/* @flow */

import type {WalkFiles} from './fs.js';
import {removeSuffix} from './misc.js';

const mm = require('micromatch');
const path = require('path');

const WHITESPACE_RE = /^\s+$/;

export type IgnoreFilter = {
  base: string,
  isNegation: boolean,
  regex: RegExp,
  pattern: string,
};

export function sortFilter(
  files: WalkFiles,
  filters: Array<IgnoreFilter>,
  keepFiles: Set<string> = new Set(),
  possibleKeepFiles: Set<string> = new Set(),
  ignoreFiles: Set<string> = new Set(),
): {
  keepFiles: Set<string>,
  ignoreFiles: Set<string>,
} {
  for (const file of files) {
    let keep = false;

    // always keep a file if a ! pattern matches it
    for (const filter of filters) {
      if (filter.isNegation && matchesFilter(filter, file.basename, file.relative)) {
        keep = true;
        break;
      }
    }

    //
    if (keep) {
      keepFiles.add(file.relative);
      continue;
    }

    // otherwise don't keep it if a pattern matches it
    keep = true;
    for (const filter of filters) {
      if (!filter.isNegation && matchesFilter(filter, file.basename, file.relative)) {
        keep = false;
        break;
      }
    }

    if (keep) {
      possibleKeepFiles.add(file.relative);
    } else {
      ignoreFiles.add(file.relative);
    }
  }

  // exclude file
  for (const file of possibleKeepFiles) {
    const parts = path.dirname(file).split(path.sep);

    while (parts.length) {
      const folder = parts.join(path.sep);
      if (ignoreFiles.has(folder)) {
        ignoreFiles.add(file);
        break;
      }
      parts.pop();
    }
  }

  //
  for (const file of possibleKeepFiles) {
    if (!ignoreFiles.has(file)) {
      keepFiles.add(file);
    }
  }

  //
  for (const file of keepFiles) {
    const parts = path.dirname(file).split(path.sep);

    while (parts.length) {
      // deregister this folder from being ignored, any files inside
      // will still be marked as ignored
      ignoreFiles.delete(parts.join(path.sep));
      parts.pop();
    }
  }

  return {ignoreFiles, keepFiles};
}

export function matchesFilter(filter: IgnoreFilter, basename: string, loc: string): boolean {
  if (filter.base && filter.base !== '.') {
    loc = path.relative(filter.base, loc);
  }
  return (
    filter.regex.test(loc) ||
    filter.regex.test(`/${loc}`) ||
    filter.regex.test(basename) ||
    mm.isMatch(loc, filter.pattern)
  );
}

export function ignoreLinesToRegex(lines: Array<string>, base: string = '.'): Array<IgnoreFilter> {
  return (
    lines
      // create regex
      .map((line): ?IgnoreFilter => {
        // remove empty lines, comments, etc
        if (line === '' || line === '!' || line[0] === '#' || WHITESPACE_RE.test(line)) {
          return null;
        }

        let pattern = line;
        let isNegation = false;

        // hide the fact that it's a negation from minimatch since we'll handle this specifically
        // ourselves
        if (pattern[0] === '!') {
          isNegation = true;
          pattern = pattern.slice(1);
        }

        // remove trailing slash
        pattern = removeSuffix(pattern, '/');

        const regex: ?RegExp = mm.makeRe(pattern.trim(), {nocase: true});

        if (regex) {
          return {
            base,
            isNegation,
            pattern,
            regex,
          };
        } else {
          return null;
        }
      })
      .filter(Boolean)
  );
}

export function filterOverridenGitignores(files: WalkFiles): WalkFiles {
  const IGNORE_FILENAMES = ['.yarnignore', '.npmignore', '.gitignore'];
  const GITIGNORE_NAME = IGNORE_FILENAMES[2];
  return files.filter(file => IGNORE_FILENAMES.indexOf(file.basename) > -1).reduce((acc: WalkFiles, file) => {
    if (file.basename !== GITIGNORE_NAME) {
      return [...acc, file];
    } else {
      //don't include .gitignore if .npmignore or .yarnignore are present
      const dir = path.dirname(file.absolute);
      const higherPriorityIgnoreFilePaths = [`${dir}/${IGNORE_FILENAMES[0]}`, `${dir}/${IGNORE_FILENAMES[1]}`];
      const hasHigherPriorityFiles = files.find(file => higherPriorityIgnoreFilePaths.indexOf(file.absolute) > -1);
      if (!hasHigherPriorityFiles) {
        return [...acc, file];
      }
    }
    return acc;
  }, []);
}
