'use strict';

const fs = require('graceful-fs');
const path = require('path');
const mkdirs = require('../mkdirs').mkdirs;
const pathExists = require('../path-exists').pathExists;
const utimesMillis = require('../util/utimes').utimesMillis;
const stat = require('../util/stat');

function copy(src, dest, opts, cb) {
  if (typeof opts === 'function' && !cb) {
    cb = opts;
    opts = {};
  } else if (typeof opts === 'function') {
    opts = { filter: opts };
  }

  cb = cb || function () {};
  opts = opts || {};

  opts.clobber = 'clobber' in opts ? !!opts.clobber : true; // default to true for now
  opts.overwrite = 'overwrite' in opts ? !!opts.overwrite : opts.clobber; // overwrite falls back to clobber

  // Warn about using preserveTimestamps on 32-bit node
  if (opts.preserveTimestamps && process.arch === 'ia32') {
    console.warn(`fs-extra: Using the preserveTimestamps option in 32-bit node is not recommended;\n
    see https://github.com/jprichardson/node-fs-extra/issues/269`);
  }

  stat.checkPaths(src, dest, 'copy', (err, stats) => {
    if (err) return cb(err);
    const { srcStat, destStat } = stats;
    stat.checkParentPaths(src, srcStat, dest, 'copy', (err) => {
      if (err) return cb(err);
      if (opts.filter)
        return handleFilter(checkParentDir, destStat, src, dest, opts, cb);
      return checkParentDir(destStat, src, dest, opts, cb);
    });
  });
}

function checkParentDir(destStat, src, dest, opts, cb) {
  const destParent = path.dirname(dest);
  pathExists(destParent, (err, dirExists) => {
    if (err) return cb(err);
    if (dirExists) return startCopy(destStat, src, dest, opts, cb);
    mkdirs(destParent, (err) => {
      if (err) return cb(err);
      return startCopy(destStat, src, dest, opts, cb);
    });
  });
}

function handleFilter(onInclude, destStat, src, dest, opts, cb) {
  Promise.resolve(opts.filter(src, dest)).then(
    (include) => {
      if (include) return onInclude(destStat, src, dest, opts, cb);
      return cb();
    },
    (error) => cb(error)
  );
}

function startCopy(destStat, src, dest, opts, cb) {
  if (opts.filter) return handleFilter(getStats, destStat, src, dest, opts, cb);
  return getStats(destStat, src, dest, opts, cb);
}

function getStats(destStat, src, dest, opts, cb) {
  const stat = opts.dereference ? fs.stat : fs.lstat;
  stat(src, (err, srcStat) => {
    if (err) return cb(err);

    if (srcStat.isDirectory())
      return onDir(srcStat, destStat, src, dest, opts, cb);
    else if (
      srcStat.isFile() ||
      srcStat.isCharacterDevice() ||
      srcStat.isBlockDevice()
    )
      return onFile(srcStat, destStat, src, dest, opts, cb);
    else if (srcStat.isSymbolicLink())
      return onLink(destStat, src, dest, opts, cb);
  });
}

function onFile(srcStat, destStat, src, dest, opts, cb) {
  if (!destStat) return copyFile(srcStat, src, dest, opts, cb);
  return mayCopyFile(srcStat, src, dest, opts, cb);
}

function mayCopyFile(srcStat, src, dest, opts, cb) {
  if (opts.overwrite) {
    fs.unlink(dest, (err) => {
      if (err) return cb(err);
      return copyFile(srcStat, src, dest, opts, cb);
    });
  } else if (opts.errorOnExist) {
    return cb(new Error(`'${dest}' already exists`));
  } else return cb();
}

function copyFile(srcStat, src, dest, opts, cb) {
  fs.copyFile(src, dest, (err) => {
    if (err) return cb(err);
    if (opts.preserveTimestamps)
      return handleTimestampsAndMode(srcStat.mode, src, dest, cb);
    return setDestMode(dest, srcStat.mode, cb);
  });
}

function handleTimestampsAndMode(srcMode, src, dest, cb) {
  // Make sure the file is writable before setting the timestamp
  // otherwise open fails with EPERM when invoked with 'r+'
  // (through utimes call)
  if (fileIsNotWritable(srcMode)) {
    return makeFileWritable(dest, srcMode, (err) => {
      if (err) return cb(err);
      return setDestTimestampsAndMode(srcMode, src, dest, cb);
    });
  }
  return setDestTimestampsAndMode(srcMode, src, dest, cb);
}

function fileIsNotWritable(srcMode) {
  return (srcMode & 0o200) === 0;
}

function makeFileWritable(dest, srcMode, cb) {
  return setDestMode(dest, srcMode | 0o200, cb);
}

function setDestTimestampsAndMode(srcMode, src, dest, cb) {
  setDestTimestamps(src, dest, (err) => {
    if (err) return cb(err);
    return setDestMode(dest, srcMode, cb);
  });
}

function setDestMode(dest, srcMode, cb) {
  return fs.chmod(dest, srcMode, cb);
}

function setDestTimestamps(src, dest, cb) {
  // The initial srcStat.atime cannot be trusted
  // because it is modified by the read(2) system call
  // (See https://nodejs.org/api/fs.html#fs_stat_time_values)
  fs.stat(src, (err, updatedSrcStat) => {
    if (err) return cb(err);
    return utimesMillis(dest, updatedSrcStat.atime, updatedSrcStat.mtime, cb);
  });
}

function onDir(srcStat, destStat, src, dest, opts, cb) {
  if (!destStat) return mkDirAndCopy(srcStat.mode, src, dest, opts, cb);
  if (destStat && !destStat.isDirectory()) {
    return cb(
      new Error(
        `Cannot overwrite non-directory '${dest}' with directory '${src}'.`
      )
    );
  }
  return copyDir(src, dest, opts, cb);
}

function mkDirAndCopy(srcMode, src, dest, opts, cb) {
  fs.mkdir(dest, (err) => {
    if (err) return cb(err);
    copyDir(src, dest, opts, (err) => {
      if (err) return cb(err);
      return setDestMode(dest, srcMode, cb);
    });
  });
}

function copyDir(src, dest, opts, cb) {
  fs.readdir(src, (err, items) => {
    if (err) return cb(err);
    return copyDirItems(items, src, dest, opts, cb);
  });
}

function copyDirItems(items, src, dest, opts, cb) {
  const item = items.pop();
  if (!item) return cb();
  return copyDirItem(items, item, src, dest, opts, cb);
}

function copyDirItem(items, item, src, dest, opts, cb) {
  const srcItem = path.join(src, item);
  const destItem = path.join(dest, item);
  stat.checkPaths(srcItem, destItem, 'copy', (err, stats) => {
    if (err) return cb(err);
    const { destStat } = stats;
    startCopy(destStat, srcItem, destItem, opts, (err) => {
      if (err) return cb(err);
      return copyDirItems(items, src, dest, opts, cb);
    });
  });
}

function onLink(destStat, src, dest, opts, cb) {
  fs.readlink(src, (err, resolvedSrc) => {
    if (err) return cb(err);
    if (opts.dereference) {
      resolvedSrc = path.resolve(process.cwd(), resolvedSrc);
    }

    if (!destStat) {
      return fs.symlink(resolvedSrc, dest, cb);
    } else {
      fs.readlink(dest, (err, resolvedDest) => {
        if (err) {
          // dest exists and is a regular file or directory,
          // Windows may throw UNKNOWN error. If dest already exists,
          // fs throws error anyway, so no need to guard against it here.
          if (err.code === 'EINVAL' || err.code === 'UNKNOWN')
            return fs.symlink(resolvedSrc, dest, cb);
          return cb(err);
        }
        if (opts.dereference) {
          resolvedDest = path.resolve(process.cwd(), resolvedDest);
        }
        if (stat.isSrcSubdir(resolvedSrc, resolvedDest)) {
          return cb(
            new Error(
              `Cannot copy '${resolvedSrc}' to a subdirectory of itself, '${resolvedDest}'.`
            )
          );
        }

        // do not copy if src is a subdir of dest since unlinking
        // dest in this case would result in removing src contents
        // and therefore a broken symlink would be created.
        if (
          destStat.isDirectory() &&
          stat.isSrcSubdir(resolvedDest, resolvedSrc)
        ) {
          return cb(
            new Error(
              `Cannot overwrite '${resolvedDest}' with '${resolvedSrc}'.`
            )
          );
        }
        return copyLink(resolvedSrc, dest, cb);
      });
    }
  });
}

function copyLink(resolvedSrc, dest, cb) {
  fs.unlink(dest, (err) => {
    if (err) return cb(err);
    return fs.symlink(resolvedSrc, dest, cb);
  });
}

module.exports = copy;