require_relative 'util'

# --- Day 8: Matchsticks ---

# Space on the sleigh is limited this year, and so Santa will be
# bringing his list as a digital copy. He needs to know how much space
# it will take up when stored.

# It is common in many programming languages to provide a way to
# escape special characters in strings. For example, C, JavaScript,
# Perl, Python, and even PHP handle special characters in very similar
# ways.

# However, it is important to realize the difference between the
# number of characters in the code representation of the string
# literal and the number of characters in the in-memory string itself.

# For example:

# - `""` is 2 characters of code (the two double quotes), but the
#   string contains zero characters.
# - `"abc"` is 5 characters of code, but 3 characters in the string
#   data.
# - `"aaa\"aaa"` is 10 characters of code, but the string itself
#   contains six `"a"` characters and a single, escaped quote
#   character, for a total of 7 characters in the string data.
# - `"\x27"` is 6 characters of code, but the string itself contains
#   just one - an apostrophe (`'`), escaped using hexadecimal notation.

# Santa's list is a file that contains many double-quoted string
# literals, one on each line. The only escape sequences used are `\\`
# (which represents a single backslash), `\"` (which represents a lone
# double-quote character), and `\x` plus two hexadecimal characters
# (which represents a single character with that ASCII code).

# Disregarding the whitespace in the file, what is the number of
# characters of code for string literals minus the number of
# characters in memory for the values of the strings in total for the
# entire file?

# For example, given the four strings above, the total number of
# characters of string code (2 + 5 + 10 + 6 = 23) minus the total
# number of characters in memory for string values (0 + 3 + 7 + 1 =
# 11) is 23 - 11 = 12.

test_input = ['""', '"abc"', '"aaa\"aaa"', '"\x27"']
input = File.open('08.txt') { |f| f.readlines.map(&:chomp) }

def easy(input)
  # so convenient
  input.map { |line| line.length - eval(line).length }.sum
end

assert(easy(test_input) == 12)
puts "easy(input): #{easy(input)}"

# --- Part Two ---

# Now, let's go the other way. In addition to finding the number of
# characters of code, you should now encode each code representation
# as a new string and find the number of characters of the new encoded
# representation, including the surrounding double quotes.

# For example:

# - `""` encodes to `"\"\""`, an increase from 2 characters to 6.
# - `"abc"` encodes to `"\"abc\""`, an increase from 5 characters to
#   9.
# - `"aaa\"aaa"` encodes to `"\"aaa\\\"aaa\""`, an increase from 10
#   characters to 16.
# - `"\x27"` encodes to `"\"\\x27\""`, an increase from 6 characters
#   to 11.

# Your task is to find the total number of characters to represent the
# newly encoded strings minus the number of characters of code in each
# original string literal. For example, for the strings above, the
# total encoded length (6 + 9 + 16 + 11 = 42) minus the characters in
# the original code representation (23, just like in the first part of
# this puzzle) is 42 - 23 = 19.

def hard(input)
  input.map { |line| line.dump.length - line.length }.sum
end

assert(hard(test_input) == 19)
puts "hard(input): #{hard(input)}"