(module string (export trim_ascii))

(fn len ((value string)) -> i32
  (std.string.len value))

(fn byte_at_result ((value string) (index i32)) -> (result i32 i32)
  (std.string.byte_at_result value index))

(fn slice_result ((value string) (start i32) (count i32)) -> (result string i32)
  (std.string.slice_result value start count))

(fn is_ascii_trim_byte ((value i32)) -> bool
  (if (= value 9)
    true
    (if (= value 10)
      true
      (if (= value 11)
        true
        (if (= value 12)
          true
          (if (= value 13)
            true
            (= value 32)))))))

(fn byte_is_ascii_trim ((value string) (position i32)) -> bool
  (match (byte_at_result value position)
    ((ok byte)
      (is_ascii_trim_byte byte))
    ((err code)
      false)))

(fn trim_ascii_start ((value string)) -> string
  (let value_len i32 (len value))
  (var start i32 0)
  (while (and (< start value_len) (byte_is_ascii_trim value start))
    (set start (+ start 1)))
  (match (slice_result value start (- value_len start))
    ((ok text)
      text)
    ((err code)
      value)))

(fn trim_ascii_end ((value string)) -> string
  (let value_len i32 (len value))
  (var end i32 value_len)
  (while (and (> end 0) (byte_is_ascii_trim value (- end 1)))
    (set end (- end 1)))
  (match (slice_result value 0 end)
    ((ok text)
      text)
    ((err code)
      value)))

(fn trim_ascii ((value string)) -> string
  (trim_ascii_end (trim_ascii_start value)))