local function table_to_nix(t)
  local entries = {}
  for _, s in ipairs(t) do
    table.insert(entries, string.format('"%s"', s))
  end
  return string.format("[ %s ]", table.concat(entries, " "))
end

local function fmt_grammar(grammar)
  local lines = {
    string.format('%s = buildGrammar {', grammar.language),
    string.format('passthru.name = "%s";', grammar.language),
    string.format('language = "%s";', grammar.language),
    string.format('version = "%s";', grammar.version),
    string.format('src = %s;', grammar.src),
    string.format('meta.homepage = "%s";', grammar.meta.homepage),
  }
  if grammar.generate then table.insert(lines, string.format('generate = %s;', grammar.generate)) end
  if grammar.location then table.insert(lines, string.format('location = "%s";', grammar.location)) end
  if grammar.requires then table.insert(
    lines,
    string.format('requires = %s;', table_to_nix(grammar.requires))
  ) end

  table.insert(lines, "};")
  return table.concat(lines, "\n")
end

local function generate_grammars(g)
  local output = {}
  for name, p in pairs(g) do
    if p.install_info then
      local out = assert(
        io.popen(
          string.format(
            "nurl %s %s",
            p.install_info.url,
            p.install_info.revision
          )
        )
      )
      local grammar = {
        version = "0.0.0+rev=" .. p.install_info.revision,
        language = name,
        src = out:read("*a"),
        meta = {
          homepage = p.install_info.url,
        },
      }
      out:close()

      if p.install_info.generate then
        grammar.generate = p.install_info.generate
      end
      if p.install_info.location then
        grammar.location = p.install_info.location
      end
      if p.requires then
        grammar.requires = p.requires
      end
      table.insert(output, fmt_grammar(grammar))
    end
  end
  table.sort(output)
  return table.concat(output)
end

local function header()
  local out = assert(io.popen("nurl -Ls ','"):read("*a"))
  return string.format([[
    # This file was generated by generate-parsers.lua for nvim-treesitter-main
    { buildGrammar, %s }: {
  ]], out)
end

local parsers = dofile(arg[1])
local output_path = arg[2]
local file = assert(io.open(output_path, "w"))

file:write(header())
file:write(generate_grammars(parsers))
file:write("}") -- footer

file:close()

assert(os.execute("nixfmt " .. output_path))