/**
 * DynamoDB client interface + thin implementation.
 *
 * The interface is what every tool handler receives — callers (including tests)
 * inject any object that satisfies it. The real implementation wraps the AWS SDK
 * DynamoDB DocumentClient, but the SDK is only instantiated when
 * RealDynamoClient.create() is explicitly called; nothing happens at import time
 * and no AWS calls are made unless you call a method.
 *
 * Tables used by this package:
 *   WorkOrders         – work-order records, keyed on `workOrderId` (PK)
 *   purchase-orders    – purchase-order records, keyed on `purchaseOrderId` (PK)
 *   SiteAssignments    – site records, keyed on `siteId` (PK)
 */

// ---------------------------------------------------------------------------
// DynamoDB record shapes returned from each table
// ---------------------------------------------------------------------------

export interface WorkOrderRecord {
  workOrderId: string;
  title: string;
  status: string;
  siteId?: string;
  assignedTo?: string;
  createdAt: string;
  updatedAt: string;
  description?: string;
  [key: string]: unknown;
}

export interface PurchaseOrderRecord {
  purchaseOrderId: string;
  vendor: string;
  status: string;
  totalAmount?: number;
  currency?: string;
  issuedAt: string;
  updatedAt: string;
  lineItems?: Array<{ description: string; quantity: number; unitPrice: number }>;
  [key: string]: unknown;
}

export interface SiteRecord {
  siteId: string;
  name: string;
  address?: string;
  region?: string;
  status: string;
  assignedTechnicians?: string[];
  [key: string]: unknown;
}

// ---------------------------------------------------------------------------
// Client interface — inject this everywhere; never import the AWS SDK directly
// ---------------------------------------------------------------------------

export interface InternalDataClient {
  getWorkOrder(workOrderId: string): Promise<WorkOrderRecord | null>;
  getPurchaseOrder(purchaseOrderId: string): Promise<PurchaseOrderRecord | null>;
  getSite(siteId: string): Promise<SiteRecord | null>;
}

// ---------------------------------------------------------------------------
// Real (AWS SDK-backed) implementation
//
// The AWS SDK import lives here — behind this class — so that:
//   a) Nothing happens at module load time (no credential resolution, no env reads).
//   b) Tests never reach this code; they inject a mock that satisfies the interface.
//
// TODO (DEFERRED auth layer): When the Gateway layer is built, the Lambda execution
// role will supply credentials via the standard AWS environment variables. At that
// point ensure the DocumentClient is constructed with the correct region and that
// the table names are injected via environment variables (WORK_ORDERS_TABLE,
// PURCHASE_ORDERS_TABLE, SITE_ASSIGNMENTS_TABLE) rather than hard-coded.
// ---------------------------------------------------------------------------

export class RealDynamoClient implements InternalDataClient {
  // Table names — override via environment variables at Lambda deploy time.
  private readonly workOrdersTable: string;
  private readonly purchaseOrdersTable: string;
  private readonly siteAssignmentsTable: string;

  // The DocumentClient is typed as `unknown` here to avoid importing the AWS SDK
  // at module scope. It is cast when needed inside each method.
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  private readonly ddb: any;

  private constructor(
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    ddb: any,
    workOrdersTable: string,
    purchaseOrdersTable: string,
    siteAssignmentsTable: string,
  ) {
    this.ddb = ddb;
    this.workOrdersTable = workOrdersTable;
    this.purchaseOrdersTable = purchaseOrdersTable;
    this.siteAssignmentsTable = siteAssignmentsTable;
  }

  /**
   * Factory — the only place the AWS SDK DocumentClient is instantiated.
   * Calling this from a Lambda handler (not at module scope) is the correct pattern.
   *
   * NOTE: @aws-sdk/client-dynamodb and @aws-sdk/lib-dynamodb are intentionally absent
   * from package.json until the Lambda runtime bundle is assembled (see TODO above).
   * The module specifiers are stored in runtime variables so TypeScript does not attempt
   * static module-resolution at build time.
   */
  static async create(): Promise<RealDynamoClient> {
    // Store specifiers in variables to prevent TypeScript static module resolution.
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const dynImport = (s: string): Promise<any> => import(/* @vite-ignore */ s);

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const { DynamoDBClient } = (await dynImport('@aws-sdk/client-dynamodb')) as {
      DynamoDBClient: new (cfg: { region: string }) => any;
    };
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const { DynamoDBDocumentClient } = (await dynImport('@aws-sdk/lib-dynamodb')) as {
      DynamoDBDocumentClient: { from: (c: any) => any };
    };

    const region = process.env['AWS_REGION'] ?? 'us-east-1';
    // eslint-disable-next-line @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-assignment
    const raw = new DynamoDBClient({ region });
    // eslint-disable-next-line @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-assignment
    const ddb = DynamoDBDocumentClient.from(raw);

    return new RealDynamoClient(
      ddb,
      process.env['WORK_ORDERS_TABLE'] ?? 'WorkOrders',
      process.env['PURCHASE_ORDERS_TABLE'] ?? 'purchase-orders',
      process.env['SITE_ASSIGNMENTS_TABLE'] ?? 'SiteAssignments',
    );
  }

  async getWorkOrder(workOrderId: string): Promise<WorkOrderRecord | null> {
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const dynImport = (s: string): Promise<any> => import(/* @vite-ignore */ s);
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const { GetCommand } = (await dynImport('@aws-sdk/lib-dynamodb')) as {
      GetCommand: new (i: any) => any;
    };
    // eslint-disable-next-line @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-assignment
    const result = await this.ddb.send(
      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
      new GetCommand({ TableName: this.workOrdersTable, Key: { workOrderId } }),
    );
    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
    return (result.Item as WorkOrderRecord) ?? null;
  }

  async getPurchaseOrder(purchaseOrderId: string): Promise<PurchaseOrderRecord | null> {
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const dynImport = (s: string): Promise<any> => import(/* @vite-ignore */ s);
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const { GetCommand } = (await dynImport('@aws-sdk/lib-dynamodb')) as {
      GetCommand: new (i: any) => any;
    };
    // eslint-disable-next-line @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-assignment
    const result = await this.ddb.send(
      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
      new GetCommand({ TableName: this.purchaseOrdersTable, Key: { purchaseOrderId } }),
    );
    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
    return (result.Item as PurchaseOrderRecord) ?? null;
  }

  async getSite(siteId: string): Promise<SiteRecord | null> {
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const dynImport = (s: string): Promise<any> => import(/* @vite-ignore */ s);
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const { GetCommand } = (await dynImport('@aws-sdk/lib-dynamodb')) as {
      GetCommand: new (i: any) => any;
    };
    // eslint-disable-next-line @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-assignment
    const result = await this.ddb.send(
      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
      new GetCommand({ TableName: this.siteAssignmentsTable, Key: { siteId } }),
    );
    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
    return (result.Item as SiteRecord) ?? null;
  }
}