#!/usr/bin/python2.5

#

# 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.

from __future__ import with_statement

"""User prompting and file access utilities."""

__authors__ = [

    # alphabetical order by last name, please

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

    ]

import error

import log

class Error(error.Error):

  pass

class FileAccessError(Error):

  """An error occured while accessing a file."""

  pass

def getString(prompt):

  """Prompt for and return a string."""

  prompt += ' '

  log.stdout.write(prompt)

  log.stdout.flush()

  response = sys.stdin.readline()

  log.terminal_echo(prompt + response.strip())

  if not response:

    raise error.AbortedByUser('Aborted by ctrl+D')

  return response.strip()

def confirm(prompt, default=False):

  """Ask a yes/no question and return the answer.

  Will reprompt the user until one of "yes", "no", "y" or "n" is

  entered. The input is case insensitive.

  Args:

    prompt: The question to ask the user.

    default: The answer to return if the user just hits enter.

  Returns:

    True if the user answered affirmatively, False otherwise.

  """

  if default:

    question = prompt + ' [Yn]'

  else:

    question = prompt + ' [yN]'

  while True:

    answer = getString(question)

    if not answer:

      return default

    elif answer in ('y', 'yes'):

      return True

    elif answer in ('n', 'no'):

      return False

    else:

      log.error('Please answer yes or no.')

def getNumber(prompt):

  """Prompt for and return a number.

  Will reprompt the user until a number is entered.

  """

  while True:

    value_str = getString(prompt)

    try:

      return int(value_str)

    except ValueError:

      log.error('Please enter a number. You entered "%s".' % value_str)

def getChoice(intro, prompt, choices, done=None, suggest=None):

  """Prompt for and return a choice from a menu.

  Will reprompt the user until a valid menu entry is chosen.

  Args:

    intro: Text to print verbatim before the choice menu.

    prompt: The prompt to print right before accepting input.

    choices: The list of string choices to display.

    done: If not None, the list of indices of previously

      selected/completed choices.

    suggest: If not None, the index of the choice to highlight as

      the suggested choice.

  Returns:

    The index in the choices list of the selection the user made.

  """

  done = set(done or [])

  while True:

    print intro

    print

    for i, entry in enumerate(choices):

      done_text = ' (done)' if i in done else ''

      indent = '--> ' if i == suggest else '    '

      print '%s%2d. %s%s' % (indent, i+1, entry, done_text)

    print

    choice = getNumber(prompt)

    if 0 < choice <= len(choices):

      return choice-1

    log.error('%d is not a valid choice between %d and %d' %

              (choice, 1, len(choices)))

    print

def fileToLines(path):

  """Read a file and return it as a list of lines."""

  try:

    with file(path) as f:

      return f.read().split('\n')

  except (IOError, OSError), e:

    raise FileAccessError(str(e))

def linesToFile(path, lines):

  """Write a list of lines to a file."""

  try:

    with file(path, 'w') as f:

      f.write('\n'.join(lines))

  except (IOError, OSError), e:

    raise FileAccessError(str(e))