package bridge

import (
	"bufio"
	"encoding/json"
	"fmt"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/vishvananda/netlink"
)

const BridgeConfigFile = "/etc/proxmox-router/bridge.json"

type BridgeConfigStore struct {
	Bridges []*BridgeInstance `json:"bridges"`
	Ports   []*BridgePort     `json:"ports"`
	VLANs   []*BridgeVLAN     `json:"vlans"`
}

type BridgeManager struct {
	mu        sync.RWMutex
	storePath string
	bridges   map[string]*BridgeInstance
	ports     map[string]*BridgePort
	vlans     map[string]*BridgeVLAN
}

func NewBridgeManager() *BridgeManager {
	bm := &BridgeManager{
		storePath: BridgeConfigFile,
		bridges:   make(map[string]*BridgeInstance),
		ports:     make(map[string]*BridgePort),
		vlans:     make(map[string]*BridgeVLAN),
	}
	bm.load()
	bm.SyncAll()
	return bm
}

func (m *BridgeManager) load() {
	m.mu.Lock()
	defer m.mu.Unlock()

	data, err := os.ReadFile(m.storePath)
	if err != nil {
		return
	}
	var store BridgeConfigStore
	if err := json.Unmarshal(data, &store); err != nil {
		return
	}

	for _, b := range store.Bridges {
		m.bridges[b.ID] = b
	}
	for _, p := range store.Ports {
		m.ports[p.ID] = p
	}
	for _, v := range store.VLANs {
		m.vlans[v.ID] = v
	}
}

func (m *BridgeManager) save() error {
	_ = os.MkdirAll(filepath.Dir(m.storePath), 0755)

	store := BridgeConfigStore{
		Bridges: make([]*BridgeInstance, 0, len(m.bridges)),
		Ports:   make([]*BridgePort, 0, len(m.ports)),
		VLANs:   make([]*BridgeVLAN, 0, len(m.vlans)),
	}

	for _, b := range m.bridges {
		store.Bridges = append(store.Bridges, b)
	}
	for _, p := range m.ports {
		store.Ports = append(store.Ports, p)
	}
	for _, v := range m.vlans {
		store.VLANs = append(store.VLANs, v)
	}

	data, err := json.MarshalIndent(store, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(m.storePath, data, 0644)
}

// ==================== Bridge Interfaces ====================

func (m *BridgeManager) ListBridges() []*BridgeInstance {
	m.mu.Lock()
	defer m.mu.Unlock()

	list := make([]*BridgeInstance, 0, len(m.bridges))
	for _, b := range m.bridges {
		m.updateBridgeLiveStats(b)
		list = append(list, b)
	}

	sort.Slice(list, func(i, j int) bool {
		return list[i].Name < list[j].Name
	})

	return list
}

func (m *BridgeManager) GetBridge(idOrName string) (*BridgeInstance, bool) {
	m.mu.Lock()
	defer m.mu.Unlock()

	if b, ok := m.bridges[idOrName]; ok {
		m.updateBridgeLiveStats(b)
		return b, true
	}
	for _, b := range m.bridges {
		if b.Name == idOrName {
			m.updateBridgeLiveStats(b)
			return b, true
		}
	}
	return nil, false
}

func (m *BridgeManager) SaveBridge(b BridgeInstance) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	if b.Name == "" {
		return fmt.Errorf("bridge name is required")
	}
	if b.MTU <= 0 {
		b.MTU = 1500
	}
	if b.PVID <= 0 {
		b.PVID = 1
	}
	if b.STP == "" {
		b.STP = "rstp"
	}
	if b.Priority <= 0 {
		b.Priority = 32768
	}

	if b.ID == "" {
		b.ID = fmt.Sprintf("br-%d", time.Now().UnixNano())
	}

	// Update existing or add new
	m.bridges[b.ID] = &b
	_ = m.save()

	// Apply in Linux kernel
	return m.syncBridge(&b)
}

func (m *BridgeManager) DeleteBridge(id string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	b, ok := m.bridges[id]
	if !ok {
		return fmt.Errorf("bridge not found")
	}

	// Detach any ports belonging to this bridge
	for _, p := range m.ports {
		if p.Bridge == b.Name {
			_ = exec.Command("ip", "link", "set", p.Interface, "nomaster").Run()
			delete(m.ports, p.ID)
		}
	}

	// Delete any VLAN entries for this bridge
	for vid, v := range m.vlans {
		if v.Bridge == b.Name {
			delete(m.vlans, vid)
		}
	}

	// Delete bridge link in kernel
	_ = exec.Command("ip", "link", "del", b.Name).Run()

	delete(m.bridges, id)
	return m.save()
}

func (m *BridgeManager) SetBridgeState(id string, disabled bool) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	b, ok := m.bridges[id]
	if !ok {
		return fmt.Errorf("bridge not found")
	}

	b.Disabled = disabled
	_ = m.save()

	if disabled {
		_ = exec.Command("ip", "link", "set", b.Name, "down").Run()
	} else {
		_ = exec.Command("ip", "link", "set", b.Name, "up").Run()
	}
	return nil
}

func (m *BridgeManager) AddBridgeIP(idOrName string, ipCIDR string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	b, ok := m.bridges[idOrName]
	if !ok {
		for _, br := range m.bridges {
			if br.Name == idOrName {
				b = br
				ok = true
				break
			}
		}
	}
	if !ok {
		return fmt.Errorf("bridge not found")
	}

	ipCIDR = strings.TrimSpace(ipCIDR)
	if _, _, err := net.ParseCIDR(ipCIDR); err != nil {
		return fmt.Errorf("invalid IP/CIDR: %w", err)
	}

	// Check if already in list
	for _, ip := range b.IPAddresses {
		if ip == ipCIDR {
			return nil
		}
	}

	b.IPAddresses = append(b.IPAddresses, ipCIDR)
	_ = m.save()

	// Add to kernel
	_ = exec.Command("ip", "addr", "add", ipCIDR, "dev", b.Name).Run()
	return nil
}

func (m *BridgeManager) DeleteBridgeIP(idOrName string, ipCIDR string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	b, ok := m.bridges[idOrName]
	if !ok {
		for _, br := range m.bridges {
			if br.Name == idOrName {
				b = br
				ok = true
				break
			}
		}
	}
	if !ok {
		return fmt.Errorf("bridge not found")
	}

	ipCIDR = strings.TrimSpace(ipCIDR)
	var updated []string
	for _, ip := range b.IPAddresses {
		if ip != ipCIDR {
			updated = append(updated, ip)
		}
	}
	b.IPAddresses = updated
	_ = m.save()

	_ = exec.Command("ip", "addr", "del", ipCIDR, "dev", b.Name).Run()
	return nil
}

func (m *BridgeManager) syncBridge(b *BridgeInstance) error {
	link, err := netlink.LinkByName(b.Name)
	if err != nil {
		// Create bridge
		args := []string{"link", "add", b.Name, "type", "bridge"}
		if b.VlanFiltering {
			args = append(args, "vlan_filtering", "1")
		} else {
			args = append(args, "vlan_filtering", "0")
		}
		if b.PVID > 0 {
			args = append(args, "vlan_default_pvid", strconv.Itoa(b.PVID))
		}
		if out, err := exec.Command("ip", args...).CombinedOutput(); err != nil {
			return fmt.Errorf("failed to create bridge %s: %s: %w", b.Name, string(out), err)
		}
		link, _ = netlink.LinkByName(b.Name)
	}

	if link != nil {
		// Set MTU
		if b.MTU > 0 {
			_ = netlink.LinkSetMTU(link, b.MTU)
		}

		// Set Admin MAC if specified
		if b.MACAddress != "" {
			if hw, err := net.ParseMAC(b.MACAddress); err == nil {
				_ = netlink.LinkSetHardwareAddr(link, hw)
			}
		}

		// Set VLAN filtering on existing bridge
		vfVal := "0"
		if b.VlanFiltering {
			vfVal = "1"
		}
		pvidVal := strconv.Itoa(b.PVID)
		if b.PVID <= 0 {
			pvidVal = "1"
		}
		_ = exec.Command("ip", "link", "set", b.Name, "type", "bridge", "vlan_filtering", vfVal, "vlan_default_pvid", pvidVal).Run()

		// Set STP
		stpVal := "0"
		if b.STP == "rstp" || b.STP == "stp" {
			stpVal = "1"
		}
		_ = os.WriteFile(fmt.Sprintf("/sys/class/net/%s/bridge/stp_state", b.Name), []byte(stpVal), 0644)

		// Set link up or down
		if b.Disabled {
			_ = netlink.LinkSetDown(link)
		} else {
			_ = netlink.LinkSetUp(link)
		}

		// Sync IP addresses
		for _, ip := range b.IPAddresses {
			_ = exec.Command("ip", "addr", "add", ip, "dev", b.Name).Run()
		}
	}

	return nil
}

func (m *BridgeManager) updateBridgeLiveStats(b *BridgeInstance) {
	// Count ports belonging to this bridge
	portsCount := 0
	for _, p := range m.ports {
		if p.Bridge == b.Name && !p.Disabled {
			portsCount++
		}
	}
	b.PortsCount = portsCount

	link, err := netlink.LinkByName(b.Name)
	if err != nil {
		b.Running = false
		return
	}

	attrs := link.Attrs()
	b.Running = (attrs.Flags&net.FlagUp != 0) && (attrs.OperState == netlink.OperUp || attrs.OperState == netlink.OperUnknown)
	if b.MACAddress == "" {
		b.MACAddress = attrs.HardwareAddr.String()
	}

	if attrs.Statistics != nil {
		b.RxPackets = attrs.Statistics.RxPackets
		b.TxPackets = attrs.Statistics.TxPackets
		b.RxBytes = attrs.Statistics.RxBytes
		b.TxBytes = attrs.Statistics.TxBytes
		b.RxHuman = formatBytes(b.RxBytes)
		b.TxHuman = formatBytes(b.TxBytes)
	}

	// Read IP addresses from kernel
	if addrs, err := netlink.AddrList(link, netlink.FAMILY_V4); err == nil {
		var ips []string
		for _, a := range addrs {
			ips = append(ips, a.IPNet.String())
		}
		b.IPAddresses = ips
	}
}

// ==================== Bridge Ports ====================

func (m *BridgeManager) ListPorts() []*BridgePort {
	m.mu.Lock()
	defer m.mu.Unlock()

	list := make([]*BridgePort, 0, len(m.ports))
	for _, p := range m.ports {
		m.updatePortLiveStatus(p)
		list = append(list, p)
	}

	sort.Slice(list, func(i, j int) bool {
		if list[i].Bridge != list[j].Bridge {
			return list[i].Bridge < list[j].Bridge
		}
		return list[i].Interface < list[j].Interface
	})

	return list
}

func (m *BridgeManager) SavePort(p BridgePort) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	if p.Bridge == "" || p.Interface == "" {
		return fmt.Errorf("bridge and interface are required")
	}
	if p.PVID <= 0 {
		p.PVID = 1
	}
	if p.Priority <= 0 {
		p.Priority = 128
	}
	if p.PathCost <= 0 {
		p.PathCost = 10
	}
	if p.FrameTypes == "" {
		p.FrameTypes = "admit-all"
	}

	if p.ID == "" {
		p.ID = fmt.Sprintf("port-%d", time.Now().UnixNano())
	}

	m.ports[p.ID] = &p
	_ = m.save()

	return m.syncPort(&p)
}

func (m *BridgeManager) DeletePort(id string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	p, ok := m.ports[id]
	if !ok {
		return fmt.Errorf("port not found")
	}

	// Remove from bridge in kernel
	_ = exec.Command("ip", "link", "set", p.Interface, "nomaster").Run()

	delete(m.ports, id)
	return m.save()
}

func (m *BridgeManager) SetPortState(id string, disabled bool) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	p, ok := m.ports[id]
	if !ok {
		return fmt.Errorf("port not found")
	}

	p.Disabled = disabled
	_ = m.save()

	if disabled {
		_ = exec.Command("ip", "link", "set", p.Interface, "nomaster").Run()
	} else {
		_ = m.syncPort(p)
	}
	return nil
}

func (m *BridgeManager) syncPort(p *BridgePort) error {
	if p.Disabled {
		_ = exec.Command("ip", "link", "set", p.Interface, "nomaster").Run()
		return nil
	}

	// Check if interface exists
	if _, err := netlink.LinkByName(p.Interface); err != nil {
		return fmt.Errorf("interface %s does not exist", p.Interface)
	}

	// Attach interface to bridge
	if out, err := exec.Command("ip", "link", "set", p.Interface, "master", p.Bridge).CombinedOutput(); err != nil {
		return fmt.Errorf("failed to attach %s to bridge %s: %s: %w", p.Interface, p.Bridge, string(out), err)
	}

	// Bring interface UP
	_ = exec.Command("ip", "link", "set", p.Interface, "up").Run()

	// Port isolation / Split Horizon
	isolated := "off"
	if p.Horizon > 0 {
		isolated = "on"
	}
	_ = exec.Command("bridge", "link", "set", "dev", p.Interface, "isolated", isolated).Run()

	// Learning
	learning := "on"
	if !p.Learn {
		learning = "off"
	}
	_ = exec.Command("bridge", "link", "set", "dev", p.Interface, "learning", learning).Run()

	// Ingress filtering
	ingress := "off"
	if p.IngressFiltering {
		ingress = "on"
	}
	_ = exec.Command("bridge", "link", "set", "dev", p.Interface, "ingress_filtering", ingress).Run()

	// Priority & Path Cost
	prioCostArgs := []string{"link", "set", "dev", p.Interface}
	if p.Priority > 0 {
		prioCostArgs = append(prioCostArgs, "priority", strconv.Itoa(p.Priority))
	}
	if p.PathCost > 0 {
		prioCostArgs = append(prioCostArgs, "cost", strconv.Itoa(p.PathCost))
	}
	if len(prioCostArgs) > 4 {
		_ = exec.Command("bridge", prioCostArgs...).Run()
	}

	// VLAN filtering configuration
	if p.PVID > 0 {
		_ = exec.Command("bridge", "vlan", "add", "dev", p.Interface, "vid", strconv.Itoa(p.PVID), "pvid", "untagged").Run()
	}

	return nil
}

func (m *BridgeManager) updatePortLiveStatus(p *BridgePort) {
	if p.Disabled {
		p.Status = "disabled"
		return
	}

	link, err := netlink.LinkByName(p.Interface)
	if err != nil {
		p.Status = "inactive"
		return
	}

	attrs := link.Attrs()
	if attrs.OperState == netlink.OperDown {
		p.Status = "disabled"
	} else if attrs.MasterIndex > 0 {
		p.Status = "forwarding"
	} else {
		p.Status = "unattached"
	}
}

// ==================== Bridge VLANs ====================

func (m *BridgeManager) ListVLANs() []*BridgeVLAN {
	m.mu.Lock()
	defer m.mu.Unlock()

	list := make([]*BridgeVLAN, 0, len(m.vlans))
	for _, v := range m.vlans {
		v.CurrentTagged = v.Tagged
		v.CurrentUntagged = v.Untagged
		list = append(list, v)
	}

	sort.Slice(list, func(i, j int) bool {
		if list[i].Bridge != list[j].Bridge {
			return list[i].Bridge < list[j].Bridge
		}
		return list[i].VlanIDs < list[j].VlanIDs
	})

	return list
}

func (m *BridgeManager) SaveVLAN(v BridgeVLAN) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	if v.Bridge == "" || v.VlanIDs == "" {
		return fmt.Errorf("bridge and vlan_ids are required")
	}

	if v.ID == "" {
		v.ID = fmt.Sprintf("bvlan-%d", time.Now().UnixNano())
	}

	m.vlans[v.ID] = &v
	_ = m.save()

	return m.syncVLAN(&v)
}

func (m *BridgeManager) DeleteVLAN(id string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	v, ok := m.vlans[id]
	if !ok {
		return fmt.Errorf("vlan entry not found")
	}

	// Remove VLANs from kernel
	vids := parseVLANRange(v.VlanIDs)
	for _, vid := range vids {
		vidStr := strconv.Itoa(vid)
		for _, iface := range append(v.Tagged, v.Untagged...) {
			_ = exec.Command("bridge", "vlan", "del", "dev", iface, "vid", vidStr).Run()
		}
	}

	delete(m.vlans, id)
	return m.save()
}

func (m *BridgeManager) SetVLANState(id string, disabled bool) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	v, ok := m.vlans[id]
	if !ok {
		return fmt.Errorf("vlan entry not found")
	}

	v.Disabled = disabled
	_ = m.save()

	if disabled {
		vids := parseVLANRange(v.VlanIDs)
		for _, vid := range vids {
			vidStr := strconv.Itoa(vid)
			for _, iface := range append(v.Tagged, v.Untagged...) {
				_ = exec.Command("bridge", "vlan", "del", "dev", iface, "vid", vidStr).Run()
			}
		}
	} else {
		_ = m.syncVLAN(v)
	}
	return nil
}

func (m *BridgeManager) syncVLAN(v *BridgeVLAN) error {
	if v.Disabled {
		return nil
	}

	vids := parseVLANRange(v.VlanIDs)
	for _, vid := range vids {
		vidStr := strconv.Itoa(vid)
		for _, iface := range v.Tagged {
			_ = exec.Command("bridge", "vlan", "add", "dev", iface, "vid", vidStr).Run()
		}
		for _, iface := range v.Untagged {
			_ = exec.Command("bridge", "vlan", "add", "dev", iface, "vid", vidStr, "untagged").Run()
		}
	}
	return nil
}

// ==================== Bridge Hosts (FDB / MAC Table) ====================

func (m *BridgeManager) ListHosts(bridgeFilter string) ([]BridgeHost, error) {
	args := []string{"fdb", "show"}
	if bridgeFilter != "" {
		args = append(args, "br", bridgeFilter)
	}

	out, err := exec.Command("bridge", args...).Output()
	if err != nil {
		return nil, fmt.Errorf("failed to run bridge fdb show: %w", err)
	}

	var hosts []BridgeHost
	scanner := bufio.NewScanner(strings.NewReader(string(out)))
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" {
			continue
		}

		fields := strings.Fields(line)
		if len(fields) < 3 {
			continue
		}

		mac := fields[0]
		dev := ""
		vlan := 1
		master := ""
		age := 0.0
		isLocal := false
		isStatic := false

		for i := 1; i < len(fields); i++ {
			switch fields[i] {
			case "dev":
				if i+1 < len(fields) {
					dev = fields[i+1]
					i++
				}
			case "vlan":
				if i+1 < len(fields) {
					vlan, _ = strconv.Atoi(fields[i+1])
					i++
				}
			case "master":
				if i+1 < len(fields) {
					master = fields[i+1]
					i++
				}
			case "self":
				isLocal = true
			case "permanent":
				isLocal = true
				isStatic = true
			case "static":
				isStatic = true
			default:
				if val, err := strconv.ParseFloat(fields[i], 64); err == nil {
					age = val
				}
			}
		}

		if master == "" && strings.HasPrefix(dev, "br") {
			master = dev
		}

		var flags []string
		if isLocal {
			flags = append(flags, "L")
		} else if isStatic {
			flags = append(flags, "S")
		} else {
			flags = append(flags, "D")
		}

		hosts = append(hosts, BridgeHost{
			MAC:       mac,
			Interface: dev,
			Bridge:    master,
			VlanID:    vlan,
			Age:       age,
			Local:     isLocal,
			Static:    isStatic,
			Flags:     strings.Join(flags, ","),
		})
	}

	return hosts, nil
}

func (m *BridgeManager) FlushHosts(bridge string) error {
	if bridge == "" {
		return fmt.Errorf("bridge name required for flush")
	}
	_ = exec.Command("bridge", "fdb", "flush", "dev", bridge, "dynamic").Run()
	return nil
}

// ==================== Summary & SyncAll ====================

func (m *BridgeManager) GetSummary() BridgeSummary {
	m.mu.RLock()
	bCount := len(m.bridges)
	pCount := len(m.ports)
	vCount := len(m.vlans)
	m.mu.RUnlock()

	hCount := 0
	if hosts, err := m.ListHosts(""); err == nil {
		hCount = len(hosts)
	}

	return BridgeSummary{
		BridgesCount: bCount,
		PortsCount:   pCount,
		VLANsCount:   vCount,
		HostsCount:   hCount,
	}
}

func (m *BridgeManager) SyncAll() {
	m.mu.RLock()
	defer m.mu.RUnlock()

	// 1. Sync all bridges
	for _, b := range m.bridges {
		_ = m.syncBridge(b)
	}

	// 2. Sync all ports
	for _, p := range m.ports {
		_ = m.syncPort(p)
	}

	// 3. Sync all VLAN entries
	for _, v := range m.vlans {
		_ = m.syncVLAN(v)
	}
}

// RenameInterface updates bridge, port, and VLAN configurations when an interface is renamed.
func (m *BridgeManager) RenameInterface(oldName, newName string) {
	m.mu.Lock()
	defer m.mu.Unlock()

	changed := false
	for _, b := range m.bridges {
		if b.Name == oldName {
			b.Name = newName
			changed = true
		}
	}
	for _, p := range m.ports {
		if p.Interface == oldName {
			p.Interface = newName
			changed = true
		}
	}
	for _, v := range m.vlans {
		if v.Bridge == oldName {
			v.Bridge = newName
			changed = true
		}
		for i, tagged := range v.Tagged {
			if tagged == oldName {
				v.Tagged[i] = newName
				changed = true
			}
		}
		for i, untagged := range v.Untagged {
			if untagged == oldName {
				v.Untagged[i] = newName
				changed = true
			}
		}
	}
	if changed {
		_ = m.save()
	}
}

// Helper: parse "10" or "10,20,30" or "10-20" into int slice
func parseVLANRange(s string) []int {
	var result []int
	parts := strings.Split(s, ",")
	for _, p := range parts {
		p = strings.TrimSpace(p)
		if strings.Contains(p, "-") {
			rangeParts := strings.Split(p, "-")
			if len(rangeParts) == 2 {
				start, err1 := strconv.Atoi(strings.TrimSpace(rangeParts[0]))
				end, err2 := strconv.Atoi(strings.TrimSpace(rangeParts[1]))
				if err1 == nil && err2 == nil && start <= end {
					for i := start; i <= end; i++ {
						result = append(result, i)
					}
					continue
				}
			}
		}
		if val, err := strconv.Atoi(p); err == nil {
			result = append(result, val)
		}
	}
	return result
}

func formatBytes(b uint64) string {
	const unit = 1024
	if b < unit {
		return fmt.Sprintf("%d B", b)
	}
	div, exp := uint64(unit), 0
	for n := b / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "KMGTPE"[exp])
}