import { SourceUnit } from 'solidity-ast';
import { Node } from 'solidity-ast/node';
import { findAll } from 'solidity-ast/utils';

import path from 'path';
import { relativePath } from '../utils/relative-path';

import { getNodeBounds } from '../solc/ast-utils';
import { Transformation } from './type';

export function appendInitializableImport(initializablePath: string) {
  return function* (sourceUnit: SourceUnit): Generator<Transformation> {
    const contracts = [...findAll('ContractDefinition', sourceUnit)];
    if (!contracts.some(c => c.contractKind === 'contract')) {
      return;
    }

    let last: Node | undefined;
    for (const node of findAll('PragmaDirective', sourceUnit)) {
      last = node;
    }
    for (const node of findAll('ImportDirective', sourceUnit)) {
      last = node;
    }

    const relativeImportPath = relativePath(
      path.dirname(sourceUnit.absolutePath),
      initializablePath,
    );

    const after = last ? getNodeBounds(last) : { start: 0, length: 0 };
    const start = after.start + after.length;

    yield {
      start,
      length: 0,
      kind: 'append-initializable-import',
      text: `\nimport "${relativeImportPath}";`,
    };
  };
}