#!/usr/bin/env julia

using Test

mutable struct Dir
  path :: String
  dnames :: Vector{String}
  fsize :: Int32
end

function get_dir_map(infile)
  cwd = Vector{String}()
  path = "/"
  dirmap = Dict{String, Dir}()
  open(infile, "r") do io
    for line in eachline(io)
      parts = split(line)
      if parts[1] == "\$"
        if parts[2] == "cd"
          if parts[3] == "/"
            empty!(cwd)
          elseif parts[3] == ".."
            pop!(cwd)
          else
            push!(cwd, parts[3])
          end
          path = "/" * join(cwd, '/')
          if ! haskey(dirmap, path)
            dirmap[path] = Dir(path, [], 0)
          end
        elseif parts[2] != "ls"
          println("Unknown command: ", line)
        end
      else
        parts = split(line, limit=2)
        if parts[1] == "dir"
          push!(dirmap[path].dnames, joinpath(path, parts[2]))
        else
          dirmap[path].fsize += parse(Int, parts[1])
        end
      end
    end
  end
  for k in sort(collect(keys(dirmap)), by=p->length(p), rev=true)
    v = dirmap[k]
    for p in v.dnames
      dirmap[k].fsize += dirmap[p].fsize
    end
  end
  return dirmap
end
  

function small_dir_sum(infile)
  dirmap = get_dir_map(infile)
  small_sum = 0
  for v in values(dirmap)
    if v.fsize <= 100000
      small_sum += v.fsize
    end
  end
  return small_sum
end

function delete_candidate_size(infile)
  dirmap = get_dir_map(infile)
  total = 70000000
  want = 30000000
  used = dirmap["/"].fsize
  free = total - used
  need = want - free
  candidates = Vector{Int64}()
  # println("used ", used)
  # println("free ", free)
  # println("need ", need)
  for v in values(dirmap)
    if v.fsize >= need
      push!(candidates, v.fsize)
    end
  end
  return minimum(candidates)
end

function test()
  @testset "disk usage small dir sum" verbose=true begin
    @test small_dir_sum("example.txt") == 95437
    @test small_dir_sum("input.txt") == 1306611
  end
  @testset "disk usage delete candidate size" verbose=true begin
    @test delete_candidate_size("example.txt") == 24933642
    @test delete_candidate_size("input.txt") == 13210366
  end
end

function main()
  if size(ARGS, 1) == 0
    test()
  else
    infile = ARGS[1]
    println("infile = ", infile)
    println("error priority sum: ", rucksack_errors(infile))
  end
end

main()