--[[

pandoc.lua

Copyright © 2017 Albert Krewinkel

Permission to use, copy, modify, and/or distribute this software for any purpose

with or without fee is hereby granted, provided that the above copyright notice

and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH

REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND

FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,

INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS

OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER

TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF

THIS SOFTWARE.

]]

---

-- Lua functions for pandoc scripts.

--

-- @author Albert Krewinkel

-- @copyright © 2017 Albert Krewinkel

-- @license MIT

local M = {

  _VERSION = "0.3.0"

}

local List = require 'pandoc.List'

------------------------------------------------------------------------

-- The base class for pandoc's AST elements.

-- @type Element

-- @local

local Element = {}

--- Create a new element subtype

-- @local

function Element:make_subtype(o)

  o = o or {}

  setmetatable(o, self)

  self.__index = self

  return o

end

--- Create a new element given its tag and arguments

-- @local

function Element:new(tag, ...)

  local element = { t = tag }

  local content = {...}

  -- special case for unary constructors

  if #content == 1 then

    element.c = content[1]

  -- Don't set 'c' field if no further arguments were given. This is important

  -- for nullary constructors like `Space` and `HorizontalRule`.

  elseif #content > 0 then

    element.c = content

  end

  setmetatable(element, self)

  self.__index = self

  return element

end

--- Create a new constructor

-- @local

-- @param tag Tag used to identify the constructor

-- @param fn Function to be called when constructing a new element

-- @param accessors names to use as accessors for numerical fields

-- @return function that constructs a new element

function Element:create_constructor(tag, fn, accessors)

  local constr = self:make_subtype({tag = tag, getters = {}, setters = {}})

  -- Add accessors to the metatable

  if type(accessors) == "string" then

    constr.getters[accessors] = function(elem)

      return elem.c

    end

    constr.setters[accessors] = function(elem, v)

      elem.c = v

    end

  else

    for i = 1, #(accessors or {}) do

      if type(accessors[i]) == "string" then

        constr.getters[accessors[i]] = function(elem)

          return elem.c[i]

        end

        constr.setters[accessors[i]] = function(elem, v)

          elem.c[i] = v

        end

      else -- only two levels of nesting are supported

        for k, v in ipairs(accessors[i]) do

          constr.getters[v] = function(elem)

            return elem.c[i][k]

          end

          constr.setters[v] = function(elem, v)

            elem.c[i][k] = v

          end

        end

      end

    end

  end

  function constr:new(...)

    local obj = fn(...)

    setmetatable(obj, self)

    self.__index = function(t, k)

      if getmetatable(t).getters[k] then

        return getmetatable(t).getters[k](t)

      elseif k == "t" then

        return getmetatable(t)["tag"]

      else

        return getmetatable(t)[k]

      end

    end

    self.__newindex = function(t, k, v)

      if getmetatable(t).setters[k] then

        getmetatable(t).setters[k](t, v)

      else

        rawset(t, k, v)

      end

    end

    return obj

  end

  self.constructor = self.constructor or {}

  self.constructor[tag] = constr

  return constr

end

--- Calls the constructor, creating a new element.

-- @local

function Element.__call(t, ...)

  return t:new(...)

end

------------------------------------------------------------------------

--- Pandoc Document

-- @section document

--- A complete pandoc document

-- @function Pandoc

-- @tparam      {Block,...} blocks      document content

-- @tparam[opt] Meta        meta        document meta data

function M.Pandoc(blocks, meta)

  meta = meta or {}

  return {

    ["blocks"] = List:new(blocks),

    ["meta"] = meta,

    ["pandoc-api-version"] = {1,17,0,5},

  }

end

-- DEPRECATED synonym:

M.Doc = M.Pandoc

------------------------------------------------------------------------

-- Meta

-- @section Meta

--- Create a new Meta object. It sets the metatable of the given table to

--- `Meta`.

-- @function Meta

-- @tparam meta table table containing document meta information

M.Meta = {}

M.Meta.__call = function(t, meta)

  return setmetatable(meta, t)

end

setmetatable(M.Meta, M.Meta)

------------------------------------------------------------------------

-- MetaValue

-- @section MetaValue

M.MetaValue = Element:make_subtype{}

M.MetaValue.__call = function(t, ...)

  return t:new(...)

end

--- Meta blocks

-- @function MetaBlocks

-- @tparam {Block,...} blocks blocks

--- Meta inlines

-- @function MetaInlines

-- @tparam {Inline,...} inlines inlines

--- Meta list

-- @function MetaList

-- @tparam {MetaValue,...} meta_values list of meta values

M.meta_value_list_types = {

  "MetaBlocks",

  "MetaInlines",

  "MetaList",

}

for i = 1, #M.meta_value_list_types do

  M[M.meta_value_list_types[i]] = M.MetaValue:create_constructor(

    M.meta_value_list_types[i],

    function(content)

      return List:new(content)

    end

  )

end

--- Meta map

-- @function MetaMap

-- @tparam table key_value_map a string-indexed map of meta values

M.MetaMap = M.MetaValue:create_constructor(

  "MetaMap",

  function (mm) return mm end

)

--- Creates string to be used in meta data.

-- Does nothing, lua strings are meta strings.

-- @function MetaString

-- @tparam string str string value

function M.MetaString(str)

  return str

end

--- Creates boolean to be used in meta data.

-- Does nothing, lua booleans are meta booleans.

-- @function MetaBool

-- @tparam boolean bool boolean value

function M.MetaBool(bool)

  return bool

end

------------------------------------------------------------------------

-- Blocks

-- @section Block

--- Block elements

M.Block = Element:make_subtype{}

M.Block.__call = function (t, ...)

  return t:new(...)

end

--- Creates a block quote element

-- @function BlockQuote

-- @tparam      {Block,...} content     block content

-- @treturn     Block                   block quote element

M.BlockQuote = M.Block:create_constructor(

  "BlockQuote",

  function(content) return {c = content} end,

  "content"

)

--- Creates a bullet (i.e. unordered) list.

-- @function BulletList

-- @tparam      {{Block,...},...} content     list of items

-- @treturn     Block block quote element

M.BulletList = M.Block:create_constructor(

  "BulletList",

  function(content) return {c = content} end,

  "content"

)

--- Creates a code block element

-- @function CodeBlock

-- @tparam      string      text        code string

-- @tparam[opt] Attr        attr element attributes

-- @treturn     Block                   code block element

M.CodeBlock = M.Block:create_constructor(

  "CodeBlock",

  function(text, attr) return {c = {attr or M.Attr(), text}} end,

  {{"identifier", "classes", "attributes"}, "text"}

)

--- Creates a definition list, containing terms and their explanation.

-- @function DefinitionList

-- @tparam      {{{Inline,...},{Block,...}},...} content     list of items

-- @treturn     Block block quote element

M.DefinitionList = M.Block:create_constructor(

  "DefinitionList",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a div element

-- @function Div

-- @tparam      {Block,...} content     block content

-- @tparam[opt] Attr        attr  element attributes

-- @treturn     Block                   code block element

M.Div = M.Block:create_constructor(

  "Div",

  function(content, attr)

    return {c = {attr or M.Attr(), List:new(content)}}

  end,

  {{"identifier", "classes", "attributes"}, "content"}

)

--- Creates a block quote element.

-- @function Header

-- @tparam      int          level       header level

-- @tparam      {Inline,...} content     inline content

-- @tparam[opt] Attr         attr element attributes

-- @treturn     Block                    header element

M.Header = M.Block:create_constructor(

  "Header",

  function(level, content, attr)

    return {c = {level, attr or M.Attr(), content}}

  end,

  {"level", {"identifier", "classes", "attributes"}, "content"}

)

--- Creates a horizontal rule.

-- @function HorizontalRule

-- @treturn     Block                   horizontal rule

M.HorizontalRule = M.Block:create_constructor(

  "HorizontalRule",

  function() return {} end

)

--- Creates a line block element.

-- @function LineBlock

-- @tparam      {{Inline,...},...} content    inline content

-- @treturn     Block                   block quote element

M.LineBlock = M.Block:create_constructor(

  "LineBlock",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a null element.

-- @function Null

-- @treturn     Block                   null element

M.Null = M.Block:create_constructor(

  "Null",

  function() return {} end

)

--- Creates an ordered list.

-- @function OrderedList

-- @tparam      {{Block,...},...} items list items

-- @param[opt]  listAttributes list parameters

-- @treturn     Block

M.OrderedList = M.Block:create_constructor(

  "OrderedList",

  function(items, listAttributes)

    listAttributes = listAttributes or {1, M.DefaultStyle, M.DefaultDelim}

    return {c = {listAttributes, List:new(items)}}

  end,

  {{"start", "style", "delimiter"}, "content"}

)

--- Creates a para element.

-- @function Para

-- @tparam      {Inline,...} content    inline content

-- @treturn     Block                   block quote element

M.Para = M.Block:create_constructor(

  "Para",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a plain element.

-- @function Plain

-- @tparam      {Inline,...} content    inline content

-- @treturn     Block                   block quote element

M.Plain = M.Block:create_constructor(

  "Plain",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a raw content block of the specified format.

-- @function RawBlock

-- @tparam      string      format      format of content

-- @tparam      string      text        string content

-- @treturn     Block                   block quote element

M.RawBlock = M.Block:create_constructor(

  "RawBlock",

  function(format, text) return {c = {format, text}} end,

  {"format", "text"}

)

--- Creates a table element.

-- @function Table

-- @tparam      {Inline,...} caption    table caption

-- @tparam      {AlignDefault|AlignLeft|AlignRight|AlignCenter,...} aligns alignments

-- @tparam      {int,...}    widths     column widths

-- @tparam      {Block,...}  headers    header row

-- @tparam      {{Block,...}} rows      table rows

-- @treturn     Block                   block quote element

M.Table = M.Block:create_constructor(

  "Table",

  function(caption, aligns, widths, headers, rows)

    return {

      c = {

        List:new(caption),

        List:new(aligns),

        List:new(widths),

        List:new(headers),

        List:new(rows)

      }

    }

  end,

  {"caption", "aligns", "widths", "headers", "rows"}

)

------------------------------------------------------------------------

-- Inline

-- @section Inline

--- Inline element class

M.Inline = Element:make_subtype{}

M.Inline.__call = function (t, ...)

  return t:new(...)

end

--- Creates a Cite inline element

-- @function Cite

-- @tparam {Inline,...}   content       List of inlines

-- @tparam {Citation,...} citations     List of citations

-- @treturn Inline citations element

M.Cite = M.Inline:create_constructor(

  "Cite",

  function(content, citations)

    return {c = {List:new(citations), List:new(content)}}

  end,

  {"citations", "content"}

)

--- Creates a Code inline element

-- @function Code

-- @tparam      string      text        brief image description

-- @tparam[opt] Attr        attr  additional attributes

-- @treturn Inline code element

M.Code = M.Inline:create_constructor(

  "Code",

  function(text, attr) return {c = {attr or M.Attr(), text}} end,

  {{"identifier", "classes", "attributes"}, "text"}

)

--- Creates an inline element representing emphasised text.

-- @function Emph

-- @tparam      {Inline,..} content     inline content

-- @treturn Inline emphasis element

M.Emph = M.Inline:create_constructor(

  "Emph",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a Image inline element

-- @function Image

-- @tparam      {Inline,..} caption     text used to describe the image

-- @tparam      string      src         path to the image file

-- @tparam[opt] string      title       brief image description

-- @tparam[opt] Attr        attr additional attributes

-- @treturn Inline image element

M.Image = M.Inline:create_constructor(

  "Image",

  function(caption, src, title, attr)

    title = title or ""

    attr = attr or M.Attr()

    return {c = {attr, List:new(caption), {src, title}}}

  end,

  {{"identifier", "classes", "attributes"}, "caption", {"src", "title"}}

)

--- Create a LineBreak inline element

-- @function LineBreak

-- @treturn Inline linebreak element

M.LineBreak = M.Inline:create_constructor(

  "LineBreak",

  function() return {} end

)

--- Creates a link inline element, usually a hyperlink.

-- @function Link

-- @tparam      {Inline,..} content     text for this link

-- @tparam      string      target      the link target

-- @tparam[opt] string      title       brief link description

-- @tparam[opt] Attr        attr additional attributes

-- @treturn Inline image element

M.Link = M.Inline:create_constructor(

  "Link",

  function(content, target, title, attr)

    title = title or ""

    attr = attr or M.Attr()

    return {c = {attr, List:new(content), {target, title}}}

  end,

  {{"identifier", "classes", "attributes"}, "content", {"target", "title"}}

)

--- Creates a Math element, either inline or displayed.

-- @function Math

-- @tparam      "InlineMath"|"DisplayMath" mathtype rendering specifier

-- @tparam      string      text        Math content

-- @treturn     Inline                  Math element

M.Math = M.Inline:create_constructor(

  "Math",

  function(mathtype, text)

    return {c = {mathtype, text}}

  end,

  {"mathtype", "text"}

)

--- Creates a DisplayMath element (DEPRECATED).

-- @function DisplayMath

-- @tparam      string      text        Math content

-- @treturn     Inline                  Math element

M.DisplayMath = M.Inline:create_constructor(

  "DisplayMath",

  function(text) return M.Math("DisplayMath", text) end,

  {"mathtype", "text"}

)

--- Creates an InlineMath inline element (DEPRECATED).

-- @function InlineMath

-- @tparam      string      text        Math content

-- @treturn     Inline                  Math element

M.InlineMath = M.Inline:create_constructor(

  "InlineMath",

  function(text) return M.Math("InlineMath", text) end,

  {"mathtype", "text"}

)

--- Creates a Note inline element

-- @function Note

-- @tparam      {Block,...} content     footnote block content

M.Note = M.Inline:create_constructor(

  "Note",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a Quoted inline element given the quote type and quoted content.

-- @function Quoted

-- @tparam      "DoubleQuote"|"SingleQuote" quotetype type of quotes to be used

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  quoted element

M.Quoted = M.Inline:create_constructor(

  "Quoted",

  function(quotetype, content) return {c = {quotetype, List:new(content)}} end,

  {"quotetype", "content"}

)

--- Creates a single-quoted inline element (DEPRECATED).

-- @function SingleQuoted

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  quoted element

-- @see Quoted

M.SingleQuoted = M.Inline:create_constructor(

  "SingleQuoted",

  function(content) return M.Quoted(M.SingleQuote, content) end,

  {"quotetype", "content"}

)

--- Creates a single-quoted inline element (DEPRECATED).

-- @function DoubleQuoted

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  quoted element

-- @see Quoted

M.DoubleQuoted = M.Inline:create_constructor(

  "DoubleQuoted",

  function(content) return M.Quoted("DoubleQuote", content) end,

  {"quotetype", "content"}

)

--- Creates a RawInline inline element

-- @function RawInline

-- @tparam      string      format      format of the contents

-- @tparam      string      text        string content

-- @treturn     Inline                  raw inline element

M.RawInline = M.Inline:create_constructor(

  "RawInline",

  function(format, text) return {c = {format, text}} end,

  {"format", "text"}

)

--- Creates text rendered in small caps

-- @function SmallCaps

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  smallcaps element

M.SmallCaps = M.Inline:create_constructor(

  "SmallCaps",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a SoftBreak inline element.

-- @function SoftBreak

-- @treturn     Inline                  softbreak element

M.SoftBreak = M.Inline:create_constructor(

  "SoftBreak",

  function() return {} end

)

--- Create a Space inline element

-- @function Space

-- @treturn Inline space element

M.Space = M.Inline:create_constructor(

  "Space",

  function() return {} end

)

--- Creates a Span inline element

-- @function Span

-- @tparam      {Inline,..} content     inline content

-- @tparam[opt] Attr        attr  additional attributes

-- @treturn Inline span element

M.Span = M.Inline:create_constructor(

  "Span",

  function(content, attr)

    return {c = {attr or M.Attr(), List:new(content)}}

  end,

  {{"identifier", "classes", "attributes"}, "content"}

)

--- Creates a Str inline element

-- @function Str

-- @tparam      string      text        content

-- @treturn     Inline                  string element

M.Str = M.Inline:create_constructor(

  "Str",

  function(text) return {c = text} end,

  "text"

)

--- Creates text which is striked out.

-- @function Strikeout

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  strikeout element

M.Strikeout = M.Inline:create_constructor(

  "Strikeout",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a Strong element, whose text is usually displayed in a bold font.

-- @function Strong

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  strong element

M.Strong = M.Inline:create_constructor(

  "Strong",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a Subscript inline element

-- @function Subscript

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  subscript element

M.Subscript = M.Inline:create_constructor(

  "Subscript",

  function(content) return {c = List:new(content)} end,

  "content"

)

--- Creates a Superscript inline element

-- @function Superscript

-- @tparam      {Inline,..} content     inline content

-- @treturn     Inline                  strong element

M.Superscript = M.Inline:create_constructor(

  "Superscript",

  function(content) return {c = List:new(content)} end,

  "content"

)

------------------------------------------------------------------------

-- Helpers

-- @section helpers

local function assoc_key_equals (x)

  return function (y) return y[1] == x end

end

-- Lookup a value in an associative list

-- @function lookup

-- @tparam {{key, value},...} alist associative list

-- @param key key for which the associated value is to be looked up

local function lookup(alist, key)

  return (List.find_if(alist, assoc_key_equals(key)) or {})[2]

end

--- Return an iterator which returns key-value pairs of an associative list.

-- @function apairs

-- @tparam {{key, value},...} alist associative list

local apairs = function (alist)

  local i = 1

  local cur

  function nxt ()

    cur = rawget(alist, i)

    if cur then

      i = i + 1

      return cur[1], cur[2]

    end

    return nil

  end

  return nxt, nil, nil

end

-- AttributeList, a metatable to allow table-like access to attribute lists

-- represented by associative lists.

local AttributeList = {

  __index = function (t, k)

    if type(k) == "number" then

      return rawget(t, k)

    else

      return lookup(t, k)

    end

  end,

  __newindex = function (t, k, v)

    local cur, idx = List.find_if(t, assoc_key_equals(k))

    if v == nil then

      table.remove(t, idx)

    elseif cur then

      cur[2] = v

    elseif type(k) == "number" then

      rawset(t, k, v)

    else

      rawset(t, #t + 1, {k, v})

    end

  end,

  __pairs = apairs

}

-- convert a table to an associative list. The order of key-value pairs in the

-- alist is undefined. The table should either contain no numeric keys or

-- already be an associative list.

-- @tparam table associative list or table without numeric keys.

-- @treturn table associative list

local to_alist = function (tbl)

  if #tbl ~= 0 or next(tbl) == nil then

    -- probably already an alist

    return tbl

  end

  local alist = {}

  local i = 1

  for k, v in pairs(tbl) do

    alist[i] = {k, v}

    i = i + 1

  end

  return alist

end

-- Attr

M.Attr = {}

M.Attr._field_names = {identifier = 1, classes = 2, attributes = 3}

--- Create a new set of attributes (Attr).

-- @function Attr

-- @tparam[opt] string       identifier element identifier

-- @tparam[opt] {string,...} classes    element classes

-- @tparam[opt] table        attributes table containing string keys and values

-- @return element attributes

M.Attr.__call = function(t, identifier, classes, attributes)

  identifier = identifier or ''

  classes = List:new(classes or {})

  attributes = setmetatable(to_alist(attributes or {}), AttributeList)

  local attr = {identifier, classes, attributes}

  setmetatable(attr, t)

  return attr

end

M.Attr.__index = function(t, k)

  return rawget(t, k) or

    rawget(t, M.Attr._field_names[k]) or

    rawget(getmetatable(t), k)

end

M.Attr.__newindex = function(t, k, v)

  if M.Attr._field_names[k] then

    rawset(t, M.Attr._field_names[k], v)

  else

    rawset(t, k, v)

  end

end

setmetatable(M.Attr, M.Attr)

--- Creates a single citation.

-- @function Citation

-- @tparam      string       id       citation identifier (like a bibtex key)

-- @tparam      AuthorInText|SuppressAuthor|NormalCitation mode citation mode

-- @tparam[opt] {Inline,...} prefix   citation prefix

-- @tparam[opt] {Inline,...} suffix   citation suffix

-- @tparam[opt] int          note_num note number

-- @tparam[opt] int          hash  hash number

M.Citation = function(id, mode, prefix, suffix, note_num, hash)

  prefix = prefix or {}

  suffix = suffix or {}

  note_num = note_num or 0

  hash = hash or 0

  return {

    citationId = id,

    citationPrefix = prefix,

    citationSuffix = suffix,

    citationMode = mode,

    citationNoteNum = note_num,

    citationHash = hash,

  }

end

------------------------------------------------------------------------

-- Constants

-- @section constants

--- Author name is mentioned in the text.

-- @see Citation

-- @see Cite

M.AuthorInText = "AuthorInText"

--- Author name is suppressed.

-- @see Citation

-- @see Cite

M.SuppressAuthor = "SuppressAuthor"

--- Default citation style is used.

-- @see Citation

-- @see Cite

M.NormalCitation = "NormalCitation"

--- Table cells aligned left.

-- @see Table

M.AlignLeft = "AlignLeft"

--- Table cells right-aligned.

-- @see Table

M.AlignRight = "AlignRight"

--- Table cell content is centered.

-- @see Table

M.AlignCenter = "AlignCenter"

--- Table cells are alignment is unaltered.

-- @see Table

M.AlignDefault = "AlignDefault"

--- Default list number delimiters are used.

-- @see OrderedList

M.DefaultDelim = "DefaultDelim"

--- List numbers are delimited by a period.

-- @see OrderedList

M.Period = "Period"

--- List numbers are delimited by a single parenthesis.

-- @see OrderedList

M.OneParen = "OneParen"

--- List numbers are delimited by a double parentheses.

-- @see OrderedList

M.TwoParens = "TwoParens"

--- List are numbered in the default style

-- @see OrderedList

M.DefaultStyle = "DefaultStyle"

--- List items are numbered as examples.

-- @see OrderedList

M.Example = "Example"

--- List are numbered using decimal integers.

-- @see OrderedList

M.Decimal = "Decimal"

--- List are numbered using lower-case roman numerals.

-- @see OrderedList

M.LowerRoman = "LowerRoman"

--- List are numbered using upper-case roman numerals

-- @see OrderedList

M.UpperRoman = "UpperRoman"

--- List are numbered using lower-case alphabetic characters.

-- @see OrderedList

M.LowerAlpha = "LowerAlpha"

--- List are numbered using upper-case alphabetic characters.

-- @see OrderedList

M.UpperAlpha = "UpperAlpha"

------------------------------------------------------------------------

-- Helper Functions

-- @section helpers

--- Use functions defined in the global namespace to create a pandoc filter.

-- All globally defined functions which have names of pandoc elements are

-- collected into a new table.

-- @return A list of filter functions