	}
	if strings.TrimSpace(item.Message) == "" {
		item.Message = fmt.Sprintf("netns=%t", item.NetnsEnabled)
	}
	return item
}

func mergeTransportNetnsToggleProvisionResponse(item *TransportNetnsToggleItem, resp TransportClientLifecycleResponse) {
	if item == nil {
		return
	}
	item.Provisioned = resp.OK
	item.Stdout = joinNonEmptyLines(item.Stdout, resp.Stdout)
	item.Stderr = joinNonEmptyLines(item.Stderr, resp.Stderr)
	item.StatusAfter = resp.StatusAfter
	if resp.OK {
		return
	}
	item.OK = false
	item.Code = strings.TrimSpace(resp.Code)
	item.Message = strings.TrimSpace(resp.Message)
	if item.Message == "" {
		item.Message = "provision failed"
	}
}

func mergeTransportNetnsToggleRestartResponse(item *TransportNetnsToggleItem, resp TransportClientLifecycleResponse) {
	if item == nil {
		return
	}
	item.Restarted = resp.OK
	item.Stdout = joinNonEmptyLines(item.Stdout, resp.Stdout)
	item.Stderr = joinNonEmptyLines(item.Stderr, resp.Stderr)
	item.StatusAfter = resp.StatusAfter
	if resp.OK {
		msg := strings.TrimSpace(resp.Message)
		if msg == "" {
			msg = "restart done"
		}
		item.Message = msg
		return
	}
	item.OK = false
	item.Code = strings.TrimSpace(resp.Code)
	item.Message = strings.TrimSpace(resp.Message)
	if item.Message == "" {
		item.Message = "restart failed"
	}
}

func markTransportNetnsTogglePlansSaveFailed(
	plans []transportNetnsToggleClientPlan,
	msg string,
) []TransportNetnsToggleItem {
	items := make([]TransportNetnsToggleItem, 0, len(plans))
	for _, plan := range plans {
		item := plan.Item
		if item.OK {
			item.OK = false
			item.Code = "TRANSPORT_CLIENT_SAVE_FAILED"
			item.Message = msg
			item.Provisioned = false
			item.Restarted = false
		}
		items = append(items, item)
	}
	return items
}

func refreshTransportNetnsToggleFinalStatuses(resp *TransportNetnsToggleResponse) {
	if resp == nil || len(resp.Items) == 0 {
		return
	}
	transportMu.Lock()
	st := loadTransportClientsState()
	transportMu.Unlock()
	for i := range resp.Items {
		idx := findTransportClientIndex(st.Items, resp.Items[i].ClientID)
		if idx < 0 {
			continue
		}
		resp.Items[i].StatusAfter = st.Items[idx].Status
		resp.Items[i].NetnsEnabled = transportNetnsEnabled(st.Items[idx])
	}
}

func finalizeTransportNetnsToggleResponse(resp TransportNetnsToggleResponse) TransportNetnsToggleResponse {
	resp.Count = len(resp.Items)
	for _, item := range resp.Items {
		if item.OK {
			resp.SuccessCount++
		} else {
			resp.FailureCount++
		}
	}
	if resp.Count == 0 {
		resp.OK = false
		resp.Code = "TRANSPORT_NETNS_NO_TARGETS"
		resp.Message = "no singbox clients found"
		return resp
	}
	if resp.FailureCount > 0 {
		resp.OK = false
	}
	if !resp.OK && resp.Code == "" {
		resp.Code = "TRANSPORT_NETNS_TOGGLE_PARTIAL_FAILED"
	}
	resp.Message = fmt.Sprintf(
		"netns=%t applied: success=%d failed=%d",
		resp.Enabled,
		resp.SuccessCount,
		resp.FailureCount,
	)
	return resp
}