package app

import (
	"strings"
	"time"
)

const (
	transportPolicyTargetAdGuardID      = "adguardvpn"
	transportPolicyTargetAdGuardIfaceID = transportDefaultIfaceID
	transportPolicyTargetAdGuardTable   = "agvpn"
)

var transportPolicyTargetAdGuardAllowedActions = []string{"start", "stop", "restart"}

func isTransportPolicyVirtualClientID(id string) bool {
	return sanitizeID(id) == transportPolicyTargetAdGuardID
}

func isTransportPolicyVirtualClient(client TransportClient) bool {
	if isTransportPolicyVirtualClientID(client.ID) {
		return true
	}
	return strings.EqualFold(strings.TrimSpace(string(client.Kind)), transportPolicyTargetAdGuardID)
}

func resolveTransportPolicyVirtualClient(id string) (TransportClient, bool) {
	if !isTransportPolicyVirtualClientID(id) {
		return TransportClient{}, false
	}
	return buildTransportPolicyAdGuardTarget()
}

func transportPolicyPersistableClients(items []TransportClient) []TransportClient {
	if len(items) == 0 {
		return nil
	}
	out := make([]TransportClient, 0, len(items))
	for _, it := range items {
		if isTransportPolicyVirtualClient(it) {
			continue
		}
		out = append(out, it)
	}
	return out
}

func transportPolicyClientsWithVirtualTargets(base []TransportClient) []TransportClient {
	out := append([]TransportClient(nil), base...)
	for i := range out {
		out[i].ID = sanitizeID(out[i].ID)
	}
	if adg, ok := buildTransportPolicyAdGuardTarget(); ok {
		if idx := findTransportClientIndex(out, adg.ID); idx >= 0 {
			out[idx] = adg
		} else {
			out = append(out, adg)
		}
	}
	return out
}

func buildTransportPolicyAdGuardTarget() (TransportClient, bool) {
	now := time.Now().UTC()

	stdout, _, _, err := runCommandTimeout(1500*time.Millisecond, "systemctl", "is-active", adgvpnUnit)
	unitState := strings.TrimSpace(stdout)
	if err != nil && unitState == "" {
		return TransportClient{}, false
	}

	word, raw := parseAutoloopStatus(tailFile(autoloopLogPath, 120))
	return buildTransportPolicyAdGuardTargetFromObservation(unitState, word, raw, now), true
}

func buildTransportPolicyAdGuardTargetFromObservation(unitState, statusWord, raw string, observedAt time.Time) TransportClient {
	ts := observedAt.UTC().Format(time.RFC3339)
	status := adGuardPolicyTargetStatus(unitState, statusWord)
	iface := adGuardPolicyTargetIface(raw, status)

	lastError := ""
	if status == TransportClientDown || status == TransportClientDegraded {
		msg := strings.TrimSpace(unitState)
		if msg == "" {
			msg = strings.TrimSpace(statusWord)
		}
		lastError = msg
	}

	return TransportClient{
		ID:           transportPolicyTargetAdGuardID,
		Name:         "AdGuard VPN",
		Kind:         TransportClientKind(transportPolicyTargetAdGuardID),
		Enabled:      true,
		Status:       status,
		IfaceID:      transportPolicyTargetAdGuardIfaceID,
		Iface:        iface,
		RoutingTable: transportPolicyTargetAdGuardTable,
		Capabilities: []string{"vpn", "systemd", "autoloop"},
		Health: TransportClientHealth{
			LastCheck: ts,
			LastError: lastError,
		},
		Runtime: TransportClientRuntime{
			Backend:        "adguard",
			AllowedActions: append([]string(nil), transportPolicyTargetAdGuardAllowedActions...),
			LastAction:     "observe",
			LastActionAt:   ts,
		},
		UpdatedAt: ts,
	}
}

func adGuardPolicyTargetStatus(unitState, statusWord string) TransportClientStatus {
	word := strings.ToUpper(strings.TrimSpace(statusWord))
	switch word {
	case "CONNECTED":
		return TransportClientUp
	case "RECONNECTING":
		return TransportClientStarting
	case "DISCONNECTED":
		return TransportClientDown
	case "ERROR":
		return TransportClientDegraded
	}

	state := strings.ToLower(strings.TrimSpace(unitState))
	switch state {
	case "active":
		return TransportClientUp
	case "activating", "reloading":
		return TransportClientStarting
	case "failed", "inactive", "deactivating":
		return TransportClientDown
	default:
		return TransportClientDown
	}
}

func adGuardPolicyTargetIface(raw string, status TransportClientStatus) string {
	v := strings.TrimSpace(raw)
	if v != "" {
		low := strings.ToLower(v)
		needle := "running on "
		if idx := strings.LastIndex(low, needle); idx >= 0 {
			tail := strings.TrimSpace(v[idx+len(needle):])
			if tail != "" {
				iface := strings.Trim(tail, ".,;:()[]{}")
				if parts := strings.Fields(iface); len(parts) > 0 {
					if strings.TrimSpace(parts[0]) != "" {
						return strings.TrimSpace(parts[0])
					}
				}
			}
		}
	}
	if iface, _ := resolveTrafficIface(loadTrafficModeState().PreferredIface); strings.TrimSpace(iface) != "" {
		return strings.TrimSpace(iface)
	}
	if status == TransportClientUp || status == TransportClientStarting {
		return "tun0"
	}
	return ""
}