package notify

import (
	"bytes"
	"context"
	"encoding/json"
	"log/slog"
	"net/http"
	"sync"
	"time"

	"git.t-juice.club/torjus/oubliette/internal/config"
)

// Event types.
const (
	EventHumanDetected  = "human_detected"
	EventSessionStarted = "session_started"
)

// SessionInfo holds session data included in webhook payloads.
type SessionInfo struct {
	ID          string   `json:"id"`
	IP          string   `json:"ip"`
	Username    string   `json:"username"`
	ShellName   string   `json:"shell_name"`
	HumanScore  float64  `json:"human_score"`
	ConnectedAt string   `json:"connected_at"`
}

// webhookPayload is the JSON body sent to webhooks.
type webhookPayload struct {
	Event     string      `json:"event"`
	Timestamp string      `json:"timestamp"`
	Session   SessionInfo `json:"session"`
}

// Notifier sends webhook notifications for honeypot events.
type Notifier struct {
	webhooks []config.WebhookNotifyConfig
	logger   *slog.Logger
	client   *http.Client

	mu   sync.Mutex
	sent map[string]struct{} // dedup key: "sessionID:eventType"
}

// NewNotifier creates a Notifier with the given webhook configurations.
func NewNotifier(webhooks []config.WebhookNotifyConfig, logger *slog.Logger) *Notifier {
	return &Notifier{
		webhooks: webhooks,
		logger:   logger,
		client:   &http.Client{Timeout: 10 * time.Second},
		sent:     make(map[string]struct{}),
	}
}

// Notify sends a notification for the given event type and session.
// Deduplicates by (sessionID, eventType) — each combination is sent at most once.
func (n *Notifier) Notify(ctx context.Context, eventType string, session SessionInfo) {
	dedupKey := session.ID + ":" + eventType

	n.mu.Lock()
	if _, ok := n.sent[dedupKey]; ok {
		n.mu.Unlock()
		return
	}
	n.sent[dedupKey] = struct{}{}
	n.mu.Unlock()

	payload := webhookPayload{
		Event:     eventType,
		Timestamp: time.Now().UTC().Format(time.RFC3339),
		Session:   session,
	}

	for _, wh := range n.webhooks {
		if !n.shouldSend(wh, eventType) {
			continue
		}
		go n.send(ctx, wh, payload)
	}
}

// CleanupSession removes dedup state for a session.
func (n *Notifier) CleanupSession(sessionID string) {
	n.mu.Lock()
	defer n.mu.Unlock()
	for key := range n.sent {
		if len(key) > len(sessionID) && key[:len(sessionID)+1] == sessionID+":" {
			delete(n.sent, key)
		}
	}
}

// shouldSend returns true if the webhook is configured to receive this event type.
func (n *Notifier) shouldSend(wh config.WebhookNotifyConfig, eventType string) bool {
	if len(wh.Events) == 0 {
		return true // empty = all events
	}
	for _, ev := range wh.Events {
		if ev == eventType {
			return true
		}
	}
	return false
}

func (n *Notifier) send(ctx context.Context, wh config.WebhookNotifyConfig, payload webhookPayload) {
	body, err := json.Marshal(payload)
	if err != nil {
		n.logger.Error("failed to marshal webhook payload", "err", err)
		return
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, wh.URL, bytes.NewReader(body))
	if err != nil {
		n.logger.Error("failed to create webhook request", "err", err, "url", wh.URL)
		return
	}

	req.Header.Set("Content-Type", "application/json")
	for k, v := range wh.Headers {
		req.Header.Set(k, v)
	}

	resp, err := n.client.Do(req)
	if err != nil {
		n.logger.Error("webhook request failed", "err", err, "url", wh.URL)
		return
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode >= 400 {
		n.logger.Warn("webhook returned error status",
			"url", wh.URL,
			"status", resp.StatusCode,
			"event", payload.Event,
		)
		return
	}

	n.logger.Debug("webhook sent",
		"url", wh.URL,
		"event", payload.Event,
		"session_id", payload.Session.ID,
	)
}

// FormatConnectedAt formats a time for use in SessionInfo.
func FormatConnectedAt(t time.Time) string {
	return t.UTC().Format(time.RFC3339)
}

// NoopNotifier is a no-op notifier used when no webhooks are configured.
type NoopNotifier struct{}

func (NoopNotifier) Notify(context.Context, string, SessionInfo) {}
func (NoopNotifier) CleanupSession(string)                       {}

// Sender is the interface for sending notifications.
type Sender interface {
	Notify(ctx context.Context, eventType string, session SessionInfo)
	CleanupSession(sessionID string)
}

var (
	_ Sender = (*Notifier)(nil)
	_ Sender = NoopNotifier{}
)

// NewSender creates a Sender from configuration. Returns a NoopNotifier
// if no webhooks are configured.
func NewSender(webhooks []config.WebhookNotifyConfig, logger *slog.Logger) Sender {
	if len(webhooks) == 0 {
		return NoopNotifier{}
	}
	return NewNotifier(webhooks, logger)
}