package sipguardian

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

	"github.com/caddyserver/caddy/v2"
	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
	"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)

func init() {
	caddy.RegisterModule(AdminHandler{})
	httpcaddyfile.RegisterHandlerDirective("sip_guardian_admin", parseSIPGuardianAdmin)
	// Register handler ordering so it can be used directly in handle blocks
	httpcaddyfile.RegisterDirectiveOrder("sip_guardian_admin", httpcaddyfile.Before, "respond")
}

// parseSIPGuardianAdmin parses the sip_guardian_admin directive
func parseSIPGuardianAdmin(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
	var handler AdminHandler
	err := handler.UnmarshalCaddyfile(h.Dispenser)
	return &handler, err
}

// AdminHandler provides HTTP endpoints to manage SIP Guardian
type AdminHandler struct {
	guardian *SIPGuardian
}

func (AdminHandler) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.handlers.sip_guardian_admin",
		New: func() caddy.Module { return new(AdminHandler) },
	}
}

func (h *AdminHandler) Provision(ctx caddy.Context) error {
	// Get the shared guardian instance from the global registry
	guardian, err := GetOrCreateGuardian(ctx, "default")
	if err != nil {
		return err
	}
	h.guardian = guardian
	return nil
}

// ServeHTTP handles admin API requests
func (h *AdminHandler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
	// Route based on path
	path := r.URL.Path

	switch {
	case strings.HasSuffix(path, "/bans"):
		return h.handleBans(w, r)
	case strings.HasSuffix(path, "/stats"):
		return h.handleStats(w, r)
	case strings.HasSuffix(path, "/dns-whitelist"):
		return h.handleDNSWhitelist(w, r)
	case strings.HasSuffix(path, "/dns-whitelist/refresh"):
		return h.handleDNSWhitelistRefresh(w, r)
	case strings.Contains(path, "/unban/"):
		return h.handleUnban(w, r, path)
	case strings.Contains(path, "/ban/"):
		return h.handleBan(w, r, path)
	default:
		return next.ServeHTTP(w, r)
	}
}

// handleBans lists all banned IPs
func (h *AdminHandler) handleBans(w http.ResponseWriter, r *http.Request) error {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return nil
	}

	bans := h.guardian.GetBannedIPs()

	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(map[string]interface{}{
		"bans":  bans,
		"count": len(bans),
	})
}

// handleStats returns current statistics
func (h *AdminHandler) handleStats(w http.ResponseWriter, r *http.Request) error {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return nil
	}

	stats := h.guardian.GetStats()

	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(stats)
}

// handleUnban removes an IP from the ban list
func (h *AdminHandler) handleUnban(w http.ResponseWriter, r *http.Request, path string) error {
	if r.Method != http.MethodPost && r.Method != http.MethodDelete {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return nil
	}

	// Extract IP from path: /admin/sip-guardian/unban/{ip}
	parts := strings.Split(path, "/unban/")
	if len(parts) != 2 || parts[1] == "" {
		http.Error(w, "IP address required", http.StatusBadRequest)
		return nil
	}

	ip := strings.TrimSuffix(parts[1], "/")

	if h.guardian.UnbanIP(ip) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"success": true,
			"message": "IP unbanned",
			"ip":      ip,
		})
	} else {
		w.WriteHeader(http.StatusNotFound)
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"success": false,
			"message": "IP not found in ban list",
			"ip":      ip,
		})
	}

	return nil
}

// handleDNSWhitelist returns DNS whitelist entries and stats
func (h *AdminHandler) handleDNSWhitelist(w http.ResponseWriter, r *http.Request) error {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return nil
	}

	entries := h.guardian.GetDNSWhitelistEntries()
	stats := h.guardian.GetStats()

	response := map[string]interface{}{
		"entries": entries,
		"count":   len(entries),
	}

	// Add DNS-specific stats if available
	if dnsStats, ok := stats["dns_whitelist"]; ok {
		response["stats"] = dnsStats
	}

	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(response)
}

// handleDNSWhitelistRefresh forces an immediate DNS refresh
func (h *AdminHandler) handleDNSWhitelistRefresh(w http.ResponseWriter, r *http.Request) error {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return nil
	}

	h.guardian.RefreshDNSWhitelist()

	// Get updated entries
	entries := h.guardian.GetDNSWhitelistEntries()

	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(map[string]interface{}{
		"success": true,
		"message": "DNS whitelist refreshed",
		"count":   len(entries),
	})
}

// handleBan manually adds an IP to the ban list
func (h *AdminHandler) handleBan(w http.ResponseWriter, r *http.Request, path string) error {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return nil
	}

	// Extract IP from path: /admin/sip-guardian/ban/{ip}
	parts := strings.Split(path, "/ban/")
	if len(parts) != 2 || parts[1] == "" {
		http.Error(w, "IP address required", http.StatusBadRequest)
		return nil
	}

	ip := strings.TrimSuffix(parts[1], "/")

	// Parse optional reason from body
	var body struct {
		Reason string `json:"reason"`
	}
	if r.Body != nil {
		json.NewDecoder(r.Body).Decode(&body)
	}
	if body.Reason == "" {
		body.Reason = "manual_ban"
	}

	// Use public BanIP method for proper encapsulation
	h.guardian.BanIP(ip, body.Reason)

	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(map[string]interface{}{
		"success": true,
		"message": "IP banned",
		"ip":      ip,
		"reason":  body.Reason,
	})
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler for AdminHandler.
// Usage in Caddyfile:
//
//	handle /api/sip-guardian/* {
//	    sip_guardian_admin
//	}
//
// Or simply: sip_guardian_admin
func (h *AdminHandler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	// Move past "sip_guardian_admin" token
	d.Next()

	// This handler doesn't have any configuration options currently
	// but we need to consume any block if present
	for nesting := d.Nesting(); d.NextBlock(nesting); {
		return d.Errf("unknown sip_guardian_admin directive: %s", d.Val())
	}

	return nil
}

// Interface guards
var (
	_ caddyhttp.MiddlewareHandler = (*AdminHandler)(nil)
	_ caddy.Provisioner           = (*AdminHandler)(nil)
	_ caddyfile.Unmarshaler       = (*AdminHandler)(nil)
)