package cisco

import "fmt"

// iosMode represents the current CLI mode of the IOS state machine.
type iosMode int

const (
	modeUserExec      iosMode = iota // Router>
	modePrivilegedExec               // Router#
	modeGlobalConfig                 // Router(config)#
	modeInterfaceConfig              // Router(config-if)#
)

// ifaceInfo holds interface metadata for show commands.
type ifaceInfo struct {
	name       string
	ip         string
	mask       string
	status     string
	protocol   string
	mac        string
	bandwidth  string
	mtu        int
	rxPackets  int
	txPackets  int
	rxBytes    int
	txBytes    int
	shutdown   bool
	desc string
}

// iosState holds all mutable state for the Cisco IOS shell session.
type iosState struct {
	mode       iosMode
	hostname   string
	model      string
	iosVersion string
	serial     string
	enablePass string
	interfaces []ifaceInfo
	currentIf  string
}

func newIOSState(hostname, model, iosVersion, enablePass string) *iosState {
	return &iosState{
		mode:       modeUserExec,
		hostname:   hostname,
		model:      model,
		iosVersion: iosVersion,
		serial:     "FTX1524Z0P3",
		enablePass: enablePass,
		interfaces: defaultInterfaces(),
	}
}

func defaultInterfaces() []ifaceInfo {
	return []ifaceInfo{
		{
			name: "GigabitEthernet0/0", ip: "192.168.1.1", mask: "255.255.255.0",
			status: "up", protocol: "up", mac: "0050.7966.6800",
			bandwidth: "1000000 Kbit", mtu: 1500,
			rxPackets: 148253, txPackets: 93127, rxBytes: 19284732, txBytes: 8291043,
		},
		{
			name: "GigabitEthernet0/1", ip: "10.0.0.1", mask: "255.255.255.252",
			status: "up", protocol: "up", mac: "0050.7966.6801",
			bandwidth: "1000000 Kbit", mtu: 1500,
			rxPackets: 52104, txPackets: 48891, rxBytes: 4182934, txBytes: 3901284,
		},
		{
			name: "GigabitEthernet0/2", ip: "unassigned", mask: "",
			status: "administratively down", protocol: "down", mac: "0050.7966.6802",
			bandwidth: "1000000 Kbit", mtu: 1500, shutdown: true,
		},
		{
			name: "Vlan1", ip: "172.16.0.1", mask: "255.255.0.0",
			status: "up", protocol: "up", mac: "0050.7966.6810",
			bandwidth: "1000000 Kbit", mtu: 1500,
			rxPackets: 8421, txPackets: 7103, rxBytes: 512384, txBytes: 423901,
		},
	}
}

// prompt returns the IOS prompt string for the current mode.
func (s *iosState) prompt() string {
	switch s.mode {
	case modeUserExec:
		return fmt.Sprintf("%s>", s.hostname)
	case modePrivilegedExec:
		return fmt.Sprintf("%s#", s.hostname)
	case modeGlobalConfig:
		return fmt.Sprintf("%s(config)#", s.hostname)
	case modeInterfaceConfig:
		return fmt.Sprintf("%s(config-if)#", s.hostname)
	default:
		return fmt.Sprintf("%s>", s.hostname)
	}
}

// findInterface returns a pointer to the interface with the given name, or nil.
func (s *iosState) findInterface(name string) *ifaceInfo {
	for i := range s.interfaces {
		if s.interfaces[i].name == name {
			return &s.interfaces[i]
		}
	}
	return nil
}