# -*- coding: utf-8 -*-
#
# Copyright © Spyder Project Contributors
# Licensed under the terms of the MIT License
# (see spyder/__init__.py for details)

"""Help Plugin"""

# Standard library imports
import re
import os.path as osp
import socket
import sys

# Third party imports
from qtpy import PYQT5
from qtpy.QtCore import QThread, QUrl, Signal, Slot
from qtpy.QtWidgets import (QActionGroup, QComboBox, QGroupBox, QHBoxLayout,
                            QLabel, QLineEdit, QMenu, QMessageBox, QSizePolicy,
                            QToolButton, QVBoxLayout, QWidget)
from qtpy.QtWebEngineWidgets import QWebEnginePage, WEBENGINE

# Local imports
from spyder import dependencies
from spyder.config.base import _, get_conf_path, get_module_source_path
from spyder.config.fonts import DEFAULT_SMALL_DELTA
from spyder.plugins import SpyderPluginWidget
from spyder.plugins.configdialog import PluginConfigPage
from spyder.py3compat import get_meth_class_inst, to_text_string
from spyder.utils import icon_manager as ima
from spyder.utils import programs
from spyder.utils.help.sphinxify import (CSS_PATH, generate_context,
                                         sphinxify, usage, warning)
from spyder.utils.qthelpers import (add_actions, create_action,
                                    create_toolbutton, create_plugin_layout)
from spyder.widgets.browser import FrameWebView
from spyder.widgets.comboboxes import EditableComboBox
from spyder.widgets.findreplace import FindReplace
from spyder.widgets.sourcecode import codeeditor


# Sphinx dependency
dependencies.add("sphinx", _("Show help for objects in the Editor and "
                             "Consoles in a dedicated pane"),
                 required_version='>=0.6.6')



class ObjectComboBox(EditableComboBox):
    """
    QComboBox handling object names
    """
    # Signals
    valid = Signal(bool, bool)

    def __init__(self, parent):
        EditableComboBox.__init__(self, parent)
        self.help = parent
        self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
        self.tips = {True: '', False: ''}

    def is_valid(self, qstr=None):
        """Return True if string is valid"""
        if not self.help.source_is_console():
            return True
        if qstr is None:
            qstr = self.currentText()
        if not re.search(r'^[a-zA-Z0-9_\.]*$', str(qstr), 0):
            return False
        objtxt = to_text_string(qstr)
        shell_is_defined = False
        if self.help.get_option('automatic_import'):
            shell = self.help.internal_shell
            if shell is not None:
                shell_is_defined = shell.is_defined(objtxt, force_import=True)
        if not shell_is_defined:
            shell = self.help.get_shell()
            if shell is not None:
                try:
                    shell_is_defined = shell.is_defined(objtxt)
                except socket.error:
                    shell = self.help.get_shell()
                    try:
                        shell_is_defined = shell.is_defined(objtxt)
                    except socket.error:
                        # Well... too bad!
                        pass
        return shell_is_defined

    def validate_current_text(self):
        self.validate(self.currentText())

    def validate(self, qstr, editing=True):
        """Reimplemented to avoid formatting actions"""
        valid = self.is_valid(qstr)
        if self.hasFocus() and valid is not None:
            if editing and not valid:
                # Combo box text is being modified: invalidate the entry
                self.show_tip(self.tips[valid])
                self.valid.emit(False, False)
            else:
                # A new item has just been selected
                if valid:
                    self.selected()
                    # See spyder-ide/spyder#9542.
                    # Backport of PR spyder-ide/spyder#9552
                    self.lineEdit().cursorWordForward(False)
                else:
                    self.valid.emit(False, False)


class HelpConfigPage(PluginConfigPage):
    def setup_page(self):
        # Connections group
        connections_group = QGroupBox(_("Automatic connections"))
        connections_label = QLabel(_("This pane can automatically "
                                     "show an object's help information after "
                                     "a left parenthesis is written next to it. "
                                     "Below you can decide to which plugin "
                                     "you want to connect it to turn on this "
                                     "feature."))
        connections_label.setWordWrap(True)
        editor_box = self.create_checkbox(_("Editor"), 'connect/editor')
        rope_installed = programs.is_module_installed('rope')
        jedi_installed = programs.is_module_installed('jedi', '>=0.8.1')
        editor_box.setEnabled(rope_installed or jedi_installed)
        if not rope_installed and not jedi_installed:
            editor_tip = _("This feature requires the Rope or Jedi libraries.\n"
                           "It seems you don't have either installed.")
            editor_box.setToolTip(editor_tip)
        ipython_box = self.create_checkbox(_("IPython Console"),
                                           'connect/ipython_console')

        connections_layout = QVBoxLayout()
        connections_layout.addWidget(connections_label)
        connections_layout.addWidget(editor_box)
        connections_layout.addWidget(ipython_box)
        connections_group.setLayout(connections_layout)

        # Features group
        features_group = QGroupBox(_("Additional features"))
        math_box = self.create_checkbox(_("Render mathematical equations"),
                                        'math')
        req_sphinx = programs.is_module_installed('sphinx', '>=1.1')
        math_box.setEnabled(req_sphinx)
        if not req_sphinx:
            sphinx_ver = programs.get_module_version('sphinx')
            sphinx_tip = _("This feature requires Sphinx 1.1 or superior.")
            sphinx_tip += "\n" + _("Sphinx %s is currently installed.") % sphinx_ver
            math_box.setToolTip(sphinx_tip)

        features_layout = QVBoxLayout()
        features_layout.addWidget(math_box)
        features_group.setLayout(features_layout)

        # Source code group
        sourcecode_group = QGroupBox(_("Source code"))
        wrap_mode_box = self.create_checkbox(_("Wrap lines"), 'wrap')

        sourcecode_layout = QVBoxLayout()
        sourcecode_layout.addWidget(wrap_mode_box)
        sourcecode_group.setLayout(sourcecode_layout)

        # Final layout
        vlayout = QVBoxLayout()
        vlayout.addWidget(connections_group)
        vlayout.addWidget(features_group)
        vlayout.addWidget(sourcecode_group)
        vlayout.addStretch(1)
        self.setLayout(vlayout)


class RichText(QWidget):
    """
    WebView widget with find dialog
    """
    def __init__(self, parent):
        QWidget.__init__(self, parent)

        self.webview = FrameWebView(self)
        self.find_widget = FindReplace(self)
        self.find_widget.set_editor(self.webview.web_widget)
        self.find_widget.hide()

        layout = QVBoxLayout()
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(self.webview)
        layout.addWidget(self.find_widget)
        self.setLayout(layout)

    def set_font(self, font, fixed_font=None):
        """Set font"""
        self.webview.set_font(font, fixed_font=fixed_font)

    def set_html(self, html_text, base_url):
        """Set html text"""
        self.webview.setHtml(html_text, base_url)

    def clear(self):
        self.set_html('', self.webview.url())


class PlainText(QWidget):
    """
    Read-only editor widget with find dialog
    """
    # Signals
    focus_changed = Signal()

    def __init__(self, parent):
        QWidget.__init__(self, parent)
        self.editor = None

        # Read-only editor
        self.editor = codeeditor.CodeEditor(self)
        self.editor.setup_editor(linenumbers=False, language='py',
                                 scrollflagarea=False, edge_line=False)
        self.editor.focus_changed.connect(lambda: self.focus_changed.emit())
        self.editor.setReadOnly(True)

        # Find/replace widget
        self.find_widget = FindReplace(self)
        self.find_widget.set_editor(self.editor)
        self.find_widget.hide()

        layout = QVBoxLayout()
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(self.editor)
        layout.addWidget(self.find_widget)
        self.setLayout(layout)

    def set_font(self, font, color_scheme=None):
        """Set font"""
        self.editor.set_font(font, color_scheme=color_scheme)

    def set_color_scheme(self, color_scheme):
        """Set color scheme"""
        self.editor.set_color_scheme(color_scheme)

    def set_text(self, text, is_code):
        self.editor.set_highlight_current_line(is_code)
        self.editor.set_occurrence_highlighting(is_code)
        if is_code:
            self.editor.set_language('py')
        else:
            self.editor.set_language(None)
        self.editor.set_text(text)
        self.editor.set_cursor_position('sof')

    def clear(self):
        self.editor.clear()


class SphinxThread(QThread):
    """
    A worker thread for handling rich text rendering.

    Parameters
    ----------
    doc : str or dict
        A string containing a raw rst text or a dict containing
        the doc string components to be rendered.
        See spyder_kernels.utils.dochelpers.getdoc for description.
    context : dict
        A dict containing the substitution variables for the
        layout template
    html_text_no_doc : unicode
        Text to be rendered if doc string cannot be extracted.
    math_option : bool
        Use LaTeX math rendering.

    """
    # Signals
    error_msg = Signal(str)
    html_ready = Signal(str)

    def __init__(self, html_text_no_doc=''):
        super(SphinxThread, self).__init__()
        self.doc = None
        self.context = None
        self.html_text_no_doc = html_text_no_doc
        self.math_option = False

    def render(self, doc, context=None, math_option=False, img_path=''):
        """Start thread to render a given documentation"""
        # If the thread is already running wait for it to finish before
        # starting it again.
        if self.wait():
            self.doc = doc
            self.context = context
            self.math_option = math_option
            self.img_path = img_path
            # This causes run() to be executed in separate thread
            self.start()

    def run(self):
        html_text = self.html_text_no_doc
        doc = self.doc
        if doc is not None:
            if type(doc) is dict and 'docstring' in doc.keys():
                try:
                    context = generate_context(name=doc['name'],
                                               argspec=doc['argspec'],
                                               note=doc['note'],
                                               math=self.math_option,
                                               img_path=self.img_path)
                    html_text = sphinxify(doc['docstring'], context)
                    if doc['docstring'] == '':
                        if any([doc['name'], doc['argspec'], doc['note']]):
                            msg = _("No further documentation available")
                            html_text += '<div class="hr"></div>'
                        else:
                            msg = _("No documentation available")
                        html_text += '<div id="doc-warning">%s</div>' % msg
                except Exception as error:
                    self.error_msg.emit(to_text_string(error))
                    return
            elif self.context is not None:
                try:
                    html_text = sphinxify(doc, self.context)
                except Exception as error:
                    self.error_msg.emit(to_text_string(error))
                    return
        self.html_ready.emit(html_text)


class Help(SpyderPluginWidget):
    """
    Docstrings viewer widget
    """
    CONF_SECTION = 'help'
    CONFIGWIDGET_CLASS = HelpConfigPage
    LOG_PATH = get_conf_path(CONF_SECTION)
    FONT_SIZE_DELTA = DEFAULT_SMALL_DELTA

    # Signals
    focus_changed = Signal()

    def __init__(self, parent=None):
        if PYQT5:
            SpyderPluginWidget.__init__(self, parent, main = parent)
        else:
            SpyderPluginWidget.__init__(self, parent)

        self.internal_shell = None
        self.console = None

        # Initialize plugin
        self.initialize_plugin()

        self.no_doc_string = _("No documentation available")

        self._last_console_cb = None
        self._last_editor_cb = None

        self.plain_text = PlainText(self)
        self.rich_text = RichText(self)

        color_scheme = self.get_color_scheme()
        self.set_plain_text_font(self.get_plugin_font(), color_scheme)
        self.plain_text.editor.toggle_wrap_mode(self.get_option('wrap'))

        # Add entries to read-only editor context-menu
        self.wrap_action = create_action(self, _("Wrap lines"),
                                         toggled=self.toggle_wrap_mode)
        self.wrap_action.setChecked(self.get_option('wrap'))
        self.plain_text.editor.readonly_menu.addSeparator()
        add_actions(self.plain_text.editor.readonly_menu, (self.wrap_action,))

        self.set_rich_text_font(self.get_plugin_font('rich_text'))

        self.shell = None

        # locked = disable link with Console
        self.locked = False
        self._last_texts = [None, None]
        self._last_editor_doc = None

        # Object name
        layout_edit = QHBoxLayout()
        layout_edit.setContentsMargins(0, 0, 0, 0)
        txt = _("Source")
        if sys.platform == 'darwin':
            source_label = QLabel("  " + txt)
        else:
            source_label = QLabel(txt)
        layout_edit.addWidget(source_label)
        self.source_combo = QComboBox(self)
        self.source_combo.addItems([_("Console"), _("Editor")])
        self.source_combo.currentIndexChanged.connect(self.source_changed)
        if (not programs.is_module_installed('rope') and
                not programs.is_module_installed('jedi', '>=0.8.1')):
            self.source_combo.hide()
            source_label.hide()
        layout_edit.addWidget(self.source_combo)
        layout_edit.addSpacing(10)
        layout_edit.addWidget(QLabel(_("Object")))
        self.combo = ObjectComboBox(self)
        layout_edit.addWidget(self.combo)
        self.object_edit = QLineEdit(self)
        self.object_edit.setReadOnly(True)
        layout_edit.addWidget(self.object_edit)
        self.combo.setMaxCount(self.get_option('max_history_entries'))
        self.combo.addItems( self.load_history() )
        self.combo.setItemText(0, '')
        self.combo.valid.connect(self.force_refresh)

        # Plain text docstring option
        self.docstring = True
        self.rich_help = self.get_option('rich_mode', True)
        self.plain_text_action = create_action(self, _("Plain Text"),
                                               toggled=self.toggle_plain_text)

        # Source code option
        self.show_source_action = create_action(self, _("Show Source"),
                                                toggled=self.toggle_show_source)

        # Rich text option
        self.rich_text_action = create_action(self, _("Rich Text"),
                                         toggled=self.toggle_rich_text)

        # Add the help actions to an exclusive QActionGroup
        help_actions = QActionGroup(self)
        help_actions.setExclusive(True)
        help_actions.addAction(self.plain_text_action)
        help_actions.addAction(self.rich_text_action)

        # Automatic import option
        self.auto_import_action = create_action(self, _("Automatic import"),
                                                toggled=self.toggle_auto_import)
        auto_import_state = self.get_option('automatic_import')
        self.auto_import_action.setChecked(auto_import_state)

        # Lock checkbox
        self.locked_button = create_toolbutton(self,
                                               triggered=self.toggle_locked)
        layout_edit.addWidget(self.locked_button)
        self._update_lock_icon()

        # Option menu
        options_button = create_toolbutton(self, text=_('Options'),
                                           icon=ima.icon('tooloptions'))
        options_button.setPopupMode(QToolButton.InstantPopup)
        menu = QMenu(self)
        add_actions(menu, [self.rich_text_action, self.plain_text_action,
                           self.show_source_action, None,
                           self.auto_import_action])
        options_button.setMenu(menu)
        layout_edit.addWidget(options_button)

        if self.rich_help:
            self.switch_to_rich_text()
        else:
            self.switch_to_plain_text()
        self.plain_text_action.setChecked(not self.rich_help)
        self.rich_text_action.setChecked(self.rich_help)
        self.source_changed()

        # Main layout
        layout = create_plugin_layout(layout_edit)
        # we have two main widgets, but only one of them is shown at a time
        layout.addWidget(self.plain_text)
        layout.addWidget(self.rich_text)
        self.setLayout(layout)

        # Add worker thread for handling rich text rendering
        self._sphinx_thread = SphinxThread(
                                  html_text_no_doc=warning(self.no_doc_string))
        self._sphinx_thread.html_ready.connect(
                                             self._on_sphinx_thread_html_ready)
        self._sphinx_thread.error_msg.connect(self._on_sphinx_thread_error_msg)

        # Handle internal and external links
        view = self.rich_text.webview
        if not WEBENGINE:
            view.page().setLinkDelegationPolicy(QWebEnginePage.DelegateAllLinks)
        view.linkClicked.connect(self.handle_link_clicks)

        self._starting_up = True

    #------ SpyderPluginWidget API ---------------------------------------------
    def on_first_registration(self):
        """Action to be performed on first plugin registration"""
        self.main.tabify_plugins(self.main.variableexplorer, self)

    def get_plugin_title(self):
        """Return widget title"""
        return _('Help')

    def get_plugin_icon(self):
        """Return widget icon"""
        return ima.icon('help')

    def get_focus_widget(self):
        """
        Return the widget to give focus to when
        this plugin's dockwidget is raised on top-level
        """
        self.combo.lineEdit().selectAll()
        return self.combo

    def get_plugin_actions(self):
        """Return a list of actions related to plugin"""
        return []

    def register_plugin(self):
        """Register plugin in Spyder's main window"""
        self.focus_changed.connect(self.main.plugin_focus_changed)
        self.main.add_dockwidget(self)
        self.main.console.set_help(self)

        self.internal_shell = self.main.console.shell
        self.console = self.main.console

    def closing_plugin(self, cancelable=False):
        """Perform actions before parent main window is closed"""
        return True

    def refresh_plugin(self):
        """Refresh widget"""
        if self._starting_up:
            self._starting_up = False
            self.switch_to_rich_text()
            self.show_intro_message()

    def update_font(self):
        """Update font from Preferences"""
        color_scheme = self.get_color_scheme()
        font = self.get_plugin_font()
        rich_font = self.get_plugin_font(rich_text=True)

        self.set_plain_text_font(font, color_scheme=color_scheme)
        self.set_rich_text_font(rich_font)

    def apply_plugin_settings(self, options):
        """Apply configuration file's plugin settings"""
        color_scheme_n = 'color_scheme_name'
        color_scheme_o = self.get_color_scheme()
        connect_n = 'connect_to_oi'
        wrap_n = 'wrap'
        wrap_o = self.get_option(wrap_n)
        self.wrap_action.setChecked(wrap_o)
        math_n = 'math'
        math_o = self.get_option(math_n)

        if color_scheme_n in options:
            self.set_plain_text_color_scheme(color_scheme_o)
        if wrap_n in options:
            self.toggle_wrap_mode(wrap_o)
        if math_n in options:
            self.toggle_math_mode(math_o)

        # To make auto-connection changes take place instantly
        self.main.editor.apply_plugin_settings(options=[connect_n])
        self.main.ipyconsole.apply_plugin_settings(options=[connect_n])

    #------ Public API (related to Help's source) -------------------------
    def source_is_console(self):
        """Return True if source is Console"""
        return self.source_combo.currentIndex() == 0

    def switch_to_editor_source(self):
        self.source_combo.setCurrentIndex(1)

    def switch_to_console_source(self):
        self.source_combo.setCurrentIndex(0)

    def source_changed(self, index=None):
        if self.source_is_console():
            # Console
            self.combo.show()
            self.object_edit.hide()
            self.show_source_action.setEnabled(True)
            self.auto_import_action.setEnabled(True)
        else:
            # Editor
            self.combo.hide()
            self.object_edit.show()
            self.show_source_action.setDisabled(True)
            self.auto_import_action.setDisabled(True)
        self.restore_text()

    def save_text(self, callback):
        if self.source_is_console():
            self._last_console_cb = callback
        else:
            self._last_editor_cb = callback

    def restore_text(self):
        if self.source_is_console():
            cb = self._last_console_cb
        else:
            cb = self._last_editor_cb
        if cb is None:
            if self.is_plain_text_mode():
                self.plain_text.clear()
            else:
                self.rich_text.clear()
        else:
            func = cb[0]
            args = cb[1:]
            func(*args)
            if get_meth_class_inst(func) is self.rich_text:
                self.switch_to_rich_text()
            else:
                self.switch_to_plain_text()

    #------ Public API (related to rich/plain text widgets) --------------------
    @property
    def find_widget(self):
        if self.plain_text.isVisible():
            return self.plain_text.find_widget
        else:
            return self.rich_text.find_widget

    def set_rich_text_font(self, font):
        """Set rich text mode font"""
        self.rich_text.set_font(font, fixed_font=self.get_plugin_font())

    def set_plain_text_font(self, font, color_scheme=None):
        """Set plain text mode font"""
        self.plain_text.set_font(font, color_scheme=color_scheme)

    def set_plain_text_color_scheme(self, color_scheme):
        """Set plain text mode color scheme"""
        self.plain_text.set_color_scheme(color_scheme)

    @Slot(bool)
    def toggle_wrap_mode(self, checked):
        """Toggle wrap mode"""
        self.plain_text.editor.toggle_wrap_mode(checked)
        self.set_option('wrap', checked)

    def toggle_math_mode(self, checked):
        """Toggle math mode"""
        self.set_option('math', checked)

    def is_plain_text_mode(self):
        """Return True if plain text mode is active"""
        return self.plain_text.isVisible()

    def is_rich_text_mode(self):
        """Return True if rich text mode is active"""
        return self.rich_text.isVisible()

    def switch_to_plain_text(self):
        """Switch to plain text mode"""
        self.rich_help = False
        self.plain_text.show()
        self.rich_text.hide()
        self.plain_text_action.setChecked(True)

    def switch_to_rich_text(self):
        """Switch to rich text mode"""
        self.rich_help = True
        self.plain_text.hide()
        self.rich_text.show()
        self.rich_text_action.setChecked(True)
        self.show_source_action.setChecked(False)

    def set_plain_text(self, text, is_code):
        """Set plain text docs"""

        # text is coming from utils.dochelpers.getdoc
        if type(text) is dict:
            name = text['name']
            if name:
                rst_title = ''.join(['='*len(name), '\n', name, '\n',
                                    '='*len(name), '\n\n'])
            else:
                rst_title = ''

            if text['argspec']:
                definition = ''.join(['Definition: ', name, text['argspec'],
                                      '\n'])
            else:
                definition = ''

            if text['note']:
                note = ''.join(['Type: ', text['note'], '\n\n----\n\n'])
            else:
                note = ''

            full_text = ''.join([rst_title, definition, note,
                                 text['docstring']])
        else:
            full_text = text

        self.plain_text.set_text(full_text, is_code)
        self.save_text([self.plain_text.set_text, full_text, is_code])

    def set_rich_text_html(self, html_text, base_url):
        """Set rich text"""
        self.rich_text.set_html(html_text, base_url)
        self.save_text([self.rich_text.set_html, html_text, base_url])

    def show_intro_message(self):
        intro_message = _("Here you can get help of any object by pressing "
                          "%s in front of it, either on the Editor or the "
                          "Console.%s"
                          "Help can also be shown automatically after writing "
                          "a left parenthesis next to an object. You can "
                          "activate this behavior in %s.")
        prefs = _("Preferences > Help")
        if sys.platform == 'darwin':
            shortcut = "Cmd+I"
        else:
            shortcut = "Ctrl+I"

        if self.is_rich_text_mode():
            title = _("Usage")
            tutorial_message = _("New to Spyder? Read our")
            tutorial = _("tutorial")
            intro_message = intro_message % ("<b>"+shortcut+"</b>", "<br><br>",
                                             "<i>"+prefs+"</i>")
            self.set_rich_text_html(usage(title, intro_message,
                                          tutorial_message, tutorial),
                                    QUrl.fromLocalFile(CSS_PATH))
        else:
            install_sphinx = "\n\n%s" % _("Please consider installing Sphinx "
                                          "to get documentation rendered in "
                                          "rich text.")
            intro_message = intro_message % (shortcut, "\n\n", prefs)
            intro_message += install_sphinx
            self.set_plain_text(intro_message, is_code=False)

    def show_rich_text(self, text, collapse=False, img_path=''):
        """Show text in rich mode"""
        self.switch_to_plugin()
        self.switch_to_rich_text()
        context = generate_context(collapse=collapse, img_path=img_path)
        self.render_sphinx_doc(text, context)

    def show_plain_text(self, text):
        """Show text in plain mode"""
        self.switch_to_plugin()
        self.switch_to_plain_text()
        self.set_plain_text(text, is_code=False)

    @Slot()
    def show_tutorial(self):
        """Show the Spyder tutorial in the Help plugin, opening it if needed"""
        self.switch_to_plugin()
        tutorial_path = get_module_source_path('spyder.utils.help')
        tutorial = osp.join(tutorial_path, 'tutorial.rst')
        text = open(tutorial).read()
        self.show_rich_text(text, collapse=True)

    def handle_link_clicks(self, url):
        url = to_text_string(url.toString())
        if url == "spy://tutorial":
            self.show_tutorial()
        elif url.startswith('http'):
            programs.start_file(url)
        else:
            self.rich_text.webview.load(QUrl(url))

    # ------ Public API -------------------------------------------------------
    @Slot()
    @Slot(bool)
    @Slot(bool, bool)
    def force_refresh(self, valid=True, editing=True):
        if valid:
            if self.source_is_console():
                self.set_object_text(None, force_refresh=True)
            elif self._last_editor_doc is not None:
                self.set_editor_doc(self._last_editor_doc, force_refresh=True)

    def set_object_text(self, text, force_refresh=False, ignore_unknown=False):
        """Set object analyzed by Help"""
        if (self.locked and not force_refresh):
            return
        self.switch_to_console_source()

        add_to_combo = True
        if text is None:
            text = to_text_string(self.combo.currentText())
            add_to_combo = False

        found = self.show_help(text, ignore_unknown=ignore_unknown)
        if ignore_unknown and not found:
            return

        if add_to_combo:
            self.combo.add_text(text)
        if found:
            self.save_history()

        if self.dockwidget is not None:
            self.dockwidget.blockSignals(True)
        self.__eventually_raise_help(text, force=force_refresh)
        if self.dockwidget is not None:
            self.dockwidget.blockSignals(False)

    def set_editor_doc(self, doc, force_refresh=False):
        """
        Use the help plugin to show docstring dictionary computed
        with introspection plugin from the Editor plugin
        """
        if (self.locked and not force_refresh):
            return
        self.switch_to_editor_source()
        self._last_editor_doc = doc
        self.object_edit.setText(doc['obj_text'])

        if self.rich_help:
            self.render_sphinx_doc(doc)
        else:
            self.set_plain_text(doc, is_code=False)

        if self.dockwidget is not None:
            self.dockwidget.blockSignals(True)
        self.__eventually_raise_help(doc['docstring'], force=force_refresh)
        if self.dockwidget is not None:
            self.dockwidget.blockSignals(False)

    def __eventually_raise_help(self, text, force=False):
        index = self.source_combo.currentIndex()
        if hasattr(self.main, 'tabifiedDockWidgets'):
            # 'QMainWindow.tabifiedDockWidgets' was introduced in PyQt 4.5
            if (self.dockwidget and (force or self.dockwidget.isVisible()) and
                    not self.ismaximized and
                    (force or text != self._last_texts[index])):
                dockwidgets = self.main.tabifiedDockWidgets(self.dockwidget)
                if (self.console.dockwidget not in dockwidgets and
                        self.main.ipyconsole is not None and
                        self.main.ipyconsole.dockwidget not in dockwidgets):
                    self.switch_to_plugin()
        self._last_texts[index] = text

    def load_history(self, obj=None):
        """Load history from a text file in user home directory"""
        if osp.isfile(self.LOG_PATH):
            history = [line.replace('\n', '')
                       for line in open(self.LOG_PATH, 'r').readlines()]
        else:
            history = []
        return history

    def save_history(self):
        """Save history to a text file in user home directory"""
        # Don't fail when saving search history to disk
        # See issues 8878 and 6864
        try:
            search_history = [to_text_string(self.combo.itemText(index))
                              for index in range(self.combo.count())]
            search_history = '\n'.join(search_history)
            open(self.LOG_PATH, 'w').write(search_history)
        except (UnicodeEncodeError, UnicodeDecodeError, EnvironmentError):
            pass

    @Slot(bool)
    def toggle_plain_text(self, checked):
        """Toggle plain text docstring"""
        if checked:
            self.docstring = checked
            self.switch_to_plain_text()
            self.force_refresh()
        self.set_option('rich_mode', not checked)

    @Slot(bool)
    def toggle_show_source(self, checked):
        """Toggle show source code"""
        if checked:
            self.switch_to_plain_text()
        self.docstring = not checked
        self.force_refresh()
        self.set_option('rich_mode', not checked)

    @Slot(bool)
    def toggle_rich_text(self, checked):
        """Toggle between sphinxified docstrings or plain ones"""
        if checked:
            self.docstring = not checked
            self.switch_to_rich_text()
        self.set_option('rich_mode', checked)

    @Slot(bool)
    def toggle_auto_import(self, checked):
        """Toggle automatic import feature"""
        self.combo.validate_current_text()
        self.set_option('automatic_import', checked)
        self.force_refresh()

    @Slot()
    def toggle_locked(self):
        """
        Toggle locked state
        locked = disable link with Console
        """
        self.locked = not self.locked
        self._update_lock_icon()

    def _update_lock_icon(self):
        """Update locked state icon"""
        icon = ima.icon('lock') if self.locked else ima.icon('lock_open')
        self.locked_button.setIcon(icon)
        tip = _("Unlock") if self.locked else _("Lock")
        self.locked_button.setToolTip(tip)

    def set_shell(self, shell):
        """Bind to shell"""
        self.shell = shell

    def get_shell(self):
        """
        Return shell which is currently bound to Help,
        or another running shell if it has been terminated
        """
        if (not hasattr(self.shell, 'get_doc') or
                (hasattr(self.shell, 'is_running') and
                 not self.shell.is_running())):
            self.shell = None
            if self.main.ipyconsole is not None:
                shell = self.main.ipyconsole.get_current_shellwidget()
                if shell is not None and shell.kernel_client is not None:
                    self.shell = shell
            if self.shell is None:
                self.shell = self.internal_shell
        return self.shell

    def render_sphinx_doc(self, doc, context=None):
        """Transform doc string dictionary to HTML and show it"""
        # Math rendering option could have changed
        if self.main.editor is not None:
            fname = self.main.editor.get_current_filename()
            dname = osp.dirname(fname)
        else:
            dname = ''
        self._sphinx_thread.render(doc, context, self.get_option('math'),
                                   dname)

    def _on_sphinx_thread_html_ready(self, html_text):
        """Set our sphinx documentation based on thread result"""
        self._sphinx_thread.wait()
        self.set_rich_text_html(html_text, QUrl.fromLocalFile(CSS_PATH))

    def _on_sphinx_thread_error_msg(self, error_msg):
        """ Display error message on Sphinx rich text failure"""
        self._sphinx_thread.wait()
        self.plain_text_action.setChecked(True)
        sphinx_ver = programs.get_module_version('sphinx')
        QMessageBox.critical(self,
                    _('Help'),
                    _("The following error occured when calling "
                      "<b>Sphinx %s</b>. <br>Incompatible Sphinx "
                      "version or doc string decoding failed."
                      "<br><br>Error message:<br>%s"
                      ) % (sphinx_ver, error_msg))

    def show_help(self, obj_text, ignore_unknown=False):
        """Show help"""
        shell = self.get_shell()
        if shell is None:
            return
        obj_text = to_text_string(obj_text)

        if not shell.is_defined(obj_text):
            if self.get_option('automatic_import') and \
               self.internal_shell.is_defined(obj_text, force_import=True):
                shell = self.internal_shell
            else:
                shell = None
                doc = None
                source_text = None

        if shell is not None:
            doc = shell.get_doc(obj_text)
            source_text = shell.get_source(obj_text)

        is_code = False

        if self.rich_help:
            self.render_sphinx_doc(doc)
            return doc is not None
        elif self.docstring:
            hlp_text = doc
            if hlp_text is None:
                hlp_text = source_text
                if hlp_text is None:
                    hlp_text = self.no_doc_string
                    if ignore_unknown:
                        return False
        else:
            hlp_text = source_text
            if hlp_text is None:
                hlp_text = doc
                if hlp_text is None:
                    hlp_text = _("No source code available.")
                    if ignore_unknown:
                        return False
            else:
                is_code = True
        self.set_plain_text(hlp_text, is_code=is_code)
        return True
