nim-codex/codex/utils.nim

## Nim-Codex
## Copyright (c) 2023 Status Research & Development GmbH
## Licensed under either of
##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
## 

import std/parseutils
import std/options

import pkg/chronos

import ./utils/asyncheapqueue
import ./utils/fileutils
import ./utils/asynciter

export asyncheapqueue, fileutils, asynciter


func divUp*[T: SomeInteger](a, b : T): T =
  ## Division with result rounded up (rather than truncated as in 'div')
  assert(b != T(0))
  if a==T(0): T(0) else: ((a - T(1)) div b) + T(1)

func roundUp*[T](a, b : T): T =
  ## Round up 'a' to the next value divisible by 'b'
  divUp(a,b) * b

proc orElse*[A](a, b: Option[A]): Option[A] =
  if (a.isSome()): 
    a 
  else: 
    b


when not declared(parseDuration): # Odd code formatting to minimize diff v. mainLine
 const Whitespace = {' ', '\t', '\v', '\r', '\l', '\f'}

 func toLowerAscii(c: char): char =
  if c in {'A'..'Z'}: char(uint8(c) xor 0b0010_0000'u8) else: c

 func parseDuration*(s: string, size: var Duration): int =
  ## Parse a size qualified by simple time into `Duration`.
  ##
  runnableExamples:
    var res: Duration  # caller must still know if 'b' refers to bytes|bits
    doAssert parseDuration("10H", res) == 3
    doAssert res == initDuration(hours=10)
    doAssert parseDuration("64m", res) == 6
    doAssert res == initDuration(minutes=64)
    doAssert parseDuration("7m/block", res) == 2 # '/' stops parse
    doAssert res == initDuration(minutes=7)  # 1 shl 30, forced binary metric
    doAssert parseDuration("3d", res) == 2 # '/' stops parse
    doAssert res == initDuration(days=3)  # 1 shl 30, forced binary metric

  const prefix = "s" & "mhdw"       # byte|bit & lowCase metric-ish prefixes
  const timeScale = [1.0, 60.0, 3600.0, 86_400.0, 604_800.0]

  var number: float
  var scale = 1.0
  result = parseFloat(s, number)
  if number < 0:                        # While parseFloat accepts negatives ..
    result = 0                          #.. we do not since sizes cannot be < 0
  else:
    let start = result                  # Save spot to maybe unwind white to EOS
    while result < s.len and s[result] in Whitespace:
      inc result
    if result < s.len:                  # Illegal starting char => unity
      if (let si = prefix.find(s[result].toLowerAscii); si >= 0):
        inc result                      # Now parse the scale
        scale = timeScale[si]
    else:                               # Unwind result advancement when there..
      result = start                    #..is no unit to the end of `s`.
    var sizeF = number * scale + 0.5    # Saturate to int64.high when too big
    size = seconds(int(sizeF))

when isMainModule:
  import unittest2

  suite "time parse":
    test "parseDuration":
      var res: Duration  # caller must still know if 'b' refers to bytes|bits
      check parseDuration("10Hr", res) == 3
      check res == hours(10)
      check parseDuration("64min", res) == 3
      check res == minutes(64)
      check parseDuration("7m/block", res) == 2 # '/' stops parse
      check res == minutes(7)  # 1 shl 30, forced binary metric
      check parseDuration("3d", res) == 2 # '/' stops parse
      check res == days(3)  # 1 shl 30, forced binary metric