package notify

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log/slog"
	"net/http"
	"time"
)

// Notifier sends notifications when tasks complete.
type Notifier interface {
	Notify(event Event) error
}

// Event represents a task completion event.
type Event struct {
	TaskID   string  `json:"task_id"`
	TaskName string  `json:"task_name"`
	Status   string  `json:"status"`
	CostUSD  float64 `json:"cost_usd"`
	Duration string  `json:"duration"`
	Error    string  `json:"error,omitempty"`
}

// WebhookNotifier sends POST requests to a configured URL.
type WebhookNotifier struct {
	URL    string
	client *http.Client
	logger *slog.Logger
}

func NewWebhookNotifier(url string, logger *slog.Logger) *WebhookNotifier {
	return &WebhookNotifier{
		URL:    url,
		client: &http.Client{Timeout: 10 * time.Second},
		logger: logger,
	}
}

func (w *WebhookNotifier) Notify(event Event) error {
	body, err := json.Marshal(event)
	if err != nil {
		return fmt.Errorf("marshaling event: %w", err)
	}

	resp, err := w.client.Post(w.URL, "application/json", bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("sending webhook: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		return fmt.Errorf("webhook returned %d", resp.StatusCode)
	}
	return nil
}

// MultiNotifier fans out to multiple notifiers.
type MultiNotifier struct {
	notifiers []Notifier
	logger    *slog.Logger
}

func NewMultiNotifier(logger *slog.Logger, notifiers ...Notifier) *MultiNotifier {
	return &MultiNotifier{notifiers: notifiers, logger: logger}
}

func (m *MultiNotifier) Notify(event Event) error {
	var lastErr error
	for _, n := range m.notifiers {
		if err := n.Notify(event); err != nil {
			m.logger.Error("notification failed", "error", err)
			lastErr = err
		}
	}
	return lastErr
}

// LogNotifier logs events (useful as a default/fallback).
type LogNotifier struct {
	Logger *slog.Logger
}

func (l *LogNotifier) Notify(event Event) error {
	l.Logger.Info("task completed",
		"task_id", event.TaskID,
		"task_name", event.TaskName,
		"status", event.Status,
		"cost_usd", event.CostUSD,
		"duration", event.Duration,
	)
	return nil
}