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// Created by David Smith on 5/29/17.
// Copyright © 2017 Unseen University. All rights reserved.
//
// Localization- and encoding-safe solution to Coraline Ada's challenge here: https://twitter.com/CoralineAda/status/869204799027372032
// Very lightly tested. Probably contains bugs.
import Foundation
func tweetStorm(input uncanonicalizedInput:String, handle:String?) -> [String] {
let input = uncanonicalizedInput.precomposedStringWithCanonicalMapping //twitter requires NFC
let handlePrefix = handle != nil ? handle! + " " : ""
var wordRanges = [Range<String.Index>]()
input.enumerateSubstrings(in: input.startIndex ..< input.endIndex, options: .byWords) { (_, wordRange, _, _) in
wordRanges.append(wordRange)
}
let inputUnicodeScalars = input.unicodeScalars
let unicodeScalarWordRanges = wordRanges.map { $0.lowerBound.samePosition(in: inputUnicodeScalars) ..< $0.upperBound.samePosition(in: inputUnicodeScalars) }
var output = [String]()
var startOfNextOutput = inputUnicodeScalars.startIndex
var endOfPreviousWord:String.UnicodeScalarIndex? = nil
for rangeIdx in unicodeScalarWordRanges.indices {
var range = unicodeScalarWordRanges[rangeIdx]
let isLast = rangeIdx == unicodeScalarWordRanges.endIndex - 1
let nextRange = !isLast ? unicodeScalarWordRanges[rangeIdx + 1] : nil
let tweetSize = (isLast ? 140 : 139) - handlePrefix.unicodeScalars.count
repeat { //tbh I'm using this as a fake goto
if nextRange == nil || inputUnicodeScalars.distance(from: startOfNextOutput, to: nextRange!.upperBound) > tweetSize {
//We've crossed a 140 character boundary, so we know we'll need to output something this iteration
let resultRangeStart = startOfNextOutput.samePosition(in: input)!
if endOfPreviousWord == nil {
//single word >tweetSize chars, need to hyphenate
var hyphenationPoint:String.Index? = nil
var offset = 139 //unconditionally 139 because we know we're putting a hyphen in
repeat {
hyphenationPoint = inputUnicodeScalars.index(startOfNextOutput, offsetBy: offset).samePosition(in: input)
offset -= 1
} while (hyphenationPoint == nil)
let resultRange = resultRangeStart ..< hyphenationPoint!
//TODO: Doing the hyphenation properly without a typesetting engine (I don't want to pull in AppKit) would be tricky to say the least…
output.append(String(handlePrefix + input[resultRange] + "-"))
startOfNextOutput = hyphenationPoint!.samePosition(in: inputUnicodeScalars)
range = startOfNextOutput ..< range.upperBound
continue //re-drive this iteration with the rest of the word
} else {
let resultRange = resultRangeStart ..< range.upperBound.samePosition(in: input)!
output.append(String(handlePrefix + input[resultRange] + (isLast ? "" : "")))
}
startOfNextOutput = inputUnicodeScalars.index(after: range.upperBound)
endOfPreviousWord = nil
break
} else {
endOfPreviousWord = range.upperBound
break
}
} while(true)
}
assert(output.map { $0.unicodeScalars.count }.filter { $0 > 140}.count == 0)
return output
}
precondition(CommandLine.arguments.count == 2) //process name, and input string
let inputURL = URL(fileURLWithPath: CommandLine.arguments[1])
let input = try! String(contentsOf: inputURL, encoding: .utf8)
let output = tweetStorm(input: input, handle: "@Catfish_Man")
for tweet in output {
print("[")
print(tweet)
print("]")
}
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