# This file is part of lyx2lyx
# Copyright (C) 2002-2024 The LyX Team
# Copyright (C) 2002-2004 Dekel Tsur <dekel@lyx.org>
# Copyright (C) 2002-2006 José Matos <jamatos@lyx.org>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

"The LyX module has all the rules related with different lyx file formats."

import codecs
import gzip
import io
import locale
import os.path
import re
import sys
import time

from parser_tools import (
    check_token,
    find_complete_lines,
    find_end_of,
    find_token,
    get_value,
)

try:
    import lyx2lyx_version

    version__ = lyx2lyx_version.version
    stable_version = True
except ModuleNotFoundError:
    # we are running from the build directory so assume the last version
    version__ = "2.5"
    stable_version = False

default_debug__ = 2


####################################################################
# Private helper functions


def find_end_of_inset(lines, i):
    "Find beginning of inset, where lines[i] is included."
    return find_end_of(lines, i, "\\begin_inset", "\\end_inset")


def minor_versions(major, last_minor_version):
    """Generate minor versions, using major as prefix and minor
    versions from 0 until last_minor_version, plus the generic version.

    Example:

      minor_versions("1.2", 4) ->
      [ "1.2", "1.2.0", "1.2.1", "1.2.2", "1.2.3"]
    """
    return [major] + [major + ".%d" % i for i in range(last_minor_version + 1)]


# End of helper functions
####################################################################


# Regular expressions used
format_re = re.compile(r"(\d)[\.,]?(\d\d)")
fileformat = re.compile(r"\\lyxformat\s*(\S*)")
original_version = re.compile(b".*?LyX ([\\d.]*)")
original_tex2lyx_version = re.compile(b".*?tex2lyx ([\\d.]*)")

##
# file format information:
#  file, supported formats, stable release versions
format_relation = [
    ("0_06", [200], minor_versions("0.6", 4)),
    ("0_08", [210], minor_versions("0.8", 6) + ["0.7"]),
    ("0_10", [210], minor_versions("0.10", 7) + ["0.9"]),
    ("0_12", [215], minor_versions("0.12", 1) + ["0.11"]),
    ("1_0", [215], minor_versions("1.0", 4)),
    ("1_1", [215], minor_versions("1.1", 4)),
    ("1_1_5", [216], ["1.1", "1.1.5", "1.1.5.1", "1.1.5.2"]),
    ("1_1_6_0", [217], ["1.1", "1.1.6", "1.1.6.1", "1.1.6.2"]),
    ("1_1_6_3", [218], ["1.1", "1.1.6.3", "1.1.6.4"]),
    ("1_2", [220], minor_versions("1.2", 4)),
    ("1_3", [221], minor_versions("1.3", 7)),
    # Note that range(i,j) is up to j *excluded*.
    ("1_4", list(range(222, 246)), minor_versions("1.4", 5)),
    ("1_5", list(range(246, 277)), minor_versions("1.5", 7)),
    ("1_6", list(range(277, 346)), minor_versions("1.6", 10)),
    ("2_0", list(range(346, 414)), minor_versions("2.0", 8)),
    ("2_1", list(range(414, 475)), minor_versions("2.1", 5)),
    ("2_2", list(range(475, 509)), minor_versions("2.2", 4)),
    ("2_3", list(range(509, 545)), minor_versions("2.3", 7)),
    ("2_4", list(range(545, 621)), minor_versions("2.4", 0)),
    ("2_5", (), minor_versions("2.5", 0)),
]

####################################################################
# This is useful just for development versions                     #
# if the list of supported formats is empty get it from last step  #
if not format_relation[-1][1]:
    step, mode = format_relation[-1][0], "convert"
    convert = getattr(__import__("lyx_" + step), mode)
    format_relation[-1] = (step, [conv[0] for conv in convert], format_relation[-1][2])
#                                                                  #
####################################################################


def formats_list():
    "Returns a list with supported file formats."
    formats = []
    for version in format_relation:
        for format in version[1]:
            if format not in formats:
                formats.append(format)
    return formats


def format_info():
    "Returns a list with the supported file formats."
    template = """
%s\tstable format:       %s
  \tstable versions:     %s
  \tdevelopment formats: %s
"""

    out = "version: formats and versions"
    for version in format_relation:
        major = str(version[2][0])
        versions = str(version[2][1:])
        if len(version[1]) == 1:
            formats = str(version[1][0])
            stable_format = str(version[1][0])
        elif not stable_version and major == version__:
            stable_format = "-- not yet --"
            versions = "-- not yet --"
            formats = f"{version[1][0]} - {version[1][-1]}"
        else:
            formats = f"{version[1][0]} - {version[1][-2]}"
            stable_format = str(version[1][-1])

        out += template % (major, stable_format, versions, formats)
    return out + "\n"


def get_end_format():
    "Returns the more recent file format available."
    # this check will fail only when we have a new version
    # and there is no format change yet.
    if format_relation[-1][1]:
        return format_relation[-1][1][-1]
    return format_relation[-2][1][-1]


def get_backend(textclass):
    "For _textclass_ returns its backend."
    if textclass == "linuxdoc" or textclass == "manpage":
        return "linuxdoc"
    if textclass.startswith("docbook") or textclass.startswith("agu-"):
        return "docbook"
    return "latex"


def trim_eol(line):
    "Remove end of line char(s)."
    if line[-1] != "\n" and line[-1] != "\r":
        # May happen for the last line of a document
        return line
    if line[-2:-1] == "\r":
        return line[:-2]
    else:
        return line[:-1]


def trim_eol_binary(line):
    "Remove end of line char(s)."
    if line[-1] != 10 and line[-1] != 13:
        # May happen for the last line of a document
        return line
    if line[-2:-1] == 13:
        return line[:-2]
    else:
        return line[:-1]


def get_encoding(language, inputencoding, format, cjk_encoding):
    "Returns enconding of the lyx file"
    if format > 248:
        return "utf8"
    # CJK-LyX encodes files using the current locale encoding.
    # This means that files created by CJK-LyX can only be converted using
    # the correct locale settings unless the encoding is given as commandline
    # argument.
    if cjk_encoding == "auto":
        return locale.getpreferredencoding()
    elif cjk_encoding:
        return cjk_encoding
    from lyx2lyx_lang import lang

    if inputencoding == "auto" or inputencoding == "default":
        return lang[language][3]
    if inputencoding == "":
        return "latin1"
    if inputencoding == "utf8x":
        return "utf8"
    # python does not know the alias latin9
    if inputencoding == "latin9":
        return "iso-8859-15"
    return inputencoding


##
# Class
#
class LyX_base:
    """This class carries all the information of the LyX file."""

    def __init__(
        self,
        end_format=0,
        input="",
        output="",
        error="",
        debug=default_debug__,
        try_hard=0,
        cjk_encoding="",
        final_version="",
        systemlyxdir="",
        language="english",
        encoding="auto",
    ):
        """Arguments:
        end_format: final format that the file should be converted. (integer)
        input: the name of the input source, if empty resort to standard input.
        output: the name of the output file, if empty use the standard output.
        error: the name of the error file, if empty use the standard error.
        debug: debug level, O means no debug, as its value increases be more verbose.
        """
        self.choose_input(input)
        self.output = output

        if error:
            self.err = open(error, "w")
        else:
            self.err = sys.stderr

        self.debug = debug
        self.try_hard = try_hard
        self.cjk_encoding = cjk_encoding

        if end_format:
            self.end_format = self.lyxformat(end_format)

            # In case the target version and format are both specified
            # verify that they are compatible. If not send a warning
            # and ignore the version.
            if final_version:
                message = "Incompatible version %s for specified format %d" % (
                    final_version,
                    self.end_format,
                )
                for version in format_relation:
                    if self.end_format in version[1]:
                        if final_version not in version[2]:
                            self.warning(message)
                            final_version = ""
        elif final_version:
            for version in format_relation:
                if final_version in version[2]:
                    # set the last format for that version
                    self.end_format = version[1][-1]
                    break
            else:
                final_version = ""
        else:
            self.end_format = get_end_format()

        if not final_version:
            for step in format_relation:
                if self.end_format in step[1]:
                    final_version = step[2][1]
        self.final_version = final_version
        self.warning("Final version: %s" % self.final_version, 10)
        self.warning("Final format: %d" % self.end_format, 10)

        self.backend = "latex"
        self.textclass = "article"
        # This is a hack: We use '' since we don't know the default
        # layout of the text class. LyX will parse it as default layout.
        # FIXME: Read the layout file and use the real default layout
        self.default_layout = ""
        self.header = []
        self.preamble = []
        self.body = []
        self.status = 0
        self.encoding = encoding
        self.language = language
        self.systemlyxdir = systemlyxdir

    def warning(self, message, debug_level=default_debug__):
        """Emits warning to self.error, if the debug_level is less
        than the self.debug."""
        if debug_level <= self.debug:
            self.err.write("lyx2lyx warning: " + message + "\n")

    def error(self, message):
        "Emits a warning and exits if not in try_hard mode."
        self.warning(message)
        if not self.try_hard:
            self.warning("Quitting.")
            sys.exit(1)

        self.status = 2

    def read(self):
        """Reads a file into the self.header and
        self.body parts, from self.input."""

        # First pass: Read header to determine file encoding
        # If we are running under python3 then all strings are binary in this
        # pass. In some cases we need to convert binary to unicode in order to
        # use our parser tools. Since we do not know the true encoding yet we
        # use latin1. This works since a) the parts we are interested in are
        # pure ASCII (subset of latin1) and b) in contrast to pure ascii or
        # utf8, one can decode any 8byte string using latin1.
        first_line = True
        while True:
            line = self.input.readline()
            if not line:
                # eof found before end of header
                self.error("Invalid LyX file: Missing body.")

            if first_line:
                # Remove UTF8 BOM marker if present
                if line.startswith(codecs.BOM_UTF8):
                    line = line[len(codecs.BOM_UTF8) :]

                first_line = False

            line = trim_eol_binary(line)
            decoded = line.decode("latin1")
            if check_token(decoded, "\\begin_preamble"):
                while True:
                    line = self.input.readline()
                    if not line:
                        # eof found before end of header
                        self.error("Invalid LyX file: Missing body.")

                    line = trim_eol_binary(line)
                    decoded = line.decode("latin1")
                    if check_token(decoded, "\\end_preamble"):
                        break

                    if decoded.split()[:0] in (
                        "\\layout",
                        "\\begin_layout",
                        "\\begin_body",
                    ):
                        self.warning(
                            "Malformed LyX file:"
                            "Missing '\\end_preamble'."
                            "\nAdding it now and hoping"
                            "for the best."
                        )

                    self.preamble.append(line)

            if check_token(decoded, "\\end_preamble"):
                continue

            line = line.rstrip()
            if not line:
                continue

            if decoded.split()[0] in (
                "\\layout",
                "\\begin_layout",
                "\\begin_body",
                "\\begin_deeper",
            ):
                self.body.append(line)
                break

            self.header.append(line)

        i = find_token(self.header, b"\\textclass", 0)
        if i == -1:
            self.warning("Malformed LyX file: Missing '\\textclass'.")
            i = find_token(self.header, b"\\lyxformat", 0) + 1
            self.header[i:i] = [b"\\textclass article"]

        self.textclass = get_value(self.header, b"\\textclass", 0, default=b"")
        self.language = get_value(self.header, b"\\language", 0, default=b"english").decode(
            "ascii"
        )
        self.inputencoding = get_value(
            self.header, b"\\inputencoding", 0, default=b"auto"
        ).decode("ascii")
        self.format = self.read_format()
        self.initial_format = self.format
        self.encoding = get_encoding(
            self.language, self.inputencoding, self.format, self.cjk_encoding
        )
        self.initial_version = self.read_version()

        # Second pass over header and preamble, now we know the file encoding
        # Do not forget the textclass (Debian bug #700828)
        self.textclass = self.textclass.decode(self.encoding)
        self.backend = get_backend(self.textclass)
        for i in range(len(self.header)):
            self.header[i] = self.header[i].decode(self.encoding)
        for i in range(len(self.preamble)):
            self.preamble[i] = self.preamble[i].decode(self.encoding)
        for i in range(len(self.body)):
            self.body[i] = self.body[i].decode(self.encoding)

        # Read document body
        while True:
            line = self.input.readline().decode(self.encoding)
            if not line:
                break
            self.body.append(trim_eol(line))

    def write(self):
        "Writes the LyX file to self.output."
        self.choose_output(self.output)
        self.set_version()
        self.set_format()
        self.set_textclass()
        if self.encoding == "auto":
            self.encoding = get_encoding(
                self.language, self.encoding, self.format, self.cjk_encoding
            )
        if self.preamble:
            i = find_token(self.header, "\\textclass", 0) + 1
            preamble = ["\\begin_preamble"] + self.preamble + ["\\end_preamble"]
            header = self.header[:i] + preamble + self.header[i:]
        else:
            header = self.header

        for line in header + [""] + self.body:
            self.output.write(line + "\n")

    def choose_output(self, output):
        """Choose output streams dealing transparently with
        compressed files."""

        # This is a bit complicated, because we need to be compatible both with
        # python 2 and python 3. Therefore we handle the encoding here and not
        # when writing individual lines and may need up to 3 layered file like
        # interfaces.
        if self.compressed:
            if output:
                outputfileobj = open(output, "wb")
            else:
                # We cannot not use stdout directly since it needs text, not bytes in python 3
                outputfileobj = os.fdopen(sys.stdout.fileno(), "wb")
            # We cannot not use gzip.open() since it is not supported by python 2
            zipbuffer = gzip.GzipFile(mode="wb", fileobj=outputfileobj)
            # We do not want to use different newlines on different OSes inside zipped files
            self.output = io.TextIOWrapper(zipbuffer, encoding=self.encoding, newline="\n")
        else:
            if output:
                self.output = open(output, "w", encoding=self.encoding)
            else:
                self.output = open(sys.stdout.fileno(), "w", encoding=self.encoding)

    def choose_input(self, input):
        """Choose input stream, dealing transparently with
        compressed files."""

        # Since we do not know the encoding yet we need to read the input as
        # bytes in binary mode, and convert later to unicode.
        if input and input != "-":
            self.dir = os.path.dirname(os.path.abspath(input))
            try:
                gzip.open(input).readline()
                self.input = gzip.open(input)
                self.compressed = True
            except OSError:
                self.input = open(input, "rb")
                self.compressed = False
        else:
            self.dir = ""
            self.input = os.fdopen(sys.stdin.fileno(), "rb")
            self.compressed = False

    def lyxformat(self, format):
        "Returns the file format representation, an integer."
        result = format_re.match(format)
        if result:
            format = int(result.group(1) + result.group(2))
        elif format == "2":
            format = 200
        else:
            self.error(str(format) + ": " + "Invalid LyX file.")

        if format in formats_list():
            return format

        self.error(str(format) + ": " + "Format not supported.")
        return None

    def read_version(self):
        """Searchs for clues of the LyX version used to write the
        file, returns the most likely value, or None otherwise."""

        for line in self.header:
            if line[0:1] != b"#":
                return None

            line = line.replace(b"fix", b".")
            # need to test original_tex2lyx_version first because tex2lyx
            # writes "#LyX file created by tex2lyx 2.2"
            result = original_tex2lyx_version.match(line)
            if not result:
                result = original_version.match(line)
                if result:
                    # Special know cases: reLyX and KLyX
                    if line.find(b"reLyX") != -1 or line.find(b"KLyX") != -1:
                        return "0.12"
            if result:
                res = result.group(1)
                if not res:
                    self.warning(line)
                # self.warning("Version %s" % result.group(1))
                return res.decode("ascii")
        self.warning(str(self.header[:2]))
        return None

    def set_version(self):
        "Set the header with the version used."

        initial_comment = " ".join(
            [
                "#LyX %s created this file." % version__,
                "For more info see https://www.lyx.org/",
            ]
        )

        # Simple heuristic to determine the comment that always starts
        # a lyx file
        if self.header[0].startswith("#"):
            self.header[0] = initial_comment
        else:
            self.header.insert(0, initial_comment)

        # Old lyx files had a two lines comment header:
        # 1) the first line had the user who had created it
        # 2) the second line had the lyx version used
        # later we decided that 1) was a privacy risk for no gain
        # here we remove the second line effectively erasing 1)
        if self.header[1][0] == "#":
            del self.header[1]

    def read_format(self):
        "Read from the header the fileformat of the present LyX file."
        for line in self.header:
            result = fileformat.match(line.decode("ascii"))
            if result:
                return self.lyxformat(result.group(1))
        else:
            self.error("Invalid LyX File: Missing format.")
        return None

    def set_format(self):
        "Set the file format of the file, in the header."
        if self.format <= 217:
            format = str(float(self.format) / 100)
        else:
            format = str(self.format)
        i = find_token(self.header, "\\lyxformat", 0)
        self.header[i] = "\\lyxformat %s" % format

    def set_textclass(self):
        i = find_token(self.header, "\\textclass", 0)
        self.header[i] = "\\textclass %s" % self.textclass

    # Note that the module will be added at the END of the extant ones
    def add_module(self, module):
        "Append module to the modules list."
        i = find_token(self.header, "\\begin_modules", 0)
        if i == -1:
            # No modules yet included
            i = find_token(self.header, "\\textclass", 0)
            if i == -1:
                self.warning("Malformed LyX document: No \\textclass!!")
                return
            modinfo = ["\\begin_modules", module, "\\end_modules"]
            self.header[i + 1 : i + 1] = modinfo
            return
        j = find_token(self.header, "\\end_modules", i)
        if j == -1:
            self.warning("(add_module)Malformed LyX document: No \\end_modules.")
            return
        k = find_token(self.header, module, i)
        if k != -1 and k < j:
            return
        self.header.insert(j, module)

    def del_module(self, module):
        "Delete `module` from module list, return success."
        modlist = self.get_module_list()
        if module not in modlist:
            return False
        self.set_module_list([line for line in modlist if line != module])
        return True

    def get_module_list(self):
        "Return list of modules."
        i = find_token(self.header, "\\begin_modules", 0)
        if i == -1:
            return []
        j = find_token(self.header, "\\end_modules", i)
        return self.header[i + 1 : j]

    def set_module_list(self, mlist):
        i = find_token(self.header, "\\begin_modules", 0)
        if i == -1:
            # No modules yet included
            tclass = find_token(self.header, "\\textclass", 0)
            if tclass == -1:
                self.warning("Malformed LyX document: No \\textclass!!")
                return
            i = j = tclass + 1
        else:
            j = find_token(self.header, "\\end_modules", i)
            if j == -1:
                self.warning("(set_module_list) Malformed LyX document: No \\end_modules.")
                return
            j += 1
        if mlist:
            mlist = ["\\begin_modules"] + mlist + ["\\end_modules"]
        self.header[i:j] = mlist

    def set_parameter(self, param, value):
        "Set the value of the header parameter."
        i = find_token(self.header, "\\" + param, 0)
        if i == -1:
            self.warning("Parameter not found in the header: %s" % param, 3)
            return
        self.header[i] = f"\\{param} {str(value)}"

    def is_default_layout(self, layout):
        "Check whether a layout is the default layout of this class."
        # FIXME: Check against the real text class default layout
        if layout == "Standard" or layout == self.default_layout:
            return 1
        return 0

    def convert(self):
        "Convert from current (self.format) to self.end_format."
        if self.format == self.end_format:
            self.warning(
                "No conversion needed: Target format %s "
                "same as current format!" % self.format,
                default_debug__,
            )
            return

        mode, conversion_chain = self.chain()
        self.warning("conversion chain: " + str(conversion_chain), 3)

        for step in conversion_chain:
            steps = getattr(__import__("lyx_" + step), mode)

            self.warning(f"Convertion step: {step} - {mode}", default_debug__ + 1)
            if not steps:
                self.error(
                    "The conversion to an older "
                    "format (%s) is not implemented." % self.format
                )

            multi_conv = len(steps) != 1
            for version, table in steps:
                if (
                    multi_conv
                    and (self.format >= version and mode == "convert")
                    or (self.format <= version and mode == "revert")
                ):
                    continue

                for conv in table:
                    init_t = time.time()
                    try:
                        conv(self)
                    except Exception as exception:
                        self.warning(
                            f"An error occurred in {version}, {conv}",
                            default_debug__,
                        )
                        if not self.try_hard:
                            raise exception
                        self.status = 2
                    else:
                        self.warning(
                            f"{time.time() - init_t:f}: Elapsed time on {conv}",
                            default_debug__ + 1,
                        )
                self.format = version
                if self.end_format == self.format:
                    return

    def chain(self):
        """This is where all the decisions related with the
        conversion are taken.  It returns a list of modules needed to
        convert the LyX file from self.format to self.end_format"""

        format = self.format
        correct_version = 0

        for rel in format_relation:
            if self.initial_version in rel[2]:
                if format in rel[1]:
                    initial_step = rel[0]
                    correct_version = 1
                    break

        if not correct_version:
            if format <= 215:
                self.warning(
                    "Version does not match file format, "
                    "discarding it. (Version %s, format %d)"
                    % (self.initial_version, self.format)
                )
            for rel in format_relation:
                if format in rel[1]:
                    initial_step = rel[0]
                    break
            else:
                # This should not happen, really.
                self.error("Format not supported.")

        # Find the final step
        for rel in format_relation:
            if self.end_format in rel[1]:
                final_step = rel[0]
                break
        else:
            self.error("Format not supported.")

        # Convertion mode, back or forth
        steps = []
        if (initial_step, self.initial_format) < (final_step, self.end_format):
            mode = "convert"
            full_steps = []
            for step in format_relation:
                if initial_step <= step[0] <= final_step and step[2][0] <= self.final_version:
                    full_steps.append(step)
            if full_steps[0][1][-1] == self.format:
                full_steps = full_steps[1:]
            for step in full_steps:
                steps.append(step[0])
        else:
            mode = "revert"
            relation_format = format_relation[:]
            relation_format.reverse()
            last_step = None

            for step in relation_format:
                if final_step <= step[0] <= initial_step:
                    steps.append(step[0])
                    last_step = step

            if last_step[1][-1] == self.end_format:
                steps.pop()

        self.warning(f"Convertion mode: {mode}\tsteps{steps}", 10)
        return mode, steps

    def append_local_layout(self, new_layout):
        "Append `new_layout` to the local layouts."
        # new_layout may be a string or a list of strings (lines)
        try:
            new_layout = new_layout.splitlines()
        except AttributeError:
            pass
        i = find_token(self.header, "\\begin_local_layout", 0)
        if i == -1:
            k = find_token(self.header, "\\language", 0)
            if k == -1:
                # this should not happen
                self.warning("Malformed LyX document! No \\language header found!")
                return
            self.header[k:k] = ["\\begin_local_layout", "\\end_local_layout"]
            i = k

        j = find_end_of(self.header, i, "\\begin_local_layout", "\\end_local_layout")
        if j == -1:
            # this should not happen
            self.warning("Malformed LyX document: Can't find end of local layout!")
            return

        self.header[i + 1 : i + 1] = new_layout

    def del_local_layout(self, layout_def):
        "Delete `layout_def` from local layouts, return success."
        i = find_complete_lines(self.header, layout_def)
        if i == -1:
            return False
        j = i + len(layout_def)
        if (
            self.header[i - 1] == "\\begin_local_layout"
            and self.header[j] == "\\end_local_layout"
        ):
            i -= 1
            j += 1
        self.header[i:j] = []
        return True

    def del_from_header(self, lines):
        "Delete `lines` from the document header, return success."
        i = find_complete_lines(self.header, lines)
        if i == -1:
            return False
        j = i + len(lines)
        self.header[i:j] = []
        return True


# Part of an unfinished attempt to make lyx2lyx gave a more
# structured view of the document.
#    def get_toc(self, depth = 4):
#        " Returns the TOC of this LyX document."
#        paragraphs_filter = {'Title' : 0,'Chapter' : 1, 'Section' : 2,
#                             'Subsection' : 3, 'Subsubsection': 4}
#        allowed_insets = ['Quotes']
#        allowed_parameters = ('\\paragraph_spacing', '\\noindent',
#                              '\\align', '\\labelwidthstring',
#                              "\\start_of_appendix", "\\leftindent")
#        sections = []
#        for section in paragraphs_filter.keys():
#            sections.append('\\begin_layout %s' % section)

#        toc_par = []
#        i = 0
#        while True:
#            i = find_tokens(self.body, sections, i)
#            if i == -1:
#                break

#            j = find_end_of(self.body,  i + 1, '\\begin_layout', '\\end_layout')
#            if j == -1:
#                self.warning('Incomplete file.', 0)
#                break

#            section = self.body[i].split()[1]
#            if section[-1] == '*':
#                section = section[:-1]

#            par = []

#            k = i + 1
#            # skip paragraph parameters
#            while not self.body[k].strip() or self.body[k].split()[0] \
#                      in allowed_parameters:
#                k += 1

#            while k < j:
#                if check_token(self.body[k], '\\begin_inset'):
#                    inset = self.body[k].split()[1]
#                    end = find_end_of_inset(self.body, k)
#                    if end == -1 or end > j:
#                        self.warning('Malformed file.', 0)

#                    if inset in allowed_insets:
#                        par.extend(self.body[k: end+1])
#                    k = end + 1
#                else:
#                    par.append(self.body[k])
#                    k += 1

#            # trim empty lines in the end.
#            while par and par[-1].strip() == '':
#                par.pop()

#            toc_par.append(Paragraph(section, par))

#            i = j + 1

#        return toc_par


class File(LyX_base):
    "This class reads existing LyX files."

    def __init__(
        self,
        end_format=0,
        input="",
        output="",
        error="",
        debug=default_debug__,
        try_hard=0,
        cjk_encoding="",
        final_version="",
        systemlyxdir="",
    ):
        LyX_base.__init__(
            self,
            end_format,
            input,
            output,
            error,
            debug,
            try_hard,
            cjk_encoding,
            final_version,
            systemlyxdir,
        )
        self.read()


# FIXME: header settings are completely outdated, don't use like this
# class NewFile(LyX_base):
#    " This class is to create new LyX files."
#    def set_header(self, **params):
#        # set default values
#        self.header.extend([
#            "#LyX xxxx created this file."
#            "For more info see http://www.lyx.org/",
#            "\\lyxformat xxx",
#            "\\begin_document",
#            "\\begin_header",
#            "\\textclass article",
#            "\\language english",
#            "\\inputencoding auto",
#            "\\font_roman default",
#            "\\font_sans default",
#            "\\font_typewriter default",
#            "\\font_default_family default",
#            "\\font_sc false",
#            "\\font_osf false",
#            "\\font_sf_scale 100",
#            "\\font_tt_scale 100",
#            "\\graphics default",
#            "\\paperfontsize default",
#            "\\papersize default",
#            "\\use_geometry false",
#            "\\use_amsmath 1",
#            "\\cite_engine basic",
#            "\\use_bibtopic false",
#            "\\use_indices false",
#            "\\paperorientation portrait",
#            "\\secnumdepth 3",
#            "\\tocdepth 3",
#            "\\paragraph_separation indent",
#            "\\defskip medskip",
#            "\\quotes_language english",
#            "\\papercolumns 1",
#            "\\papersides 1",
#            "\\paperpagestyle default",
#            "\\tracking_changes false",
#            "\\end_header"])

#        self.format = get_end_format()
#        for param in params:
#            self.set_parameter(param, params[param])


#    def set_body(self, paragraphs):
#        self.body.extend(['\\begin_body',''])

#        for par in paragraphs:
#            self.body.extend(par.asLines())

#        self.body.extend(['','\\end_body', '\\end_document'])


# Part of an unfinished attempt to make lyx2lyx gave a more
# structured view of the document.
# class Paragraph:
#    # unfinished implementation, it is missing the Text and Insets
#    # representation.
#    " This class represents the LyX paragraphs."
#    def __init__(self, name, body=[], settings = [], child = []):
#        """ Parameters:
#        name: paragraph name.
#        body: list of lines of body text.
#        child: list of paragraphs that descend from this paragraph.
#        """
#        self.name = name
#        self.body = body
#        self.settings = settings
#        self.child = child

#    def asLines(self):
#        """ Converts the paragraph to a list of strings, representing
#        it in the LyX file."""

#        result = ['','\\begin_layout %s' % self.name]
#        result.extend(self.settings)
#        result.append('')
#        result.extend(self.body)
#        result.append('\\end_layout')

#        if not self.child:
#            return result

#        result.append('\\begin_deeper')
#        for node in self.child:
#            result.extend(node.asLines())
#        result.append('\\end_deeper')

#        return result