/**
 * DynamoDB operations handler
 *
 * Tables:
 *  - email-rules          → OOO / Forward rules per address
 *  - ses-outbound-messages → Bounce info (MessageId → original sender)
 *  - email-blocked-senders → Blocked patterns per address
 */

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import {
  DynamoDBDocumentClient,
  GetCommand,
  BatchGetCommand,
} from '@aws-sdk/lib-dynamodb';
import { config } from '../config.js';
import { log } from '../logger.js';

// ---------------------------------------------------------------------------
// Types
// ---------------------------------------------------------------------------
export interface EmailRule {
  email_address: string;
  ooo_active?: boolean;
  ooo_message?: string;
  ooo_content_type?: string;
  forwards?: string[];
  [key: string]: unknown;
}

export interface BounceInfo {
  original_source: string;
  bounceType: string;
  bounceSubType: string;
  bouncedRecipients: string[];
  timestamp: string;
}

// ---------------------------------------------------------------------------
// Handler
// ---------------------------------------------------------------------------
export class DynamoDBHandler {
  private docClient: DynamoDBDocumentClient;
  public available = false;

  constructor() {
    const raw = new DynamoDBClient({ region: config.awsRegion });
    this.docClient = DynamoDBDocumentClient.from(raw, {
      marshallOptions: { removeUndefinedValues: true },
    });
    this.initialize();
  }

  // -----------------------------------------------------------------------
  // Init
  // -----------------------------------------------------------------------
  private initialize(): void {
    // We just mark as available; actual connectivity is tested on first call.
    // The Python version tested table_status, but that's a DescribeTable call
    // which is heavy and not needed – the first GetItem will tell us.
    this.available = true;
    log('✓ DynamoDB client initialized');
  }

  /**
   * Verify tables exist by doing a cheap GetItem on each.
   * Called once during startup.
   */
  async verifyTables(): Promise<boolean> {
    try {
      await Promise.all([
        this.docClient.send(
          new GetCommand({ TableName: config.rulesTable, Key: { email_address: '__probe__' } }),
        ),
        this.docClient.send(
          new GetCommand({ TableName: config.messagesTable, Key: { MessageId: '__probe__' } }),
        ),
        this.docClient.send(
          new GetCommand({ TableName: config.blockedTable, Key: { email_address: '__probe__' } }),
        ),
      ]);
      this.available = true;
      log('✓ DynamoDB tables connected successfully');
      return true;
    } catch (err: any) {
      log(`⚠ DynamoDB not fully available: ${err.message ?? err}`, 'WARNING');
      this.available = false;
      return false;
    }
  }

  // -----------------------------------------------------------------------
  // Email rules
  // -----------------------------------------------------------------------
  async getEmailRules(emailAddress: string): Promise<EmailRule | null> {
    if (!this.available) return null;
    try {
      const resp = await this.docClient.send(
        new GetCommand({
          TableName: config.rulesTable,
          Key: { email_address: emailAddress },
        }),
      );
      return (resp.Item as EmailRule) ?? null;
    } catch (err: any) {
      if (err.name !== 'ResourceNotFoundException') {
        log(`⚠ DynamoDB error for ${emailAddress}: ${err.message ?? err}`, 'ERROR');
      }
      return null;
    }
  }

  // -----------------------------------------------------------------------
  // Bounce info
  // -----------------------------------------------------------------------
  async getBounceInfo(
    messageId: string,
    workerName = 'unified',
  ): Promise<BounceInfo | null> {
    if (!this.available) return null;

    for (let attempt = 0; attempt < config.bounceLookupRetries; attempt++) {
      try {
        const resp = await this.docClient.send(
          new GetCommand({
            TableName: config.messagesTable,
            Key: { MessageId: messageId },
          }),
        );

        if (resp.Item) {
          return {
            original_source: (resp.Item.original_source as string) ?? '',
            bounceType: (resp.Item.bounceType as string) ?? 'Unknown',
            bounceSubType: (resp.Item.bounceSubType as string) ?? 'Unknown',
            bouncedRecipients: (resp.Item.bouncedRecipients as string[]) ?? [],
            timestamp: (resp.Item.timestamp as string) ?? '',
          };
        }

        if (attempt < config.bounceLookupRetries - 1) {
          log(
            `  Bounce record not found yet, retrying in ${config.bounceLookupDelay}s ` +
              `(attempt ${attempt + 1}/${config.bounceLookupRetries})...`,
            'INFO',
            workerName,
          );
          await sleep(config.bounceLookupDelay * 1000);
        } else {
          log(
            `⚠ No bounce record found after ${config.bounceLookupRetries} attempts ` +
              `for Message-ID: ${messageId}`,
            'WARNING',
            workerName,
          );
          return null;
        }
      } catch (err: any) {
        log(
          `⚠ DynamoDB Error (attempt ${attempt + 1}/${config.bounceLookupRetries}): ` +
            `${err.message ?? err}`,
          'ERROR',
          workerName,
        );
        if (attempt < config.bounceLookupRetries - 1) {
          await sleep(config.bounceLookupDelay * 1000);
        } else {
          return null;
        }
      }
    }
    return null;
  }

  // -----------------------------------------------------------------------
  // Blocked senders
  // -----------------------------------------------------------------------
  async getBlockedPatterns(emailAddress: string): Promise<string[]> {
    if (!this.available) return [];
    try {
      const resp = await this.docClient.send(
        new GetCommand({
          TableName: config.blockedTable,
          Key: { email_address: emailAddress },
        }),
      );
      return (resp.Item?.blocked_patterns as string[]) ?? [];
    } catch (err: any) {
      log(`⚠ Error getting block list for ${emailAddress}: ${err.message ?? err}`, 'ERROR');
      return [];
    }
  }

  async batchGetBlockedPatterns(
    emailAddresses: string[],
  ): Promise<Record<string, string[]>> {
    const empty: Record<string, string[]> = {};
    for (const a of emailAddresses) empty[a] = [];
    if (!this.available || emailAddresses.length === 0) return empty;

    try {
      const keys = emailAddresses.map((a) => ({ email_address: a }));
      const resp = await this.docClient.send(
        new BatchGetCommand({
          RequestItems: {
            [config.blockedTable]: { Keys: keys },
          },
        }),
      );

      const items = resp.Responses?.[config.blockedTable] ?? [];
      const result: Record<string, string[]> = { ...empty };
      for (const item of items) {
        const addr = item.email_address as string;
        result[addr] = (item.blocked_patterns as string[]) ?? [];
      }
      return result;
    } catch (err: any) {
      log(`⚠ Batch blocklist check error: ${err.message ?? err}`, 'ERROR');
      return empty;
    }
  }
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------
function sleep(ms: number): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, ms));
}