#! /usr/bin/env python3

"""
Snapshot a project into another project and perform the necessary repo actions
to provide a commit message that can be used to trace back to the exact point
in the source repository.
"""

#todo:
#  Support svn
#  Allow renaming of the source dir in the destination path
#  Check if a new snapshot is necessary?
#

import sys

#This checks for python version >= 3.2 (which is when argparse was added to python3)
#See https://docs.python.org/3/library/argparse.html for reference
if sys.version_info[:2] < (3, 2):
  print(f"Error snapshot requires python 3.2 or newer, detected version is {sys.version_info[0]}.{sys.version_info[1]}.")
  sys.exit(1)

import subprocess, argparse, re, doctest, os, datetime, traceback

def parse_cmdline(description):
  parser = argparse.ArgumentParser(usage="snapshot.py [options] source destination", description=description)

  parser.add_argument("-n", "--no-commit", action="store_false", dest="create_commit", default=True,
                      help="Do not perform a commit or create a commit message.")
  parser.add_argument("-v", "--verbose", action="store_true", dest="verbose_mode", default=False,
                      help="Enable verbose mode.")
  parser.add_argument("-d", "--debug", action="store_true", dest="debug_mode", default=False,
                      help="Enable debugging output.")
  parser.add_argument("--no-validate-repo", action="store_true", dest="no_validate_repo", default=False,
                      help="Reduce the validation that the source and destination repos are clean to a warning.")
  parser.add_argument("--source-repo", choices=["git","none"], default="",
                      help="Type of repository of the source, use none to skip all repository operations.")
  parser.add_argument("--dest-repo", choices=["git","none"], default="",
                      help="Type of repository of the destination, use none to skip all repository operations.")
  parser.add_argument("--small", action="store_true", dest="small_mode",
                      help="Don't include tests and other extra files when copying.")

  parser.add_argument("source",      help="Source project to snapshot from.")
  parser.add_argument("destination", help="Destination to snapshot too.")

  options = parser.parse_args()
  options = validate_options(options)
  return options
#end parseCmdline

def validate_options(options):
  apparent_source_repo_type="none"
  apparent_dest_repo_type="none"

  #prevent user from accidentally giving us a path that rsync will treat differently than expected.
  options.source      = options.source.rstrip(os.sep)
  options.destination = options.destination.rstrip(os.sep)

  options.source      = os.path.abspath(options.source)
  options.destination = os.path.abspath(options.destination)

  if os.path.exists(options.source):
    apparent_source_repo_type, source_root = determine_repo_type(options.source)
  else:
    raise RuntimeError(f"Could not find source directory of {options.source}.")
  options.source_root = source_root

  if not os.path.exists(options.destination):
    print(f"Could not find destination directory of {options.destination} so it will be created.")
    os.makedirs(options.destination)

  apparent_dest_repo_type, dest_root = determine_repo_type(options.destination)
  options.dest_root = dest_root

  #error on svn repo types for now
  if apparent_source_repo_type == "svn" or apparent_dest_repo_type == "svn":
    raise RuntimeError("SVN repositories are not supported at this time.")

  if options.source_repo == "":
    #source repo type is not specified to just using the apparent type.
    options.source_repo = apparent_source_repo_type
  else:
    if options.source_repo != "none" and options.source_repo != apparent_source_repo_type:
      raise RuntimeError(f"Specified source repository type of {options.source_repo} conflicts with determined type of {apparent_source_repo_type}")

  if options.dest_repo == "":
    #destination repo type is not specified to just using the apparent type.
    options.dest_repo = apparent_dest_repo_type
  else:
    if options.dest_repo != "none" and options.dest_repo != apparent_dest_repo_type:
      raise RuntimeError(f"Specified destination repository type of {options.dest_repo} conflicts with determined type of {apparent_dest_repo_type}")

  return options
#end validate_options

def run_cmd(cmd, options, working_dir="."):
  cmd_str = " ".join(cmd)
  if options.verbose_mode:
    print(f"Running command '{cmd_str}' in dir {working_dir}")

  proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, cwd=working_dir)
  proc_stdout, proc_stderr = proc.communicate()
  ret_val = proc.wait()
  proc_stdout_text = proc_stdout.decode('utf-8')
  proc_stderr_text = proc_stderr.decode('utf-8')

  if options.debug_mode:
    print(f"==== {cmd_str} stdout start ====")
    print(proc_stdout_text)
    print(f"==== {cmd_str} stdout end ====")
    print(f"==== {cmd_str} stderr start ====")
    print(proc_stderr_text)
    print(f"==== {cmd_str} stderr end ====")

  if ret_val != 0:
    raise RuntimeError(f"Command '{cmd_str}' failed with error code {ret_val}. Error message:{os.linesep}{proc_stderr_text}{os.linesep}stdout:{proc_stdout_text}")

  return proc_stdout_text, proc_stderr_text
#end run_cmd

def determine_repo_type(location):
  apparent_repo_type = "none"

  while location != "":
    if os.path.exists(os.path.join(location, ".git")):
      apparent_repo_type = "git"
      break
    elif os.path.exists(os.path.join(location, ".svn")):
      apparent_repo_type = "svn"
      break
    else:
      location = location[:location.rfind(os.sep)]

  return apparent_repo_type, location
#end determine_repo_type

def rsync(source, dest, options):
  rsync_cmd = ["rsync", "-ar", "--delete"]
  if options.debug_mode:
    rsync_cmd.append("-v")

  if options.small_mode or options.source_repo == "git":
    rsync_cmd.append("--delete-excluded")

  if options.small_mode:
    rsync_cmd.append("--include=config/master_history.txt")
    rsync_cmd.append("--include=cmake/tpls")
    rsync_cmd.append("--exclude=benchmarks/")
    rsync_cmd.append("--exclude=config/*")
    rsync_cmd.append("--exclude=doc/")
    rsync_cmd.append("--exclude=example/")
    rsync_cmd.append("--exclude=tpls/")
    rsync_cmd.append("--exclude=HOW_TO_SNAPSHOT")
    rsync_cmd.append("--exclude=unit_test")
    rsync_cmd.append("--exclude=unit_tests")
    rsync_cmd.append("--exclude=perf_test")
    rsync_cmd.append("--exclude=performance_tests")

  if options.source_repo == "git":
    rsync_cmd.append("--exclude=.git*")

  rsync_cmd.append(options.source)
  rsync_cmd.append(options.destination)
  run_cmd(rsync_cmd, options)
#end rsync

def create_commit_message(commit_id, commit_log, project_name, project_location):
  eol = os.linesep
  message = f"Snapshot of {project_name} from commit {commit_id}"
  message += eol * 2
  message += f"From repository at {project_location}"
  message += eol * 2
  message += "At commit:" + eol
  message += commit_log
  return message
#end create_commit_message

def find_git_commit_information(options):
  r"""
  >>> class fake_options:
  ...   source="."
  ...   verbose_mode=False
  ...   debug_mode=False
  >>> myoptions = fake_options()
  >>> find_git_commit_information(myoptions)[2:]
  ('sems', 'software.sandia.gov:/git/sems')
  """
  git_log_cmd = ["git", "log", "-1"]

  output, error = run_cmd(git_log_cmd, options, options.source)

  commit_match = re.match("commit ([0-9a-fA-F]+)", output)
  commit_id = commit_match.group(1)
  commit_log = output

  git_remote_cmd = ["git", "remote", "-v"]
  output, error = run_cmd(git_remote_cmd, options, options.source)

  remote_match = re.search(r"origin\s([^ ]*/([^ ]+))", output, re.MULTILINE)
  if not remote_match:
    raise RuntimeError(f"Could not find origin of repo at {options.source}. Consider using none for source repo type.")

  source_location = remote_match.group(1)
  source_name     = remote_match.group(2).strip()

  if source_name[-1] == "/":
    source_name = source_name[:-1]

  return commit_id, commit_log, source_name, source_location
#end find_git_commit_information

def do_git_commit(message, options):
  if options.verbose_mode:
    print("Committing to destination repository.")

  git_add_cmd = ["git", "add", "-A"]
  run_cmd(git_add_cmd, options, options.destination)

  git_commit_cmd = ["git", "commit", f"-m{message}", "--signoff"]
  run_cmd(git_commit_cmd, options, options.destination)

  git_log_cmd = ["git", "log", "--format=%h", "-1"]
  commit_sha1, error = run_cmd(git_log_cmd, options, options.destination)

  print(f"Commit {commit_sha1.strip()} was made to {options.dest_root}.")
#end do_git_commit

def verify_git_repo_clean(location, options):
  git_status_cmd = ["git", "status", "--porcelain"]
  output, error = run_cmd(git_status_cmd, options, location)

  if output != "":
    if options.no_validate_repo == False:
      raise RuntimeError(f"{location} is not clean.{os.linesep}Please commit or stash all changes before running snapshot.")
    else:
      print(f"WARNING: {location} is not clean. Proceeding anyway.")
      print("WARNING:   This could lead to differences in the source and destination.")
      print("WARNING:   It could also lead to extra files being included in the snapshot commit.")
#end verify_git_repo_clean

def main(options):
  if options.verbose_mode:
    print(f"Snapshotting {options.source} to {options.destination}.")

  if options.source_repo == "git":
    verify_git_repo_clean(options.source, options)
    commit_id, commit_log, repo_name, repo_location = find_git_commit_information(options)
  elif options.source_repo == "none":
    commit_id     = "N/A"
    commit_log    = f"Unknown commit from {options.source} snapshotted at: {datetime.datetime.now()}"
    repo_name     = options.source
    repo_location = options.source

  commit_message = create_commit_message(commit_id, commit_log, repo_name, repo_location) + os.linesep*2

  if options.dest_repo == "git":
    verify_git_repo_clean(options.destination, options)

  rsync(options.source, options.destination, options)

  if options.dest_repo == "git":
    do_git_commit(commit_message, options)
  elif options.dest_repo == "none":
    file_name = "snapshot_message.txt"
    message_file = open(file_name, "w")
    message_file.write(commit_message)
    message_file.close()
    cwd = os.getcwd()
    print("No commit done by request. Please use file at:")
    print(f"{cwd+"/"+file_name}{os.linesep}if you wish to commit this to a repo later.")
#end main

if (__name__ == "__main__"):
  if ("--test" in sys.argv):
    doctest.testmod()
    sys.exit(0)

  try:
    options = parse_cmdline(__doc__)
    main(options)
  except RuntimeError as e:
    print(f"Error occurred: {e}")
    if "--debug" in sys.argv:
      traceback.print_exc()
    sys.exit(1)
  else:
    sys.exit(0)