Module:Infobox television episode

--- @module
local p = {}

local maintenance_categories = {
 incorrectly_formatted = "[[Category:Pages using infobox television episode with incorrectly formatted values|%s]]",
 unlinked_values = "[[Category:Pages using infobox television episode with unlinked values|%s]]",
 image_values_without_an_image = "[[Category:Pages using infobox television episode with image-related values without an image]]",
 unnecessary_title_parameter = "[[Category:Pages using infobox television episode with unnecessary title parameter]]",
 non_matching_title = "[[Category:Pages using infobox television episode with non-matching title]]",
 flag_icon = "[[Category:Pages using infobox television with flag icon]]",
 dates_incorrectly_formatted = "[[Category:Pages using infobox television episode with nonstandard dates]]",
 manual_display_title = "[[Category:Pages using infobox television episode with unnecessary manual displaytitle]]",
 list_markup = "[[Category:Pages using infobox television episode with unnecessary list markup]]",
}

--- Returns the text after removing line breaks (<br> tags) and additional spaces as a result.
---
--- @param text string
--- @return string
local function get_name_with_br_fixes(text)
 local title, _ = string.gsub(text, "<br%s?/?>", "")
 title, _ = string.gsub(title, "  ", " ")
 return title
end

--- Returns the page name after replacing quotation marks for single quotes and fixing it to use the
--- "Space+single" and "Single+space" templates if a leading or trailing apostrophe or quotation mark is used.
---
--- Note: per [[MOS:QWQ]] an episode title with quotation marks should be replaced with single quotes.
---
--- @param frame table
--- @param article_title string
--- @return string
local function get_page_name_with_apostrophe_quotation_fixes(frame, article_title)
 local page_name, _ = string.gsub(article_title, '"', "'")

 local left_side_template = frame:expandTemplate{title = "Space+single"}
 local right_side_template = frame:expandTemplate{title = "Single+space"}
 page_name, _ = string.gsub(string.gsub(page_name, "^'", left_side_template), "'$", right_side_template)

 return page_name
end

--- Returns the series link.
---
--- @param series string
--- @return string
local function get_series_link(series)
 local delink = require("Module:Delink")._delink
 return delink({series, wikilinks = "target"})
end

--- Returns two strings:
---- The series name after de-linking it and escaping "-".
---- The series name after de-linking it.
---
--- @param series string
--- @return string, string
local function get_series_name(series)
 local delink = require("Module:Delink")._delink
 local series_name = delink({series})

 -- Escape the character "-" as it is needed for string.find() to work.
 local _
 local series_name_escaped, _ = string.gsub(series_name, "-", "%%-")
 return series_name_escaped, series_name
end

--- Returns a table consisting of the episode's title parts.
---
--- The return table's properties:
--- - title - The episode's title.
--- - disambiguation - the disambiguation text without parentheses.
---
--- Note: could potentially be moved to an outside module for other template and module uses.
---
--- @param text string
--- @return table<string, string | nil>
local function get_title_parts(text)
 local title, disambiguation = string.match(text, "^(.+) (%b())$")

 local titleString = title -- TODO: needed until https://github.com/Benjamin-Dobell/IntelliJ-Luanalysis/issues/63 is resolved.
 if not title or type(title) ~= "string" then
  titleString = text
 end

 ---@type table<string, string | nil>
 local title_parts = {title = --[[---@not number | nil]] titleString, disambiguation = nil}

 if not disambiguation or type(disambiguation) ~= "string" then
  return title_parts
 end

 -- Remove outside parentheses from names which use parentheses as part of the name such as "episode (Randall and Hopkirk (Deceased))".
 disambiguation = string.sub(--[[---@not number | nil]] disambiguation, 2, -2)
 title_parts.disambiguation = --[[---@not number]] disambiguation
 return title_parts
end

--- Returns the title used in the {{Lowercase title}} template and an optional maintenance category.
---
--- @param page_text string
--- @param args table
--- @param title_parts table
--- @return string | nil
local function get_lowercase_template_status(page_text, args, title_parts)
 local lowercase_template =  string.match(page_text, "{{[Ll]owercase title.-}}")
 if lowercase_template then
  local lowercase_title, _ = string.gsub(title_parts.title,"^%u", string.lower)
  if args.title then
   if args.title == lowercase_title then
    return maintenance_categories.unnecessary_title_parameter
   else
    return maintenance_categories.non_matching_title
   end
   return ""
  end
  return lowercase_title
 end

 return nil
end

--- Returns the title used in the {{Correct title}} template and an optional maintenance category.
---
--- @param page_text string
--- @param args table
--- @param return_category boolean
--- @return string | nil
local function get_correct_title_value(page_text, args, return_category)
 local correct_title_template_pattern = "{{[Cc]orrect title|title=(.*)|reason=.-}}"

 local correct_title = string.match(page_text, correct_title_template_pattern)

 if not correct_title then
  correct_title_template_pattern = "{{[Cc]orrect title|(.*)|reason=.-}}"
  correct_title = string.match(page_text, correct_title_template_pattern)
 end

 if not correct_title and type(correct_title) ~= "string" then
  return nil
 end

 local correct_title_title_parts = get_title_parts(correct_title)

 if not correct_title_title_parts.disambiguation then
  -- If the correct title value has no disambiguation, check if the title used in the infobox is the same as the title used for the correct title value.
  if return_category and args.title then
   if args.title == correct_title_title_parts.title then
    return maintenance_categories.unnecessary_title_parameter
   else
    return maintenance_categories.non_matching_title
   end
  end
  return correct_title_title_parts.title
 end

 local series_name_escaped, _ = get_series_name(args.series)

 if series_name_escaped ~= "" and (correct_title_title_parts.disambiguation == series_name_escaped or string.find(correct_title_title_parts.disambiguation, series_name_escaped)) then
  if return_category and args.title then
   if args.title == correct_title_title_parts.title then
    return maintenance_categories.unnecessary_title_parameter
   else
    return maintenance_categories.non_matching_title
   end
  end
  return correct_title_title_parts.title
 end

 -- Can't determine if the text in parentheses is disambiguation or part of the title since |series= isn't used.
 if return_category then
  return ""
 end

 return correct_title
end

--- Returns the display title text used in either the {{DISPLAYTITLE}} or {{Italic title}} templates.
---
--- @param page_text string
--- @param article_title string
--- @return string | nil
local function get_display_title_text(page_text, article_title)
 local title_modification = string.match(page_text, "{{DISPLAYTITLE:(.-)}}")
 if title_modification and type(title_modification) == "string" then
  return --[[---@not number | nil]] title_modification
 end

 title_modification = string.match(page_text, "{{Italic title|string=(.-)}}")
 if title_modification and type(title_modification) == "string" then
  local italic_title_text, _ = string.gsub(article_title, --[[---@not number | nil]] title_modification, "''" .. title_modification .. "''")
  return italic_title_text
 end

 return nil
end

--- Returns a maintenance category if the italic_title value is not "no".
---
--- Infobox parameters checked:
--- - |italic_title=
---
--- @param args table
--- @return string
local function is_italic_title_valid_value(args)
 if args.italic_title and args.italic_title ~= "no" then
  return string.format(maintenance_categories.incorrectly_formatted, "italic_title")
 end
 return ""
end

--- Returns a maintenance category if the date is not formatted correctly with a {{Start date}} template.
--- Allow "Unaired" as a valid value for unaired television episodes.
---
--- Infobox parameters checked:
--- - |airdate=
--- - |released=
--- - |airdate_overall=
---
--- @param start_date string
--- @return string
local function are_dates_formatted_correctly(start_date)
 if start_date and (string.find(start_date, "film%-date") or not string.find(start_date, "itvstart") and start_date ~= "Unaired") then
  return maintenance_categories.dates_incorrectly_formatted
 end
 return ""
end

--- Returns a maintenance category if list markup is used. The infobox can handle list markup correctly.
---
--- Note: the code here is temporarily checking only the parameters which have been converted
--- to use the plainlist class directly. Once current uses will be converted, the function will check all parameters
--- for incorrect usage.
---
--- Infobox parameters checked:
--- - Parameters listed below.
---
--- Currently checks for the following list markup:
--- - <br> tags - per [[MOS:NOBR]].
--- - <li> tags.
--- - "plainlist" class.
--- - "hlist" class.
---
--- @param args table
--- @return string
local function uses_list_markup(args)
 local invalid_tags = {
  ["br"] = "<[bB][rR]%s?/?>",
  ["li"] = "<li>",
  ["plainlist"] = "plainlist",
  ["hlist"] = "hlist",
 }

 ---@type table<string, boolean>
 local parameters = {
  director = true,
  writer = true,
  story = true,
  teleplay = true,
  narrator = true,
  presenter = true,
  producer = true,
  music = true,
  photographer = true,
  editor = true,
  production = true,
  airdate = true,
  guests = true,
  commentary = true,
 }

 for parameter_name, _ in pairs(parameters) do
  for _, list_pattern in pairs(invalid_tags) do
   local parameter_value = args[parameter_name]
   if parameter_value and string.find(parameter_value, list_pattern) then
    return maintenance_categories.list_markup
   end
  end
 end
 return ""
end

--- Returns a maintenance category if a flag icon is used.
---
--- All of the infobox values are checked.
---
--- @param args table
--- @return string
local function has_flag_icon(args)
 for _, value in pairs(args) do
  if string.find(value, "flagicon") then
   return maintenance_categories.flag_icon
  end
 end
 return ""
end

--- Returns a maintenance category if the values are linked.
---
--- Infobox parameters checked:
--- - |episode=
--- - |season=
--- - |series_no=
--- - |episode_list=
---
--- The function currently checks if the following values are present:
--- - ]] - links.
---
--- @param args table
--- @return string
local function are_values_linked(args)
 local parameters = {
  episode = args.episode,
  season = args.season,
  series_no = args.series_no,
  episode_list = args.episode_list,
 }

 for key, value in pairs(parameters) do
  if string.find(value, "]]", 1, true) then
   return string.format(maintenance_categories.incorrectly_formatted, key)
  end
 end
 return ""
end

--- Returns a maintenance category if the values are formatted.
---
--- Most of the infobox values are checked. Not included are:
--- - |title= - is handled in is_infobox_title_equal_to_article_title()
--- - |series= - is handled in are_values_links_only()
--- - |next= - is handled in are_values_links_only()
--- - |prev= is handled in are_values_links_only()
--- - |rtitle=
--- - |rprev=
--- - |rnext=
--- - |image_alt=
--- - |alt=
--- - |caption=
--- - |based_on=
--- - |music=
--- - |guests=
--- - |module=
---
--- The function currently checks if the following values are present:
--- - '' - italics or bold.
---
--- Note:
--- If the series is American Horror Story then the season_article value is allowed to be formatted.
--- If in the future more series need this exception then the hardcoded value in the function should be taken out into a list.
---
--- @param args table
--- @return string
local function are_values_formatted(args)
 ---@type table<string, boolean>
 local ignore_parameters = {
  title = true,
  series = true,
  prev = true,
  next = true,
  rtitle = true,
  rprev = true,
  rnext = true,
  image_alt = true,
  alt = true,
  caption = true,
  based_on = true,
  music = true,
  guests = true,
  module = true,
 }

 for key, value in pairs(args) do
  if not ignore_parameters[key] and string.find(value, "''", 1, true) then
   if key == "season_article" and args.series == "[[American Horror Story]]" then --TODO: This is hardcoded for now.
    -- Do nothing.
   else
    return string.format(maintenance_categories.incorrectly_formatted, key)
   end
  end
 end
 return ""
end

--- Returns a maintenance category if the values use additional overall numbering.
---
--- Infobox parameters checked:
--- - |episode=
--- - |season=
--- - |series_no=
---
--- The function currently checks if the following values are present:
--- - overall - unsupported series overall numbering.
---
--- @param args table
--- @return string
local function are_values_using_overall(args)
 local parameters = {
  episode = args.episode,
  season = args.season,
  series_no = args.series_no,
 }

 for key, value in pairs(parameters) do
  if string.find(value, "overall") then
   return string.format(maintenance_categories.incorrectly_formatted, key)
  end
 end

 return ""
end

--- Returns a maintenance category if the values are unlinked and if additional characters are found in the text.
---
--- Infobox parameters checked:
--- - |series=
--- - |prev=
--- - |next=
---
--- The function currently checks if a value is unlinked or if there is any additional character
--- before or after the linked text.
---
--- @param args table
--- @return string
local function are_values_links_only(args)
 local parameters = {
  series = args.series,
  prev = args.prev,
  next = args.next,
 }

 for key, value in pairs(parameters) do
  -- Check whether the values are linked.
  if not string.find(value, "%[%[.*%]%]") then
   return string.format(maintenance_categories.unlinked_values, key)
  end

  -- Check whether the values have anything before or after link brackets.
  if string.gsub(value, "(%[%[.*%]%])", "") ~= "" then
   return string.format(maintenance_categories.incorrectly_formatted, key)
  end
 end

 return ""
end

--- Returns a maintenance category if the |image= value includes the "File:" or "Image:" prefix.
---
--- Infobox parameters checked:
--- - |image=
---
--- @param image string
--- @return string
local function is_image_using_incorrect_syntax(image)
 if not image then
  return ""
 end

 if string.find(image, "[Ff]ile:") or string.find(image, "[Ii]mage:") then
  return string.format(maintenance_categories.incorrectly_formatted, "image")
 end

 return ""
end

--- Returns a maintenance category if the |image_size= value includes "px".
---
--- Infobox parameters checked:
--- - |image_size=
---
--- @param image_size string
--- @return string
local function is_image_size_using_px(image_size)
 if image_size and string.find(image_size, "px") then
  return string.format(maintenance_categories.incorrectly_formatted, "image_size")
 end
 return ""
end

--- Returns a maintenance category if there is no image file while image auxiliary values are present.
---
--- Infobox parameters checked:
--- - |image=
--- - |image_size=
--- - |image_upright=
--- - |image_alt=
--- - |alt=
--- - |caption=
---
--- @param args table
--- @return string
local function are_image_auxiliary_values_used_for_no_image(args)
 if args.image then
  return ""
 end

 if args.image_size or args.image_upright or args.image_alt or args.alt or args.caption then
  return maintenance_categories.image_values_without_an_image
 end

 return ""
end

--- Returns a maintenance category if the infobox title is equal to the article title.
---
--- Infobox parameters checked:
--- - |title=
--- - |series=
--- - |italic_title
---
--- The function currently checks if the infobox title is equal to the article title while ignoring styling such as:
--- - Nowrap spans.
--- - Line breaks.
--- - Leading and trailing apostrophe spaces.
---
--- A return value can be one of three options:
--- - The value of maintenance_categories.non_matching_title - when the args.title does not match the article title.
--- - The value of maintenance_categories.unnecessary_title_parameter - when the args.title matches the article title.
--- - An empty string - when args.title isn't used or the args.title uses an allowed modification
--- (such as a nowrap template) while the rest of the args.title matchs the article title.
---
--- Testing parameters:
--- - |page_test= - a real Wikipedia page to read the content of the page.
--- - |page_title_test= - the title of the page being checked.
---
--- @param frame table
--- @param args table
--- @return string
local function is_infobox_title_equal_to_article_title(frame, args)
 if not args.title then
  return ""
 end

 local page_text
 if args.page_test then
  page_text = mw.title.new(args.page_test):getContent()
 else
  page_text = mw.title.getCurrentTitle():getContent()
 end

 -- Check if the article is using a {{Correct title}} template.
 local correct_title = get_correct_title_value(page_text, args, true)
 if correct_title then
  return correct_title
 end

 local article_title = args.page_title_test
 if not args.page_title_test then
  article_title = mw.title.getCurrentTitle().text
 end

 local title_parts = get_title_parts(article_title)

 -- Check if the article is using a {{Lowercase title}} template.
 local lowercase_title = get_lowercase_template_status(page_text, args, title_parts)
 if lowercase_title then
  return lowercase_title
 end

 if title_parts.disambiguation then
  local series_name_escaped, _ = get_series_name(args.series)
  series_name_escaped = get_name_with_br_fixes(series_name_escaped)
  if series_name_escaped ~= "" and (title_parts.disambiguation == series_name_escaped or string.find(title_parts.disambiguation, series_name_escaped)) then
   -- Remove disambiguation.
   article_title = title_parts.title
  end
 end

 if args.italic_title then
  -- Check if the article is using a {{DISPLAYTITLE}} or {{Italic title}} template.
  local title_modification = get_display_title_text(page_text, article_title)
  if title_modification then
   if title_modification == args.title then
    return maintenance_categories.unnecessary_title_parameter
   else
    return maintenance_categories.non_matching_title
   end
  end
 end

 local page_name = get_page_name_with_apostrophe_quotation_fixes(frame, article_title)

 -- Remove nowrap span.
 if string.find(args.title, "nowrap") then
  local title = frame:expandTemplate{title = "Strip tags", args = {args.title}}
  if title == page_name then
   return ""
  end
  return maintenance_categories.non_matching_title
 end

 -- Remove line breaks and additional spaces as a result.
 if string.find(args.title, "<br%s?/?>") then
  local title = get_name_with_br_fixes(args.title)
  if title == page_name then
   return ""
  end
  return maintenance_categories.non_matching_title
 end

 if args.title == page_name then
  return maintenance_categories.unnecessary_title_parameter
 end

 -- Article and infobox titles do not match.
 return maintenance_categories.non_matching_title
end

--- Returns the relevant maintenance categories based on the {{Infobox television episode}} values validated.
---
--- @param frame table
--- @return string
function p.validate_values(frame)
 local getArgs = require("Module:Arguments").getArgs
 local args = getArgs(frame)

 ---@type string[]
 local categories = {}
 table.insert(categories, is_infobox_title_equal_to_article_title(frame, args))
 table.insert(categories, are_image_auxiliary_values_used_for_no_image(args))
 table.insert(categories, is_image_using_incorrect_syntax(args.image))
 table.insert(categories, is_image_size_using_px(args.image_size))
 table.insert(categories, are_values_links_only(args))
 table.insert(categories, are_values_using_overall(args))
 table.insert(categories, are_values_formatted(args))
 table.insert(categories, are_values_linked(args))
 table.insert(categories, has_flag_icon(args))
 table.insert(categories, uses_list_markup(args))
 table.insert(categories, are_dates_formatted_correctly(args.airdate or args.released))
 table.insert(categories, is_italic_title_valid_value(args))

 return table.concat(categories)
end

--- Returns an {{Italic dab2}} instance if title qualifies. Also returns a maintenance category if conditions are met.
---
--- The article's title is italicized if the series name is included in the article's title disambiguation.
--- No italicization happens if one of the following conditions is met:
---
--- - |italic_title= is set to "no".
--- - The article's title does not use disambiguation.
--- - No |series= value is set.
--- - The article's disambiguation is not equal or does not include the series name.
---
--- The page is added to a maintenance category if the title is italicized and there is already an
--- {{Italic dab}}, {{Italic title}} or {{DISPLAYTITLE}} template.
---
--- Infobox parameters checked:
--- - |series=
--- - |italic_title=
---
--- Testing parameters:
--- - |page_test= - a real Wikipedia page to read the content of the page.
--- - |page_title_test= - the title of the page being checked.
---
--- @param frame table
--- @return string, string
function p.italic_title(frame)
 local getArgs = require("Module:Arguments").getArgs
 local args = getArgs(frame)

 local page_text
 if args.page_test then
  page_text = mw.title.new(args.page_test):getContent()
 else
  page_text = mw.title.getCurrentTitle():getContent()
 end

 local maintenance_category = ""
 -- In case the page does not need to be italicized or can't be automatically done, a "no" value will disable both
 -- the italicization and the error handling.
 if args.italic_title == "no" then
  return "", maintenance_category
 end

 local article_title = args.page_title_test
 if not args.page_title_test then
  article_title = mw.title.getCurrentTitle().text
 end

 -- Check if the page already has an {{Italic dab}}, {{Italic title}} or {{DISPLAYTITLE}} template.
 local has_italic_dab, _ = string.find(page_text, "{{[Ii]talic dab")
 local has_italic_title, _ = string.find(page_text, "{{[Ii]talic title")
 local has_display_title, _ = string.find(page_text, "{{DISPLAYTITLE")

 if has_italic_dab or has_italic_title or has_display_title then
  maintenance_category = maintenance_categories.manual_display_title
 end

 local title_parts = get_title_parts(article_title)

 -- The title is not italicized if the title does not use disambiguation or if the series parameter isn't used.
 if not title_parts.disambiguation or not args.series then
  return "", maintenance_category
 end

 local series_name_escaped, series_name = get_series_name(args.series)
 series_name_escaped = get_name_with_br_fixes(series_name_escaped)
 series_name = get_name_with_br_fixes(series_name)

 -- Check if the disambiguation equals the series name or if the series name can be found in the disambiguation.
 local italic_dab
 if title_parts.disambiguation == series_name then
  italic_dab = frame:expandTemplate{title = "Italic dab2"}
 elseif string.find(title_parts.disambiguation, series_name_escaped) then
  italic_dab = frame:expandTemplate{title = "Italic dab2", args = {string = series_name}}
 else
  return "", maintenance_category
 end

 if args.page_title_test and italic_dab then
  italic_dab = "italic_dab"
 end
 return italic_dab, maintenance_category

end

--- Returns a formatted title string.
---
--- @param rtitle string
--- @return string
local function create_title_with_rtitle_value(rtitle)
 local title_pattern = '"(.*)" and "(.*)"'
 if string.find(rtitle, title_pattern) then
  local episode1, episode2 = string.match(rtitle, title_pattern)
  local title_format = "\"'''%s'''\" and \"'''%s'''\""
  return string.format(title_format, episode1, episode2)
 end

 local title_pattern_br = '"(.*)" and%s?<br%s?/?>%s?"(.*)"'
 if string.find(rtitle, title_pattern_br) then
  local episode1, episode2 = string.match(rtitle, title_pattern_br)
  local title_format = "\"'''%s'''\" and<br/> \"'''%s'''\""
  return string.format(title_format, episode1, episode2)
 end

 return string.format("'''%s'''", rtitle)
end

--- Returns the text used for the |above= field of the infobox.
---
--- Infobox parameters checked:
--- - |rtitle=
--- - |title=
--- - |series=
---
--- Testing parameters:
--- - |page_test= - a real Wikipedia page to read the content of the page.
--- - |page_title_test= - the title of the page being checked.
---
--- @param frame table
--- @return string
local function _above_title(frame, args)
 if args.rtitle then
  return create_title_with_rtitle_value(args.rtitle)
 end

 local page
 if args.page_test then
  page = mw.title.new(args.page_test)
 else
  page = mw.title.getCurrentTitle()
 end

 local page_text = page:getContent()

 local article_title = args.page_title_test
 if not args.page_title_test then
  article_title = page.text
 end

 local title_format = "\"'''%s'''\""

 local correct_title = get_correct_title_value(page_text, args, false)
 if correct_title then
  return string.format(title_format, correct_title)
 end

 local title_parts = get_title_parts(article_title)

 local lowercase_title = get_lowercase_template_status(page_text, args, title_parts)
 if lowercase_title then
  return string.format(title_format, lowercase_title)
 end

 local series_name_escaped, _ = get_series_name(args.series)

 -- args.no_bold is used from IMDb episode so it requires this correction here also.
 if (args.italic_title and not args.rtitle) or args.no_bold then
  local title_modification = get_display_title_text(page_text, article_title)

  if title_modification then
   if title_parts.disambiguation == series_name_escaped then
    local correct_title_title_parts = get_title_parts(title_modification)
    title_modification = correct_title_title_parts.title
   end
   return string.format(title_format, title_modification)
  end
 end

 if args.title then
  return string.format(title_format, args.title)
 end

 if not title_parts.disambiguation or (series_name_escaped ~= "" and (title_parts.disambiguation == series_name_escaped or string.find(title_parts.disambiguation, series_name_escaped))) or args.no_bold then
  return string.format(title_format, get_page_name_with_apostrophe_quotation_fixes(frame, title_parts.title))
 end

 return string.format(title_format, get_page_name_with_apostrophe_quotation_fixes(frame, article_title))
end

--- Returns the episode title from the article title, with textual fixes if needed.
---
--- Used by {{Infobox television episode}} and {{IMDb episode}} to automatically style the title without needing manual input.
---
--- @param frame table
--- @return string
function p.above_title(frame)
 local getArgs = require("Module:Arguments").getArgs
 local args = getArgs(frame)
 local title = _above_title(frame, args)
 
 -- The title used by {{IMDb episode}} should not be in bold.
 if args.no_bold then
  title = string.gsub(title, "'''", "")
 end
 return title
end

--- Returns a list of episodes link if not formatted, otherwise returns the text used for args.episode_list.
---
--- Infobox parameters checked:
--- - |episode_list=
--- - |series=
---
--- @param frame table
--- @return string
function p.episode_list(frame)
 local getArgs = require("Module:Arguments").getArgs
 ---@type table<string, string>
 local args = getArgs(frame)

 if args.episode_list then
  for _, v in pairs({"]]", "''"}) do
   if string.find(args.episode_list, v) then
    return args.episode_list
   end
  end

  if string.find(args.episode_list, "[Ss]toryline") then
   return "[[" .. args.episode_list .. "|Storylines]]"
  end

  return "[[" .. args.episode_list .. "|List of episodes]]"
 end

 if args.series then
  local series_name = get_series_link(args.series)
  local list_of_episodes = "List of " .. series_name .. " episodes"

  if mw.title.new(list_of_episodes):getContent() then
   return "[[" .. list_of_episodes .. "|List of episodes]]"
  end
 end
end

--- Returns the relevant maintenance categories based on the {{Infobox television crossover episode}} values validated.
---
--- @param frame table
--- @return string
function p.validate_values_crossover(frame)
 local getArgs = require("Module:Arguments").getArgs
 local args = getArgs(frame)

 ---@type string[]
 local categories = {}
 table.insert(categories, are_image_auxiliary_values_used_for_no_image(args))
 table.insert(categories, is_image_using_incorrect_syntax(args.image))
 table.insert(categories, is_image_size_using_px(args.image_size))
 table.insert(categories, has_flag_icon(args))
 table.insert(categories, are_dates_formatted_correctly(args.airdate_overall))

 for i = 1, 5 do
  if not args["series" .. i] then
   break
  end

  local nested_args = {
   series = args["series" .. i],
   episode = args["episode_no" .. i],
   season = args["season" .. i],
   airdate = args["airdate" .. i],
   prev = args["prev" .. i],
   next = args["next" .. i],
   episode_list = args["episode_list" .. i],
  }

  table.insert(categories, are_values_links_only(nested_args))
  table.insert(categories, are_values_using_overall(nested_args))
  table.insert(categories, are_values_formatted(nested_args))
  table.insert(categories, are_values_linked(nested_args))
  table.insert(categories, are_dates_formatted_correctly(nested_args.airdate))
 end

 return table.concat(categories, "")
end

return p