package server

import (
	"encoding/json"
	"errors"
	"os"
	"sort"
	"sync"
	"time"

	"github.com/openp2p-cn/inp2p/pkg/protocol"
)

type sdwanStore struct {
	mu    sync.RWMutex
	path  string
	cfg   protocol.SDWANConfig
	multi map[int64]protocol.SDWANConfig
}

func newSDWANStore(path string) *sdwanStore {
	s := &sdwanStore{path: path, multi: make(map[int64]protocol.SDWANConfig)}
	_ = s.load()
	return s
}

func (s *sdwanStore) load() error {
	s.mu.Lock()
	defer s.mu.Unlock()
	b, err := os.ReadFile(s.path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return nil
		}
		return err
	}
	// try multi-tenant first
	var m map[int64]protocol.SDWANConfig
	if err := json.Unmarshal(b, &m); err == nil && len(m) > 0 {
		for k, v := range m {
			m[k] = normalizeSDWAN(v)
		}
		s.multi = m
		return nil
	}
	var c protocol.SDWANConfig
	if err := json.Unmarshal(b, &c); err != nil {
		return err
	}
	s.cfg = normalizeSDWAN(c)
	return nil
}

func (s *sdwanStore) save(cfg protocol.SDWANConfig) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	cfg = normalizeSDWAN(cfg)
	cfg.UpdatedAt = time.Now().Unix()
	b, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	if err := os.WriteFile(s.path, b, 0644); err != nil {
		return err
	}
	s.cfg = cfg
	return nil
}

func (s *sdwanStore) saveTenant(tenantID int64, cfg protocol.SDWANConfig) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	cfg = normalizeSDWAN(cfg)
	cfg.UpdatedAt = time.Now().Unix()
	if s.multi == nil {
		s.multi = make(map[int64]protocol.SDWANConfig)
	}
	s.multi[tenantID] = cfg
	b, err := json.MarshalIndent(s.multi, "", "  ")
	if err != nil {
		return err
	}
	if err := os.WriteFile(s.path, b, 0644); err != nil {
		return err
	}
	return nil
}

func (s *sdwanStore) get() protocol.SDWANConfig {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.cfg
}

func (s *sdwanStore) getTenant(tenantID int64) protocol.SDWANConfig {
	s.mu.RLock()
	defer s.mu.RUnlock()
	if s.multi == nil {
		return protocol.SDWANConfig{}
	}
	return s.multi[tenantID]
}

func normalizeSDWAN(c protocol.SDWANConfig) protocol.SDWANConfig {
	if c.Mode == "" {
		c.Mode = "hub"
	}
	if !c.Enabled {
		c.Enabled = true
	}
	// de-dup nodes by node name, keep last and sort for stable output
	m := make(map[string]string)
	for _, n := range c.Nodes {
		if n.Node == "" {
			continue
		}
		m[n.Node] = n.IP
	}
	c.Nodes = c.Nodes[:0]
	for node, ip := range m {
		c.Nodes = append(c.Nodes, protocol.SDWANNode{Node: node, IP: ip})
	}
	sort.Slice(c.Nodes, func(i, j int) bool { return c.Nodes[i].Node < c.Nodes[j].Node })
	return c
}