#!/usr/bin/ruby

require 'date'
require 'optparse'

# always keep the last 4 weeks
ALWAYS_KEEP_DAYS = 4 * 7

# otherwise, bucket by month and keep the earliest in the bucket
def bucket(date)
  Date.new(date.year, date.month, 1)
end

Candidate = Struct.new(:filename, :date)

def list_files(glob, date_pattern)
  # find all candidates for deletion
  real_files = Dir.glob(glob).select do |file|
    File.file?(file) && !File.symlink?(file)
  end

  real_files.map do |file|
    # extract the date
    m = date_pattern.match(file)
    raise "Unable to extract date string from #{file.inspect}" if m.nil?
    d = Date.strptime(m[1], "%y%m%d")
    Candidate.new(file, d)
  end
end

def deletion_candidates(today, candidates)
  candidate_buckets = Hash.new

  candidates.each do |c|
    next if today - c.date < ALWAYS_KEEP_DAYS
    b = bucket(c.date)

    candidate_buckets[b] = Array.new unless candidate_buckets.has_key?(b)
    candidate_buckets[b] << c
  end

  # delete all but the earliest in each bucket
  candidate_buckets.collect_concat do |bucket, contents|
    contents.sort_by {|c| c.date}[1..-1]
  end
end

def deletions(glob, date_pattern, today, expansions)
  candidates = list_files(glob, date_pattern)
  to_delete = deletion_candidates(today, candidates)

  expanded = to_delete.collect_concat do |candidate|
    dir = File.dirname(candidate.filename)
    expansions.map do |e|
      exp = candidate.date.strftime(e)
      "#{dir}/#{exp}"
    end
  end

  expanded.select {|e| File.exist?(e)}
end

dry_run = false
debug = false

OptionParser.new do |opt|
  opt.on('--dry-run') { dry_run = true }
  opt.on('--debug') { debug = true }
end.parse!

xml_directory = "<%= node[:planet][:dump][:xml_directory] %>"
xml_history_directory = "<%= node[:planet][:dump][:xml_history_directory] %>"
pbf_directory = "<%= node[:planet][:dump][:pbf_directory] %>"
pbf_history_directory = "<%= node[:planet][:dump][:pbf_history_directory] %>"

today = Date.today
to_delete = Array.new

to_delete += deletions(
  "#{xml_directory}/20??/planet-??????.osm.bz2",
  /planet-([0-9]{6}).osm.bz2/,
  today,
  ["changesets-%y%m%d.osm.bz2",
   "changesets-%y%m%d.osm.bz2.md5",
   "discussions-%y%m%d.osm.bz2",
   "discussions-%y%m%d.osm.bz2.md5",
   "planet-%y%m%d.osm.bz2",
   "planet-%y%m%d.osm.bz2.md5"])

to_delete += deletions(
  "#{xml_history_directory}/20??/history-??????.osm.bz2",
  /history-([0-9]{6}).osm.bz2/,
  today,
  ["history-%y%m%d.osm.bz2",
   "history-%y%m%d.osm.bz2.md5"])

to_delete += deletions(
  "#{pbf_directory}/planet-??????.osm.pbf",
  /planet-([0-9]{6}).osm.pbf/,
  today,
  ["planet-%y%m%d.osm.pbf",
   "planet-%y%m%d.osm.pbf.md5"])

to_delete += deletions(
  "#{pbf_history_directory}/history-??????.osm.pbf",
  /history-([0-9]{6}).osm.pbf/,
  today,
  ["history-%y%m%d.osm.pbf",
   "history-%y%m%d.osm.pbf.md5"])

total_size = 0
num_deleted = 0
cmd = dry_run ? "Would delete" : "Deleted"
to_delete.each do |file|
  s = File.stat(file)
  File.delete(file) unless dry_run
  puts "#{cmd} #{file.inspect}, #{s.size / 1000000} MB" if debug
  total_size += s.size
  num_deleted += 1
end
if debug
  puts "#{cmd} files of total size #{total_size / 1000000000.0} GB"
  puts "#{cmd} #{num_deleted} files"
end