import Io from "@specs-feup/lara/api/lara/Io.js";
import { debug } from "@specs-feup/lara/api/lara/core/LaraCore.js";
import { JavaClasses } from "@specs-feup/lara/api/lara/util/JavaTypes.js";
import { FileJp } from "../../Joinpoints.js";
import Clava from "../Clava.js";

/**
 * Given a folder, collects sources in that folder, parses and returns one each time next() is called.
 *
 * Pushes an empty Clava AST. Parsed files are added one at a time, and the AST contains at most one file at any given time.
 *
 * @param srcFoldername - Name of the folder with the source files to iterate.
 * @param sourceExt - Extensions of the source files.
 * @param headerExt - Extensions of the header files.
 */
export default class FileIterator {
  files: JavaClasses.File[] = [];
  currentFile: number = 0;
  isInit: boolean = false;
  isClosed: boolean = false;
  pushedAst: boolean = false;

  srcFoldername: string;
  sourceExt: string[];
  headerExt: string[];

  constructor(
    srcFoldername: string,
    sourceExt: string[] = ["c", "cpp"],
    headerExt: string[] = ["h", "hpp"]
  ) {
    this.srcFoldername = srcFoldername;
    this.sourceExt = sourceExt;
    this.headerExt = headerExt;
  }

  /**
   * @returns $file join point, if there are still files to iterate over, or undefined otherwise
   */
  next(): FileJp | undefined {
    // Initialized, in case it has not been initialized yet
    this.init();

    // Check if finished
    if (!this.hasNext()) {
      return undefined;
    }

    // Next file
    const sourceFile = this.files[this.currentFile];

    // Increment
    this.currentFile++;

    debug("FileIterator.next: Processing file " + sourceFile.toString());

    // Ensure program tree is empty before adding file
    Clava.getProgram().removeChildren();

    Clava.getProgram().addFileFromPath(sourceFile);

    // Rebuild
    Clava.rebuild();

    const $firstChild = Clava.getProgram().getDescendants("file")?.[0] as
      | FileJp
      | undefined;

    return $firstChild;
  }

  /**
   * @returns True if there are still files to iterate over, false otherwise.
   */
  hasNext(): boolean {
    // Init, if not yet initalized
    this.init();

    if (this.currentFile < this.files.length) {
      return true;
    }

    // Close, if not yet closed
    this.close();

    return false;
  }

  private init() {
    if (this.isInit) {
      // Already initialized
      return;
    }

    this.isInit = true;

    const srcFolder = Io.getPath(
      Clava.getData().getContextFolder(),
      this.srcFoldername
    );

    this.addIncludes(srcFolder, this.headerExt);

    this.files = this.getFiles(srcFolder, this.sourceExt);

    // Sort files
    this.files.sort();

    debug("FileIterator: found " + this.files.length + " files");

    // Work on new AST tree
    Clava.pushAst();
    this.pushedAst = true;
  }

  private close() {
    if (this.isClosed) {
      return;
    }

    this.isClosed = true;

    // Recover previous AST
    if (this.pushedAst) {
      Clava.popAst();
    }
  }

  /**
   * Attempts to add folders of header files as includes.
   *
   */
  private addIncludes(
    srcFolder: string | JavaClasses.File,
    headerExt: string[]
  ) {
    // TODO: If needed, add a 'nestingLevel' parameter, which includes up to X ancestors for each header,
    // cutting off if ancestors go before srcFolder

    // Current user includes
    const data = Clava.getData();
    const userIncludes = data.getUserIncludes();
    debug(
      "FileIterator._addIncludes: User includes before " +
        userIncludes.join(", ")
    );

    // Populate initial set with user includes
    const parents: Set<string> = new Set();

    for (const userInclude of userIncludes) {
      parents.add(Io.getAbsolutePath(userInclude));
    }

    // Get folders of hFiles
    const headerFiles = this.getFiles(srcFolder, headerExt);

    for (const hFile of headerFiles) {
      parents.add(Io.getAbsolutePath(hFile.getParentFile()));
    }

    // Build new value
    const includeFolders: JavaClasses.File[] = [];
    for (const parent of parents.values()) {
      // Converting to File
      includeFolders.push(Io.getPath(parent));
    }
    data.setUserIncludes(
      ...includeFolders.map((folder) => folder.getAbsolutePath())
    );
    debug(
      "FileIterator._addIncludes: User includes after " +
        data.getUserIncludes().join(", ")
    );
  }

  private getFiles(folder: string | JavaClasses.File, extensions: string[]) {
    let files: JavaClasses.File[] = [];

    for (const extension of extensions) {
      const sourceFiles = Io.getFiles(folder, "*." + extension, true);
      files = files.concat(sourceFiles);
    }

    return files;
  }
}