# cmd.py
# Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
#
# This module is part of GitPython and is released under
# the BSD License: http://www.opensource.org/licenses/bsd-license.php

import os, sys
import subprocess
from utils import *
from errors import GitCommandError

# Enables debugging of GitPython's git commands
GIT_PYTHON_TRACE = os.environ.get("GIT_PYTHON_TRACE", False)

execute_kwargs = ('istream', 'with_keep_cwd', 'with_extended_output',
				  'with_exceptions', 'as_process', 
				  'output_stream' )

extra = {}
if sys.platform == 'win32':
	extra = {'shell': True}

def dashify(string):
	return string.replace('_', '-')

class Git(object):
	"""
	The Git class manages communication with the Git binary.
	
	It provides a convenient interface to calling the Git binary, such as in::
	
	 g = Git( git_dir )
	 g.init()					# calls 'git init' program
	 rval = g.ls_files()		# calls 'git ls-files' program
	
	``Debugging``
		Set the GIT_PYTHON_TRACE environment variable print each invocation 
		of the command to stdout.
		Set its value to 'full' to see details about the returned values.
	"""
	class AutoInterrupt(object):
		"""
		Kill/Interrupt the stored process instance once this instance goes out of scope. It is 
		used to prevent processes piling up in case iterators stop reading.
		Besides all attributes are wired through to the contained process object.
		
		The wait method was overridden to perform automatic status code checking
		and possibly raise.
		"""
		__slots__= ("proc", "args")
		
		def __init__(self, proc, args ):
			self.proc = proc
			self.args = args
			
		def __del__(self):
			# did the process finish already so we have a return code ?
			if self.proc.poll() is not None:
				return 
			
			# try to kill it
			try:
				os.kill(self.proc.pid, 2)	# interrupt signal
			except AttributeError:
				# try windows 
				subprocess.call(("TASKKILL", "/T", "/PID", self.proc.pid))
			# END exception handling 
			
		def __getattr__(self, attr):
			return getattr(self.proc, attr)
			
		def wait(self):
			"""
			Wait for the process and return its status code. 
			
			Raise
				GitCommandError if the return status is not 0
			"""
			status = self.proc.wait()
			if status != 0:
				raise GitCommandError(self.args, status, self.proc.stderr.read())
			# END status handling 
			return status
			
	
	
	def __init__(self, git_dir=None):
		"""
		Initialize this instance with:
		
		``git_dir``
		   Git directory we should work in. If None, we always work in the current 
		   directory as returned by os.getcwd()
		"""
		super(Git, self).__init__()
		self.git_dir = git_dir
		
		# cached command slots
		self.cat_file_header = None
		self.cat_file_all = None

	def __getattr__(self, name):
		"""
		A convenience method as it allows to call the command as if it was 
		an object.
		Returns
			Callable object that will execute call _call_process with your arguments.
		"""
		if name[:1] == '_':
			raise AttributeError(name)
		return lambda *args, **kwargs: self._call_process(name, *args, **kwargs)

	@property
	def get_dir(self):
		"""
		Returns
			Git directory we are working on
		"""
		return self.git_dir

	def execute(self, command,
				istream=None,
				with_keep_cwd=False,
				with_extended_output=False,
				with_exceptions=True,
				as_process=False, 
				output_stream=None
				):
		"""
		Handles executing the command on the shell and consumes and returns
		the returned information (stdout)

		``command``
			The command argument list to execute.
			It should be a string, or a sequence of program arguments. The
			program to execute is the first item in the args sequence or string.

		``istream``
			Standard input filehandle passed to subprocess.Popen.

		``with_keep_cwd``
			Whether to use the current working directory from os.getcwd().
			GitPython uses get_work_tree() as its working directory by
			default and get_git_dir() for bare repositories.

		``with_extended_output``
			Whether to return a (status, stdout, stderr) tuple.

		``with_exceptions``
			Whether to raise an exception when git returns a non-zero status.

		``as_process``
			Whether to return the created process instance directly from which 
			streams can be read on demand. This will render with_extended_output and 
			with_exceptions ineffective - the caller will have 
			to deal with the details himself.
			It is important to note that the process will be placed into an AutoInterrupt
			wrapper that will interrupt the process once it goes out of scope. If you 
			use the command in iterators, you should pass the whole process instance 
			instead of a single stream.
			
		``output_stream``
			If set to a file-like object, data produced by the git command will be 
			output to the given stream directly.
			This feature only has any effect if as_process is False. Processes will
			always be created with a pipe due to issues with subprocess.
			This merely is a workaround as data will be copied from the 
			output pipe to the given output stream directly.
			
		
		Returns::
		
		 str(output)								   # extended_output = False (Default)
		 tuple(int(status), str(stdout), str(stderr)) # extended_output = True
		 
		 if ouput_stream is True, the stdout value will be your output stream:
		 output_stream									# extended_output = False
		 tuple(int(status), output_stream, str(stderr))# extended_output = True
		
		Raise
			GitCommandError
		
		NOTE
		   If you add additional keyword arguments to the signature of this method, 
		   you must update the execute_kwargs tuple housed in this module.
		"""
		if GIT_PYTHON_TRACE and not GIT_PYTHON_TRACE == 'full':
			print ' '.join(command)

		# Allow the user to have the command executed in their working dir.
		if with_keep_cwd or self.git_dir is None:
		  cwd = os.getcwd()
		else:
		  cwd=self.git_dir
		  
		# Start the process
		proc = subprocess.Popen(command,
								cwd=cwd,
								stdin=istream,
								stderr=subprocess.PIPE,
								stdout=subprocess.PIPE,
								**extra
								)
		if as_process:
			return self.AutoInterrupt(proc, command)
		
		# Wait for the process to return
		status = 0
		try:
			if output_stream is None:
				stdout_value = proc.stdout.read().rstrip()		# strip trailing "\n"
			else:
				max_chunk_size = 1024*64
				while True:
					chunk = proc.stdout.read(max_chunk_size)
					output_stream.write(chunk)
					if len(chunk) < max_chunk_size:
						break
				# END reading output stream
				stdout_value = output_stream
			# END stdout handling
			stderr_value = proc.stderr.read().rstrip()			# strip trailing "\n"
			# waiting here should do nothing as we have finished stream reading
			status = proc.wait()
		finally:
			proc.stdout.close()
			proc.stderr.close()

		if with_exceptions and status != 0:
			raise GitCommandError(command, status, stderr_value)

		if GIT_PYTHON_TRACE == 'full':
			if stderr_value:
			  print "%s -> %d: '%s' !! '%s'" % (command, status, stdout_value, stderr_value)
			elif stdout_value:
			  print "%s -> %d: '%s'" % (command, status, stdout_value)
			else:
			  print "%s -> %d" % (command, status)

		# Allow access to the command's status code
		if with_extended_output:
			return (status, stdout_value, stderr_value)
		else:
			return stdout_value

	def transform_kwargs(self, **kwargs):
		"""
		Transforms Python style kwargs into git command line options.
		"""
		args = []
		for k, v in kwargs.items():
			if len(k) == 1:
				if v is True:
					args.append("-%s" % k)
				elif type(v) is not bool:
					args.append("-%s%s" % (k, v))
			else:
				if v is True:
					args.append("--%s" % dashify(k))
				elif type(v) is not bool:
					args.append("--%s=%s" % (dashify(k), v))
		return args

	@classmethod
	def __unpack_args(cls, arg_list):
		if not isinstance(arg_list, (list,tuple)):
			return [ str(arg_list) ]
			
		outlist = list()
		for arg in arg_list:
			if isinstance(arg_list, (list, tuple)):
				outlist.extend(cls.__unpack_args( arg ))
			# END recursion 
			else:
				outlist.append(str(arg))
		# END for each arg
		return outlist

	def _call_process(self, method, *args, **kwargs):
		"""
		Run the given git command with the specified arguments and return
		the result as a String

		``method``
			is the command. Contained "_" characters will be converted to dashes,
			such as in 'ls_files' to call 'ls-files'.

		``args``
			is the list of arguments. If None is included, it will be pruned.
			This allows your commands to call git more conveniently as None
			is realized as non-existent

		``kwargs``
			is a dict of keyword arguments.
			This function accepts the same optional keyword arguments
			as execute().

		Examples::
			git.rev_list('master', max_count=10, header=True)

		Returns
			Same as execute()
		"""

		# Handle optional arguments prior to calling transform_kwargs
		# otherwise these'll end up in args, which is bad.
		_kwargs = {}
		for kwarg in execute_kwargs:
			try:
				_kwargs[kwarg] = kwargs.pop(kwarg)
			except KeyError:
				pass

		# Prepare the argument list
		opt_args = self.transform_kwargs(**kwargs)
		
		ext_args = self.__unpack_args([a for a in args if a is not None])
		args = opt_args + ext_args

		call = ["git", dashify(method)]
		call.extend(args)

		return self.execute(call, **_kwargs)
		
	def _parse_object_header(self, header_line):
		"""
		``header_line``
			<hex_sha> type_string size_as_int
			
		Returns
			(hex_sha, type_string, size_as_int)
			
		Raises
			ValueError if the header contains indication for an error due to incorrect 
			input sha
		"""
		tokens = header_line.split()
		if len(tokens) != 3:
			raise ValueError( "SHA named %s could not be resolved" % tokens[0] )
			
		return (tokens[0], tokens[1], int(tokens[2]))
	
	def __prepare_ref(self, ref):
		# required for command to separate refs on stdin
		refstr = str(ref)				# could be ref-object
		if refstr.endswith("\n"):
			return refstr
		return refstr + "\n"
	
	def __get_persistent_cmd(self, attr_name, cmd_name, *args,**kwargs):
		cur_val = getattr(self, attr_name)
		if cur_val is not None:
			return cur_val
			
		options = { "istream" : subprocess.PIPE, "as_process" : True }
		options.update( kwargs )
		
		cmd = self._call_process( cmd_name, *args, **options )
		setattr(self, attr_name, cmd )
		return cmd
	
	def __get_object_header(self, cmd, ref):
		cmd.stdin.write(self.__prepare_ref(ref))
		cmd.stdin.flush()
		return self._parse_object_header(cmd.stdout.readline())
	
	def get_object_header(self, ref):
		"""
		Use this method to quickly examine the type and size of the object behind 
		the given ref. 
		
		NOTE
			The method will only suffer from the costs of command invocation 
			once and reuses the command in subsequent calls. 
		
		Return:
			(hexsha, type_string, size_as_int)
		"""
		cmd = self.__get_persistent_cmd("cat_file_header", "cat_file", batch_check=True)
		return self.__get_object_header(cmd, ref)
		
	def get_object_data(self, ref):
		"""
		As get_object_header, but returns object data as well
		
		Return:
			(hexsha, type_string, size_as_int,data_string)
		"""
		cmd = self.__get_persistent_cmd("cat_file_all", "cat_file", batch=True)
		hexsha, typename, size = self.__get_object_header(cmd, ref)
		data = cmd.stdout.read(size)
		cmd.stdout.read(1)		# finishing newlines
		
		return (hexsha, typename, size, data)