#!/usr/bin/env python
#
# Copyright 2016 The Android Open Source Project. All Rights Reserved.
#
# 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.
#

"""Generate a C++ data table containing locale data."""

import collections
import glob
import os.path
import sys


def get_locale_parts(locale):
    """Split a locale into three parts, for langauge, script, and region."""
    parts = locale.split('_')
    if len(parts) == 1:
        return (parts[0], None, None)
    elif len(parts) == 2:
        if len(parts[1]) == 4:  # parts[1] is a script
            return (parts[0], parts[1], None)
        else:
            return (parts[0], None, parts[1])
    else:
        assert len(parts) == 3
        return tuple(parts)


def read_likely_subtags(input_file_name):
    """Read and parse ICU's likelySubtags.txt."""
    with open(input_file_name) as input_file:
        likely_script_dict = {
            # Android's additions for pseudo-locales. These internal codes make
            # sure that the pseudo-locales would not match other English or
            # Arabic locales. (We can't use private-use ISO 15924 codes, since
            # they may be used by apps for other purposes.)
            "en_XA": "~~~A",
            "ar_XB": "~~~B",
            # Removed data from later versions of ICU
            "ji": "Hebr", # Old code for Yiddish, still used in Java and Android
        }
        representative_locales = {
            # Android's additions
            "en_Latn_GB", # representative for en_Latn_001
            "es_Latn_MX", # representative for es_Latn_419
            "es_Latn_US", # representative for es_Latn_419 (not the best idea,
                          # but Android has been shipping with it for quite a
                          # while. Fortunately, MX < US, so if both exist, MX
                          # would be chosen.)
        }
        for line in input_file:
            line = unicode(line, 'UTF-8').strip(u' \n\uFEFF').encode('UTF-8')
            if line.startswith('//'):
                continue
            if '{' in line and '}' in line:
                from_locale = line[:line.index('{')]
                to_locale = line[line.index('"')+1:line.rindex('"')]
                from_lang, from_scr, from_region = get_locale_parts(from_locale)
                _, to_scr, to_region = get_locale_parts(to_locale)
                if from_lang == 'und':
                    continue  # not very useful for our purposes
                if from_region is None and to_region not in ['001', 'ZZ']:
                    representative_locales.add(to_locale)
                if from_scr is None:
                    likely_script_dict[from_locale] = to_scr
        return likely_script_dict, frozenset(representative_locales)


# From packLanguageOrRegion() in ResourceTypes.cpp
def pack_language_or_region(inp, base):
    """Pack langauge or region in a two-byte tuple."""
    if inp is None:
        return (0, 0)
    elif len(inp) == 2:
        return ord(inp[0]), ord(inp[1])
    else:
        assert len(inp) == 3
        base = ord(base)
        first = ord(inp[0]) - base
        second = ord(inp[1]) - base
        third = ord(inp[2]) - base

        return (0x80 | (third << 2) | (second >>3),
                ((second << 5) | first) & 0xFF)


# From packLanguage() in ResourceTypes.cpp
def pack_language(language):
    """Pack language in a two-byte tuple."""
    return pack_language_or_region(language, 'a')


# From packRegion() in ResourceTypes.cpp
def pack_region(region):
    """Pack region in a two-byte tuple."""
    return pack_language_or_region(region, '0')


def pack_to_uint32(locale):
    """Pack language+region of locale into a 32-bit unsigned integer."""
    lang, _, region = get_locale_parts(locale)
    plang = pack_language(lang)
    pregion = pack_region(region)
    return (plang[0] << 24) | (plang[1] << 16) | (pregion[0] << 8) | pregion[1]


def dump_script_codes(all_scripts):
    """Dump the SCRIPT_CODES table."""
    print 'const char SCRIPT_CODES[][4] = {'
    for index, script in enumerate(all_scripts):
        print "    /* %-2d */ {'%c', '%c', '%c', '%c'}," % (
            index, script[0], script[1], script[2], script[3])
    print '};'
    print


def dump_script_data(likely_script_dict, all_scripts):
    """Dump the script data."""
    print
    print 'const std::unordered_map<uint32_t, uint8_t> LIKELY_SCRIPTS({'
    for locale in sorted(likely_script_dict.keys()):
        script = likely_script_dict[locale]
        print '    {0x%08Xu, %2du}, // %s -> %s' % (
            pack_to_uint32(locale),
            all_scripts.index(script),
            locale.replace('_', '-'),
            script)
    print '});'


def pack_to_uint64(locale):
    """Pack a full locale into a 64-bit unsigned integer."""
    _, script, _ = get_locale_parts(locale)
    return ((pack_to_uint32(locale) << 32) |
            (ord(script[0]) << 24) |
            (ord(script[1]) << 16) |
            (ord(script[2]) << 8) |
            ord(script[3]))


def dump_representative_locales(representative_locales):
    """Dump the set of representative locales."""
    print
    print 'std::unordered_set<uint64_t> REPRESENTATIVE_LOCALES({'
    for locale in sorted(representative_locales):
        print '    0x%08XLLU, // %s' % (
            pack_to_uint64(locale),
            locale)
    print '});'


def read_and_dump_likely_data(icu_data_dir):
    """Read and dump the likely-script data."""
    likely_subtags_txt = os.path.join(icu_data_dir, 'misc', 'likelySubtags.txt')
    likely_script_dict, representative_locales = read_likely_subtags(
        likely_subtags_txt)

    all_scripts = list(set(likely_script_dict.values()))
    assert len(all_scripts) <= 256
    all_scripts.sort()

    dump_script_codes(all_scripts)
    dump_script_data(likely_script_dict, all_scripts)
    dump_representative_locales(representative_locales)
    return likely_script_dict

def escape_script_variable_name(script):
    """Escape characters, e.g. '~', in a C++ variable name"""
    return script.replace("~", "_")

def read_parent_data(icu_data_dir):
    """Read locale parent data from ICU data files."""
    all_icu_data_files = glob.glob(os.path.join(icu_data_dir, '*', '*.txt'))
    parent_dict = {}
    for data_file in all_icu_data_files:
        locale = os.path.splitext(os.path.basename(data_file))[0]
        with open(data_file) as input_file:
            for line in input_file:
                if '%%Parent' in line:
                    parent = line[line.index('"')+1:line.rindex('"')]
                    if locale in parent_dict:
                        # Different files shouldn't have different parent info
                        assert parent_dict[locale] == parent
                    else:
                        parent_dict[locale] = parent
                elif locale.startswith('ar_') and 'default{"latn"}' in line:
                    # Arabic parent overrides for ASCII digits. Since
                    # Unicode extensions are not supported in ResourceTypes,
                    # we will use ar-015 (Arabic, Northern Africa) instead
                    # of the more correct ar-u-nu-latn.
                    parent_dict[locale] = 'ar_015'
    return parent_dict


def get_likely_script(locale, likely_script_dict):
    """Find the likely script for a locale, given the likely-script dictionary.
    """
    if locale.count('_') == 2:
        # it already has a script
        return locale.split('_')[1]
    elif locale in likely_script_dict:
        return likely_script_dict[locale]
    else:
        language = locale.split('_')[0]
        return likely_script_dict[language]


def dump_parent_data(script_organized_dict):
    """Dump information for parents of locales."""
    sorted_scripts = sorted(script_organized_dict.keys())
    print
    for script in sorted_scripts:
        parent_dict = script_organized_dict[script]
        print ('const std::unordered_map<uint32_t, uint32_t> %s_PARENTS({'
            % escape_script_variable_name(script.upper()))
        for locale in sorted(parent_dict.keys()):
            parent = parent_dict[locale]
            print '    {0x%08Xu, 0x%08Xu}, // %s -> %s' % (
                pack_to_uint32(locale),
                pack_to_uint32(parent),
                locale.replace('_', '-'),
                parent.replace('_', '-'))
        print '});'
        print

    print 'const struct {'
    print '    const char script[4];'
    print '    const std::unordered_map<uint32_t, uint32_t>* map;'
    print '} SCRIPT_PARENTS[] = {'
    for script in sorted_scripts:
        print "    {{'%c', '%c', '%c', '%c'}, &%s_PARENTS}," % (
            script[0], script[1], script[2], script[3],
            escape_script_variable_name(script.upper()))
    print '};'


def dump_parent_tree_depth(parent_dict):
    """Find and dump the depth of the parent tree."""
    max_depth = 1
    for locale, _ in parent_dict.items():
        depth = 1
        while locale in parent_dict:
            locale = parent_dict[locale]
            depth += 1
        max_depth = max(max_depth, depth)
    assert max_depth < 5 # Our algorithms assume small max_depth
    print
    print 'const size_t MAX_PARENT_DEPTH = %d;' % max_depth


def read_and_dump_parent_data(icu_data_dir, likely_script_dict):
    """Read parent data from ICU and dump it."""
    parent_dict = read_parent_data(icu_data_dir)
    script_organized_dict = collections.defaultdict(dict)
    for locale in parent_dict:
        parent = parent_dict[locale]
        if parent == 'root':
            continue
        script = get_likely_script(locale, likely_script_dict)
        script_organized_dict[script][locale] = parent_dict[locale]
    dump_parent_data(script_organized_dict)
    dump_parent_tree_depth(parent_dict)


def main():
    """Read the data files from ICU and dump the output to a C++ file."""
    source_root = sys.argv[1]
    icu_data_dir = os.path.join(
        source_root,
        'external', 'icu', 'icu4c', 'source', 'data')

    print '// Auto-generated by %s' % sys.argv[0]
    print
    likely_script_dict = read_and_dump_likely_data(icu_data_dir)
    read_and_dump_parent_data(icu_data_dir, likely_script_dict)


if __name__ == '__main__':
    main()