package v1

import (
	"encoding/json"
	"fmt"
	"net/http"

	"github.com/gorilla/mux"

	"github.com/wild-cloud/wild-central/internal/config"
	"github.com/wild-cloud/wild-central/internal/wireguard"
)

// VPNManager is the interface for VPN operations used by these handlers.
type VPNManager interface {
	GetStatus() (*wireguard.Status, error)
	GetConfig() (*wireguard.Config, error)
	SaveConfig(cfg *wireguard.Config) error
	GetPublicKey() string
	GenerateKeypair() error
	Apply() error
	ListPeers() ([]*wireguard.Peer, error)
	AddPeer(name string) (*wireguard.Peer, error)
	GetPeer(id string) (*wireguard.Peer, error)
	DeletePeer(id string) error
	GeneratePeerConfigText(peerID string) (string, error)
}

// vpnHandlers groups VPN HTTP handlers with their dependencies.
type vpnHandlers struct {
	vpn          VPNManager
	statePath    string
	syncNftables func(globalCfg *config.State) // callback to resync firewall after config changes
}

func (h *vpnHandlers) Status(w http.ResponseWriter, r *http.Request) {
	status, err := h.vpn.GetStatus()
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to get VPN status: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, status)
}

func (h *vpnHandlers) GetConfig(w http.ResponseWriter, r *http.Request) {
	cfg, err := h.vpn.GetConfig()
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to get VPN config: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, map[string]any{
		"enabled":    cfg.Enabled,
		"listenPort": cfg.ListenPort,
		"address":    cfg.Address,
		"endpoint":   cfg.Endpoint,
		"dns":        cfg.DNS,
		"lanCIDR":    cfg.LanCIDR,
		"publicKey":  h.vpn.GetPublicKey(),
	})
}

func (h *vpnHandlers) UpdateConfig(w http.ResponseWriter, r *http.Request) {
	var req wireguard.Config
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		respondError(w, http.StatusBadRequest, fmt.Sprintf("Invalid request: %v", err))
		return
	}
	if req.ListenPort == 0 {
		req.ListenPort = 51820
	}
	if err := h.vpn.SaveConfig(&req); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to save VPN config: %v", err))
		return
	}
	// Resync nftables so the VPN listen port is automatically allowed/removed
	if globalCfg, err := config.LoadState(h.statePath); err == nil {
		go h.syncNftables(globalCfg)
	}
	respondJSON(w, http.StatusOK, map[string]string{"message": "VPN configuration saved"})
}

func (h *vpnHandlers) GenerateKeypair(w http.ResponseWriter, r *http.Request) {
	if err := h.vpn.GenerateKeypair(); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to generate keypair: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, map[string]string{
		"message":   "Server keypair generated",
		"publicKey": h.vpn.GetPublicKey(),
	})
}

func (h *vpnHandlers) Apply(w http.ResponseWriter, r *http.Request) {
	if err := h.vpn.Apply(); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to apply VPN config: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, map[string]string{"message": "WireGuard interface applied successfully"})
}

func (h *vpnHandlers) ListPeers(w http.ResponseWriter, r *http.Request) {
	peers, err := h.vpn.ListPeers()
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to list peers: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, map[string]any{"peers": redactPeers(peers)})
}

func (h *vpnHandlers) AddPeer(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Name string `json:"name"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Name == "" {
		respondError(w, http.StatusBadRequest, "name is required")
		return
	}
	peer, err := h.vpn.AddPeer(req.Name)
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to add peer: %v", err))
		return
	}
	respondJSON(w, http.StatusCreated, redactPeer(peer))
}

func (h *vpnHandlers) GetPeerConfig(w http.ResponseWriter, r *http.Request) {
	id := mux.Vars(r)["id"]
	text, err := h.vpn.GeneratePeerConfigText(id)
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to generate peer config: %v", err))
		return
	}
	peer, err := h.vpn.GetPeer(id)
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to get peer: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, map[string]string{
		"name":   peer.Name,
		"config": text,
	})
}

func (h *vpnHandlers) DeletePeer(w http.ResponseWriter, r *http.Request) {
	id := mux.Vars(r)["id"]
	if err := h.vpn.DeletePeer(id); err != nil {
		respondError(w, http.StatusNotFound, fmt.Sprintf("Failed to delete peer: %v", err))
		return
	}
	respondJSON(w, http.StatusOK, map[string]string{"message": "Peer deleted"})
}

// redactPeers strips private keys from a peer list before sending to clients.
func redactPeers(peers []*wireguard.Peer) []map[string]any {
	out := make([]map[string]any, len(peers))
	for i, p := range peers {
		out[i] = redactPeer(p)
	}
	return out
}

func redactPeer(p *wireguard.Peer) map[string]any {
	return map[string]any{
		"id":         p.ID,
		"name":       p.Name,
		"publicKey":  p.PublicKey,
		"allowedIPs": p.AllowedIPs,
		"createdAt":  p.CreatedAt,
	}
}