#!/usr/bin/env python

from os.path import join, dirname, abspath
import inspect
from pathlib import Path
from IPython.terminal.ipapp import TerminalIPythonApp
from ipykernel.kernelapp import IPKernelApp
from traitlets import Undefined
from collections import defaultdict

here = abspath(dirname(__file__))
options = join(here, 'source', 'config', 'options')
generated = join(options, 'config-generated.txt')

import textwrap
indent = lambda text,n: textwrap.indent(text,n*' ')


def interesting_default_value(dv):
    if (dv is None) or (dv is Undefined):
        return False
    if isinstance(dv, (str, list, tuple, dict, set)):
        return bool(dv)
    return True

def format_aliases(aliases):
    fmted = []
    for a in aliases:
        dashes = '-' if len(a) == 1 else '--'
        fmted.append('``%s%s``' % (dashes, a))
    return ', '.join(fmted)

def class_config_rst_doc(cls, trait_aliases):
    """Generate rST documentation for this class' config options.

    Excludes traits defined on parent classes.
    """
    lines = []
    classname = cls.__name__
    for k, trait in sorted(cls.class_traits(config=True).items()):
        ttype = trait.__class__.__name__

        fullname = classname + '.' + trait.name
        lines += ['.. configtrait:: ' + fullname,
                  ''
                 ]

        help = trait.help.rstrip() or 'No description'
        lines.append(indent(inspect.cleandoc(help), 4) + '\n')

        # Choices or type
        if 'Enum' in ttype:
            # include Enum choices
            lines.append(indent(
                ':options: ' + ', '.join('``%r``' % x for x in trait.values), 4))
        else:
            lines.append(indent(':trait type: ' + ttype, 4))

        # Default value
        # Ignore boring default values like None, [] or ''
        if interesting_default_value(trait.default_value):
            try:
                dvr = trait.default_value_repr()
            except Exception:
                dvr = None  # ignore defaults we can't construct
            if dvr is not None:
                if len(dvr) > 64:
                    dvr = dvr[:61] + '...'
                # Double up backslashes, so they get to the rendered docs
                dvr = dvr.replace('\\n', '\\\\n')
                lines.append(indent(':default: ``%s``' % dvr, 4))

        # Command line aliases
        if trait_aliases[fullname]:
            fmt_aliases = format_aliases(trait_aliases[fullname])
            lines.append(indent(':CLI option: ' + fmt_aliases, 4))

        # Blank line
        lines.append('')

    return '\n'.join(lines)

def reverse_aliases(app):
    """Produce a mapping of trait names to lists of command line aliases.
    """
    res = defaultdict(list)
    for alias, trait in app.aliases.items():
        res[trait].append(alias)

    # Flags also often act as aliases for a boolean trait.
    # Treat flags which set one trait to True as aliases.
    for flag, (cfg, _) in app.flags.items():
        if len(cfg) == 1:
            classname = list(cfg)[0]
            cls_cfg = cfg[classname]
            if len(cls_cfg) == 1:
                traitname = list(cls_cfg)[0]
                if cls_cfg[traitname] is True:
                    res[classname+'.'+traitname].append(flag)

    return res

def write_doc(name, title, app, preamble=None):
    trait_aliases = reverse_aliases(app)
    filename = join(options, name+'.rst')
    with open(filename, 'w') as f:
        f.write(title + '\n')
        f.write(('=' * len(title)) + '\n')
        f.write('\n')
        if preamble is not None:
            f.write(preamble + '\n\n')
        #f.write(app.document_config_options())

        for c in app._classes_inc_parents():
            f.write(class_config_rst_doc(c, trait_aliases))
            f.write('\n')


if __name__ == '__main__':
    # Touch this file for the make target
    Path(generated).write_text("")

    write_doc('terminal', 'Terminal IPython options', TerminalIPythonApp())
    write_doc('kernel', 'IPython kernel options', IPKernelApp(),
        preamble=("These options can be used in :file:`ipython_kernel_config.py`. "
                  "The kernel also respects any options in `ipython_config.py`"),
    )