defmodule Toml.Decoder do
  @moduledoc false

  alias Toml.Document
  alias Toml.Builder
  alias Toml.Lexer

  @compile :inline_list_funs
  @compile inline: [
             pop_skip: 2,
             peek_skip: 2,
             iodata_to_str: 1,
             iodata_to_integer: 1,
             iodata_to_float: 1
           ]

  @doc """
  Decodes a raw binary into a map.

  `Toml.Error` is raised if decoding fails.
  """
  @spec decode!(binary, Toml.opts()) :: map | no_return
  def decode!(bin, opts) when is_binary(bin) and is_list(opts) do
    # Raise if the filename is invalid
    filename =
      case Keyword.get(opts, :filename, "nofile") do
        name when is_binary(name) ->
          name

        n ->
          raise ArgumentError, "invalid :filename option '#{inspect(n)}', must be a binary!"
      end

    # Get our lexer outside the try so that we can stop it if things go south
    # This can only fail if the lexer process itself crashes during init
    {:ok, lexer} = Lexer.new(bin)

    try do
      case do_decode(lexer, bin, Builder.new(opts)) do
        {:ok, doc} ->
          case Document.to_map(doc) do
            {:ok, result} ->
              result

            {:error, reason} ->
              raise Toml.Error, reason
          end

        {:error, reason, skip, lines} ->
          raise Toml.Error, format_error(reason, bin, filename, skip, lines)
      end
    catch
      :throw, {:error, {:invalid_toml, reason}} ->
        raise Toml.Error, reason
    after
      Lexer.stop(lexer)
    end
  end

  @doc """
  Decodes a raw binary safely, returns `{:ok, map}` or `{:error, reason}`
  """
  @spec decode(binary, Toml.opts()) :: {:ok, map} | Toml.error()
  def decode(bin, opts) when is_binary(bin) and is_list(opts) do
    {:ok, decode!(bin, opts)}
  rescue
    err in [Toml.Error] ->
      {:error, {:invalid_toml, Exception.message(err)}}

    err in [ArgumentError] ->
      {:error, err.message}
  catch
    :error, reason ->
      {:error, Toml.Error.format_reason(reason)}
  end

  @doc """
  Decodes a stream.

  Raises `Toml.Error` if decoding fails.
  """
  @spec decode_stream!(Enumerable.t(), Toml.opts()) :: map | no_return
  def decode_stream!(stream, opts) do
    decode!(Enum.into(stream, <<>>), opts)
  end

  @doc """
  Decodes a stream safely.

  Returns same type as `decode/2`
  """
  @spec decode_stream(Enumerable.t(), Toml.opts()) :: {:ok, map} | Toml.error()
  def decode_stream(stream, opts) do
    decode(Enum.into(stream, <<>>), opts)
  end

  @doc """
  Decodes a file.

  Raises `Toml.Error` if decoding fails.
  """
  @spec decode_file!(String.t(), Toml.opts()) :: map | no_return
  def decode_file!(path, opts) when is_binary(path) do
    with {:ok, opts} <- set_filename_opt(opts, path),
         bin = File.read!(path) do
      decode!(bin, opts)
    end
  end

  @doc """
  Decodes a file safely.

  Returns same type as `decode/2`
  """
  @spec decode_file(String.t(), Toml.opts()) :: {:ok, map} | Toml.error()
  def decode_file(path, opts) when is_binary(path) do
    with {:ok, opts} <- set_filename_opt(opts, path),
         {:ok, bin} <- File.read(path) do
      decode(bin, opts)
    else
      {:error, reason} ->
        {:error, "unable to open file '#{Path.relative_to_cwd(path)}': #{inspect(reason)}"}
    end
  end

  defp set_filename_opt(opts, default) do
    case Keyword.get(opts, :filename) do
      nil ->
        {:ok, Keyword.put(opts, :filename, default)}

      _name ->
        {:ok, opts}
    end
  end

  ## Decoder Implementation

  @spec do_decode(Lexer.t(), binary, Document.t()) :: {:ok, Document.t()} | Lexer.lexer_err()
  defp do_decode(lexer, original, %Document{} = doc) do
    with {:ok, {type, skip, data, lines}} <- Lexer.pop(lexer) do
      handle_token(lexer, original, doc, type, skip, data, lines)
    end
  end

  # Converts an error into a friendly, printable representation
  defp format_error(reason, original, filename, skip, lines) do
    msg =
      "#{Toml.Error.format_reason(reason)} in #{Path.relative_to_cwd(filename)} on line #{lines}"

    {ctx, pos} = seek_line(original, skip - 1, lines)

    """
    #{msg}:

        #{ctx}
        #{String.duplicate(" ", pos)}^ at column #{pos}
    """
  end

  # Finds the line of context for display in a formatted error
  defp seek_line(original, skip, lines) do
    seek_line(original, original, 0, 0, skip, lines - 1)
  end

  defp seek_line(original, rest, lastnl, from, len, 0) do
    case seek_to_eol(rest, 0) do
      0 ->
        {binary_part(original, lastnl, from - lastnl), from - lastnl}

      len_to_eol when len_to_eol > 0 ->
        {binary_part(original, from, len_to_eol), len}
    end
  end

  defp seek_line(original, <<?\r, ?\n, rest::binary>>, lastnl, from, len, 1) when len <= 0 do
    # Content occurred on the last line right before the newline
    seek_line(original, rest, lastnl, from + 2, 0, 0)
  end

  defp seek_line(original, <<?\r, ?\n, rest::binary>>, _, from, len, lines) do
    seek_line(original, rest, from + 2, from + 2, len - 2, lines - 1)
  end

  defp seek_line(original, <<?\n, rest::binary>>, lastnl, from, len, 1) when len <= 0 do
    # Content occurred on the last line right before the newline
    seek_line(original, rest, lastnl, from + 1, 0, 0)
  end

  defp seek_line(original, <<?\n, rest::binary>>, _, from, len, lines) do
    seek_line(original, rest, from + 1, from + 1, len - 1, lines - 1)
  end

  defp seek_line(original, <<_::utf8, rest::binary>>, lastnl, from, len, lines) do
    seek_line(original, rest, lastnl, from + 1, len - 1, lines)
  end

  # Find the number of bytes to the end of the current line in the input
  defp seek_to_eol(<<>>, len), do: len
  defp seek_to_eol(<<?\r, ?\n, _::binary>>, len), do: len
  defp seek_to_eol(<<?\n, _::binary>>, len), do: len

  defp seek_to_eol(<<_::utf8, rest::binary>>, len) do
    seek_to_eol(rest, len + 1)
  end

  # Handles invalid byte sequences (i.e. invalid unicode)
  # Considers the invalid byte as EOL so context can still be shown
  defp seek_to_eol(<<_, _rest::binary>>, len), do: len

  # Skip top-level whitespace and newlines
  @spec handle_token(
          Lexer.t(),
          binary,
          Document.t(),
          Lexer.type(),
          Lexer.skip(),
          binary | non_neg_integer,
          Lexer.lines()
        ) :: {:ok, Document.t()} | Lexer.lexer_err()
  defp handle_token(lexer, original, doc, :whitespace, _skip, _data, _lines),
    do: do_decode(lexer, original, doc)

  defp handle_token(lexer, original, doc, :newline, _skip, _data, _lines),
    do: do_decode(lexer, original, doc)

  # Push comments on the comment stack
  defp handle_token(lexer, original, doc, :comment, skip, size, _lines) do
    comment = binary_part(original, skip - size, size)
    do_decode(lexer, original, Builder.push_comment(doc, comment))
  end

  # Handle valid top-level entities
  # - array of tables
  # - table
  # - key/value
  defp handle_token(lexer, original, doc, ?\[, skip, data, lines) do
    case peek_skip(lexer, [:whitespace]) do
      {:error, _, _, _} = err ->
        err

      {:ok, {?\[, _, _, _}} ->
        # Push opening bracket, second was peeked, so no need
        Lexer.push(lexer, {?\[, skip, data, lines})
        handle_table_array(lexer, original, doc)

      {:ok, {_, _, _, _}} ->
        Lexer.push(lexer, {?\[, skip, data, lines})
        handle_table(lexer, original, doc)
    end
  end

  defp handle_token(lexer, original, doc, type, skip, data, lines)
       when type in [:digits, :alpha, :string] do
    Lexer.push(lexer, {type, skip, data, lines})

    with {:ok, key, _skip, _lines} <- key(lexer) do
      handle_key(lexer, original, doc, key)
    end
  end

  defp handle_token(lexer, original, doc, type, skip, _data, lines) when type in '-_' do
    handle_token(lexer, original, doc, :string, skip, <<type::utf8>>, lines)
  end

  # We're done
  defp handle_token(_lexer, _original, doc, :eof, _skip, _data, _lines) do
    {:ok, doc}
  end

  # Anything else at top-level is invalid
  defp handle_token(_lexer, _original, _doc, type, skip, data, lines) do
    {:error, {:invalid_token, {type, data}}, skip, lines}
  end

  defp handle_key(lexer, original, doc, key) do
    with {:ok, {?=, _, _, _}} <- pop_skip(lexer, [:whitespace]),
         {:ok, value} <- value(lexer),
         {:ok, doc} <- Builder.push_key(doc, key, value) do
      # Make sure key/value pairs are separated by a newline
      case peek_skip(lexer, [:whitespace]) do
        {:error, _, _, _} = err ->
          err

        {:ok, {:comment, _, _, _}} ->
          # Implies newline
          do_decode(lexer, original, doc)

        {:ok, {type, _, _, _}} when type in [:newline, :eof] ->
          do_decode(lexer, original, doc)

        {:ok, {type, skip, data, lines}} ->
          {:error, {:expected, :newline, {type, data}}, skip, lines}
      end
    else
      {:error, _, _, _} = err ->
        err

      {:ok, {type, skip, data, lines}} ->
        {:error, {:expected, ?=, {type, data}}, skip, lines}
    end
  end

  defp handle_table(lexer, original, doc) do
    # Guaranteed to have an open bracket
    with {:ok, {?\[, _, _, _}} <- pop_skip(lexer, [:whitespace]),
         {:ok, key, _line, _col} <- key(lexer),
         {:ok, {?\], _, _, _}} <- pop_skip(lexer, [:whitespace]),
         {:ok, doc} <- Builder.push_table(doc, key) do
      # Make sure table opening is followed by newline
      case peek_skip(lexer, [:whitespace]) do
        {:error, _, _, _} = err ->
          err

        {:ok, {:comment, _, _, _}} ->
          do_decode(lexer, original, doc)

        {:ok, {type, _, _, _}} when type in [:newline, :eof] ->
          do_decode(lexer, original, doc)

        {:ok, {type, skip, data, lines}} ->
          {:error, {:expected, :newline, {type, data}}, skip, lines}
      end
    else
      {:error, _, _, _} = err ->
        err

      {:ok, {type, skip, data, lines}} ->
        {:error, {:invalid_token, {type, data}}, skip, lines}
    end
  end

  defp handle_table_array(lexer, original, doc) do
    # Guaranteed to have two open brackets
    with {:ok, {?\[, _, _, _}} <- pop_skip(lexer, [:whitespace]),
         {:ok, {?\[, _, _, _}} <- pop_skip(lexer, [:whitespace]),
         {:ok, key, _, _} <- key(lexer),
         {_, {:ok, {?\], _, _, _}}} <- {:close, pop_skip(lexer, [:whitespace])},
         {_, {:ok, {?\], _, _, _}}} <- {:close, pop_skip(lexer, [:whitespace])},
         {:ok, doc} <- Builder.push_table_array(doc, key) do
      # Make sure table opening is followed by newline
      case peek_skip(lexer, [:whitespace]) do
        {:error, _, _, _} = err ->
          err

        {:ok, {:comment, _, _, _}} ->
          do_decode(lexer, original, doc)

        {:ok, {type, _, _, _}} when type in [:newline, :eof] ->
          do_decode(lexer, original, doc)

        {:ok, {type, skip, data, lines}} ->
          {:error, {:expected, :newline, {type, data}}, skip, lines}
      end
    else
      {:error, _, _, _} = err ->
        err

      {_, {:error, _, _, _} = err} ->
        err

      {:close, {:ok, {type, skip, data, lines}}} ->
        {:error, {:unclosed_table_array_name, {type, data}}, skip, lines}
    end
  end

  defp maybe_integer(lexer) do
    case pop_skip(lexer, [:whitespace]) do
      {:ok, {type, _skip, _data, _lines}} when type in '-+' ->
        # Can be integer, float
        case Lexer.peek(lexer) do
          {:error, _, _, _} = err ->
            err

          # Handle infinity/nan with leading sign
          {:ok, {:alpha, _, "inf", _}} ->
            Lexer.advance(lexer)

            if type == ?\+ do
              {:ok, :infinity}
            else
              {:ok, :negative_infinity}
            end

          {:ok, {:alpha, _, "nan", _}} ->
            Lexer.advance(lexer)

            if type == ?\+ do
              {:ok, :nan}
            else
              {:ok, :negative_nan}
            end

          # Must be a signed integer or float
          {:ok, {:digits, _, d, _}} ->
            Lexer.advance(lexer)
            maybe_integer(lexer, [d, type])

          # Invalid
          {:ok, {type, skip, data, lines}} ->
            {:error, {:invalid_token, {type, data}}, skip, lines}
        end

      {:ok, {:digits, skip, <<leader::utf8, _::utf8, _::utf8, _::utf8>> = d, lines} = token} ->
        # Could be a datetime
        case Lexer.peek(lexer) do
          {:ok, {?-, _, _, _}} ->
            # This is a date or datetime
            Lexer.push(lexer, token)
            maybe_datetime(lexer)

          {:ok, {?., _, _, _}} ->
            # Float
            Lexer.advance(lexer)
            float(lexer, ?., [?., d])

          {:ok, {:alpha, _, <<c::utf8>>, _}} when c in 'eE' ->
            # Float
            Lexer.advance(lexer)
            float(lexer, ?e, [?e, ?0, ?., d])

          {:ok, {?_, _, _, _}} ->
            # Integer
            maybe_integer(lexer, [d])

          _ ->
            # Just an integer
            if leader == ?0 do
              # Leading zeroes not allowed
              {:error, {:invalid_integer, :leading_zero}, skip, lines}
            else
              {:ok, String.to_integer(d)}
            end
        end

      {:ok, {:digits, skip, <<leader::utf8, _::utf8>> = d, lines} = token} ->
        # Could be a time
        case Lexer.peek(lexer) do
          {:ok, {?:, _, _, _}} ->
            # This is a local time
            Lexer.push(lexer, token)
            time(lexer)

          _ ->
            # It's just an integer
            if leader == ?0 do
              # Leading zeros not allowed
              {:error, {:invalid_integer, :leading_zero}, skip, lines}
            else
              maybe_integer(lexer, [d])
            end
        end

      {:ok, {:digits, _, d, _}} ->
        # Just a integer or float
        maybe_integer(lexer, [d])

      {:ok, {type, skip, data, lines}} ->
        {:error, {:invalid_token, {type, data}}, skip, lines}
    end
  end

  defp maybe_integer(lexer, parts) do
    case Lexer.pop(lexer) do
      {:error, _, _, _} = err ->
        err

      {:ok, {?., _, _, _}} ->
        # Float
        float(lexer, ?., [?. | parts])

      {:ok, {:alpha, _, <<c::utf8>>, _}} when c in 'eE' ->
        # Float, need to add .0 before e, or String.to_float fails
        float(lexer, ?e, [?e, ?0, ?. | parts])

      {:ok, {?_, _, _, _}} ->
        case Lexer.peek(lexer) do
          {:ok, {:digits, _, d, _}} ->
            # Allowed, just skip the underscore
            Lexer.advance(lexer)
            maybe_integer(lexer, [d | parts])

          {:ok, {type, skip, data, lines}} ->
            {:error, {:invalid_token, {type, data}}, skip, lines}

          {:error, _, _, _} = err ->
            err
        end

      {:ok, {_, skip, _, lines} = token} ->
        # Just an integer
        Lexer.push(lexer, token)

        with {:ok, _} = result <- iodata_to_integer(parts) do
          result
        else
          {:error, reason} ->
            {:error, reason, skip, lines}
        end
    end
  end

  defp float(lexer, signal, [last | _] = parts) do
    case Lexer.pop(lexer) do
      {:error, _, _, _} = err ->
        err

      {:ok, {?., skip, _, lines}} ->
        # Always an error at this point, as either duplicate or after E
        {:error, {:invalid_float, {?., 0}}, skip, lines}

      {:ok, {sign, _, _, _}} when sign in '-+' and last == ?e ->
        # +/- are allowed after e/E
        float(lexer, signal, [sign | parts])

      {:ok, {:alpha, _, <<c::utf8>>, _}} when c in 'eE' and signal == ?. ->
        # Valid if after a dot
        float(lexer, ?e, [?e | parts])

      {:ok, {?_, skip, _, lines}} when last not in '_e.' ->
        # Valid only when surrounded by digits
        with {:ok, {:digits, _, d, _}} <- Lexer.peek(lexer),
             _ = Lexer.advance(lexer) do
          float(lexer, signal, [d | parts])
        else
          {:error, _, _, _} = err ->
            err

          {:ok, {_, _, _, _}} ->
            {:error, {:invalid_float, {?_, 0}}, skip, lines}
        end

      {:ok, {:digits, _, d, _}} ->
        float(lexer, signal, [d | parts])

      {:ok, {type, skip, data, lines}} when last in 'e.' ->
        # Incomplete float
        {:error, {:invalid_float, {type, data}}, skip, lines}

      {:ok, {_type, skip, _data, lines} = token} when last not in '_e.' ->
        # Done
        Lexer.push(lexer, token)

        with {:ok, _} = result <- iodata_to_float(parts) do
          result
        else
          {:error, reason} ->
            {:error, reason, skip, lines}
        end
    end
  end

  defp time(lexer) do
    # At this point we know we have at least HH:
    with {:ok, {:digits, skip, <<_::utf8, _::utf8>> = hh, lines}} <- Lexer.pop(lexer),
         {:ok, {?:, _, _, _}} <- Lexer.pop(lexer),
         {:ok, {:digits, _, <<_::utf8, _::utf8>> = mm, _}} <- Lexer.pop(lexer),
         {:ok, {?:, _, _, _}} <- Lexer.pop(lexer),
         {:ok, {:digits, _, <<_::utf8, _::utf8>> = ss, _}} <- Lexer.pop(lexer) do
      # Check for fractional
      parts = [ss, ?:, mm, ?:, hh]

      parts =
        case Lexer.peek(lexer) do
          {:ok, {?., _, _, _}} ->
            Lexer.advance(lexer)

            case Lexer.pop(lexer) do
              {:ok, {:digits, _, d, _}} ->
                [d, ?. | parts]

              {:ok, {type, skip, data, lines}} ->
                # Invalid
                throw({:error, {:invalid_token, {type, data}}, skip, lines})

              {:error, reason, skip, lines} ->
                throw({:error, {:invalid_fractional_seconds, reason}, skip, lines})
            end

          {:ok, _} ->
            parts
        end

      case Time.from_iso8601(iodata_to_str(parts)) do
        {:ok, _} = result ->
          result

        {:error, :invalid_time} ->
          {:error, :invalid_time, skip, lines}

        {:error, reason} ->
          {:error, {:invalid_time, reason}, skip, lines}
      end
    else
      {:error, _, _, _} = err ->
        err

      {:ok, {type, skip, data, lines}} ->
        {:error, {:invalid_token, {type, data}}, skip, lines}
    end
  catch
    :throw, {:error, _, _, _} = err ->
      err
  end

  defp maybe_datetime(lexer) do
    # At this point we have at least YYYY-
    with {:ok, {:digits, _, <<_::utf8, _::utf8, _::utf8, _::utf8>> = yy, _}} <- Lexer.pop(lexer),
         {:ok, {?-, _, _, _}} <- Lexer.pop(lexer),
         {:ok, {:digits, _, <<_::utf8, _::utf8>> = mm, _}} <- Lexer.pop(lexer),
         {:ok, {?-, _, _, _}} <- Lexer.pop(lexer),
         {:ok, {:digits, skip, <<_::utf8, _::utf8>> = dd, lines}} <- Lexer.pop(lexer) do
      # At this point we have a full date, check for time
      case Lexer.pop(lexer) do
        {:ok, {:alpha, _, "T", _}} ->
          # Expecting a time
          with {:ok, time} <- time(lexer) do
            datetime(lexer, [dd, ?-, mm, ?-, yy], time)
          end

        {:ok, {:whitespace, _, _, _}} ->
          case Lexer.peek(lexer) do
            {:ok, {:digits, _, <<_::utf8, _::utf8>>, _}} ->
              # Expecting a time
              with {:ok, time} <- time(lexer) do
                datetime(lexer, [dd, ?-, mm, ?-, yy], time)
              end

            _ ->
              # Just a date
              case Date.from_iso8601(iodata_to_str([dd, ?-, mm, ?-, yy])) do
                {:ok, _} = result ->
                  result

                {:error, :invalid_date} ->
                  {:error, :invalid_date, skip, lines}

                {:error, reason} ->
                  {:error, {:invalid_date, reason}, skip, lines}
              end
          end

        {:ok, {_type, skip, _data, lines} = token} ->
          # Just a date
          Lexer.push(lexer, token)

          case Date.from_iso8601(iodata_to_str([dd, ?-, mm, ?-, yy])) do
            {:ok, _} = result ->
              result

            {:error, :invalid_date} ->
              {:error, :invalid_date, skip, lines}

            {:error, reason} ->
              {:error, {:invalid_date, reason}, skip, lines}
          end
      end
    else
      {:error, _, _, _} = err ->
        err

      {:ok, {type, skip, data, lines}} ->
        {:error, {:invalid_token, {type, data}}, skip, lines}
    end
  end

  defp datetime(lexer, parts, time) do
    # Track the current lexer position for errors
    {:ok, skip, lines} = Lexer.pos(lexer)
    # Convert parts to string
    datestr = iodata_to_str(parts)
    # At this point we have at least YYYY-mm-dd and a fully decoded time
    with {_, {:ok, date}} <- {:date, Date.from_iso8601(datestr)},
         {_, {:ok, naive}} <- {:datetime, NaiveDateTime.new(date, time)} do
      # We just need to check for Z or UTC offset
      case Lexer.pop(lexer) do
        {:ok, {:alpha, _, "Z", _}} ->
          DateTime.from_naive(naive, "Etc/UTC")

        {:ok, {sign, _, _, _}} when sign in '-+' ->
          # We have an offset
          with {:ok, {:digits, _, <<_::utf8, _::utf8>> = hh, _}} <- Lexer.pop(lexer),
               {:ok, {?:, _, _, _}} <- Lexer.pop(lexer),
               {:ok, {:digits, _, <<_::utf8, _::utf8>> = mm, _}} <- Lexer.pop(lexer) do
            # Shift naive to account for offset
            hours = String.to_integer(hh)
            mins = String.to_integer(mm)
            offset = hours * 60 * 60 + mins * 60

            naive =
              case sign do
                ?- ->
                  NaiveDateTime.add(naive, offset * -1, :second)

                ?+ ->
                  NaiveDateTime.add(naive, offset, :second)
              end

            DateTime.from_naive(naive, "Etc/UTC")
          else
            {:error, _, _, _} = err ->
              err

            {:ok, {type, skip, data, lines}} ->
              {:error, {:invalid_datetime_offset, {type, data}}, skip, lines}
          end

        {:ok, {type, _, _, _} = token} when type in [:eof, :whitespace, :newline] ->
          # Just a local date/time
          Lexer.push(lexer, token)
          {:ok, naive}
      end
    else
      {:date, {:error, :invalid_date}} ->
        {:error, {:invalid_date, datestr}, skip, lines}

      {:date, {:error, reason}} ->
        {:error, {:invalid_date, reason, datestr}, skip, lines}

      {:datetime, {:error, :invalid_date}} ->
        {:error, {:invalid_datetime, {datestr, time}}, skip, lines}

      {:datetime, {:error, reason}} ->
        {:error, {:invalid_date, reason, {datestr, time}}, skip, lines}

      {:error, _, _, _} = err ->
        err

      {:ok, {type, skip, data, lines}} ->
        {:error, {:invalid_token, {type, data}}, skip, lines}
    end
  end

  # Allowed values
  # - Array
  # - Inline table
  # - Integer (in all forms)
  # - Float
  # - String
  # - DateTime
  defp value(lexer) do
    case peek_skip(lexer, [:whitespace]) do
      {:error, _, _, _} = err ->
        err

      {:ok, {:comment, _, _, _}} ->
        Lexer.advance(lexer)
        value(lexer)

      {:ok, {?\[, skip, _, lines}} ->
        # Need to embellish some errors with line/col
        with {:ok, _} = ok <- array(lexer) do
          ok
        else
          {:error, _, _, _} = err ->
            err

          {:error, {:invalid_array, _} = reason} ->
            {:error, reason, skip, lines}
        end

      {:ok, {?\{, _, _, _}} ->
        inline_table(lexer)

      {:ok, {:hex, _, v, _}} ->
        Lexer.advance(lexer)
        {:ok, String.to_integer(v, 16)}

      {:ok, {:octal, _, v, _}} ->
        Lexer.advance(lexer)
        {:ok, String.to_integer(v, 8)}

      {:ok, {:binary, _, v, _}} ->
        Lexer.advance(lexer)
        {:ok, String.to_integer(v, 2)}

      {:ok, {true, _, _, _}} ->
        Lexer.advance(lexer)
        {:ok, true}

      {:ok, {false, _, _, _}} ->
        Lexer.advance(lexer)
        {:ok, false}

      {:ok, {:alpha, _, "inf", _}} ->
        Lexer.advance(lexer)
        {:ok, :infinity}

      {:ok, {:alpha, _, "nan", _}} ->
        Lexer.advance(lexer)
        {:ok, :nan}

      {:ok, {type, _, v, _}} when type in [:string, :multiline_string] ->
        Lexer.advance(lexer)
        {:ok, v}

      {:ok, {sign, _, _, _}} when sign in '-+' ->
        maybe_integer(lexer)

      {:ok, {:digits, _, _, _}} ->
        maybe_integer(lexer)

      {:ok, {type, skip, data, lines}} ->
        {:error, {:invalid_token, {type, data}}, skip, lines}
    end
  end

  defp array(lexer) do
    with {:ok, {?\[, skip, _, lines}} <- pop_skip(lexer, [:whitespace]),
         {:ok, elements} <- accumulate_array_elements(lexer),
         {:valid?, true} <- {:valid?, valid_array?(elements)},
         {_, _, {:ok, {?\], _, _, _}}} <-
           {:close, {skip, lines}, pop_skip(lexer, [:whitespace, :newline, :comment])} do
      {:ok, elements}
    else
      {:error, _, _, _} = err ->
        err

      {:close, {:error, _, _, _} = err} ->
        err

      {:close, {_oline, _ocol} = opened, {:ok, {_, eskip, _, elines}}} ->
        {:error, {:unclosed_array, opened}, eskip, elines}

      {:valid?, err} ->
        err
    end
  end

  defp valid_array?([]),
    do: true

  defp valid_array?([h | t]),
    do: valid_array?(t, typeof(h))

  defp valid_array?([], _type),
    do: true

  defp valid_array?([h | t], type) do
    if typeof(h) == type do
      valid_array?(t, type)
    else
      {:error, {:invalid_array, {:expected_type, t, h}}}
    end
  end

  defp typeof(v) when is_integer(v), do: :integer
  defp typeof(v) when is_float(v), do: :float
  defp typeof(v) when is_binary(v), do: :string
  defp typeof(%Time{}), do: :time
  defp typeof(%Date{}), do: :date
  defp typeof(%DateTime{}), do: :datetime
  defp typeof(%NaiveDateTime{}), do: :datetime
  defp typeof(v) when is_list(v), do: :list
  defp typeof(v) when is_map(v), do: :map
  defp typeof(v) when is_boolean(v), do: :boolean

  defp inline_table(lexer) do
    with {:ok, {?\{, skip, _, lines}} <- pop_skip(lexer, [:whitespace]),
         {:ok, elements} <- accumulate_table_elements(lexer),
         {_, _, {:ok, {?\}, _, _, _}}} <- {:close, {skip, lines}, pop_skip(lexer, [:whitespace])} do
      {:ok, elements}
    else
      {:error, _, _, _} = err ->
        err

      {:close, {:error, _, _, _} = err} ->
        err

      {:close, {_oskip, _olines} = opened, {:ok, {_, eskip, _, elines}}} ->
        {:error, {:unclosed_inline_table, opened}, eskip, elines}
    end
  end

  defp accumulate_array_elements(lexer) do
    accumulate_array_elements(lexer, [])
  end

  defp accumulate_array_elements(lexer, acc) do
    with {:ok, {type, _, _, _}} <- peek_skip(lexer, [:whitespace, :newline, :comment]),
         {_, false} <- {:trailing_comma, type == ?\]},
         {:ok, value} <- value(lexer),
         {:ok, {next, _, _, _}} <- peek_skip(lexer, [:whitespace]) do
      if next == ?, do
        Lexer.advance(lexer)
        accumulate_array_elements(lexer, [value | acc])
      else
        {:ok, Enum.reverse([value | acc])}
      end
    else
      {:error, _, _, _} = err ->
        err

      {:trailing_comma, true} ->
        {:ok, Enum.reverse(acc)}
    end
  end

  defp accumulate_table_elements(lexer) do
    accumulate_table_elements(lexer, %{})
  end

  defp accumulate_table_elements(lexer, acc) do
    with {:ok, {type, _, _, _}} <- peek_skip(lexer, [:whitespace, :newline, :comment]),
         {_, false} <- {:trailing_comma, type == ?\}},
         {:ok, key, skip, lines} <- key(lexer),
         {_, _, false, _, _} <- {:key_exists, key, Map.has_key?(acc, key), skip, lines},
         {:ok, {?=, _, _, _}} <- pop_skip(lexer, [:whitespace, :comments]),
         {:ok, value} <- value(lexer),
         {_, {:ok, acc2}} <- {key, Builder.push_key_into_table(acc, key, value)},
         {:ok, {next, _, _, _}} <- peek_skip(lexer, [:whitespace, :comments]) do
      if next == ?, do
        Lexer.advance(lexer)
        accumulate_table_elements(lexer, acc2)
      else
        {:ok, acc2}
      end
    else
      {:error, _, _, _} = err ->
        err

      {:key_exists, key, true, line, col} ->
        {:error, {:key_exists, key}, line, col}

      {table, {:error, :key_exists}} ->
        {:error, {:key_exists_in_table, table}, -1, -1}

      {:trailing_comma, true} ->
        {:ok, acc}

      {:ok, {type, skip, data, lines} = token} ->
        Lexer.push(lexer, token)
        {:error, {:invalid_key_value, {type, data}}, skip, lines}
    end
  end

  defp key(lexer) do
    result =
      case pop_skip(lexer, [:whitespace]) do
        {:error, _, _, _} = err ->
          err

        {:ok, {type, skip, s, lines}} when type in [:digits, :alpha, :string] ->
          {key(lexer, s, []), skip, lines}

        {:ok, {type, skip, _, lines}} when type in '-_' ->
          {key(lexer, <<type::utf8>>, []), skip, lines}

        {:ok, {type, skip, data, lines} = token} ->
          Lexer.push(lexer, token)
          {:error, {:invalid_token, {type, data}}, skip, lines}
      end

    case result do
      {:error, _, _, _} = err ->
        err

      {{:ok, key}, skip, lines} ->
        {:ok, key, skip, lines}

      {{:error, _, _, _} = err, _, _} ->
        err
    end
  end

  defp key(lexer, word, acc) do
    case Lexer.peek(lexer) do
      {:error, _, _, _} = err ->
        err

      {:ok, {:whitespace, _, _, _}} ->
        # The only allowed continuation now is a . followed by key char
        case peek_skip(lexer, [:whitespace]) do
          {:ok, {?., _, _, _}} ->
            Lexer.advance(lexer)

            case peek_skip(lexer, [:whitespace]) do
              {:error, _, _, _} = err ->
                err

              {:ok, {type, _, _, _}} when type in [:digits, :alpha, :string] ->
                key(lexer, "", [word | acc])

              {:ok, {type, _, _, _}} when type in '-_' ->
                key(lexer, "", [word | acc])

              {:ok, {type, skip, data, lines}} ->
                {:error, {:invalid_token, {type, data}}, skip, lines}
            end

          {:ok, _} ->
            {:ok, Enum.reverse([word | acc])}
        end

      {:ok, {type, _, s, _}} when type in [:digits, :alpha, :string] ->
        Lexer.advance(lexer)
        key(lexer, word <> s, acc)

      {:ok, {type, _, _, _}} when type in '-_' ->
        Lexer.advance(lexer)
        key(lexer, word <> iodata_to_str([type]), acc)

      {:ok, {?., _, _, _}} ->
        Lexer.advance(lexer)

        case peek_skip(lexer, [:whitespace]) do
          {:error, _, _, _} = err ->
            err

          {:ok, {type, _, _, _}} when type in [:digits, :alpha, :string] ->
            key(lexer, "", [word | acc])

          {:ok, {type, _, _, _}} when type in '-_' ->
            key(lexer, "", [word | acc])

          {:ok, {type, skip, data, lines}} ->
            {:error, {:invalid_token, {type, data}}, skip, lines}
        end

      {:ok, _} ->
        {:ok, Enum.reverse([word | acc])}
    end
  end

  defp iodata_to_integer(data) do
    case iodata_to_str(data) do
      <<?0, rest::binary>> when byte_size(rest) > 0 ->
        {:error, {:invalid_integer, :leading_zero}}

      <<sign::utf8, ?0, rest::binary>> when (sign == ?- or sign == ?+) and byte_size(rest) > 0 ->
        {:error, {:invalid_integer, :leading_zero}}

      s ->
        {:ok, String.to_integer(s)}
    end
  end

  defp iodata_to_float(data) do
    case iodata_to_str(data) do
      <<?0, next::utf8, _::binary>> when next != ?. ->
        {:error, {:invalid_float, :leading_zero}}

      <<sign::utf8, ?0, next::utf8, _::binary>> when (sign == ?- or sign == ?+) and next != ?. ->
        {:error, {:invalid_float, :leading_zero}}

      s ->
        {:ok, String.to_float(s)}
    end
  end

  defp iodata_to_str(parts) do
    parts
    |> Enum.reverse()
    |> IO.chardata_to_string()
  end

  defp pop_skip(lexer, skip) do
    case Lexer.pop(lexer) do
      {:error, _, _, _} = err ->
        err

      {:ok, {type, _, _, _}} = result ->
        if :lists.member(type, skip) do
          pop_skip(lexer, skip)
        else
          result
        end
    end
  end

  defp peek_skip(lexer, skip) do
    case Lexer.peek(lexer) do
      {:error, _, _, _} = err ->
        err

      {:ok, {type, _, _, _}} = result ->
        if :lists.member(type, skip) do
          Lexer.advance(lexer)
          peek_skip(lexer, skip)
        else
          result
        end
    end
  end
end