# GHC User's Guide flag extension
#
# This file defines a Sphinx extension to document GHC flags.
# It introduces a directive:
#
# .. ghc-flag::
#     :shortdesc: A short description (REQUIRED)
#     :type: dynamic, mode, dynamix/ ``:set`` (REQUIRED)
#     :reverse: The reverse of the flag
#     :category: The category to list the flag under (default: 'misc')
#     :noindex: Do not list the flag anywhere (good for duplicates)
#
# That can be referenced using:
#
# :ghc-flag:`flag`
#
# As well as a directive to generate a display of flags:
#
# .. flag-print::
#     :type: table/list/summary (REQUIRED)
#     :category: Limit the output to a single category
#
# The two main functions in this extension are Flag.after_content() which adds
# flag metadata into the environment, and flagprint.generate_output(), which
# reads the metadata back out and formats it as desired.

from docutils import nodes
from docutils.parsers.rst import Directive, directives
from sphinx import addnodes
from sphinx.domains.std import GenericObject
from sphinx.errors import SphinxError

### Settings

# Categories to titles as well as a canonical list of categories
categories = {
    '': 'All flags',
    'codegen': 'Code generation',
    'coverage': 'Program coverage',
    'cpp': 'C pre-processor',
    'debugging': 'Debugging the compiler',
    'interactive': 'Interactive mode',
    'interface-files': 'Interface files',
    'keep-intermediates': 'Keeping intermediate files',
    'language': 'Language options',
    'linking': 'Linking options',
    'misc': 'Miscellaneous options',
    'modes': 'Modes of operation',
    'optimization': 'Individual optimizations',
    'optimization-levels': 'Optimization levels',
    'packages': 'Package options',
    'phases': 'Phases of compilation',
    'phase-programs': 'Overriding external programs',
    'phase-options': 'Phase-specific options',
    'platform-options': 'Platform-specific options',
    'plugins': 'Compiler plugins',
    'profiling': 'Profiling',
    'recompilation': 'Recompilation checking',
    'redirect-output': 'Redirecting output',
    'search-path': 'Finding imports',
    'temp-files': 'Temporary files',
    'verbosity': 'Verbosity options',
    'warnings': 'Warnings',
}

# Map file names to default flag categories
file_defaults = {
    'debugging': 'debugging',
    'ghci': 'interactive',
    'glasgow_exts': 'language',
    'packages': 'packages',
    'profiling': 'profiling',
    'safe_haskell': 'language',
    'separate_compilation': 'redirect-output',
    'using-warnings': 'warnings',
    'using-optimisation': 'optimization'
}


### Flag declaration

# This class inherits from Sphinx's internal GenericObject, which drives
# the add_object_type() utility function. We want to keep that tooling,
# but need to override some of the functionality.
class Flag(GenericObject):

    # The options that can be passed to our directive and their validators
    option_spec = {
        'shortdesc': directives.unchanged_required,
        'type': directives.unchanged_required,
        'reverse': directives.unchanged,
        'category': directives.unchanged,
        'noindex': directives.flag
    }

    # The index directive generated unless :noindex: is specified
    indextemplate = 'pair: %s; GHC option'


    # Generate docutils node from directive arguments
    @staticmethod
    def _parse_flag(env, sig, signode):

        # Break flag into name and args
        import re
        parts = re.split(r'( |=|\[)', sig, 1)
        flag = parts[0]
        # Bold printed name
        signode += addnodes.desc_name(flag, flag)
        if len(parts) > 1:
            args = ''.join(parts[1:])
            # Smaller arguments
            signode += addnodes.desc_addname(args, args)

        # Reference name left unchanged
        return sig

    # Used in the GenericObject class
    parse_node = _parse_flag

    # Override the (empty) function that is called at the end of run()
    # to append metadata about this flag into the environment
    def after_content(self):

        # If noindex, then do not include this flag in the table
        if 'noindex' in self.options:
            return

        # Validity checking
        if 'shortdesc' not in self.options:
            raise SphinxError('ghc-flag (%s) directive missing :shortdesc: key' % self.names)
        if 'type' not in self.options:
            raise SphinxError('ghc-flag (%s) directive missing :type: key' % self.names)

        # Set the flag category (default: misc)
        self.category = 'misc'
        if not 'category' in self.options or self.options['category'] == '':
            if self.env.docname in file_defaults:
                self.category = file_defaults[self.env.docname]
        else:
            self.category = self.options['category']

        # Manually create references
        name_string = ", ".join([':ghc-flag:`'+n+'`' for n in self.names])
        reverse_string = ''
        if 'reverse' in self.options and self.options['reverse'] != '':
            reverse_string = ':ghc-flag:`' + self.options['reverse'] + '`'

        # Create nodes for each cell of the table
        name_node = nodes.paragraph()
        shortdesc_node = nodes.paragraph()
        type_node = nodes.paragraph()
        reverse_node = nodes.paragraph()


        # Nodes expect an internal ViewList type for the content,
        # we are just spoofing it here
        from docutils.statemachine import ViewList
        name_vl = ViewList(initlist=[name_string],
                                source=self.env.docname, parent=[])
        shortdesc_vl = ViewList(initlist=[self.options['shortdesc']],
                                source=self.env.docname, parent=[])
        type_vl = ViewList(initlist=[self.options['type']],
                                source=self.env.docname, parent=[])
        reverse_vl = ViewList(initlist=[reverse_string],
                                source=self.env.docname, parent=[])


        # Parse the content into the nodes
        self.state.nested_parse(name_vl, 0, name_node)
        self.state.nested_parse(shortdesc_vl, 0, shortdesc_node)
        self.state.nested_parse(type_vl, 0, type_node)
        self.state.nested_parse(reverse_vl, 0, reverse_node)


        # The parsing adds extra layers that we don't need
        name_node = name_node[0]
        shortdesc_node = shortdesc_node[0]

        # Append this flag to the environment, initializing if necessary
        if not hasattr(self.env, 'all_flags'):
            self.env.all_flags = []
        self.env.all_flags.append({
            'names': self.names,
            'docname': self.env.docname,
            'category': self.category,
            'cells': [name_node, shortdesc_node, type_node, reverse_node],
        })


### Flag Printing

# Taken from Docutils source inside the ListTable class. We must bypass
# using the class itself, but this function comes in handy.
def build_table_from_list(table_data, col_widths):
    table = nodes.table()
    tgroup = nodes.tgroup(cols=len(col_widths))
    table += tgroup
    for col_width in col_widths:
        colspec = nodes.colspec(colwidth=col_width)
        tgroup += colspec
    rows = []
    for row in table_data:
        row_node = nodes.row()
        for cell in row:
            entry = nodes.entry()
            entry += cell
            row_node += entry
        rows.append(row_node)
    thead = nodes.thead()
    thead.extend(rows[:1])
    tgroup += thead
    tbody = nodes.tbody()
    tbody.extend(rows[1:])
    tgroup += tbody
    return table


# Generate a table of flags
def generate_flag_table(flags, category):

    # Create column headers for table
    header = []
    for h in ["Flag", "Description", "Type", "Reverse"]:
        inline = nodes.inline(text=h)
        header.append(inline)

    flags_list = [header]

    for flag_info in flags:

        flags_list.append(flag_info['cells'])

    # The column width hints only apply to html,
    # latex widths are set in file (see flags.rst)
    table = build_table_from_list(flags_list, [28, 34, 10, 28])

    # Flag tables have lots of content, so we need to set 'longtable'
    # to allow for pagebreaks. (latex specific)
    table['classes'].append('longtable')

    return table


# Generate a list of flags and their short descriptions
def generate_flag_list(flags, category):

    list_node = nodes.definition_list()

    for flag_info in flags:

        dl_item_node = nodes.definition_list_item()
        term_node = nodes.term()
        # The man writer is picky, so we have to remove the outer
        # paragraph node to get just the flag name
        term_node += flag_info['cells'][0][0]
        dl_item_node += term_node
        def_node = nodes.definition()
        def_node += flag_info['cells'][1]
        dl_item_node += def_node

        list_node += dl_item_node

    return list_node


# Generate a block of flag names under a category
def generate_flag_summary(flags, category):

    summary_node = nodes.definition_list_item()
    term_node = nodes.term(text=categories[category])
    summary_node += term_node
    block = nodes.definition()
    summary_node += block

    # Fill block with flags
    for flag_info in flags:

        for name in flag_info['names']:
            block += nodes.literal(text=name)
            block += nodes.inline(text=' ')

    block += nodes.inline(text='\n')

    return summary_node

# Output dispatch table
handlers = {
    'table': generate_flag_table,
    'list': generate_flag_list,
    'summary': generate_flag_summary
}


# Generic node for printing flag output
class flagprint(nodes.General, nodes.Element):

    def __init__(self, output_type='', category='', **kwargs):

        nodes.Element.__init__(self, rawsource='', **kwargs)

        # Verify options
        if category not in categories:
            error = "flagprint: Unknown category: " + category
            raise ValueError(error)
        if output_type not in handlers:
            error = "flagprint: Unknown output type: " + output_type
            raise ValueError(error)

        # Store the options
        self.options = {
            'type': output_type,
            'category': category
        }


    # The man writer has a copy issue, so we explicitly override it here
    def copy(self):
        newnode = flagprint(output_type=self.options['type'],
                category=self.options['category'], **self.attributes)
        newnode.source = self.source
        newnode.line = self.line
        return newnode


    def generate_output(self, app, fromdocname):
        env = app.builder.env

        # Filter flags before passing to handlers
        flags = []

        for flag_info in sorted(env.all_flags,
                key=lambda fi: fi['names'][0].lower()):

            if not (self.options['category'] == '' or
                    self.options['category'] == flag_info['category']):
                continue

            # Resolve all references as if they were originated from this node.
            # This fixes the relative uri.
            for cell in flag_info['cells']:
                for ref in cell.traverse(addnodes.pending_xref):
                    ref['refdoc'] = fromdocname
                env.resolve_references(cell, flag_info['docname'], app.builder)

            flags.append(flag_info)

        handler = handlers[self.options['type']]
        self.replace_self(handler(flags, self.options['category']))


# A directive to create flagprint nodes
class FlagPrintDirective(Directive):

    option_spec = {
        'type': directives.unchanged_required,
        'category': directives.unchanged
    }

    def run(self):

        # Process options
        category = ''
        if 'category' in self.options:
            category = self.options['category']

        # Create a flagprint node
        node = flagprint(output_type=self.options['type'], category=category)
        return [node]


### Additional processing

# Convert every flagprint node into its output format
def process_print_nodes(app, doctree, fromdocname):

    for node in doctree.traverse(flagprint):
        node.generate_output(app, fromdocname)


# To avoid creating duplicates in the serialized environment, clear all
# flags originating from a file before re-reading it.
def purge_flags(app, env, docname):

    if not hasattr(env, 'all_flags'):
        return

    env.all_flags = [flag for flag in env.all_flags
                     if flag['docname'] != docname]

### Initialization

def setup(app):

    # Add ghc-flag directive, and override the class with our own
    app.add_object_type('ghc-flag', 'ghc-flag')
    app.add_directive_to_domain('std', 'ghc-flag', Flag)

    # Add new node and directive
    app.add_node(flagprint)
    app.add_directive('flag-print', FlagPrintDirective)

    # Add our generator and cleanup functions as callbacks
    app.connect('doctree-resolved', process_print_nodes)
    app.connect('env-purge-doc', purge_flags)

    return {'version': '1.0'}