// Package notify provides notification services.
package notify

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

	"go.uber.org/fx"

	"git.eeqj.de/sneak/upaas/internal/logger"
	"git.eeqj.de/sneak/upaas/internal/models"
)

// HTTP client timeout.
const (
	httpClientTimeout = 10 * time.Second
)

// HTTP status code thresholds.
const (
	httpStatusClientError = 400
)

// Display constants.
const (
	shortCommitLength = 12
	secondsPerMinute  = 60
)

// Sentinel errors for notification failures.
var (
	// ErrNtfyFailed indicates the ntfy notification request failed.
	ErrNtfyFailed = errors.New("ntfy notification failed")
	// ErrSlackFailed indicates the Slack notification request failed.
	ErrSlackFailed = errors.New("slack notification failed")
)

// ServiceParams contains dependencies for Service.
type ServiceParams struct {
	fx.In

	Logger *logger.Logger
}

// Service provides notification functionality.
type Service struct {
	log    *slog.Logger
	client *http.Client
	params *ServiceParams
}

// New creates a new notify Service.
func New(_ fx.Lifecycle, params ServiceParams) (*Service, error) {
	return &Service{
		log: params.Logger.Get(),
		client: &http.Client{
			Timeout: httpClientTimeout,
		},
		params: &params,
	}, nil
}

// NotifyBuildStart sends a build started notification.
func (svc *Service) NotifyBuildStart(
	ctx context.Context,
	app *models.App,
	deployment *models.Deployment,
) {
	title := "Build started: " + app.Name
	message := "Building from branch " + app.Branch

	if deployment.CommitSHA.Valid {
		shortSHA := deployment.CommitSHA.String[:minInt(shortCommitLength, len(deployment.CommitSHA.String))]
		message += " at " + shortSHA
	}

	svc.sendNotifications(ctx, app, title, message, "info")
}

// NotifyBuildSuccess sends a build success notification.
func (svc *Service) NotifyBuildSuccess(
	ctx context.Context,
	app *models.App,
	deployment *models.Deployment,
) {
	duration := time.Since(deployment.StartedAt)
	title := "Build success: " + app.Name
	message := "Image built successfully in " + formatDuration(duration)

	svc.sendNotifications(ctx, app, title, message, "success")
}

// NotifyBuildFailed sends a build failed notification.
func (svc *Service) NotifyBuildFailed(
	ctx context.Context,
	app *models.App,
	deployment *models.Deployment,
	buildErr error,
) {
	duration := time.Since(deployment.StartedAt)
	title := "Build failed: " + app.Name
	message := "Build failed after " + formatDuration(duration) + ": " + buildErr.Error()

	svc.sendNotifications(ctx, app, title, message, "error")
}

// NotifyDeploySuccess sends a deploy success notification.
func (svc *Service) NotifyDeploySuccess(
	ctx context.Context,
	app *models.App,
	deployment *models.Deployment,
) {
	duration := time.Since(deployment.StartedAt)
	title := "Deploy success: " + app.Name
	message := "Successfully deployed in " + formatDuration(duration)

	if deployment.CommitSHA.Valid {
		shortSHA := deployment.CommitSHA.String[:minInt(shortCommitLength, len(deployment.CommitSHA.String))]
		message += " (commit " + shortSHA + ")"
	}

	svc.sendNotifications(ctx, app, title, message, "success")
}

// NotifyDeployFailed sends a deploy failed notification.
func (svc *Service) NotifyDeployFailed(
	ctx context.Context,
	app *models.App,
	deployment *models.Deployment,
	deployErr error,
) {
	duration := time.Since(deployment.StartedAt)
	title := "Deploy failed: " + app.Name
	message := "Deployment failed after " + formatDuration(duration) + ": " + deployErr.Error()

	svc.sendNotifications(ctx, app, title, message, "error")
}

// formatDuration formats a duration for display.
func formatDuration(d time.Duration) string {
	if d < time.Minute {
		return fmt.Sprintf("%ds", int(d.Seconds()))
	}

	minutes := int(d.Minutes())
	seconds := int(d.Seconds()) % secondsPerMinute

	return fmt.Sprintf("%dm %ds", minutes, seconds)
}

// minInt returns the smaller of two integers.
func minInt(a, b int) int {
	if a < b {
		return a
	}

	return b
}

func (svc *Service) sendNotifications(
	ctx context.Context,
	app *models.App,
	title, message, priority string,
) {
	// Send to ntfy if configured
	if app.NtfyTopic.Valid && app.NtfyTopic.String != "" {
		ntfyTopic := app.NtfyTopic.String
		appName := app.Name

		go func() {
			// Use context.WithoutCancel to ensure notification completes
			// even if the parent context is cancelled.
			notifyCtx := context.WithoutCancel(ctx)

			ntfyErr := svc.sendNtfy(notifyCtx, ntfyTopic, title, message, priority)
			if ntfyErr != nil {
				svc.log.Error(
					"failed to send ntfy notification",
					"error", ntfyErr,
					"app", appName,
				)
			}
		}()
	}

	// Send to Slack if configured
	if app.SlackWebhook.Valid && app.SlackWebhook.String != "" {
		slackWebhook := app.SlackWebhook.String
		appName := app.Name

		go func() {
			// Use context.WithoutCancel to ensure notification completes
			// even if the parent context is cancelled.
			notifyCtx := context.WithoutCancel(ctx)

			slackErr := svc.sendSlack(notifyCtx, slackWebhook, title, message, priority)
			if slackErr != nil {
				svc.log.Error(
					"failed to send slack notification",
					"error", slackErr,
					"app", appName,
				)
			}
		}()
	}
}

func (svc *Service) sendNtfy(
	ctx context.Context,
	topic, title, message, priority string,
) error {
	svc.log.Debug("sending ntfy notification", "topic", topic, "title", title)

	request, err := http.NewRequestWithContext(
		ctx,
		http.MethodPost,
		topic,
		bytes.NewBufferString(message),
	)
	if err != nil {
		return fmt.Errorf("failed to create ntfy request: %w", err)
	}

	request.Header.Set("Title", title)
	request.Header.Set("Priority", svc.ntfyPriority(priority))

	resp, err := svc.client.Do(request)
	if err != nil {
		return fmt.Errorf("failed to send ntfy request: %w", err)
	}

	defer func() {
		_ = resp.Body.Close()
	}()

	if resp.StatusCode >= httpStatusClientError {
		return fmt.Errorf("%w: status %d", ErrNtfyFailed, resp.StatusCode)
	}

	return nil
}

func (svc *Service) ntfyPriority(priority string) string {
	switch priority {
	case "error":
		return "urgent"
	case "success":
		return "default"
	case "info":
		return "low"
	default:
		return "default"
	}
}

func (svc *Service) slackColor(priority string) string {
	switch priority {
	case "error":
		return "#dc3545" // red
	case "success":
		return "#28a745" // green
	case "info":
		return "#17a2b8" // blue
	default:
		return "#6c757d" // gray
	}
}

// SlackPayload represents a Slack webhook payload.
type SlackPayload struct {
	Text        string            `json:"text"`
	Attachments []SlackAttachment `json:"attachments,omitempty"`
}

// SlackAttachment represents a Slack attachment.
type SlackAttachment struct {
	Color string `json:"color"`
	Title string `json:"title"`
	Text  string `json:"text"`
}

func (svc *Service) sendSlack(
	ctx context.Context,
	webhookURL, title, message, priority string,
) error {
	svc.log.Debug(
		"sending slack notification",
		"url", webhookURL,
		"title", title,
	)

	payload := SlackPayload{
		Attachments: []SlackAttachment{
			{
				Color: svc.slackColor(priority),
				Title: title,
				Text:  message,
			},
		},
	}

	body, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("failed to marshal slack payload: %w", err)
	}

	request, err := http.NewRequestWithContext(
		ctx,
		http.MethodPost,
		webhookURL,
		bytes.NewBuffer(body),
	)
	if err != nil {
		return fmt.Errorf("failed to create slack request: %w", err)
	}

	request.Header.Set("Content-Type", "application/json")

	resp, err := svc.client.Do(request)
	if err != nil {
		return fmt.Errorf("failed to send slack request: %w", err)
	}

	defer func() {
		_ = resp.Body.Close()
	}()

	if resp.StatusCode >= httpStatusClientError {
		return fmt.Errorf("%w: status %d", ErrSlackFailed, resp.StatusCode)
	}

	return nil
}