Fast cd with learning

xd.rb

#!/usr/bin/env ruby
#encoding: utf-8

require 'sqlite3'

SEPARATOR = ''

class Stats
  DB_FILE=File.join Dir.home, ".xd.sqlite3"

	def initialize
		exist = File.exist? DB_FILE
		@db = SQLite3::Database.new DB_FILE
		self.create unless exist
		self.purge
	end

	def create
		@db.execute "CREATE TABLE stats (path TEXT NOT NULL, occurrence INTEGER NOT NULL, last_used TEXT NOT NULL)"
	end

	def purge
		date = DateTime.now.prev_month.to_s
		@db.execute "DELETE FROM stats WHERE last_used < ?", date
	end

	def close
		@db.close
	end

	def get(paths)
		paths.uniq!
		result = {}
		@db.execute "SELECT path, occurrence FROM stats WHERE path in ( ? )", paths.join(", ") do |row|
			path = row[0]
			occurrence = row[1]
			result[path] = occurrence
			paths.delete path
		end
		paths.each { |path| result[path] = 0 }
		result.sort { |a, b| a[1] <=> b[1]}.reverse
	end

	def add(path)
		@db.execute "UPDATE stats SET occurrence = occurrence + 1, last_used = datetime('now') WHERE path = ?", path
		if @db.changes == 0
			@db.execute "INSERT INTO stats (path, occurrence, last_used) VALUES (?, 0, datetime('now'))", path
		end
	end

	def get_target(path)
		result = []
		l = path.split(SEPARATOR).length
		@db.execute "SELECT path FROM stats" do |row|
			file = row[0]
			expected = file.split File::SEPARATOR
			next if expected.length < l
			expected = expected.collect { |p| p[0] }[-l, l] .join SEPARATOR
			result << file if expected == path
		end
		result
	end
end

class DirectoryChanger
	def initialize stats
		@stats = stats
	end

	def get_target(path)
		path = path.downcase
		if path.start_with?('/')
			start = '/'
			path = path.sub /^#{Regexp.escape('/')}/, ""
		elsif path.start_with?('-')
			start = Dir.home
			path = path.sub /^#{Regexp.escape('-')}/, ""
		else
			start = Dir.pwd
		end
		path = path.split SEPARATOR

		target = self.find_target start, path
	end

	def find_target(directory, path)
		return [] unless File.readable? directory
		if path.length <= 0
			return [directory]
		end
		result = []
		Dir.entries(directory).each do |entry|
			subdirectory = File.join(directory, entry)
			if File.directory?(subdirectory) && entry.downcase.start_with?(path[0])
				result.concat self.find_target subdirectory, path[1..-1]
			end
		end
		result
	end

	def perform(path)
		if path.start_with? '+'
			force = true
			path = path.sub /^#{Regexp.escape('+')}/, ""
		else
			force = false
		end

		target = self.get_target path
		target.concat @stats.get_target path
		target = @stats.get target

		if force && target.length > 1
			target = target[0, 1]
		end

		if target.length == 0
			return 1
		elsif target.length == 1
			target = target[0]
		else
			begin
				i = 1
				target.each do |t|
					STDERR.puts "#{i} → #{t[0]}"
					i+=1
				end
				STDERR.print "? > "
				value = STDIN.gets.chomp
				if value == ""
					value = 0
				else
					value = value.to_i - 1
				end
			end while 0 > value || value >= target.length
			target = target[value]
		end

		target = target[0]
		@stats.add target
		print target
		return 0
	end
end

stats = Stats.new
changer = DirectoryChanger.new stats
code = changer.perform ARGV[0]
stats.close
exit code