export class WorkflowImportError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'WorkflowImportError';
  }
}

export type WorkflowEditorNodeType =
  | 'text'
  | 'asset'
  | 'aspectRatio'
  | 'model'
  | 'llm'
  | 'transformText'
  | 'splitText'
  | 'ifElse'
  | 'groupItems'
  | 'sliceAssets'
  | 'forEach'
  | 'forEachEnd'
  | 'stickyNote'
  | 'approval'
  | 'modelInput';

export const VALID_EDITOR_NODE_TYPES: readonly WorkflowEditorNodeType[] = [
  'text',
  'asset',
  'aspectRatio',
  'model',
  'llm',
  'transformText',
  'splitText',
  'ifElse',
  'groupItems',
  'sliceAssets',
  'forEach',
  'forEachEnd',
  'stickyNote',
  'approval',
  'modelInput',
];

export interface WorkflowExportData {
  version: '1.0';
  name: string;
  description: string;
  editorInfo: {
    nodes: Array<{ type: WorkflowEditorNodeType; [key: string]: unknown }>;
    edges: Array<{ [key: string]: unknown }>;
    inputKeys: string[];
  };
  inputs: unknown[];
  tagSet: string[];
  uiConfig?: object;
  exportedAt: string;
  exportedBy: string;
}

/**
 * Validates a workflow export payload (e.g. from a JSON file import).
 *
 * Throws a `WorkflowImportError` with a human-readable message on the first
 * violation found. Returns the validated data cast to `WorkflowExportData`.
 *
 * Checks performed:
 *  1. Data is a non-null object
 *  2. `version` field is present and equals "1.0"
 *  3. `editorInfo` has non-empty `nodes` and `edges` arrays
 *  4. Each node's `type` is a recognized editor node type
 *  5. `inputs` is an array
 */
export function validateEditorInfo(data: unknown): WorkflowExportData {
  if (typeof data !== 'object' || data === null) {
    throw new WorkflowImportError('Invalid JSON format');
  }

  const workflow = data as Partial<WorkflowExportData>;

  if (!workflow.version) {
    throw new WorkflowImportError('Missing version field');
  }

  if (workflow.version !== '1.0') {
    throw new WorkflowImportError(`Unsupported version: ${workflow.version}`);
  }

  if (!workflow.editorInfo || !workflow.editorInfo.nodes || !workflow.editorInfo.edges) {
    throw new WorkflowImportError('Missing editorInfo structure');
  }

  if (!Array.isArray(workflow.editorInfo.nodes)) {
    throw new WorkflowImportError('Invalid nodes array');
  }

  if (!Array.isArray(workflow.editorInfo.edges)) {
    throw new WorkflowImportError('Invalid edges array');
  }

  if (!workflow.inputs || !Array.isArray(workflow.inputs)) {
    throw new WorkflowImportError('Invalid inputs array');
  }

  for (const node of workflow.editorInfo.nodes) {
    if (!(VALID_EDITOR_NODE_TYPES as readonly string[]).includes(node.type)) {
      throw new WorkflowImportError(`Invalid node type: ${node.type}`);
    }
  }

  return workflow as WorkflowExportData;
}