#!/usr/bin/env python3

#
# html_preview_plugin.py
#
# Copyright (C) 2015 Christian Hergert <chris@dronelabs.com>
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#

import builtins
import gi
import io
import locale
import os
import shutil
import sys
import subprocess
import threading

gi.require_version('Gtk', '3.0')
gi.require_version('Ide', '1.0')
gi.require_version('WebKit2', '4.0')

from gi.repository import GLib
from gi.repository import Gio
from gi.repository import Gtk
from gi.repository import GObject
from gi.repository import Ide
from gi.repository import WebKit2
from gi.repository import Peas

try:
    locale.setlocale(locale.LC_ALL, '')
except:
    pass

can_preview_rst = True
can_preview_sphinx = True
old_open = None

try:
    from docutils.core import publish_string
except ImportError:
    can_preview_rst = False

try:
    import sphinx
except ImportError:
    can_preview_sphinx = False

sphinx_states = {}
sphinx_override = {}


def add_override_file(path, content):
    if path in sphinx_override:
        return False
    else:
        sphinx_override[path] = content.encode('utf-8')
        return True


def remove_override_file(path):
    try:
        del sphinx_override[path]
    except KeyError:
        return False

    return True


def new_open(*args, **kwargs):
    path = args[0]
    if path in sphinx_override:
        return io.BytesIO(sphinx_override[path])

    return old_open(*args, **kwargs)

old_open = builtins.open
builtins.open = new_open

_ = Ide.gettext


def is_sphinx_installed():
    with open(os.devnull, 'w') as devnull:
        try:
            if subprocess.call(['sphinx-build', '--version'],
                               stdout=devnull, stderr=devnull) == 0:
                return True
        except FileNotFoundError:
            pass

        return False


class SphinxState():
    def __init__(self, builddir):
        self.builddir = builddir
        self.is_running = False
        self.need_build = False


class HtmlPreviewData(GObject.Object, Ide.ApplicationAddin):
    MARKDOWN_CSS = None
    MARKED_JS = None
    MARKDOWN_VIEW_JS = None

    def do_load(self, app):
        HtmlPreviewData.MARKDOWN_CSS = self.get_data('markdown.css')
        HtmlPreviewData.MARKED_JS = self.get_data('marked.js')
        HtmlPreviewData.MARKDOWN_VIEW_JS = self.get_data('markdown-view.js')

    def do_unload(self, app):
        for state in sphinx_states.items():
            # Be extra sure that we are in the tmp dir
            tmpdir = GLib.get_tmp_dir()
            if state.builddir.startswith(tmpdir):
                shutil.rmtree(state.builddir)

    def get_data(self, name):
        engine = Peas.Engine.get_default()
        info = engine.get_plugin_info('html_preview_plugin')
        datadir = info.get_data_dir()
        path = os.path.join(datadir, name)
        return open(path, 'r').read()


class HtmlWorkbenchAddin(GObject.Object, Ide.WorkbenchAddin):
    def do_load(self, workbench):
        self.workbench = workbench

        group = Gio.SimpleActionGroup()

        self.install_action = Gio.SimpleAction(name='install-docutils', enabled=True)
        self.install_action.connect('activate', lambda *_: self.install_docutils())
        group.insert(self.install_action)

        self.install_action = Gio.SimpleAction(name='install-sphinx', enabled=True)
        self.install_action.connect('activate', lambda *_: self.install_sphinx())
        group.insert(self.install_action)

        self.workbench.insert_action_group('html-preview', group)

    def do_unload(self, workbench):
        self.workbench = None

    def install_docutils(self):
        transfer = Ide.PkconTransfer(packages=['python3-docutils'])
        context = self.workbench.get_context()
        manager = context.get_transfer_manager()

        manager.execute_async(transfer, None, self.docutils_installed, None)

    def install_sphinx(self):
        transfer = Ide.PkconTransfer(packages=['python3-sphinx'])
        context = self.workbench.get_context()
        manager = context.get_transfer_manager()

        manager.execute_async(transfer, None, self.sphinx_installed, None)

    def docutils_installed(self, object, result, data):
        global can_preview_rst
        global publish_string

        try:
            from docutils.core import publish_string
        except ImportError:
            return

        can_preview_rst = True
        self.workbench.pop_message('org.gnome.builder.docutils.install')

    def sphinx_installed(self, object, result, data):
        global can_preview_sphinx
        global sphinx

        try:
            import sphinx
        except ImportError:
            return

        can_preview_sphinx = True
        self.workbench.pop_message('org.gnome.builder.sphinx.install')


class HtmlPreviewAddin(GObject.Object, Ide.EditorViewAddin):
    def do_load(self, view):
        self.workbench = view.get_ancestor(Ide.Workbench)
        self.view = view
        self.can_preview = False
        self.sphinx_basedir = None
        self.sphinx_builddir = None

        self.action = Gio.SimpleAction(name='preview-as-html', enabled=True)
        self.action.connect('activate', lambda *_: self.preview_activated(view))

        actions = view.get_action_group('view')
        actions.add_action(self.action)

        document = view.get_document()
        language = document.get_language()
        language_id = language.get_id() if language else None

        self.do_language_changed(language_id)

    def do_unload(self, view):
        actions = view.get_action_group('view')
        actions.remove_action('preview-as-html')

    def do_language_changed(self, language_id):
        enabled = (language_id in ('html', 'markdown', 'rst'))
        self.action.set_enabled(enabled)
        self.lang_id = language_id
        self.can_preview = enabled

        if self.lang_id == 'rst':
            if not self.sphinx_basedir:
                document = self.view.get_document()
                path = document.get_file().get_file().get_path()
                self.sphinx_basedir = self.search_sphinx_base_dir(path)

            if self.sphinx_basedir:
                self.sphinx_builddir = self.setup_sphinx_states(self.sphinx_basedir)

        if not enabled:
            self.sphinx_basedir = None
            self.sphinx_builddir = None

    def setup_sphinx_states(self, basedir):
        global sphinx_states

        if basedir in sphinx_states:
            state = sphinx_states[basedir]
            sphinx_builddir = state.builddir
        else:
            sphinx_builddir = GLib.Dir.make_tmp('gnome-builder-sphinx-build-XXXXXX')
            state = SphinxState(sphinx_builddir)
            sphinx_states[basedir] = state

        return sphinx_builddir

    def preview_activated(self, view):
        global can_preview_rst

        if self.lang_id == 'rst':
            if self.sphinx_basedir:
                if not can_preview_sphinx:
                    self.show_missing_sphinx_message(view)
                    return
            elif not can_preview_rst:
                self.show_missing_docutils_message(view)
                return

        document = view.get_document()
        web_view = HtmlPreviewView(document,
                                   self.sphinx_basedir,
                                   self.sphinx_builddir,
                                   visible=True)

        stack = view.get_ancestor(Ide.LayoutStack)
        stack.add(web_view)

        self.action.set_enabled(False)
        web_view.connect('destroy', lambda *_: self.web_view_destroyed(web_view))

    def web_view_destroyed(self, web_view):
        self.action.set_enabled(True)

    def search_sphinx_base_dir(self, path):
        context = self.workbench.get_context()
        vcs = context.get_vcs()
        working_dir = vcs.get_working_directory().get_path()

        try:
            if os.path.commonpath([working_dir, path]) != working_dir:
                working_dir = '/'
        except:
            working_dir = '/'

        folder = os.path.dirname(path)
        level = 10

        while level > 0:
            files = os.scandir(folder)
            for file in files:
                if file.name == 'conf.py':
                    return folder

            if folder == working_dir:
                return None

            level -= 1
            folder = os.path.dirname(folder)

    def show_missing_docutils_message(self, view):
        message = Ide.WorkbenchMessage(
            id='org.gnome.builder.docutils.install',
            title=_('Your computer is missing python3-docutils'),
            show_close_button=True,
            visible=True)

        message.add_action(_('Install'), 'html-preview.install-docutils')
        self.workbench.push_message(message)

    def show_missing_sphinx_message(self, view):
        message = Ide.WorkbenchMessage(
            id='org.gnome.builder.sphinx.install',
            title=_('Your computer is missing python3-sphinx'),
            show_close_button=True,
            visible=True)

        message.add_action(_('Install'), 'html-preview.install-sphinx')
        self.workbench.push_message(message)


class HtmlPreviewView(Ide.LayoutView):
    markdown = False
    rst = False

    def __init__(self, document, sphinx_basedir, sphinx_builddir, *args, **kwargs):
        global old_open

        super().__init__(*args, **kwargs)

        self.sphinx_basedir = sphinx_basedir
        self.sphinx_builddir = sphinx_builddir
        self.document = document

        self.webview = WebKit2.WebView(visible=True, expand=True)
        self.add(self.webview)

        settings = self.webview.get_settings()
        settings.enable_html5_local_storage = False

        language = document.get_language()
        if language:
            id = language.get_id()
            if id == 'markdown':
                self.markdown = True
            elif id == 'rst':
                self.rst = True

        document.connect('changed', self.on_changed)
        self.on_changed(document)

    def do_get_title(self):
        title = self.document.get_title()
        return '%s (Preview)' % title

    def do_get_document(self):
        return self.document

    def get_markdown(self, text):
        text = text.replace("\"", "\\\"").replace("\n", "\\n")
        params = (HtmlPreviewData.MARKDOWN_CSS,
                  text,
                  HtmlPreviewData.MARKED_JS,
                  HtmlPreviewData.MARKDOWN_VIEW_JS)

        return """
<html>
 <head>
  <style>%s</style>
  <script>var str="%s";</script>
  <script>%s</script>
  <script>%s</script>
 </head>
 <body onload="preview()">
  <div class="markdown-body" id="preview">
  </div>
 </body>
</html>
""" % params

    def get_rst(self, text, path):
        return publish_string(text,
                              writer_name='html5',
                              source_path=path,
                              destination_path=path)

    def get_sphinx_rst_async(self, text, path, basedir, builddir, cancellable, callback):
        task = Gio.Task.new(self, cancellable, callback)
        threading.Thread(target=self.get_sphinx_rst_worker,
                         args=[task, text, path, basedir, builddir],
                         name='sphinx-rst-thread').start()

    def purge_cache(self, basedir, builddir, document):
        path = document.get_file().get_file().get_path()
        rel_path = os.path.relpath(path, start=basedir)
        rel_path_doctree = os.path.splitext(rel_path)[0] + '.doctree'
        doctree_path = os.path.join(builddir, '.doctrees', rel_path_doctree)

        tmpdir = GLib.get_tmp_dir()
        if doctree_path.startswith(tmpdir):
            try:
                os.remove(doctree_path)
            except:
                pass

    def get_sphinx_rst_worker(self, task, text, path, basedir, builddir):
        add_override_file(path, text)

        rel_path = os.path.relpath(path, start=basedir)
        command = ['sphinx-build', '-Q', '-b', 'html', basedir, builddir, path]

        rel_path_html = os.path.splitext(rel_path)[0] + '.html'
        builddir_path = os.path.join(builddir, rel_path_html)

        result = not sphinx.build_main(command)
        remove_override_file(path)

        if not result:
            task.builddir_path = None
            task.return_error(GLib.Error('\'sphinx-build\' command error for {}'.format(path)))
            return

        task.builddir_path = builddir_path
        task.return_boolean(True)

    def get_sphinx_rst_finish(self, result):
        succes = result.propagate_boolean()
        builddir_path = result.builddir_path

        return builddir_path

    def get_sphinx_state(self, basedir):
        global sphinx_states

        try:
            state = sphinx_states[basedir]
        except KeyError:
            return None

        return state

    def reload(self):
        state = self.get_sphinx_state(self.sphinx_basedir)
        if state and state.is_running:
            state.need_build = True
            return

        gfile = self.document.get_file().get_file()
        base_uri = gfile.get_uri()

        begin, end = self.document.get_bounds()
        text = self.document.get_text(begin, end, True)

        if self.markdown:
            text = self.get_markdown(text)
        elif self.rst:
            if self.sphinx_basedir:
                self.purge_cache(self.sphinx_basedir, self.sphinx_builddir, self.document)
                state.is_running = True

                self.get_sphinx_rst_async(text,
                                          gfile.get_path(),
                                          self.sphinx_basedir,
                                          self.sphinx_builddir,
                                          None,
                                          self.get_sphinx_rst_cb)

                return
            else:
                text = self.get_rst(text, gfile.get_path()).decode("utf-8")

        self.webview.load_html(text, base_uri)

    def get_sphinx_rst_cb(self, obj, result):
        builddir_path = self.get_sphinx_rst_finish(result)
        if builddir_path:
            uri = 'file:///' + builddir_path
            self.webview.load_uri(uri)

        state = self.get_sphinx_state(self.sphinx_basedir)
        state.is_running = False
        if state.need_build:
            state.need_build = False
            self.reload()

    def on_changed(self, document):
        self.reload()