# code:
# * George Moschovitis  <gm@navel.gr>
# design:
# * Anastastios Koutoumanos  <ak@navel.gr>
# * Elias Karakoulakis  <ekarak@ktismata.com>
#
# (c) 2004 Navel, all rights reserved.
# $Id: property.rb 185 2004-12-10 13:29:09Z gmosx $

require "glue/array"
require "glue/hash"

module G

# = Property
#
# Ruby attributes are typeless and generally this is good. Some times
# we need extra metadata though, for example in relational mapping,
# or web form population.
#
# Only Fixnums, Strings, Floats, Times, Booleans are converted.
#
# The default = methods do not force the  types. A special 
# __force_set method should be used instead.
#
#--
# TODO:
# Inject only the really needd methods into Module.
# Perhaps a sync is needed in evals (!!!!)
#++
#
class Property
	# the symbol of the property
	attr_accessor :symbol
	# the string representation of the symbol
	attr_accessor :name
	# the class of the property
	attr_accessor :klass
	# additional metadata (like sql declaratio, sql index, etc)
	attr_accessor :meta
	
	def initialize(symbol, klass, meta = {})
		@symbol, @klass = symbol, klass
		@meta = meta
		@name = @symbol.to_s()
	end
	
	def ==(other)
		return @symbol == other.symbol
	end
	
	def to_s
		return name
	end
end

end # module

class Module

	# Define a property (== typed attribute)
	# This works like Ruby's standard attr method, ie creates
	# only one property. 
	#
	# Use the prop_reader, prop_writer, prop_accessor methods 
	# for multiple properties.
	#
	# Examples:
	#	prop String, :name, :sql => "char(32), :sql_index => "name(32)"
	# --> creates only writer.
	# prop Fixnum, :oid, writer = true, :sql => "integer PRIMARY KEY"
	#	--> creates reader and writer.
	# 
	def prop(*params)
		meta = {}
		klass = Object
		
		for param in params
			if param.is_a?(Class)
				klass = param
			elsif param.is_a?(Symbol)
				symbol = param
			elsif param.is_a?(TrueClass) or param.is_a?(TrueClass) 
				writer = param
			elsif param.is_a?(Hash)
				# the meta hash.
				meta = param
			else
				raise "Error when defining property!"
			end
		end

		unless self.methods.include?("__props")
			eval %{
				# Properties
				# An array is used to enforce order.
				def __props
					@__props
				end

				def __props=(props)
					@__props = props
				end
				
				def __meta
					@__meta
				end

				def __meta=(meta)
					@__meta = meta
				end				
			}
		end

		@__props = G::SafeArray.new() unless @__props
				
		property = G::Property.new(symbol, klass, meta)
		
		reader = meta[:reader] || true
		writer = writer || meta[:writer] || false
		
		__add_prop(property, reader, writer)
	end

	# Helper method. Accepts a collection of symbols and generates
	# properties. Only generates reader.
	#
	# Example:
	#	prop_reader String, :name, :title, :body, :sql => "char(32)"
	#
	def prop_reader(*params)
		meta = {}
		klass = Object
		symbols = []

		for param in params
			if param.is_a?(Class)
				klass = param
			elsif param.is_a?(Symbol)
				symbols << param
			elsif param.is_a?(Hash)
				# the meta hash.
				meta = param
			else
				raise "Error when defining property!"
			end
		end
		
		meta[:reader] = true
		meta[:writer] = false
		
		for symbol in symbols
			prop(klass, symbol, meta)
		end
	end

	# Helper method. Accepts a collection of symbols and generates
	# properties. Only generates writer.
	#
	# Example:
	#	prop_writer String, :name, :title, :body, :sql => "char(32)"
	#
	def prop_writer(*params)
		meta = {}
		klass = Object
		symbols = []

		for param in params
			if param.is_a?(Class)
				klass = param
			elsif param.is_a?(Symbol)
				symbols << param
			elsif param.is_a?(Hash)
				# the meta hash.
				meta = param
			else
				raise "Error when defining property!"
			end
		end
		
		meta[:reader] = false
		meta[:writer] = true
		
		for symbol in symbols
			prop(klass, symbol, meta)
		end
	end

	# Helper method. Accepts a collection of symbols and generates
	# properties. Generates reader and writer.
	#
	# Example:
	#	prop_accessor String, :name, :title, :body, :sql => "char(32)"
	#
	def prop_accessor(*params)
		meta = {}
		klass = Object
		symbols = []

		for param in params
			if param.is_a?(Class)
				klass = param
			elsif param.is_a?(Symbol)
				symbols << param
			elsif param.is_a?(Hash)
				# the meta hash.
				meta = param
			else
				raise "Error when defining property!"
			end
		end
		
		meta[:reader] = true
		meta[:writer] = true
		
		for symbol in symbols
			prop(klass, symbol, meta)
		end
	end
	
	# Add the property
	#
	def __add_prop(prop, reader = true, writer = true)
		if idx = @__props.index(prop)
			# override in case of duplicates. Keep the order of the props.
			@__props[idx] = prop
		else
			@__props << prop
		end
		
		# Precompile the property read/write methods

		s, klass = prop.symbol, prop.klass 

		if reader		
			module_eval %{
				def #{s}
					return @#{s}
				end
			}
		end
			
		# gmosx: __force_xxx reuses xxx= to allow for easier
		# overrides.
		if writer 
			module_eval %{
				def #{s}=(val)
					@#{s} = val
				end
				
				def __force_#{s}(val)
						self.#{s}=(} + case klass.name
													when Fixnum.name
														"val.to_i()"
													when String.name
														"val.to_s()"
													when Float.name
														"val.to_f()"
													when Time.name
														"Time.parse(val.to_s())"
													when TrueClass.name, FalseClass.name
														"val.to_i() > 0"
													else
														"val"
												end + %{) 
				end
			}
		end
	end
	
	# Attach metadata 
	#
	def meta(key, val)
		@__meta = G::SafeHash.new unless @__meta

		@__meta[key] = [] unless @__meta[key]

		# guard against duplicates, no need to keep order.
		@__meta[key].delete_if { |v| val == v }
		@__meta[key] << val			
	end
	
	# This method is typically called before including other
	# modules to preserve properties order. 
	#
	def inherit_meta(mod = superclass)
		# concat props.
		if mod.__props
			@__props = G::SafeArray.new unless @__props
			
			mod.__props.each { |p|
				__add_prop(p)
			} 
		end

		# concat metadata
		if mod.__meta
			mod.__meta.each { |k, val|
				val.each { |v|
					meta(k, v)
				} if val
			}
		end
	end
	
end