local env_types = {
  theorem = true,
  lemma = true,
  proposition = true,
  corollary = true,
  definition = true,
  example = true,
  remark = true,
  proof = true,
}

local function has_class(el, class_name)
  for _, value in ipairs(el.classes) do
    if value == class_name then
      return true
    end
  end
  return false
end

local function first_env_class(el)
  for _, value in ipairs(el.classes) do
    if env_types[value] then
      return value
    end
  end
  return nil
end

local function latex_escape(value)
  value = tostring(value or "")
  value = value:gsub("\\", "\\textbackslash{}")
  value = value:gsub("([{}%%$&#_])", "\\%1")
  value = value:gsub("%^", "\\textasciicircum{}")
  value = value:gsub("~", "\\textasciitilde{}")
  return value
end

local function internal_link_to_cref(el)
  if FORMAT:match("latex") and el.target:sub(1, 1) == "#" then
    local label = el.target:sub(2)
    if label ~= "" then
      return pandoc.RawInline("latex", "\\cref{" .. label .. "}")
    end
  end
  return nil
end

local function markdown_to_latex(markdown)
  local doc = pandoc.read(
    markdown or "",
    "markdown+fenced_code_attributes+tex_math_dollars+tex_math_single_backslash+footnotes+raw_html"
  )
  doc = doc:walk({ Link = internal_link_to_cref })
  return pandoc.write(doc, "latex")
end

local function label_line(label)
  if label and label ~= "" then
    return "\\label{" .. label .. "}\n"
  end
  return ""
end

local function interactive_to_latex(el)
  local label = el.identifier
  local caption = el.attributes.caption or el.attributes.title or ""
  local fallback = el.attributes.pdf or el.attributes.fallback or el.text
  local fallback_latex = markdown_to_latex(fallback)
  local caption_line = ""

  if caption ~= "" then
    caption_line = "\\caption{" .. latex_escape(caption) .. "}\n"
  end

  return pandoc.RawBlock(
    "latex",
    table.concat({
      "\\begin{figure}[htbp]\n",
      "\\centering\n",
      "\\fbox{\\begin{minipage}{0.86\\linewidth}\n",
      fallback_latex,
      "\n\\end{minipage}}\n",
      caption_line,
      label_line(label),
      "\\end{figure}",
    })
  )
end

local function env_to_latex(el)
  local env_type = el.attributes.type or first_env_class(el)
  if not env_type or not env_types[env_type] then
    return nil
  end

  local title = el.attributes.title or el.attributes.name or ""
  local begin_env = "\\begin{" .. env_type .. "}"
  if title ~= "" then
    begin_env = begin_env .. "[" .. latex_escape(title) .. "]"
  end

  return pandoc.RawBlock(
    "latex",
    table.concat({
      begin_env,
      "\n",
      label_line(el.identifier),
      markdown_to_latex(el.text),
      "\n\\end{",
      env_type,
      "}",
    })
  )
end

function CodeBlock(el)
  if FORMAT:match("latex") and has_class(el, "interactive") then
    return interactive_to_latex(el)
  end

  if FORMAT:match("latex") and (has_class(el, "env") or has_class(el, "latex-env") or first_env_class(el)) then
    return env_to_latex(el)
  end

  return nil
end

function Link(el)
  return internal_link_to_cref(el)
end