import { dirname, relative, resolve } from 'path';
import findUnusedExports from 'ts-unused-exports';
import { RuleFailure, Rules, RuleWalker } from 'tslint';
import { ClassDeclaration, Identifier, SourceFile } from 'typescript';

const srcDir = resolve(dirname(__filename), '../src');
const unusedExports: Record<string, string[]> = findUnusedExports(resolve(srcDir, 'tsconfig.app.json'));

export class Rule extends Rules.AbstractRule {
  static FAILURE_STRING = 'Class is not used in project';

  apply(sourceFile: SourceFile): RuleFailure[] {
    return this.applyWithWalker(new NoUnusedExportWalker(sourceFile, this.getOptions()));
  }
}

class NoUnusedExportWalker extends RuleWalker {
  visitClassDeclaration(node: ClassDeclaration) {
    const nodeName = node.name;
    if (nodeName && this.isUnused(nodeName)) {
      this.addFailureAt(nodeName.getStart(), nodeName.text.length, Rule.FAILURE_STRING);
    }
    super.visitClassDeclaration(node);
  }

  private isUnused(nodeName: Identifier): boolean {
    const { fileName } = nodeName.getSourceFile();
    const relativePath = relative(srcDir, fileName).replace(/\.ts$/, '');
    const unusedVars = unusedExports[relativePath];
    return unusedVars && unusedVars.includes(`${nodeName.text}`);
  }
}