Module:Italic title

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-- This module implements {{italic title}}.

require('Module:No globals')
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local checkTypeForNamedArg = libraryUtil.checkTypeForNamedArg
local yesno = require('Module:Yesno')

--------------------------------------------------------------------------------
-- ItalicTitle class
--------------------------------------------------------------------------------

local ItalicTitle = {}

do
    ----------------------------------------------------------------------------
    -- Class attributes and functions
    -- Things that belong to the class are here. Things that belong to each
    -- object are in the constructor.
    ----------------------------------------------------------------------------

    -- Keys of title parts that can be italicized.
    local italicizableKeys = {
        namespace = true,
        title = true,
        dab = true,
    }

    ----------------------------------------------------------------------------
    -- ItalicTitle constructor
    -- This contains all the dynamic attributes and methods.
    ----------------------------------------------------------------------------

    function ItalicTitle.new()
        local obj = {}

        -- Function for checking self variable in methods.
        local checkSelf = libraryUtil.makeCheckSelfFunction(
            'ItalicTitle',
            'obj',
            obj,
            'ItalicTitle object'
        )

        -- Checks a key is present in a lookup table.
        -- Param: name - the function name.
        -- Param: argId - integer position of the key in the argument list.
        -- Param: key - the key.
        -- Param: lookupTable - the table to look the key up in.
        local function checkKey(name, argId, key, lookupTable)
            if not lookupTable[key] then
                error(string.format(
                    "bad argument #%d to '%s' ('%s' is not a valid key)",
                    argId,
                    name,
                    key
                ), 3)
            end
        end

        -- Set up object structure.
        local parsed = false
        local categories = {}
        local italicizedKeys = {}
        local italicizedSubstrings = {}

        -- Parses a title object into its namespace text, title, and
        -- disambiguation text.
        -- Param: options - a table of options with the following keys:
        --     title - the title object to parse
        --     ignoreDab - ignore any disambiguation parentheses
        -- Returns the current object.
        function obj:parseTitle(options)
            checkSelf(self, 'parseTitle')
            checkType('parseTitle', 1, options, 'table')
            checkTypeForNamedArg('parseTitle', 'title', options.title, 'table')
            local title = options.title
        
            -- Title and dab text
            local prefix, parentheses
            if not options.ignoreDab then
                prefix, parentheses = mw.ustring.match(
                    title.text,
                    '^(.+) %(([^%(%)]+)%)$'
                )
            end
            if prefix and parentheses then
                self.title = prefix
                self.dab = parentheses
            else
                self.title = title.text
            end
        
            -- Namespace
            local namespace = mw.site.namespaces[title.namespace].name
            if namespace and #namespace >= 1 then
                self.namespace = namespace
            end

            -- Register the object as having parsed a title.
            parsed = true
        
            return self
        end

        -- Italicizes part of the title.
        -- Param: key - the key of the title part to be italicized. Possible
        -- keys are contained in the italicizableKeys table.
        -- Returns the current object.
        function obj:italicize(key)
            checkSelf(self, 'italicize')
            checkType('italicize', 1, key, 'string')
            checkKey('italicize', 1, key, italicizableKeys)
            italicizedKeys[key] = true
            return self
        end

        -- Un-italicizes part of the title.
        -- Param: key - the key of the title part to be un-italicized. Possible
        -- keys are contained in the italicizableKeys table.
        -- Returns the current object.
        function obj:unitalicize(key)
            checkSelf(self, 'unitalicize')
            checkType('unitalicize', 1, key, 'string')
            checkKey('unitalicize', 1, key, italicizableKeys)
            italicizedKeys[key] = nil
            return self
        end

        -- Italicizes a substring in the title. This only affects the main part
        -- of the title, not the namespace or the disambiguation text.
        -- Param: s - the substring to be italicized.
        -- Returns the current object.
        function obj:italicizeSubstring(s)
            checkSelf(self, 'italicizeSubstring')
            checkType('italicizeSubstring', 1, s, 'string')
            italicizedSubstrings[s] = true
            return self
        end

        -- Un-italicizes a substring in the title. This only affects the main
        -- part of the title, not the namespace or the disambiguation text.
        -- Param: s - the substring to be un-italicized.
        -- Returns the current object.
        function obj:unitalicizeSubstring(s)
            checkSelf(self, 'unitalicizeSubstring')
            checkType('unitalicizeSubstring', 1, s, 'string')
            italicizedSubstrings[s] = nil
            return self
        end

        -- Renders the object into a page name. If no title has yet been parsed,
        -- the current title is used.
        -- Returns string
        function obj:renderTitle()
            checkSelf(self, 'renderTitle')

            -- Italicizes a string
            -- Param: s - the string to italicize
            -- Returns string.
            local function italicize(s)
                assert(type(s) == 'string', 's was not a string')
                assert(s ~= '', 's was the empty string')
                return string.format('<i>%s</i>', s)
            end
        
            -- Escape characters in a string that are magic in Lua patterns.
            -- Param: pattern - the pattern to escape
            -- Returns string.
            local function escapeMagicCharacters(s)
                assert(type(s) == 'string', 's was not a string')
                return s:gsub('%p', '%%%0')
            end

            -- If a title hasn't been parsed yet, parse the current title.
            if not parsed then
                self:parseTitle{title = mw.title.getCurrentTitle()}
            end

            -- Italicize the different parts of the title and store them in a
            -- titleParts table to be joined together later.
            local titleParts = {}

            -- Italicize the italicizable keys.
            for key in pairs(italicizableKeys) do
                if self[key] then
                    if italicizedKeys[key] then
                        titleParts[key] = italicize(self[key])
                    else
                        titleParts[key] = self[key]
                    end
                end
            end

            -- Italicize substrings. If there are any substrings to be
            -- italicized then start from the raw title, as this overrides any
            -- italicization of the main part of the title.
            if next(italicizedSubstrings) then
                titleParts.title = self.title
                for s in pairs(italicizedSubstrings) do
                    local pattern = escapeMagicCharacters(s)
                    local italicizedTitle, nReplacements = titleParts.title:gsub(
                        pattern,
                        italicize
                    )
                    titleParts.title = italicizedTitle

                    -- If we didn't make any replacements then it means that we
                    -- have been passed a bad substring or that the page has
                    -- been moved to a bad title, so add a tracking category.
                    if nReplacements < 1 then
                        categories['Pages using italic title with no matching string'] = true
                    end
                end
            end

            -- Assemble the title together from the parts.
            local ret = ''
            if titleParts.namespace then
                ret = ret .. titleParts.namespace .. ':'
            end
            ret = ret .. titleParts.title
            if titleParts.dab then
                ret = ret .. ' (' .. titleParts.dab .. ')'
            end

            return ret
        end

        -- Returns an expanded DISPLAYTITLE parser function called with the
        -- result of obj:renderTitle, plus any other optional arguments.
        -- Returns string
        function obj:renderDisplayTitle(...)
            checkSelf(self, 'renderDisplayTitle')
            return mw.getCurrentFrame():callParserFunction(
                'DISPLAYTITLE',
                self:renderTitle(),
                ...
            )
        end

        -- Returns an expanded DISPLAYTITLE parser function called with the
        -- result of obj:renderTitle, plus any other optional arguments, plus
        -- any tracking categories.
        -- Returns string
        function obj:render(...)
            checkSelf(self, 'render')
            local ret = self:renderDisplayTitle(...)
            for cat in pairs(categories) do
                ret = ret .. string.format(
                    '[[Category:%s]]',
                    cat
                )
            end
            return ret
        end

        return obj
    end
end

--------------------------------------------------------------------------------
-- Exports
--------------------------------------------------------------------------------

local p = {}

local function getArgs(frame, wrapper)
    assert(type(wrapper) == 'string', 'wrapper was not a string')
    return require('Module:Arguments').getArgs(frame, {
        wrappers = wrapper
    })
end

-- Main function for {{italic title}}
function p._main(args)
    checkType('_main', 1, args, 'table')
    local italicTitle = ItalicTitle.new()
    italicTitle:parseTitle{
        title = mw.title.getCurrentTitle(),
        ignoreDab = yesno(args.all, false)
    }
    if args.string then
        italicTitle:italicizeSubstring(args.string)
    else
        italicTitle:italicize('title')
    end
    return italicTitle:render(args[1])
end

function p.main(frame)
    return p._main(getArgs(frame, 'Template:Italic title'))
end

function p._dabonly(args)
    return ItalicTitle.new()
        :italicize('dab')
        :render(args[1])
end

function p.dabonly(frame)
    return p._dabonly(getArgs(frame, 'Template:Italic dab'))
end


return p