# Copyright 2009 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Various utilities.

Current contents:

 - Text colorization using ANSI color codes

 - A class to construct and manage paths under a root path.

 - A helper to manage running subprocesses, wrapping the subprocess module.

"""

__authors__ = [

    # alphabetical order by last name, please

    '"David Anderson" <dave@natulte.net>',

    ]

import os.path

import subprocess

import error

class Error(error.Error):

    pass

class SubprocessFailed(Error):

    """A subprocess returned a non-zero error code."""

# The magic escape sequence understood by modern terminal emulators to

# configure fore/background colors and other basic text display

# settings.

_ANSI_ESCAPE = '\x1b[%dm'

# Some internal non-color settings that we use.

_RESET = 0  # Reset to terminal defaults.

_BOLD = 1   # Brighter colors.

# ANSI color codes.

RED = 31

GREEN = 32

WHITE = 37

def _ansi_escape(code):

    return _ANSI_ESCAPE % code

def colorize(text, color, bold=False):

    """Colorize some text using ANSI color codes.

    Note that while ANSI color codes look good in a terminal they look

    like noise in log files unless viewed in an ANSI color capable

    viewer (such as 'less -R').

    Args:

      text: The text to colorize.

      color: One of the color symbols from this module.

      bold: If True, make the color brighter.

    Returns:

      The input text string, appropriately sprinkled with color

      codes. Colors are reset to terminal defaults after the input

      text.

    """

    bold = _ansi_escape(_BOLD) if bold else ''

    return '%s%s%s%s' % (bold, _ansi_escape(color),

                         text, _ansi_escape(_RESET))

class Paths(object):

    """A helper to construct and check paths under a given root."""

    def __init__(self, root):

        """Initializer.

        Args:

          root: The root of all paths this instance will consider.

        """

        self._root = os.path.abspath(

            os.path.expandvars(os.path.expanduser(root)))

    def path(self, path=''):

        """Construct and return a path under the path root.

        Args:

          path: The desired path string relative to the root.

        Returns:

          The absolute path corresponding to the relative input path.

        """

        assert not os.path.isabs(path)

        return os.path.abspath(os.path.join(self._root, path))

    def exists(self, path=''):

        """Check for the existence of a path under the path root.

        Does not discriminate on the path type (ie. it could be a

        directory, a file, a symbolic link...), just checks for the

        existence of the path.

        Args:

          path: The path string relative to the root.

        Returns:

          True if the path exists, False otherwise.

        """

        return os.path.exists(self.path(path))

def run(argv, cwd=None, capture=False, split_capture=True, stdin=''):

    """Run the given command and optionally return its output.

    Note that if you set capture=True, the command's output is

    buffered in memory. Output capture should only be used with

    commands that output small amounts of data. O(kB) is fine, O(MB)

    is starting to push it a little.

    Args:

      argv: A list containing the name of the program to run, followed

            by its argument vector.

      cwd: Run the program from this directory.

      capture: If True, capture the program's stdout stream. If False,

               stdout will output to sys.stdout.

      split_capture: If True, return the captured output as a list of

                     lines. Else, return as a single unaltered string.

      stdin: The string to feed to the program's stdin stream.

    Returns:

      If capture is True, a string containing the combined

      stdout/stderr output of the program. If capture is False,

      nothing is returned.

    Raises:

      SubprocessFailed: The subprocess exited with a non-zero exit

                        code.

    """

    print colorize('# ' + ' '.join(argv), WHITE, bold=True)

    process = subprocess.Popen(argv,

                               shell=False,

                               cwd=cwd,

                               stdin=subprocess.PIPE,

                               stdout=(subprocess.PIPE if capture else None),

                               stderr=None)

    output, _ = process.communicate(input=stdin)

    if process.returncode != 0:

        raise SubprocessFailed('Process %s failed with output: %s' %

                               (argv[0], output))

    if output is not None and split_capture:

        return output.strip().split('\n')

    else:

        return output