const NotificationProvider = require("./notification-provider");
const { finalizeEvent, Relay, nip19, nip59 } = require("nostr-tools");

// polyfill WebSocket for nostr-tools
global.WebSocket = require("isomorphic-ws");

class Nostr extends NotificationProvider {
    name = "nostr";

    /**
     * @inheritdoc
     */
    async send(notification, msg, monitorJSON = null, heartbeatJSON = null) {
        const senderPrivateKey = await this.getPrivateKey(notification.sender);
        const recipientsPublicKeys = await this.getPublicKeys(notification.recipients);

        // Create NIP-59 gift-wrapped events for each recipient
        // This uses NIP-17 kind 14 (private direct message) wrapped with NIP-59
        // to prevent metadata leakage (sender/recipient public keys are hidden)
        const createdAt = Math.floor(Date.now() / 1000);
        const events = [];
        for (const recipientPublicKey of recipientsPublicKeys) {
            const event = {
                kind: 14, // NIP-17 private direct message
                created_at: createdAt,
                tags: [["p", recipientPublicKey]],
                content: msg,
            };
            try {
                const wrappedEvent = nip59.wrapEvent(event, senderPrivateKey, recipientPublicKey);
                events.push(wrappedEvent);
            } catch (error) {
                throw new Error(`Failed to create gift-wrapped event for recipient: ${error.message}`);
            }
        }

        // Publish events to each relay
        const relays = notification.relays.split("\n");
        let successfulRelays = 0;
        for (const relayUrl of relays) {
            const relay = await Relay.connect(relayUrl);
            let eventIndex = 0;

            // Authenticate to the relay, if required
            try {
                await relay.publish(events[0]);
                eventIndex = 1;
            } catch (error) {
                if (relay.challenge) {
                    await relay.auth(async (evt) => {
                        return finalizeEvent(evt, senderPrivateKey);
                    });
                }
            }

            try {
                for (let i = eventIndex; i < events.length; i++) {
                    await relay.publish(events[i]);
                }
                successfulRelays++;
            } catch (error) {
                console.error(`Failed to publish event to ${relayUrl}:`, error);
            } finally {
                relay.close();
            }
        }

        // Report success or failure
        if (successfulRelays === 0) {
            throw Error("Failed to connect to any relays.");
        }
        return `${successfulRelays}/${relays.length} relays connected.`;
    }

    /**
     * Get the private key for the sender
     * @param {string} sender Sender to retrieve key for
     * @returns {nip19.DecodeResult} Private key
     */
    async getPrivateKey(sender) {
        try {
            const senderDecodeResult = await nip19.decode(sender);
            const { data } = senderDecodeResult;
            return data;
        } catch (error) {
            throw new Error(`Failed to decode private key for sender ${sender}: ${error.message}`);
        }
    }

    /**
     * Get public keys for recipients
     * @param {string} recipients Newline delimited list of recipients
     * @returns {Promise<nip19.DecodeResult[]>} Public keys
     */
    async getPublicKeys(recipients) {
        const recipientsList = recipients.split("\n");
        const publicKeys = [];
        for (const recipient of recipientsList) {
            try {
                const recipientDecodeResult = await nip19.decode(recipient);
                const { type, data } = recipientDecodeResult;
                if (type === "npub") {
                    publicKeys.push(data);
                } else {
                    throw new Error(`Recipient ${recipient} is not an npub`);
                }
            } catch (error) {
                throw new Error(`Error decoding recipient ${recipient}: ${error}`);
            }
        }
        return publicKeys;
    }
}

module.exports = Nostr;