""" help.py: Implement the Idle help menu.
Contents are subject to revision at any time, without notice.


Help => About IDLE: display About Idle dialog

<to be moved here from help_about.py>


Help => IDLE Help: Display help.html with proper formatting.
Doc/library/idle.rst (Sphinx)=> Doc/build/html/library/idle.html
(help.copy_strip)=> Lib/idlelib/help.html

HelpParser - Parse help.html and render to tk Text.

HelpText - Display formatted help.html.

HelpFrame - Contain text, scrollbar, and table-of-contents.
(This will be needed for display in a future tabbed window.)

HelpWindow - Display HelpFrame in a standalone window.

copy_strip - Copy idle.html to help.html, rstripping each line.

show_idlehelp - Create HelpWindow. Called in EditorWindow.help_dialog.
"""
from html.parser import HTMLParser
from os.path import abspath, dirname, isfile, join
from platform import python_version

from tkinter import Toplevel, Frame, Text, Menu
from tkinter.ttk import Menubutton, Scrollbar
from tkinter import font as tkfont

from idlelib.config import idleConf

## About IDLE ##


## IDLE Help ##

class HelpParser(HTMLParser):
 """Render help.html into a text widget.

 The overridden handle_xyz methods handle a subset of html tags.
 The supplied text should have the needed tag configurations.
 The behavior for unsupported tags, such as table, is undefined.
 If the tags generated by Sphinx change, this class, especially
 the handle_starttag and handle_endtags methods, might have to also.
 """
 def __init__(self, text):
 HTMLParser.__init__(self, convert_charrefs=True)
 self.text = text # text widget we're rendering into
 self.tags = '' # current block level text tags to apply
 self.chartags = '' # current character level text tags
 self.show = False # used so we exclude page navigation
 self.hdrlink = False # used so we don't show header links
 self.level = 0 # indentation level
 self.pre = False # displaying preformatted text
 self.hprefix = '' # prefix such as '25.5' to strip from headings
 self.nested_dl = False # if we're in a nested <dl>
 self.simplelist = False # simple list (no double spacing)
 self.toc = [] # pair headers with text indexes for toc
 self.header = '' # text within header tags for toc

 def indent(self, amt=1):
 self.level += amt
 self.tags = '' if self.level == 0 else 'l'+str(self.level)

 def handle_starttag(self, tag, attrs):
 "Handle starttags in help.html."
 class_ = ''
 for a, v in attrs:
 if a == 'class':
 class_ = v
 s = ''
 if tag == 'div' and class_ == 'section':
 self.show = True # start of main content
 elif tag == 'div' and class_ == 'sphinxsidebar':
 self.show = False # end of main content
 elif tag == 'p' and class_ != 'first':
 s = '\n\n'
 elif tag == 'span' and class_ == 'pre':
 self.chartags = 'pre'
 elif tag == 'span' and class_ == 'versionmodified':
 self.chartags = 'em'
 elif tag == 'em':
 self.chartags = 'em'
 elif tag in ['ul', 'ol']:
 if class_.find('simple') != -1:
 s = '\n'
 self.simplelist = True
 else:
 self.simplelist = False
 self.indent()
 elif tag == 'dl':
 if self.level > 0:
 self.nested_dl = True
 elif tag == 'li':
 s = '\n* ' if self.simplelist else '\n\n* '
 elif tag == 'dt':
 s = '\n\n' if not self.nested_dl else '\n' # avoid extra line
 self.nested_dl = False
 elif tag == 'dd':
 self.indent()
 s = '\n'
 elif tag == 'pre':
 self.pre = True
 if self.show:
 self.text.insert('end', '\n\n')
 self.tags = 'preblock'
 elif tag == 'a' and class_ == 'headerlink':
 self.hdrlink = True
 elif tag == 'h1':
 self.tags = tag
 elif tag in ['h2', 'h3']:
 if self.show:
 self.header = ''
 self.text.insert('end', '\n\n')
 self.tags = tag
 if self.show:
 self.text.insert('end', s, (self.tags, self.chartags))

 def handle_endtag(self, tag):
 "Handle endtags in help.html."
 if tag in ['h1', 'h2', 'h3']:
 self.indent(0) # clear tag, reset indent
 if self.show:
 indent = (' ' if tag == 'h3' else
 ' ' if tag == 'h2' else
 '')
 self.toc.append((indent+self.header, self.text.index('insert')))
 elif tag in ['span', 'em']:
 self.chartags = ''
 elif tag == 'a':
 self.hdrlink = False
 elif tag == 'pre':
 self.pre = False
 self.tags = ''
 elif tag in ['ul', 'dd', 'ol']:
 self.indent(amt=-1)

 def handle_data(self, data):
 "Handle date segments in help.html."
 if self.show and not self.hdrlink:
 d = data if self.pre else data.replace('\n', ' ')
 if self.tags == 'h1':
 try:
 self.hprefix = d[0:d.index(' ')]
 except ValueError:
 self.hprefix = ''
 if self.tags in ['h1', 'h2', 'h3']:
 if (self.hprefix != '' and
 d[0:len(self.hprefix)] == self.hprefix):
 d = d[len(self.hprefix):]
 self.header += d.strip()
 self.text.insert('end', d, (self.tags, self.chartags))


class HelpText(Text):
 "Display help.html."
 def __init__(self, parent, filename):
 "Configure tags and feed file to parser."
 uwide = idleConf.GetOption('main', 'EditorWindow', 'width', type='int')
 uhigh = idleConf.GetOption('main', 'EditorWindow', 'height', type='int')
 uhigh = 3 * uhigh // 4 # lines average 4/3 of editor line height
 Text.__init__(self, parent, wrap='word', highlightthickness=0,
 padx=5, borderwidth=0, width=uwide, height=uhigh)

 normalfont = self.findfont(['TkDefaultFont', 'arial', 'helvetica'])
 fixedfont = self.findfont(['TkFixedFont', 'monaco', 'courier'])
 self['font'] = (normalfont, 12)
 self.tag_configure('em', font=(normalfont, 12, 'italic'))
 self.tag_configure('h1', font=(normalfont, 20, 'bold'))
 self.tag_configure('h2', font=(normalfont, 18, 'bold'))
 self.tag_configure('h3', font=(normalfont, 15, 'bold'))
 self.tag_configure('pre', font=(fixedfont, 12), background='#f6f6ff')
 self.tag_configure('preblock', font=(fixedfont, 10), lmargin1=25,
 borderwidth=1, relief='solid', background='#eeffcc')
 self.tag_configure('l1', lmargin1=25, lmargin2=25)
 self.tag_configure('l2', lmargin1=50, lmargin2=50)
 self.tag_configure('l3', lmargin1=75, lmargin2=75)
 self.tag_configure('l4', lmargin1=100, lmargin2=100)

 self.parser = HelpParser(self)
 with open(filename, encoding='utf-8') as f:
 contents = f.read()
 self.parser.feed(contents)
 self['state'] = 'disabled'

 def findfont(self, names):
 "Return name of first font family derived from names."
 for name in names:
 if name.lower() in (x.lower() for x in tkfont.names(root=self)):
 font = tkfont.Font(name=name, exists=True, root=self)
 return font.actual()['family']
 elif name.lower() in (x.lower()
 for x in tkfont.families(root=self)):
 return name


class HelpFrame(Frame):
 "Display html text, scrollbar, and toc."
 def __init__(self, parent, filename):
 Frame.__init__(self, parent)
 # keep references to widgets for test access.
 self.text = text = HelpText(self, filename)
 self['background'] = text['background']
 self.toc = toc = self.toc_menu(text)
 self.scroll = scroll = Scrollbar(self, command=text.yview)
 text['yscrollcommand'] = scroll.set

 self.rowconfigure(0, weight=1)
 self.columnconfigure(1, weight=1) # text
 toc.grid(row=0, column=0, sticky='nw')
 text.grid(row=0, column=1, sticky='nsew')
 scroll.grid(row=0, column=2, sticky='ns')

 def toc_menu(self, text):
 "Create table of contents as drop-down menu."
 toc = Menubutton(self, text='TOC')
 drop = Menu(toc, tearoff=False)
 for lbl, dex in text.parser.toc:
 drop.add_command(label=lbl, command=lambda dex=dex:text.yview(dex))
 toc['menu'] = drop
 return toc


class HelpWindow(Toplevel):
 "Display frame with rendered html."
 def __init__(self, parent, filename, title):
 Toplevel.__init__(self, parent)
 self.wm_title(title)
 self.protocol("WM_DELETE_WINDOW", self.destroy)
 HelpFrame(self, filename).grid(column=0, row=0, sticky='nsew')
 self.grid_columnconfigure(0, weight=1)
 self.grid_rowconfigure(0, weight=1)


def copy_strip():
 """Copy idle.html to idlelib/help.html, stripping trailing whitespace.

 Files with trailing whitespace cannot be pushed to the git cpython
 repository. For 3.x (on Windows), help.html is generated, after
 editing idle.rst on the master branch, with
 sphinx-build -bhtml . build/html
 python_d.exe -c "from idlelib.help import copy_strip; copy_strip()"
 Check build/html/library/idle.html, the help.html diff, and the text
 displayed by Help => IDLE Help. Add a blurb and create a PR.

 It can be worthwhile to occasionally generate help.html without
 touching idle.rst. Changes to the master version and to the doc
 build system may result in changes that should not changed
 the displayed text, but might break HelpParser.

 As long as master and maintenance versions of idle.rst remain the
 same, help.html can be backported. The internal Python version
 number is not displayed. If maintenance idle.rst diverges from
 the master version, then instead of backporting help.html from
 master, repeat the proceedure above to generate a maintenance
 version.
 """
 src = join(abspath(dirname(dirname(dirname(__file__)))),
 'Doc', 'build', 'html', 'library', 'idle.html')
 dst = join(abspath(dirname(__file__)), 'help.html')
 with open(src, 'rb') as inn,\
 open(dst, 'wb') as out:
 for line in inn:
 out.write(line.rstrip() + b'\n')
 print(f'{src} copied to {dst}')

def show_idlehelp(parent):
 "Create HelpWindow; called from Idle Help event handler."
 filename = join(abspath(dirname(__file__)), 'help.html')
 if not isfile(filename):
 # try copy_strip, present message
 return
 HelpWindow(parent, filename, 'IDLE Help (%s)' % python_version())

if __name__ == '__main__':
 from unittest import main
 main('idlelib.idle_test.test_help', verbosity=2, exit=False)

 from idlelib.idle_test.htest import run
 run(show_idlehelp)