# 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

### 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

        # 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'}