# * George Moschovitis  <gm@navel.gr>
# (c) 2004-2005 Navel, all rights reserved.
# $Id: filesys.rb 281 2005-03-10 12:24:14Z gmosx $

require 'fileutils'

require 'og/adapter'
require 'og/connection'
require 'glue/attribute'

module Og

# The Filesys adapter. This adapter stores Og objectes in
# the filesystem. This adapter is a proof of concept and
# at the moment severely limited. For extra documentation 
# see lib/og/adapter.rb

class FilesysAdapter < Adapter

	# Creates the name of the database root dir.

	def self.dir(database)
		"#{database}_db"
	end

	def create_db(database, user = nil, password = nil)
		begin
			FileUtils.mkdir_p(self.class.dir(database))
		rescue
			Logger.error "Cannot create '#{database}'!"
		end
	end

	def drop_db(database, user = nil, password = nil)
		begin
			FileUtils.rmdir(self.class.dir(database))	
			super
		rescue
			Logger.error "Cannot drop '#{database}'!"
		end
	end

	def insert_code(klass, db, pre_cb, post_cb)
		props = props_for_insert(klass)
		values = props.collect { |p| write_prop(p) }.join(',') 
		
		sql = "INSERT INTO #{klass::DBTABLE} (#{props.collect {|p| p.name}.join(',')}) VALUES (#{values})"

		%{
			#{pre_cb}
			conn.store.query("#{sql}").close
			@oid = conn.store.last_insert_row_id
			#{post_cb}
		}
	end

	def new_connection(db)
		return FilesysConnection.new(db)
	end

	# A 'table' is emulated by using a directory to store
	# one file per table row. Each file contains an object
	# marshaled in YAML format. A special file called
	# '_sequence' stores the sequence for this 'table'.
	
	def create_table(klass, db)
		class_dir = File.join(self.class.dir(db.config[:database]), klass::DBTABLE)
		FileUtils.mkdir_p(class_dir)
		
		seq_file = File.join(class_dir, 'seq')
		File.open(seq_file, 'w') { |f| f << '1' }
	rescue => ex
		Logger.error "Cannot create directory to store '#{klass}' classes!"
	end

end

# The Filesys adapter connection.

class FilesysConnection < Connection

	def initialize(db)
		super
		config = db.config

		begin
			raise unless File.directory?(FilesysAdapter.dir(config[:database]))
		rescue => ex 
			if true # ex.to_s =~ /database .* does not exist/i
				Logger.info "Database '#{config[:database]}' not found!"
				@db.adapter.create_db(config[:database], config[:user])
				retry
			end
			raise
		end
	end

	def save(obj)
		seq = nil
		class_dir = File.join(FilesysAdapter.dir(@db.config[:database]), obj.class::DBTABLE)
		File.open(File.join(class_dir, 'seq'), 'r') { |f| seq = f.read.to_i }
		obj.oid = seq
		File.open(File.join(class_dir, "#{seq}.yml"), 'w') { |f| f << obj.to_yaml }
		seq += 1
		File.open(File.join(class_dir, 'seq'), 'w') { |f| f << seq }
	end

	def load(oid, klass)
		obj = nil
		class_dir = File.join(FilesysAdapter.dir(@db.config[:database]), klass::DBTABLE)
		File.open(File.join(class_dir, "#{oid}.yml"), 'r') { |f| obj = YAML::load(f.read) }
		return obj
	end

	def close
		Logger.debug "Closed DB connection." if $DBG
	end

end

end