#!/usr/bin/env python3
# Copyright (c) 2016 The Bitcoin Core developers
# Copyright (c) 2019 The Gem Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.

import re
import fnmatch
import sys
import subprocess
import datetime
import os

################################################################################
# file filtering
################################################################################

EXCLUDE = [
    # libsecp256k1:
    'src/secp256k1/include/secp256k1.h',
    'src/secp256k1/include/secp256k1_ecdh.h',
    'src/secp256k1/include/secp256k1_recovery.h',
    'src/secp256k1/include/secp256k1_schnorr.h',
    'src/secp256k1/src/java/org_bitcoin_NativeSecp256k1.c',
    'src/secp256k1/src/java/org_bitcoin_NativeSecp256k1.h',
    'src/secp256k1/src/java/org_bitcoin_Secp256k1Context.c',
    'src/secp256k1/src/java/org_bitcoin_Secp256k1Context.h',
    # auto generated:
    'src/univalue/lib/univalue_escapes.h',
    'src/qt/bitcoinstrings.cpp',
    'src/chainparamsseeds.h',
    # other external copyrights:
    'src/tinyformat.h',
    'src/leveldb/util/env_win.cc',
    'src/crypto/ctaes/bench.c',
    'qa/rpc-tests/test_framework/bignum.py',
    # python init:
    '*__init__.py',
]
EXCLUDE_COMPILED = re.compile('|'.join([fnmatch.translate(m) for m in EXCLUDE]))

INCLUDE = ['*.h', '*.cpp', '*.cc', '*.c', '*.py']
INCLUDE_COMPILED = re.compile('|'.join([fnmatch.translate(m) for m in INCLUDE]))

def applies_to_file(filename):
    return ((EXCLUDE_COMPILED.match(filename) is None) and
            (INCLUDE_COMPILED.match(filename) is not None))

################################################################################
# obtain list of files in repo according to INCLUDE and EXCLUDE
################################################################################

GIT_LS_CMD = 'git ls-files'

def call_git_ls():
    out = subprocess.check_output(GIT_LS_CMD.split(' '))
    return [f for f in out.decode("utf-8").split('\n') if f != '']

def get_filenames_to_examine():
    filenames = call_git_ls()
    return sorted([filename for filename in filenames if
                   applies_to_file(filename)])

################################################################################
# define and compile regexes for the patterns we are looking for
################################################################################


COPYRIGHT_WITH_C = 'Copyright \(c\)'
COPYRIGHT_WITHOUT_C = 'Copyright'
ANY_COPYRIGHT_STYLE = '(%s|%s)' % (COPYRIGHT_WITH_C, COPYRIGHT_WITHOUT_C)

YEAR = "20[0-9][0-9]"
YEAR_RANGE = '(%s)(-%s)?' % (YEAR, YEAR)
YEAR_LIST = '(%s)(, %s)+' % (YEAR, YEAR)
ANY_YEAR_STYLE = '(%s|%s)' % (YEAR_RANGE, YEAR_LIST)
ANY_COPYRIGHT_STYLE_OR_YEAR_STYLE = ("%s %s" % (ANY_COPYRIGHT_STYLE,
                                                ANY_YEAR_STYLE))

ANY_COPYRIGHT_COMPILED = re.compile(ANY_COPYRIGHT_STYLE_OR_YEAR_STYLE)

def compile_copyright_regex(copyright_style, year_style, name):
    return re.compile('%s %s %s' % (copyright_style, year_style, name))

EXPECTED_HOLDER_NAMES = [
    "Satoshi Nakamoto\n",
    "The Bitcoin Core developers\n",
    "The Bitcoin Core developers \n",
    "Bitcoin Core Developers\n",
    "the Bitcoin Core developers\n",
    "The Bitcoin developers\n",
    "The LevelDB Authors\. All rights reserved\.\n",
    "BitPay Inc\.\n",
    "BitPay, Inc\.\n",
    "University of Illinois at Urbana-Champaign\.\n",
    "MarcoFalke\n",
    "Pieter Wuille\n",
    "Pieter Wuille +\*\n",
    "Pieter Wuille, Gregory Maxwell +\*\n",
    "Pieter Wuille, Andrew Poelstra +\*\n",
    "Andrew Poelstra +\*\n",
    "Wladimir J. van der Laan\n",
    "Jeff Garzik\n",
    "Diederik Huys, Pieter Wuille +\*\n",
    "Thomas Daede, Cory Fields +\*\n",
    "Jan-Klaas Kollhof\n",
    "Sam Rushing\n",
    "ArtForz -- public domain half-a-node\n",
    "The Gem Core developers\n",
]

DOMINANT_STYLE_COMPILED = {}
YEAR_LIST_STYLE_COMPILED = {}
WITHOUT_C_STYLE_COMPILED = {}

for holder_name in EXPECTED_HOLDER_NAMES:
    DOMINANT_STYLE_COMPILED[holder_name] = (
        compile_copyright_regex(COPYRIGHT_WITH_C, YEAR_RANGE, holder_name))
    YEAR_LIST_STYLE_COMPILED[holder_name] = (
        compile_copyright_regex(COPYRIGHT_WITH_C, YEAR_LIST, holder_name))
    WITHOUT_C_STYLE_COMPILED[holder_name] = (
        compile_copyright_regex(COPYRIGHT_WITHOUT_C, ANY_YEAR_STYLE,
                                holder_name))

################################################################################
# search file contents for copyright message of particular category
################################################################################

def get_count_of_copyrights_of_any_style_any_holder(contents):
    return len(ANY_COPYRIGHT_COMPILED.findall(contents))

def file_has_dominant_style_copyright_for_holder(contents, holder_name):
    match = DOMINANT_STYLE_COMPILED[holder_name].search(contents)
    return match is not None

def file_has_year_list_style_copyright_for_holder(contents, holder_name):
    match = YEAR_LIST_STYLE_COMPILED[holder_name].search(contents)
    return match is not None

def file_has_without_c_style_copyright_for_holder(contents, holder_name):
    match = WITHOUT_C_STYLE_COMPILED[holder_name].search(contents)
    return match is not None

################################################################################
# get file info
################################################################################

def read_file(filename):
    return open(os.path.abspath(filename), 'r').read()

def gather_file_info(filename):
    info = {}
    info['filename'] = filename
    c = read_file(filename)
    info['contents'] = c

    info['all_copyrights'] = get_count_of_copyrights_of_any_style_any_holder(c)

    info['classified_copyrights'] = 0
    info['dominant_style'] = {}
    info['year_list_style'] = {}
    info['without_c_style'] = {}
    for holder_name in EXPECTED_HOLDER_NAMES:
        has_dominant_style = (
            file_has_dominant_style_copyright_for_holder(c, holder_name))
        has_year_list_style = (
            file_has_year_list_style_copyright_for_holder(c, holder_name))
        has_without_c_style = (
            file_has_without_c_style_copyright_for_holder(c, holder_name))
        info['dominant_style'][holder_name] = has_dominant_style
        info['year_list_style'][holder_name] = has_year_list_style
        info['without_c_style'][holder_name] = has_without_c_style
        if has_dominant_style or has_year_list_style or has_without_c_style:
            info['classified_copyrights'] = info['classified_copyrights'] + 1
    return info

################################################################################
# report execution
################################################################################

SEPARATOR = '-'.join(['' for _ in range(80)])

def print_filenames(filenames, verbose):
    if not verbose:
        return
    for filename in filenames:
        print("\t%s" % filename)

def print_report(file_infos, verbose):
    print(SEPARATOR)
    examined = [i['filename'] for i in file_infos]
    print("%d files examined according to INCLUDE and EXCLUDE fnmatch rules" %
          len(examined))
    print_filenames(examined, verbose)

    print(SEPARATOR)
    print('')
    zero_copyrights = [i['filename'] for i in file_infos if
                       i['all_copyrights'] == 0]
    print("%4d with zero copyrights" % len(zero_copyrights))
    print_filenames(zero_copyrights, verbose)
    one_copyright = [i['filename'] for i in file_infos if
                     i['all_copyrights'] == 1]
    print("%4d with one copyright" % len(one_copyright))
    print_filenames(one_copyright, verbose)
    two_copyrights = [i['filename'] for i in file_infos if
                      i['all_copyrights'] == 2]
    print("%4d with two copyrights" % len(two_copyrights))
    print_filenames(two_copyrights, verbose)
    three_copyrights = [i['filename'] for i in file_infos if
                        i['all_copyrights'] == 3]
    print("%4d with three copyrights" % len(three_copyrights))
    print_filenames(three_copyrights, verbose)
    four_or_more_copyrights = [i['filename'] for i in file_infos if
                               i['all_copyrights'] >= 4]
    print("%4d with four or more copyrights" % len(four_or_more_copyrights))
    print_filenames(four_or_more_copyrights, verbose)
    print('')
    print(SEPARATOR)
    print('Copyrights with dominant style:\ne.g. "Copyright (c)" and '
          '"<year>" or "<startYear>-<endYear>":\n')
    for holder_name in EXPECTED_HOLDER_NAMES:
        dominant_style = [i['filename'] for i in file_infos if
                          i['dominant_style'][holder_name]]
        if len(dominant_style) > 0:
            print("%4d with '%s'" % (len(dominant_style),
                                     holder_name.replace('\n', '\\n')))
            print_filenames(dominant_style, verbose)
    print('')
    print(SEPARATOR)
    print('Copyrights with year list style:\ne.g. "Copyright (c)" and '
          '"<year1>, <year2>, ...":\n')
    for holder_name in EXPECTED_HOLDER_NAMES:
        year_list_style = [i['filename'] for i in file_infos if
                           i['year_list_style'][holder_name]]
        if len(year_list_style) > 0:
            print("%4d with '%s'" % (len(year_list_style),
                                     holder_name.replace('\n', '\\n')))
            print_filenames(year_list_style, verbose)
    print('')
    print(SEPARATOR)
    print('Copyrights with no "(c)" style:\ne.g. "Copyright" and "<year>" or '
          '"<startYear>-<endYear>":\n')
    for holder_name in EXPECTED_HOLDER_NAMES:
        without_c_style = [i['filename'] for i in file_infos if
                           i['without_c_style'][holder_name]]
        if len(without_c_style) > 0:
            print("%4d with '%s'" % (len(without_c_style),
                                     holder_name.replace('\n', '\\n')))
            print_filenames(without_c_style, verbose)

    print('')
    print(SEPARATOR)

    unclassified_copyrights = [i['filename'] for i in file_infos if
                               i['classified_copyrights'] < i['all_copyrights']]
    print("%d with unexpected copyright holder names" %
          len(unclassified_copyrights))
    print_filenames(unclassified_copyrights, verbose)
    print(SEPARATOR)

def exec_report(base_directory, verbose):
    original_cwd = os.getcwd()
    os.chdir(base_directory)
    filenames = get_filenames_to_examine()
    file_infos = [gather_file_info(f) for f in filenames]
    print_report(file_infos, verbose)
    os.chdir(original_cwd)

################################################################################
# report cmd
################################################################################

REPORT_USAGE = """
Produces a report of all copyright header notices found inside the source files
of a repository.

Usage:
    $ ./copyright_header.py report <base_directory> [verbose]

Arguments:
    <base_directory> - The base directory of a Gem Core source code repository.
    [verbose] - Includes a list of every file of each subcategory in the report.
"""

def report_cmd(argv):
    if len(argv) == 2:
        sys.exit(REPORT_USAGE)
        
    base_directory = argv[2]
    if not os.path.exists(base_directory):
        sys.exit("*** bad <base_directory>: %s" % base_directory)

    if len(argv) == 3:
        verbose = False
    elif argv[3] == 'verbose':
        verbose = True
    else:
        sys.exit("*** unknown argument: %s" % argv[2])

    exec_report(base_directory, verbose)

################################################################################
# query git for year of last change
################################################################################

GIT_LOG_CMD = "git log --pretty=format:%%ai %s"

def call_git_log(filename):
    out = subprocess.check_output((GIT_LOG_CMD % filename).split(' '))
    return out.decode("utf-8").split('\n')

def get_git_change_years(filename):
    git_log_lines = call_git_log(filename)
    if len(git_log_lines) == 0:
        return [datetime.date.today().year]
    # timestamp is in ISO 8601 format. e.g. "2016-09-05 14:25:32 -0600"
    return [line.split(' ')[0].split('-')[0] for line in git_log_lines]

def get_most_recent_git_change_year(filename):
    return max(get_git_change_years(filename))

################################################################################
# read and write to file
################################################################################

def read_file_lines(filename):
    f = open(os.path.abspath(filename), 'r')
    file_lines = f.readlines()
    f.close()
    return file_lines

def write_file_lines(filename, file_lines):
    f = open(os.path.abspath(filename), 'w')
    f.write(''.join(file_lines))
    f.close()

################################################################################
# update header years execution
################################################################################

COPYRIGHT = 'Copyright \(c\)'
YEAR = "20[0-9][0-9]"
YEAR_RANGE = '(%s)(-%s)?' % (YEAR, YEAR)
HOLDER = 'The Gem Core developers'
UPDATEABLE_LINE_COMPILED = re.compile(' '.join([COPYRIGHT, YEAR_RANGE, HOLDER]))

def get_updatable_copyright_line(file_lines):
    index = 0
    for line in file_lines:
        if UPDATEABLE_LINE_COMPILED.search(line) is not None:
            return index, line
        index = index + 1
    return None, None

def parse_year_range(year_range):
    year_split = year_range.split('-')
    start_year = year_split[0]
    if len(year_split) == 1:
        return start_year, start_year
    return start_year, year_split[1]

def year_range_to_str(start_year, end_year):
    if start_year == end_year:
        return start_year
    return "%s-%s" % (start_year, end_year)

def create_updated_copyright_line(line, last_git_change_year):
    copyright_splitter = 'Copyright (c) '
    copyright_split = line.split(copyright_splitter)
    # Preserve characters on line that are ahead of the start of the copyright
    # notice - they are part of the comment block and vary from file-to-file.
    before_copyright = copyright_split[0]
    after_copyright = copyright_split[1]

    space_split = after_copyright.split(' ')
    year_range = space_split[0]
    start_year, end_year = parse_year_range(year_range)
    if end_year == last_git_change_year:
        return line
    return (before_copyright + copyright_splitter +
            year_range_to_str(start_year, last_git_change_year) + ' ' +
            ' '.join(space_split[1:]))

def update_updatable_copyright(filename):
    file_lines = read_file_lines(filename)
    index, line = get_updatable_copyright_line(file_lines)
    if not line:
        print_file_action_message(filename, "No updatable copyright.")
        return
    last_git_change_year = get_most_recent_git_change_year(filename)
    new_line = create_updated_copyright_line(line, last_git_change_year)
    if line == new_line:
        print_file_action_message(filename, "Copyright up-to-date.")
        return
    file_lines[index] = new_line
    write_file_lines(filename, file_lines)
    print_file_action_message(filename,
                              "Copyright updated! -> %s" % last_git_change_year)

def exec_update_header_year(base_directory):
    original_cwd = os.getcwd()
    os.chdir(base_directory)
    for filename in get_filenames_to_examine():
        update_updatable_copyright(filename)
    os.chdir(original_cwd)

################################################################################
# update cmd
################################################################################

UPDATE_USAGE = """
Updates all the copyright headers of "The Gem Core developers" which were
changed in a year more recent than is listed. For example:

// Copyright (c) <firstYear>-<lastYear> The Gem Core developers

will be updated to:

// Copyright (c) <firstYear>-<lastModifiedYear> The Gem Core developers

where <lastModifiedYear> is obtained from the 'git log' history.

This subcommand also handles copyright headers that have only a single year. In those cases:

// Copyright (c) <year> The Gem Core developers

will be updated to:

// Copyright (c) <year>-<lastModifiedYear> The Gem Core developers

where the update is appropriate.

Usage:
    $ ./copyright_header.py update <base_directory>

Arguments:
    <base_directory> - The base directory of Gem Core source code repository.
"""

def print_file_action_message(filename, action):
    print("%-52s %s" % (filename, action))

def update_cmd(argv):
    if len(argv) != 3:
        sys.exit(UPDATE_USAGE)
    
    base_directory = argv[2]
    if not os.path.exists(base_directory):
        sys.exit("*** bad base_directory: %s" % base_directory)
    exec_update_header_year(base_directory)

################################################################################
# inserted copyright header format
################################################################################

def get_header_lines(header, start_year, end_year):
    lines = header.split('\n')[1:-1]
    lines[0] = lines[0] % year_range_to_str(start_year, end_year)
    return [line + '\n' for line in lines]

CPP_HEADER = '''
// Copyright (c) %s The Gem Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
'''

def get_cpp_header_lines_to_insert(start_year, end_year):
    return reversed(get_header_lines(CPP_HEADER, start_year, end_year))

PYTHON_HEADER = '''
# Copyright (c) %s The Gem Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
'''

def get_python_header_lines_to_insert(start_year, end_year):
    return reversed(get_header_lines(PYTHON_HEADER, start_year, end_year))

################################################################################
# query git for year of last change
################################################################################

def get_git_change_year_range(filename):
    years = get_git_change_years(filename)
    return min(years), max(years)

################################################################################
# check for existing core copyright
################################################################################

def file_already_has_core_copyright(file_lines):
    index, _ = get_updatable_copyright_line(file_lines)
    return index != None

################################################################################
# insert header execution
################################################################################

def file_has_hashbang(file_lines):
    if len(file_lines) < 1:
        return False
    if len(file_lines[0]) <= 2:
        return False
    return file_lines[0][:2] == '#!'

def insert_python_header(filename, file_lines, start_year, end_year):
    if file_has_hashbang(file_lines):
        insert_idx = 1 
    else:
        insert_idx = 0
    header_lines = get_python_header_lines_to_insert(start_year, end_year)
    for line in header_lines:
        file_lines.insert(insert_idx, line)
    write_file_lines(filename, file_lines)

def insert_cpp_header(filename, file_lines, start_year, end_year):
    header_lines = get_cpp_header_lines_to_insert(start_year, end_year)
    for line in header_lines:
        file_lines.insert(0, line)
    write_file_lines(filename, file_lines)

def exec_insert_header(filename, style):
    file_lines = read_file_lines(filename)
    if file_already_has_core_copyright(file_lines):
        sys.exit('*** %s already has a copyright by The Gem Core developers'
                 % (filename))
    start_year, end_year = get_git_change_year_range(filename)
    if style == 'python':
        insert_python_header(filename, file_lines, start_year, end_year)
    else:
        insert_cpp_header(filename, file_lines, start_year, end_year)

################################################################################
# insert cmd
################################################################################

INSERT_USAGE = """
Inserts a copyright header for "The Gem Core developers" at the top of the
file in either Python or C++ style as determined by the file extension. If the
file is a Python file and it has a '#!' starting the first line, the header is
inserted in the line below it.

The copyright dates will be set to be:

"<year_introduced>-<current_year>"

where <year_introduced> is according to the 'git log' history. If
<year_introduced> is equal to <current_year>, the date will be set to be:

"<current_year>"

If the file already has a copyright for "The Gem Core developers", the
script will exit.

Usage:
    $ ./copyright_header.py insert <file>

Arguments:
    <file> - A source file in the Gem Core repository.
"""

def insert_cmd(argv):
    if len(argv) != 3:
        sys.exit(INSERT_USAGE)

    filename = argv[2]
    if not os.path.isfile(filename):
        sys.exit("*** bad filename: %s" % filename)
    _, extension = os.path.splitext(filename)
    if extension not in ['.h', '.cpp', '.cc', '.c', '.py']:
        sys.exit("*** cannot insert for file extension %s" % extension)
   
    if extension == '.py': 
        style = 'python'
    else:
        style = 'cpp'
    exec_insert_header(filename, style)
         
################################################################################
# UI
################################################################################

USAGE = """
copyright_header.py - utilities for managing copyright headers of 'The Gem
Core developers' in repository source files.

Usage:
    $ ./copyright_header <subcommand>

Subcommands:
    report
    update
    insert

To see subcommand usage, run them without arguments.
"""

SUBCOMMANDS = ['report', 'update', 'insert']

if __name__ == "__main__":
    if len(sys.argv) == 1:
        sys.exit(USAGE)
    subcommand = sys.argv[1]
    if subcommand not in SUBCOMMANDS:
        sys.exit(USAGE)
    if subcommand == 'report':
        report_cmd(sys.argv)
    elif subcommand == 'update':
        update_cmd(sys.argv)
    elif subcommand == 'insert':
        insert_cmd(sys.argv)
