import {
  CodeLensProvider,
  TextDocument,
  CodeLens,
  Range,
  Command
} from "vscode";
import { findReferences } from "./reference";

export 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 references = findReferences(document);

    // some sorting and filtering to have a nicer lens
    return references
      // sort by line, citekey, pagenr
      .sort((a, b) => {
        if (a.range.start.line !== b.range.start.line) {
          return a.range.start.line - b.range.start.line;
        }
        if (a.citekey !== b.citekey) {
          return a.citekey.localeCompare(b.citekey);
        }
        // nulls sort before anything else
        if (a.pagenr === null) {
          return -1;
        }
        if (b.pagenr === null) {
          return 1;
        }
        return a.pagenr - b.pagenr;
      })
      // remove duplicate items (which are in sequence)
      .filter((reference, index) => {
        if (index === 0) { return true; }
        if (
          references[index - 1].range.start.line !== reference.range.start.line ||
          references[index - 1].citekey !== reference.citekey ||
          references[index - 1].pagenr !== reference.pagenr
        ) {
          return true;
        }
        return false;
      })
      .map((reference, index) => {
        let title = "";
        if (
          index === 0 ||
          references[index - 1].range.start.line !== reference.range.start.line ||
          references[index - 1].citekey !== reference.citekey
        ) {
          title = `@${reference.citekey}`;
          if (reference.pagenr) {
            title += ` p.${reference.pagenr}`;
          }
        } else {
          // there has to be a pagenr because of filtering
          title = `p.${reference.pagenr}`; 
        }

        // ignore char pos so that the order of the array
        // is actually used (by default CodeLenses are sorted by position)
        const range = new Range(
          reference.range.start.line, 0,
          reference.range.end.line, 0
        );

        return [
          new CodeLens(range, {
            title: title,
            // command: 'zoterolens.showInZotero',
            command: 'zoterolens.openZoteroPDF',
            arguments: [reference]
          }),
          // new CodeLens(reference.range, {
          //   title: '(pdf)',
          //   command: 'zoterolens.openZoteroPDF',
          //   arguments: [reference]
          // })
        ]
      })
      .flat();


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

    // return [codeLens];
  }

  
}