import type { LibSQLDatabase } from 'drizzle-orm/libsql';
import type * as schema from '../db/schema/index';
import { getEnabledNotificationSettings } from '../db/repositories/notification-repository';

// ── Types ──

type Db = LibSQLDatabase<typeof schema>;

/** Payload shape for notification callbacks from QueueService. */
export interface NotificationEvent {
  contentTitle: string;
  channelName: string;
  platform: string;
  url: string;
  filePath?: string;
  error?: string;
  attempt?: number;
  maxAttempts?: number;
}

/** Discord embed field shape. */
interface DiscordEmbedField {
  name: string;
  value: string;
  inline?: boolean;
}

/** Discord embed shape sent in webhook payload. */
interface DiscordEmbed {
  title: string;
  description: string;
  color: number;
  fields: DiscordEmbedField[];
  timestamp: string;
}

// ── Colors ──

const COLOR_GRAB = 0x3498db;    // blue
const COLOR_DOWNLOAD = 0x2ecc71; // green
const COLOR_FAILURE = 0xe74c3c;  // red

// ── NotificationService ──

/**
 * Dispatches notification embeds to configured Discord webhooks.
 * All dispatch is fire-and-forget — errors are logged but never thrown.
 */
export class NotificationService {
  constructor(private readonly db: Db) {}

  /**
   * Notify about a content grab (added to queue).
   */
  async notifyGrab(
    contentTitle: string,
    channelName: string,
    platform: string,
    url: string
  ): Promise<void> {
    const embed: DiscordEmbed = {
      title: '📥 Content Grabbed',
      description: `**${contentTitle}**`,
      color: COLOR_GRAB,
      fields: [
        { name: 'Channel', value: channelName, inline: true },
        { name: 'Platform', value: platform, inline: true },
        { name: 'URL', value: url },
      ],
      timestamp: new Date().toISOString(),
    };

    await this.dispatch('onGrab', embed);
  }

  /**
   * Notify about a successful download.
   */
  async notifyDownload(
    contentTitle: string,
    channelName: string,
    platform: string,
    url: string,
    filePath?: string
  ): Promise<void> {
    const fields: DiscordEmbedField[] = [
      { name: 'Channel', value: channelName, inline: true },
      { name: 'Platform', value: platform, inline: true },
      { name: 'URL', value: url },
    ];

    if (filePath) {
      fields.push({ name: 'File', value: filePath });
    }

    const embed: DiscordEmbed = {
      title: '✅ Download Complete',
      description: `**${contentTitle}**`,
      color: COLOR_DOWNLOAD,
      fields,
      timestamp: new Date().toISOString(),
    };

    await this.dispatch('onDownload', embed);
  }

  /**
   * Notify about a download failure.
   */
  async notifyFailure(
    contentTitle: string,
    channelName: string,
    platform: string,
    error: string,
    attempt: number,
    maxAttempts: number
  ): Promise<void> {
    const embed: DiscordEmbed = {
      title: '❌ Download Failed',
      description: `**${contentTitle}**`,
      color: COLOR_FAILURE,
      fields: [
        { name: 'Channel', value: channelName, inline: true },
        { name: 'Platform', value: platform, inline: true },
        { name: 'Error', value: error.slice(0, 1024) },
        { name: 'Attempt', value: `${attempt} / ${maxAttempts}`, inline: true },
      ],
      timestamp: new Date().toISOString(),
    };

    await this.dispatch('onFailure', embed);
  }

  // ── Private ──

  /**
   * Load enabled notification settings with the matching event toggle,
   * and POST the embed to each Discord webhook. Errors are logged with
   * channel name but never thrown — dispatch is fire-and-forget.
   */
  private async dispatch(
    eventType: 'onGrab' | 'onDownload' | 'onFailure',
    embed: DiscordEmbed
  ): Promise<void> {
    let settings;
    try {
      settings = await getEnabledNotificationSettings(this.db);
    } catch (err) {
      console.log(
        `[notification] failed to load settings: ${err instanceof Error ? err.message : String(err)}`
      );
      return;
    }

    // Filter to settings that have the matching event toggle enabled
    const matching = settings.filter((s) => s[eventType] === true);

    for (const setting of matching) {
      const config = setting.config as { webhookUrl?: string };
      const webhookUrl = config?.webhookUrl;

      if (!webhookUrl) {
        console.log(
          `[notification] skip channel="${setting.name}" — no webhook URL configured`
        );
        continue;
      }

      try {
        const response = await fetch(webhookUrl, {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({ embeds: [embed] }),
        });

        if (!response.ok) {
          console.log(
            `[notification] dispatch failed channel="${setting.name}" event=${eventType} httpStatus=${response.status}`
          );
        } else {
          console.log(
            `[notification] dispatch success channel="${setting.name}" event=${eventType}`
          );
        }
      } catch (err) {
        console.log(
          `[notification] dispatch error channel="${setting.name}" event=${eventType} error="${err instanceof Error ? err.message : String(err)}"`
        );
      }
    }
  }
}