##############################################################################
# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
# Produced at the Lawrence Livermore National Laboratory.
#
# This file is part of Spack.
# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
# LLNL-CODE-647188
#
# For details, see https://github.com/llnl/spack
# Please also see the LICENSE file for our notice and the LGPL.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License (as published by
# the Free Software Foundation) version 2.1 dated February 1999.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
# conditions of the GNU General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##############################################################################
__all__ = ['set_install_permissions', 'install', 'install_tree', 'traverse_tree',
           'expand_user', 'working_dir', 'touch', 'touchp', 'mkdirp',
           'force_remove', 'join_path', 'ancestor', 'can_access', 'filter_file',
           'FileFilter', 'change_sed_delimiter', 'is_exe', 'force_symlink',
           'set_executable', 'copy_mode', 'unset_executable_mode',
           'remove_dead_links', 'remove_linked_tree', 'find_library_path',
           'fix_darwin_install_name']

import os
import glob
import sys
import re
import shutil
import stat
import errno
import getpass
from contextlib import contextmanager, closing
from tempfile import NamedTemporaryFile
import subprocess

import llnl.util.tty as tty
from spack.util.compression import ALLOWED_ARCHIVE_TYPES

def filter_file(regex, repl, *filenames, **kwargs):
    """Like sed, but uses python regular expressions.

       Filters every line of file through regex and replaces the file
       with a filtered version.  Preserves mode of filtered files.

       As with re.sub, ``repl`` can be either a string or a callable.
       If it is a callable, it is passed the match object and should
       return a suitable replacement string.  If it is a string, it
       can contain ``\1``, ``\2``, etc. to represent back-substitution
       as sed would allow.

       Keyword Options:
         string[=False]         If True, treat regex as a plain string.
         backup[=True]          Make a backup files suffixed with ~
         ignore_absent[=False]  Ignore any files that don't exist.
    """
    string = kwargs.get('string', False)
    backup = kwargs.get('backup', True)
    ignore_absent = kwargs.get('ignore_absent', False)

    # Allow strings to use \1, \2, etc. for replacement, like sed
    if not callable(repl):
        unescaped = repl.replace(r'\\', '\\')
        def replace_groups_with_groupid(m):
            def groupid_to_group(x):
                return m.group(int(x.group(1)))
            return re.sub(r'\\([1-9])', groupid_to_group, unescaped)
        repl = replace_groups_with_groupid

    if string:
        regex = re.escape(regex)

    for filename in filenames:
        backup = filename + "~"

        if ignore_absent and not os.path.exists(filename):
            continue

        shutil.copy(filename, backup)
        try:
            with closing(open(backup)) as infile:
                with closing(open(filename, 'w')) as outfile:
                    for line in infile:
                        foo = re.sub(regex, repl, line)
                        outfile.write(foo)
        except:
            # clean up the original file on failure.
            shutil.move(backup, filename)
            raise

        finally:
            if not backup:
                shutil.rmtree(backup, ignore_errors=True)


class FileFilter(object):
    """Convenience class for calling filter_file a lot."""
    def __init__(self, *filenames):
        self.filenames = filenames

    def filter(self, regex, repl, **kwargs):
        return filter_file(regex, repl, *self.filenames, **kwargs)


def change_sed_delimiter(old_delim, new_delim, *filenames):
    """Find all sed search/replace commands and change the delimiter.
       e.g., if the file contains seds that look like 's///', you can
       call change_sed_delimeter('/', '@', file) to change the
       delimiter to '@'.

       NOTE that this routine will fail if the delimiter is ' or ".
       Handling those is left for future work.
    """
    assert(len(old_delim) == 1)
    assert(len(new_delim) == 1)

    # TODO: handle these cases one day?
    assert(old_delim != '"')
    assert(old_delim != "'")
    assert(new_delim != '"')
    assert(new_delim != "'")

    whole_lines = "^s@([^@]*)@(.*)@[gIp]$"
    whole_lines = whole_lines.replace('@', old_delim)

    single_quoted = r"'s@((?:\\'|[^@'])*)@((?:\\'|[^'])*)@[gIp]?'"
    single_quoted = single_quoted.replace('@', old_delim)

    double_quoted = r'"s@((?:\\"|[^@"])*)@((?:\\"|[^"])*)@[gIp]?"'
    double_quoted = double_quoted.replace('@', old_delim)

    repl = r's@\1@\2@g'
    repl = repl.replace('@', new_delim)

    for f in filenames:
        filter_file(whole_lines, repl, f)
        filter_file(single_quoted, "'%s'" % repl, f)
        filter_file(double_quoted, '"%s"' % repl, f)


def set_install_permissions(path):
    """Set appropriate permissions on the installed file."""
    if os.path.isdir(path):
        os.chmod(path, 0755)
    else:
        os.chmod(path, 0644)


def copy_mode(src, dest):
    src_mode = os.stat(src).st_mode
    dest_mode = os.stat(dest).st_mode
    if src_mode & stat.S_IXUSR: dest_mode |= stat.S_IXUSR
    if src_mode & stat.S_IXGRP: dest_mode |= stat.S_IXGRP
    if src_mode & stat.S_IXOTH: dest_mode |= stat.S_IXOTH
    os.chmod(dest, dest_mode)


def unset_executable_mode(path):
    mode = os.stat(path).st_mode
    mode &= ~stat.S_IXUSR
    mode &= ~stat.S_IXGRP
    mode &= ~stat.S_IXOTH
    os.chmod(path, mode)


def install(src, dest):
    """Manually install a file to a particular location."""
    tty.debug("Installing %s to %s" % (src, dest))

    # Expand dsst to its eventual full path if it is a directory.
    if os.path.isdir(dest):
        dest = join_path(dest, os.path.basename(src))

    shutil.copy(src, dest)
    set_install_permissions(dest)
    copy_mode(src, dest)


def install_tree(src, dest, **kwargs):
    """Manually install a file to a particular location."""
    tty.debug("Installing %s to %s" % (src, dest))
    shutil.copytree(src, dest, **kwargs)

    for s, d in traverse_tree(src, dest, follow_nonexisting=False):
        set_install_permissions(d)
        copy_mode(s, d)


def is_exe(path):
    """True if path is an executable file."""
    return os.path.isfile(path) and os.access(path, os.X_OK)


def expand_user(path):
    """Find instances of '%u' in a path and replace with the current user's
       username."""
    username = getpass.getuser()
    if not username and '%u' in path:
        tty.die("Couldn't get username to complete path '%s'" % path)

    return path.replace('%u', username)


def mkdirp(*paths):
    """Creates a directory, as well as parent directories if needed."""
    for path in paths:
        if not os.path.exists(path):
            os.makedirs(path)
        elif not os.path.isdir(path):
            raise OSError(errno.EEXIST, "File alredy exists", path)


def force_remove(*paths):
    """Remove files without printing errors.  Like rm -f, does NOT
       remove directories."""
    for path in paths:
        try:
            os.remove(path)
        except OSError, e:
            pass

@contextmanager
def working_dir(dirname, **kwargs):
    if kwargs.get('create', False):
        mkdirp(dirname)

    orig_dir = os.getcwd()
    os.chdir(dirname)
    yield
    os.chdir(orig_dir)


def touch(path):
    """Creates an empty file at the specified path."""
    with open(path, 'a') as file:
        os.utime(path, None)


def touchp(path):
    """Like touch, but creates any parent directories needed for the file."""
    mkdirp(os.path.dirname(path))
    touch(path)


def force_symlink(src, dest):
    try:
        os.symlink(src, dest)
    except OSError as e:
        os.remove(dest)
        os.symlink(src, dest)


def join_path(prefix, *args):
    path = str(prefix)
    for elt in args:
        path = os.path.join(path, str(elt))
    return path


def ancestor(dir, n=1):
    """Get the nth ancestor of a directory."""
    parent = os.path.abspath(dir)
    for i in range(n):
        parent = os.path.dirname(parent)
    return parent


def can_access(file_name):
    """True if we have read/write access to the file."""
    return os.access(file_name, os.R_OK|os.W_OK)


def traverse_tree(source_root, dest_root, rel_path='', **kwargs):
    """Traverse two filesystem trees simultaneously.

    Walks the LinkTree directory in pre or post order.  Yields each
    file in the source directory with a matching path from the dest
    directory, along with whether the file is a directory.
    e.g., for this tree::

        root/
          a/
            file1
            file2
          b/
            file3

    When called on dest, this yields::

        ('root',         'dest')
        ('root/a',       'dest/a')
        ('root/a/file1', 'dest/a/file1')
        ('root/a/file2', 'dest/a/file2')
        ('root/b',       'dest/b')
        ('root/b/file3', 'dest/b/file3')

    Optional args:

    order=[pre|post] -- Whether to do pre- or post-order traveral.

    ignore=<predicate> -- Predicate indicating which files to ignore.

    follow_nonexisting -- Whether to descend into directories in
                          src that do not exit in dest. Default True.

    follow_links -- Whether to descend into symlinks in src.

    """
    follow_nonexisting = kwargs.get('follow_nonexisting', True)
    follow_links = kwargs.get('follow_link', False)

    # Yield in pre or post order?
    order  = kwargs.get('order', 'pre')
    if order not in ('pre', 'post'):
        raise ValueError("Order must be 'pre' or 'post'.")

    # List of relative paths to ignore under the src root.
    ignore = kwargs.get('ignore', lambda filename: False)

    # Don't descend into ignored directories
    if ignore(rel_path):
        return

    source_path = os.path.join(source_root, rel_path)
    dest_path   = os.path.join(dest_root, rel_path)

    # preorder yields directories before children
    if order == 'pre':
        yield (source_path, dest_path)

    for f in os.listdir(source_path):
        source_child = os.path.join(source_path, f)
        dest_child   = os.path.join(dest_path, f)
        rel_child    = os.path.join(rel_path, f)

        # Treat as a directory
        if os.path.isdir(source_child) and (
            follow_links or not os.path.islink(source_child)):

            # When follow_nonexisting isn't set, don't descend into dirs
            # in source that do not exist in dest
            if follow_nonexisting or os.path.exists(dest_child):
                tuples = traverse_tree(source_root, dest_root, rel_child, **kwargs)
                for t in tuples: yield t

        # Treat as a file.
        elif not ignore(os.path.join(rel_path, f)):
            yield (source_child, dest_child)

    if order == 'post':
        yield (source_path, dest_path)


def set_executable(path):
    st = os.stat(path)
    os.chmod(path, st.st_mode | stat.S_IEXEC)


def remove_dead_links(root):
    """
    Removes any dead link that is present in root

    Args:
        root: path where to search for dead links

    """
    for file in os.listdir(root):
        path = join_path(root, file)
        if os.path.islink(path):
            real_path = os.path.realpath(path)
            if not os.path.exists(real_path):
                os.unlink(path)

def remove_linked_tree(path):
    """
    Removes a directory and its contents.  If the directory is a
    symlink, follows the link and removes the real directory before
    removing the link.

    Args:
        path: directory to be removed

    """
    if os.path.exists(path):
        if os.path.islink(path):
            shutil.rmtree(os.path.realpath(path), True)
            os.unlink(path)
        else:
            shutil.rmtree(path, True)


def fix_darwin_install_name(path):
    """
    Fix install name of dynamic libraries on Darwin to have full path.
    There are two parts of this task:
    (i) use install_name('-id',...) to change install name of a single lib;
    (ii) use install_name('-change',...) to change the cross linking between libs.
    The function assumes that all libraries are in one folder and currently won't
    follow subfolders.

    Args:
        path: directory in which .dylib files are alocated

    """
    libs = glob.glob(join_path(path,"*.dylib"))
    for lib in libs:
        # fix install name first:
        subprocess.Popen(["install_name_tool", "-id",lib,lib], stdout=subprocess.PIPE).communicate()[0]
        long_deps = subprocess.Popen(["otool", "-L",lib], stdout=subprocess.PIPE).communicate()[0].split('\n')
        deps = [dep.partition(' ')[0][1::] for dep in long_deps[2:-1]]
        # fix all dependencies:
        for dep in deps:
            for loc in libs:
                if dep == os.path.basename(loc):
                    subprocess.Popen(["install_name_tool", "-change",dep,loc,lib], stdout=subprocess.PIPE).communicate()[0]
                    break


def find_library_path(libname, *paths):
    """Searches for a file called <libname> in each path.

    Return:
      directory where the library was found, if found.  None otherwise.

    """
    for path in paths:
        library = join_path(path, libname)
        if os.path.exists(library):
            return path
    return None