#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Build a songbook, according to parameters found in a .sb file."""

import codecs
import glob
import logging
import os.path
import re
import subprocess

from songbook_core import __DATADIR__
from songbook_core import errors
from songbook_core.files import recursive_find
from songbook_core.index import process_sxd
from songbook_core.songs import Song, SongsList
from songbook_core.templates import TexRenderer

EOL = "\n"
DEFAULT_AUTHWORDS = {
        "after": ["by"],
        "ignore": ["unknown"],
        "sep": ["and"],
        }
DEFAULT_STEPS = ['tex', 'pdf', 'sbx', 'pdf', 'clean']


# pylint: disable=too-few-public-methods
class Songbook(object):
    """Represent a songbook (.sb) file.

    - Low level: provide a Python representation of the values stored in the
      '.sb' file.
    - High level: provide some utility functions to manipulate these data.
    """

    def __init__(self, raw_songbook, basename):
        super(Songbook, self).__init__()
        self.basename = basename
        # Default values: will be updated while parsing raw_songbook
        self.config = {
                'template': "default.tex",
                'titleprefixwords': [],
                'authwords': {},
                'lang': 'french',
                'sort': [u"by", u"album", u"@title"],
                'songs': None,
                'datadir': os.path.abspath('.'),
                }
        self.songslist = None
        self._parse(raw_songbook)
        self._set_songs_default()

    def _set_songs_default(self):
        """Set the default values for the Song() class."""
        Song.sort = self.config['sort']
        Song.prefixes = self.config['titleprefixwords']
        Song.authwords['after'] = [
                re.compile(r"^.*%s\b(.*)" % after)
                for after
                in self.config['authwords']["after"]
                ]
        Song.authwords['ignore'] = self.config['authwords']['ignore']
        Song.authwords['sep'] = [
                re.compile(r"^(.*)%s (.*)$" % sep)
                for sep in ([
                    " %s" % sep for sep in self.config['authwords']["sep"]
                            ] + [','])
                ]

    def _parse(self, raw_songbook):
        """Parse raw_songbook.

        The principle is: some special keys have their value processed; others
        are stored verbatim in self.config.
        """
        self.config.update(raw_songbook)
        self.config['datadir'] = os.path.abspath(self.config['datadir'])
        ### Some post-processing
        # Compute song list
        if self.config['songs'] is None:
            self.config['songs'] = [
                    os.path.relpath(
                        filename,
                        os.path.join(self.config['datadir'], 'songs'),
                        )
                    for filename
                    in recursive_find(
                                os.path.join(self.config['datadir'], 'songs'),
                                '*.sg',
                                )
                    ]
        self.songslist = SongsList(self.config['datadir'], self.config["lang"])
        self.songslist.append_list(self.config['songs'])

        # Ensure self.config['authwords'] contains all entries
        for (key, value) in DEFAULT_AUTHWORDS.items():
            if key not in self.config['authwords']:
                self.config['authwords'][key] = value

    def write_tex(self, output):
        """Build the '.tex' file corresponding to self.

        Arguments:
        - output: a file object, in which the file will be written.
        """
        renderer = TexRenderer(
                self.config['template'],
                self.config['datadir'],
                )

        context = renderer.get_variables()

        context.update(self.config)
        context['titleprefixkeys'] = ["after", "sep", "ignore"]
        context['songlist'] = self.songslist
        context['filename'] = output.name[:-4]

        renderer.render_tex(output, context)


def clean(basename):
    """Clean (some) temporary files used during compilation.

    Depending of the LaTeX modules used in the template, there may be others
    that are not deleted by this function."""
    generated_extensions = [
            "_auth.sbx",
            "_auth.sxd",
            ".aux",
            ".log",
            ".out",
            ".sxc",
            ".tex",
            "_title.sbx",
            "_title.sxd",
            ]

    for ext in generated_extensions:
        if os.path.isfile(basename + ext):
            try:
                os.unlink(basename + ext)
            except Exception as exception:
                raise errors.CleaningError(basename + ext, exception)


def buildsongbook(
        raw_songbook,
        basename,
        steps=None,
        interactive=False,
        logger=logging.getLogger(),
        ):
    """Build a songbook

    Arguments:
    - raw_songbook: Python representation of the .sb songbook configuration
      file.
    - steps: list of steps to perform to compile songbook. Available steps are:
      - tex: build .tex file from templates;
      - pdf: compile .tex using pdflatex;
      - sbx: compile song and author indexes;
      - clean: remove temporary files.
    - basename: basename of the songbook to be built.
    - interactive: in False, do not expect anything from stdin.
    """

    if steps is None:
        steps = DEFAULT_STEPS

    songbook = Songbook(raw_songbook, basename)
    if not 'TEXINPUTS' in os.environ.keys():
        os.environ['TEXINPUTS'] = ''
    os.environ['TEXINPUTS'] += os.pathsep + os.path.join(
            __DATADIR__,
            'latex',
            )
    os.environ['TEXINPUTS'] += os.pathsep + os.path.join(
            songbook.config['datadir'],
            'latex',
            )

    # pdflatex options
    pdflatex_options = []
    pdflatex_options.append("--shell-escape")  # Lilypond compilation
    if not interactive:
        pdflatex_options.append("-halt-on-error")

    # Compilation
    for step in steps:
        if step == 'tex':
            # Building .tex file from templates
            with codecs.open("{}.tex".format(basename), 'w', 'utf-8') as output:
                songbook.write_tex(output)
        elif step == 'pdf':
            if subprocess.call(["pdflatex"] + pdflatex_options + [basename]):
                raise errors.LatexCompilationError(basename)
        elif step == 'sbx':
            # Make index
            sxd_files = glob.glob("%s_*.sxd" % basename)
            for sxd_file in sxd_files:
                logger.info("processing " + sxd_file)
                idx = process_sxd(sxd_file)
                index_file = open(sxd_file[:-3] + "sbx", "w")
                index_file.write(idx.entries_to_str().encode('utf8'))
                index_file.close()
        elif step == 'clean':
            # Cleaning
            clean(basename)
        else:
            # Unknown step name
            raise errors.UnknownStep(step)