import {
  CodeLensProvider,
  TextDocument,
  CodeLens,
  Range,
  Command
} from "vscode";

interface Reference {
  document: TextDocument;
  citekey: string;
  pagenr: number | null;
  range: Range;
}

class ZoteroCodeLensProvider implements CodeLensProvider {
  // Each provider requires a provideCodeLenses function which will give the various documents
  // the code lenses
  async provideCodeLenses(document: TextDocument): Promise<CodeLens[]> {
    // const txt = document.getText();

    const references = this.findReferences(document);

    return references.map(reference => [
      new CodeLens(reference.range, {
        title: '@' + reference.citekey,
        command: 'extension.showInZotero',
        arguments: [reference]
      }),
      new CodeLens(reference.range, {
        title: '(pdf)',
        command: 'extension.openZoteroPDF',
        arguments: [reference]
      })]).flat();


    // let codeLens = new CodeLens(topOfDocument, c);

    // return [codeLens];
  }

  // TODO match citations in brackets [@citation] inline @citatinon,
  // but also page number in [see @citation p.23] and
  // inlince @citation [p.23] (so brackets after inline)
  // TODO possibly use https://github.com/martinring/markdown-it-citations/blob/ba82a511de047a2438b4ac060c4c71b5a5c82da9/src/index.ts#L43
  findReferences(document: TextDocument): Reference[] {
    const matches: Reference[] = [];
    for (let lineNr = 0; lineNr < document.lineCount; lineNr++) {
      const line = document.lineAt(lineNr);
      let match: RegExpExecArray | null;
      let regex = /(?<=@)\w+/g;
      regex.lastIndex = 0;
      const text = line.text;//.substring(0, 1000);
      while ((match = regex.exec(text))) {
        const result = {
          document: document,
          citekey: match[0],
          pagenr: null,
          range: new Range(lineNr, match.index, lineNr, match.index + match[0].length)
        };
        // if (result) {
        matches.push(result);
        // }
      }
    }
    return matches;
  }
}

export default ZoteroCodeLensProvider;