Abbreviations, automatic

# title: Abbreviations, automatic
# source: https://rosettacode.org/wiki/Abbreviations,_automatic
# category: Rosetta Code
# difficulty: Intro
# summary: Compute the shortest unique command prefixes for a fixed command set and resolve sample abbreviations.
# tags: popular, strings, search, prefixes
# vibe: 0.2

def commands
  [
    "add",
    "append",
    "commit",
    "copy",
    "delete",
    "insert",
    "move",
    "print",
    "quit"
  ]
end

def unique_prefix?(prefix, commands)
  matches = 0
  index = 0

  while index < commands.length
    if commands[index].index(prefix) == 0
      matches = matches + 1
    end
    index = index + 1
  end

  matches == 1
end

def shortest_abbreviation(command, commands)
  length = 1

  while length <= command.length
    prefix = command.slice(0, length)
    if unique_prefix?(prefix, commands)
      return prefix
    end
    length = length + 1
  end

  command
end

def automatic_abbreviations(commands)
  rows = []
  index = 0

  while index < commands.length
    command = commands[index]
    rows = rows.push({
      command: command,
      abbreviation: shortest_abbreviation(command, commands)
    })
    index = index + 1
  end

  rows
end

def resolve(token, commands)
  matches = []
  index = 0

  while index < commands.length
    command = commands[index]
    if command.index(token.downcase) == 0
      matches = matches.push(command)
    end
    index = index + 1
  end

  if matches.empty?
    "unknown"
  elsif matches.length == 1
    matches[0]
  else
    "ambiguous"
  end
end

def run
  available = commands
  {
    abbreviations: automatic_abbreviations(available),
    resolve_app: resolve("app", available),
    resolve_pr: resolve("pr", available),
    resolve_c: resolve("c", available)
  }
end