import { FSWatcher } from "fs";
import { Gulp } from "gulp";
import { Minimatch } from "minimatch";
import { TaskFunction } from "../utils/gulp-task-function";
import { asString, join } from "../utils/matcher";

export interface Options {
  /**
   * An array of minimatch patterns
   */
  files: string[];

  /**
   * Base-directory for copy
   */
  from: string;

  /**
   * Target directory
   */
  to: string;
}

/**
 * Return a list of sources, prefixed by "from"
 */
export function getSources({files, from}: Options): string[] {
  return files.map((val: string): string => asString(join(from, new Minimatch(val))));
}

export function copy(gulp: Gulp, options: Options): NodeJS.ReadableStream {
  return gulp
    .src(getSources(options), {base: options.from})
    .pipe(gulp.dest(options.to));
}

/**
 * Generate a task to copy files from one directory to an other.
 */
export function generateTask(gulp: Gulp, options: Options): TaskFunction {
  const task: TaskFunction = function (): NodeJS.ReadableStream {
    return copy(gulp, options);
  };
  task.displayName = "_copy";
  return task;
}

export function watch(gulp: Gulp, options: Options): FSWatcher {
  const buildTask: TaskFunction = generateTask(gulp, options);
  const sources: string[] = getSources(options);
  return gulp.watch(sources, {cwd: options.from}, buildTask) as FSWatcher;
}