#!/usr/bin/env python3
# coding=utf-8
"""
Chaine de traduction de l'extension, sans dependance a gettext.

    python i18n.py            # extract + update + compile
    python i18n.py extract    # po/yarrowpattern.pot depuis le .inx et le .py
    python i18n.py update     # reporte le modele dans po/<langue>.po
    python i18n.py compile    # po/<langue>.po -> locale/<langue>/LC_MESSAGES/*.mo

Les textes source (.inx et appels _() du .py) sont en anglais : c'est ce
qu'Inkscape affiche pour une langue sans catalogue. Le catalogue anglais est
rempli automatiquement avec les textes source ; seul fr.po se traduit a la main.

Les chaines retenues dans le .inx suivent les regles d'Inkscape (inx.its) :
<name>, attributs gui-text et gui-description, contenu de <option>, <item> et
<label>, sauf translatable="no". Les espaces sont normalises, sauf sous
xml:space="preserve".
"""

import ast
import os
import re
import struct
import sys
import xml.etree.ElementTree as ET

HERE = os.path.dirname(os.path.abspath(__file__))
DOMAIN = "yarrowpattern"
SOURCES = ["y_pattern.inx", "y_pattern.py"]
LANGUAGES = ["en", "fr"]
SOURCE_LANGUAGE = "en"
PO_DIR = os.path.join(HERE, "po")
LOCALE_DIR = os.path.join(HERE, "locale")

XML_SPACE = "{http://www.w3.org/XML/1998/namespace}space"


# --------------------------------------------------------------------------
# Extraction
# --------------------------------------------------------------------------

def _local(tag):
    return tag.rsplit("}", 1)[-1]


def _normalize(text, preserve):
    return text if preserve else " ".join(text.split())


def extract_inx(path):
    """Chaines traduisibles d'un fichier .inx, dans l'ordre du document."""
    messages = []

    def walk(elem, preserve):
        preserve = elem.get(XML_SPACE, "preserve" if preserve else "default") == "preserve"
        if elem.get("translatable") != "no":
            for attr in ("gui-text", "gui-description"):
                if elem.get(attr):
                    messages.append(_normalize(elem.get(attr), preserve))
            if _local(elem.tag) in ("name", "option", "item", "label") and elem.text:
                messages.append(_normalize(elem.text, preserve))
        for child in elem:
            walk(child, preserve)

    walk(ET.parse(path).getroot(), False)
    return [m for m in messages if m]


def extract_py(path):
    """Arguments litteraux des appels _("...") d'un script Python."""
    with open(path, encoding="utf-8") as handle:
        tree = ast.parse(handle.read(), path)
    calls = [node for node in ast.walk(tree)
             if isinstance(node, ast.Call) and isinstance(node.func, ast.Name)
             and node.func.id == "_" and len(node.args) == 1
             and isinstance(node.args[0], ast.Constant)
             and isinstance(node.args[0].value, str)]
    calls.sort(key=lambda node: (node.lineno, node.col_offset))
    return [node.args[0].value for node in calls]


def extract():
    """Liste ordonnee et sans doublon de (msgid, [fichiers sources])."""
    found = {}
    for name in SOURCES:
        path = os.path.join(HERE, name)
        strings = extract_inx(path) if name.endswith(".inx") else extract_py(path)
        for msgid in strings:
            found.setdefault(msgid, [])
            if name not in found[msgid]:
                found[msgid].append(name)
    return list(found.items())


# --------------------------------------------------------------------------
# Lecture / ecriture des fichiers .po
# --------------------------------------------------------------------------

_ESCAPES = {"n": "\n", "t": "\t", '"': '"', "\\": "\\"}


def _unquote(line):
    body = line.strip()[1:-1]
    return re.sub(r'\\(.)', lambda m: _ESCAPES.get(m.group(1), m.group(1)), body)


def _quote(text):
    text = text.replace("\\", "\\\\").replace('"', '\\"').replace("\t", "\\t")
    lines = text.split("\n")
    parts = [line + "\\n" for line in lines[:-1]]
    if lines[-1]:
        parts.append(lines[-1])
    if len(parts) <= 1:
        return '"{}"'.format(parts[0] if parts else "")
    return '""\n' + "\n".join('"{}"'.format(part) for part in parts)


def read_po(path):
    """Dictionnaire msgid -> (msgstr, fuzzy). L'en-tete a pour cle ""."""
    entries = {}
    if not os.path.exists(path):
        return entries
    msgid = msgstr = None
    field = None
    fuzzy = False

    def flush():
        if msgid is not None:
            entries[msgid] = (msgstr or "", fuzzy)

    with open(path, encoding="utf-8") as handle:
        for raw in handle:
            line = raw.strip()
            if line.startswith("#,") and "fuzzy" in line:
                flush()
                msgid = msgstr = field = None
                fuzzy = True
            elif line.startswith("msgid "):
                if field == "msgstr":
                    flush()
                    fuzzy = False
                msgid, msgstr, field = _unquote(line[6:]), None, "msgid"
            elif line.startswith("msgstr "):
                msgstr, field = _unquote(line[7:]), "msgstr"
            elif line.startswith('"') and field == "msgid":
                msgid += _unquote(line)
            elif line.startswith('"') and field == "msgstr":
                msgstr += _unquote(line)
            elif not line and field == "msgstr":
                flush()
                msgid = msgstr = field = None
                fuzzy = False
    flush()
    return entries


def _header(language):
    fields = [
        ("Project-Id-Version", DOMAIN),
        ("Language", language or ""),
        ("MIME-Version", "1.0"),
        ("Content-Type", "text/plain; charset=UTF-8"),
        ("Content-Transfer-Encoding", "8bit"),
        ("Plural-Forms", {"fr": "nplurals=2; plural=(n > 1);",
                          "en": "nplurals=2; plural=(n != 1);"}.get(language, "")),
    ]
    return "".join("{}: {}\n".format(key, value) for key, value in fields if value)


def write_po(path, language, messages, translations):
    title = ("Modele de traduction" if language is None
             else "Traduction ({})".format(language))
    out = ["# {} de l'extension Inkscape « Remplissage motif Y fléché ».".format(title),
           "# Genere par i18n.py ; ne modifier que les msgstr.",
           "msgid \"\"",
           "msgstr " + _quote(_header(language)),
           ""]
    for msgid, refs in messages:
        msgstr, fuzzy = translations.get(msgid, ("", False))
        out.append("#: " + " ".join(refs))
        if fuzzy:
            out.append("#, fuzzy")
        out.append("msgid " + _quote(msgid))
        out.append("msgstr " + _quote(msgstr))
        out.append("")
    with open(path, "w", encoding="utf-8", newline="\n") as handle:
        handle.write("\n".join(out))


# --------------------------------------------------------------------------
# Compilation .mo (format GNU gettext)
# --------------------------------------------------------------------------

def write_mo(path, catalog):
    """Ecrit un catalogue {msgid: msgstr} au format .mo, cles triees."""
    keys = sorted(catalog)
    ids = [key.encode("utf-8") for key in keys]
    strs = [catalog[key].encode("utf-8") for key in keys]
    count = len(keys)
    ids_start = 7 * 4 + 16 * count
    strs_start = ids_start + sum(len(b) + 1 for b in ids)

    table_ids, table_strs = [], []
    offset = ids_start
    for data in ids:
        table_ids += [len(data), offset]
        offset += len(data) + 1
    offset = strs_start
    for data in strs:
        table_strs += [len(data), offset]
        offset += len(data) + 1

    output = struct.pack("<7I", 0x950412DE, 0, count, 7 * 4, 7 * 4 + 8 * count, 0, 0)
    output += struct.pack("<{}I".format(2 * count), *table_ids)
    output += struct.pack("<{}I".format(2 * count), *table_strs)
    output += b"".join(data + b"\0" for data in ids)
    output += b"".join(data + b"\0" for data in strs)

    os.makedirs(os.path.dirname(path), exist_ok=True)
    with open(path, "wb") as handle:
        handle.write(output)


# --------------------------------------------------------------------------
# Commandes
# --------------------------------------------------------------------------

def po_path(language):
    return os.path.join(PO_DIR, "{}.po".format(language))


def mo_path(language):
    return os.path.join(LOCALE_DIR, language, "LC_MESSAGES", DOMAIN + ".mo")


def cmd_extract():
    os.makedirs(PO_DIR, exist_ok=True)
    messages = extract()
    write_po(os.path.join(PO_DIR, DOMAIN + ".pot"), None, messages, {})
    print("{} chaines -> po/{}.pot".format(len(messages), DOMAIN))


def cmd_update():
    messages = extract()
    for language in LANGUAGES:
        translations = read_po(po_path(language))
        if language == SOURCE_LANGUAGE:
            translations = {msgid: (msgid, False) for msgid, _refs in messages}
        write_po(po_path(language), language, messages, translations)
        missing = [m for m, _r in messages if not translations.get(m, ("", False))[0]]
        print("po/{}.po : {} a traduire".format(language, len(missing)))
        for msgid in missing:
            print("    " + msgid.splitlines()[0])


def cmd_compile():
    for language in LANGUAGES:
        entries = read_po(po_path(language))
        catalog = {msgid: msgstr for msgid, (msgstr, fuzzy) in entries.items()
                   if msgid and msgstr and not fuzzy}
        catalog[""] = _header(language)
        write_mo(mo_path(language), catalog)
        print("{} -> {} ({} chaines)".format(
            os.path.relpath(po_path(language), HERE),
            os.path.relpath(mo_path(language), HERE), len(catalog) - 1))


def main(argv):
    commands = {"extract": [cmd_extract], "update": [cmd_update],
                "compile": [cmd_compile],
                "all": [cmd_extract, cmd_update, cmd_compile]}
    name = argv[0] if argv else "all"
    if name not in commands:
        print(__doc__)
        return 1
    for command in commands[name]:
        command()
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))