//
//  NotificationService.swift
//  NotificationService
//
//  Created by Matias Carulli on 5/7/26.
//

import UserNotifications
import Intents

class NotificationService: UNNotificationServiceExtension {

    var contentHandler: ((UNNotificationContent) -> Void)?
    var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.contentHandler = contentHandler
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)

        guard
            let content = bestAttemptContent,
            let imageUrlString = request.content.userInfo["imageUrl"] as? String,
            let imageUrl = URL(string: imageUrlString)
        else {
            contentHandler(request.content)
            return
        }

        let userInfo = request.content.userInfo

        // Download the avatar (the sending network's photo), then render the
        // notification. A data task lets us hand the bytes straight to INImage.
        URLSession.shared.dataTask(with: imageUrl) { data, _, error in
            guard let data = data, !data.isEmpty, error == nil else {
                contentHandler(content)
                return
            }

            // iOS 15+: render as a communication notification — large circular
            // avatar with the app icon badged in the corner.
            if #available(iOS 15.0, *) {
                self.deliverAsCommunicationNotification(content: content, imageData: data, userInfo: userInfo, contentHandler: contentHandler)
            } else {
                // iOS 14 fallback: attach the image as a plain thumbnail.
                let tmpFile = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("avatar.png")
                try? data.write(to: tmpFile)
                if let attachment = try? UNNotificationAttachment(identifier: "avatar", url: tmpFile) {
                    content.attachments = [attachment]
                }
                contentHandler(content)
            }
        }.resume()
    }

    @available(iOS 15.0, *)
    private func deliverAsCommunicationNotification(
        content: UNMutableNotificationContent,
        imageData: Data,
        userInfo: [AnyHashable: Any],
        contentHandler: @escaping (UNNotificationContent) -> Void
    ) {
        // The conversation title shown in bold. Defaults to the notification's own
        // title so existing copy (e.g. "Group | Alice") is preserved.
        let senderName = (userInfo["senderName"] as? String) ?? content.title
        let isGroup = (userInfo["isGroup"] as? Bool) ?? false
        // Group related notifications into one conversation so iOS stacks them.
        let conversationId = (userInfo["conversationId"] as? String)
            ?? (userInfo["threadId"] as? String)
            ?? content.threadIdentifier

        let avatar = INImage(imageData: imageData)

        let handle = INPersonHandle(value: conversationId, type: .unknown)
        let sender = INPerson(
            personHandle: handle,
            nameComponents: nil,
            displayName: senderName,
            image: avatar,
            contactIdentifier: nil,
            customIdentifier: conversationId
        )

        let intent = INSendMessageIntent(
            recipients: nil,
            outgoingMessageType: .outgoingMessageText,
            content: content.body,
            speakableGroupName: isGroup ? INSpeakableString(spokenPhrase: senderName) : nil,
            conversationIdentifier: conversationId,
            serviceName: nil,
            sender: sender,
            attachments: nil
        )

        // For a group conversation the avatar comes from the group image; for a
        // 1:1 it comes from the sender's INPerson image (set above).
        if isGroup {
            intent.setImage(avatar, forParameterNamed: \.speakableGroupName)
        }

        let interaction = INInteraction(intent: intent, response: nil)
        interaction.direction = .incoming
        interaction.donate(completion: nil)

        do {
            let updated = try content.updating(from: intent)
            contentHandler(updated)
        } catch {
            // If the intent can't be applied, fall back to the unmodified content
            // so the notification still shows.
            contentHandler(content)
        }
    }

    override func serviceExtensionTimeWillExpire() {
        if let contentHandler = contentHandler, let content = bestAttemptContent {
            contentHandler(content)
        }
    }

}