%D \module
%D   [       file=m-poetry,
%D        version=2022.08.28
%D          title=\CONTEXT\ Extra Modules,
%D       subtitle=Whatever comes up,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

% For Denis Maier (see mails to list end of August 2022)

\startluacode

local      poetry = moduledata.poetry or { }
moduledata.poetry = poetry

function poetry.sidebyside(specification)
    local first   = string.splitlines(buffers.getcontent(specification.left))
    local second  = string.splitlines(buffers.getcontent(specification.right))
    local template = specification.template or "|||"
    context.starttabulate { template }
        for i=1,#first do
            local f = first [i] or ""
            local s = second[i] or ""
            if f == "" and s == "" then
                context.TB { "medium" }
            else
                context.NC() context(f)
                context.NC() context(s)
                context.NC() context.NR()
            end
        end
    context.stoptabulate()
end

function poetry.sidebyside(specification)
    local left    = specification.left
    local right   = specification.right
    local first   = left  and string.splitlines(buffers.getcontent(left )) or { }
    local second  = right and string.splitlines(buffers.getcontent(right)) or { }

    if #first > 0 and #second == 0 then
        for i=1,#first do
            local t = string.split(first[i], "|")
            first[i]  = string.strip(t[1] or "")
            second[i] = string.strip(t[2] or "")
        end
    end

    local template = specification.template or "|||"

    context.starttabulate { template }
        for i=1,#first do
            local f = first [i] or ""
            local s = second[i] or ""
            if f == "" and s == "" then
                context.TB { "medium" }
            else
                context.NC() context(f)
                context.NC() context(s)
                context.NC() context.NR()
            end
        end
    context.stoptabulate()
end

interfaces.implement {
    name      = "poetrysidebyside",
    protected = true,
    public    = true,
    actions   = poetry.sidebyside,
    arguments = "hash",
}

\stopluacode

\continueifinputfile{m-poetry.mkxl}

\starttext

\startbuffer[lines-1]
THIS
IS
A
POEM

WITH
TWO
STANZAS
\stopbuffer

\startbuffer[lines-2]
this
is
a
poem

with
two
stanzas
\stopbuffer

\startbuffer[lines-3]
this         | THIS
is           | IS
a            | A
poem         | POEM
             |
with         | WITH
two          | TWO
stanzas      | STANZAS
\stopbuffer

\ctxlua {
    moduledata.poetry.sidebyside {
        left     = "lines-1",
        right    = "lines-2",
        template = "|l|i2r|"
    }
}

\ctxlua {
    moduledata.poetry.sidebyside {
        left     = "lines-3",
        template = "|r|il|"
    }
}

\poetrysidebyside
  [left=lines-3,
   template={|r|il|}]

\stoptext