#!/usr/bin/env python
#  -*- coding: utf8 -*-

# Copyright (C) 2017  CEA/DEN, EDF R&D
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License Version 3 as
# published by the Free Software Foundation.
#
# 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 GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, you may download a copy of license
# from https://www.gnu.org/licenses/gpl-3.0.

"""
Command line tool to insert copyright notice to a file.
Usage: type "insert_copyright --help" to learn how to use tool.
"""

import argparse
import os
import re
import sys
import time

# pragma pylint: disable=redefined-builtin

# -----------------------------------------------------------------------------
_COMMENTS = {
    'cpp': '//',
    'shell': '#',
    'python': '#',
    'auto': None,
    }

_OWNERS = {
    'cea': 'CEA/DEN',
    'edf': 'EDF R&D',
    'occ': 'OPEN CASCADE'
    }


# -----------------------------------------------------------------------------
def error_exit(msg):
    """
    Print error message to stderr and exit.

    Arguments:
        msg (str): Error message.
    """
    sys.stderr.write("ERROR: {}\n".format(msg))
    sys.exit(-1)


# -----------------------------------------------------------------------------
def warning(msg):
    """
    Print wating message to stderr.

    Arguments:
        msg (str): Warning message.
    """
    sys.stderr.write("WARNING: {}\n".format(msg))


# -----------------------------------------------------------------------------
def formats():
    """
    Get supported formats of comments.

    Returns:
        list[str]: List of formats.
    """
    return list(_COMMENTS)


# -----------------------------------------------------------------------------
def search_line(lines, rex, depth=1):
    """
    Search regexp in given lines.

    Arguments:
        lines (list[str]): List of strings.
        regex (str): Regular expression.
        depth (Optional[int]): Depth of search. Defaults to 1 line.

    Returns:
        int: Index of first matched line.
    """
    for i in range(depth if depth >= 0 else len(lines)):
        if i < len(lines):
            if re.search(rex, lines[i]):
                return i
    return -1


# -----------------------------------------------------------------------------
def get_owner(owner):
    """
    Get owner's title

    Arguments:
        owner (str): Owner's name of alias or list of owners separated
            by comma.

    Returns:
        str: Owner's title.
    """
    if owner.lower() in 'all':
        return get_owner('cea,edf,occ')

    owners = [i.strip() for i in owner.split(',')]
    result = []
    for i in owners:
        i = _OWNERS.get(i.lower(), i)
        if i not in result:
            result.append(i)
    return ', '.join(result)


# -----------------------------------------------------------------------------
def get_comment(file_format):
    """
    Get comment for given format.

    Arguments:
        format (str): Format of comments.

    Returns:
        str: Comment signature for given format; *None* for unsupported
        format.
    """
    return _COMMENTS.get(file_format) if file_format else None


# -----------------------------------------------------------------------------
def get_copyright(comment, owner, year):
    """
    Generate copyright from template.

    Arguments:
        comment (str): Comment signature.
        owner (str): Copyright owner.
        year (str): Copyright year(s).

    Returns:
        list[str]: List of strings with copyright data.
    """
    template = os.path.join(os.path.dirname(sys.argv[0]), 'copyright.template')
    the_copyright = []
    try:
        with open(template) as fid:
            the_copyright = fid.readlines()
    except IOError:
        error_exit("cannot find copyright template")
    the_copyright = [i.replace('@year@', year) for i in the_copyright]
    the_copyright = [i.replace('@owner@', owner) for i in the_copyright]
    the_copyright = [comment + ' ' + i if i.strip() else comment + '\n'
                     for i in the_copyright]
    return the_copyright


# -----------------------------------------------------------------------------
def get_module_owner(module):
    """
    Get owner of given module.

    Arguments:
        module (str): Module name.

    Returns:
        str: Module's owner.
    """
    modules_info = os.path.join(os.path.dirname(sys.argv[0]), 'modules.info')
    owner = None
    try:
        with open(modules_info) as fid:
            lines = fid.readlines()
            index = search_line(lines, r'^{}:'.format(module), -1)
            if index >= 0:
                return get_owner(lines[index].split(":")[1].strip())
    except IOError:
        warning("cannot find modules info file")
    return owner


# -----------------------------------------------------------------------------
def autodetect_owner(filename):
    """
    Auto-detect owner from file path.

    Arguments:
        filename (str): File path.

    Returns:
        str: Owner; *None* if owner isn't detected.
    """
    filename = os.path.realpath(filename)
    if os.path.exists(filename):
        directory = os.path.dirname(filename)
        while directory != '/':
            config_file = os.path.join(directory, '.git', 'config')
            if os.path.exists(config_file):
                from ConfigParser import ConfigParser
                from StringIO import StringIO
                with open(config_file) as fid:
                    gitcfg = fid.readlines()
                    cfg = ConfigParser()
                    data = StringIO(''.join([l.lstrip() for l in gitcfg]))
                    cfg.readfp(data)
                    url = cfg.get('remote "origin"', 'url')
                    module = os.path.split(url)[-1]
                    if module.endswith('.git'):
                        module = module[:-4]
                    return get_module_owner(module)
                break
            directory = os.path.dirname(directory)
    return None


# -----------------------------------------------------------------------------
def autodetect_format(filename):
    """
    Auto-detect format from filename.

    Arguments:
        filename (str): File path.

    Returns:
        str: Format of comments; *None* if format isn't detected.
    """
    extensions = {
        'cpp': ('c', 'cpp', 'cxx', 'cc', 'c++',
                'h', 'hxx', 'hpp', 'hh', 'h++',
                'idl', 'i'),
        'shell': ('sh', 'bash', 'csh', 'cmake', 'txt', 'cfg', 'ini', 'm4'),
        'python': ('py',),
        }
    rev_extensions = {e: k for k, exts in extensions.items() for e in exts}
    if filename and os.path.isfile(filename):
        extension = os.path.splitext(filename)[1][1:].lower()
        if extension in ('in',):
            name = os.path.splitext(filename)[0]
            extension = os.path.splitext(name)[1][1:].lower()
        if extension in rev_extensions:
            return rev_extensions[extension]

    try:
        import magic
        m = magic.open(magic.MAGIC_MIME_TYPE)
        m.load()
        file_formats = {
            'cpp': ('text/x-c', 'text/x-c++'),
            'shell': ('text/x-shellscript',),
            'python': ('text/x-python',),
            }
        rev_file_formats = {f: k for k, ff in file_formats.items() for f in ff}
        file_format = m.file(filename)
        if file_format in rev_file_formats:
            return rev_file_formats[file_format]
    except ImportError:
        pass

    return None


# -----------------------------------------------------------------------------
def insert_copyright(filename, owner, year, file_format):
    """
    Insert copyright note to a file.

    Arguments:
        filename (str): File path.
        owner (str): Copyright owner.
        year (str): Copyright year(s).
        file_format (str): Format of comments.
    """
    try:
        with open(filename) as fid:
            lines = fid.readlines()
    except IOError:
        warning("cannot read file: {}".format(filename))
        return

    if file_format in ('auto',):
        file_format = autodetect_format(filename)

    if owner.lower() in ('auto',):
        owner = autodetect_owner(filename) or get_owner('all')
    else:
        owner = get_owner(owner)

    comment = get_comment(file_format)
    if comment is None:
        warning("cannot detect format")
        return

    shell_row = search_line(lines, r'^#!') \
        if file_format in ('sh', 'bash', 'csh', 'py', 'python') else -1
    coding_row = search_line(lines, r'coding:', 3) \
        if file_format in ('py', 'python') else -1
    insert_point = max(0, shell_row + 1, coding_row + 1)

    the_copyright = get_copyright(comment, owner, year)
    if the_copyright:
        lines = lines[:insert_point] + the_copyright + ['\n'] \
            + lines[insert_point:]
        try:
            with open(filename, 'w') as fid:
                for line in lines:
                    fid.write(line)
        except IOError:
            warning("cannot write file: {}".format(filename))
            return


# -----------------------------------------------------------------------------
def main():
    """Main function."""

    # Parse command line.
    description = "Command line tool to insert copyright notice to a file."
    parser = argparse.ArgumentParser(description=description)

    help_string = "copyright owner; if not specified, tool tries to " \
        "autodetect an owner from the file path; if auto-detection fails, " \
        "an owner is set to '{owner}'"
    owner = 'auto'
    parser.add_argument("-o", "--owner", action="store",
                        dest="owner", default=owner,
                        help=help_string.format(owner=get_owner('all')))
    help_string = "copyright year(s); default: current year ({year})"
    year = str(time.localtime().tm_year)
    parser.add_argument("-y", "--year", action="store",
                        dest="year", default=year,
                        help=help_string.format(year=year))
    help_string = "format of comments ({choices}); default: {file_format}"
    file_format = 'auto'
    parser.add_argument("-f", "--format", action="store", choices=formats(),
                        dest="format", default=file_format,
                        help=help_string.format(file_format=file_format,
                                                choices="|".join(formats())))
    parser.add_argument('files', nargs='+', metavar='FILE')

    args = parser.parse_args(sys.argv[1:])

    owner = args.owner
    year = args.year
    file_format = args.format
    files = args.files

    for filename in files:
        insert_copyright(filename, owner, year, file_format)

    return 0

# -----------------------------------------------------------------------------
if __name__ == "__main__":
    sys.exit(main())