note
	description: "An electronic health (e-Health) system."
	author: "Jackie Wang"

class 
	HEALTH_SYSTEM

create 
	make

feature {NONE} -- Initialization

	default_create
			-- Process instances of classes with no creation clause.
			-- (Default: do nothing.)
			-- (from ANY)
		do
		end
	
feature -- Access

	generating_type: TYPE [detachable HEALTH_SYSTEM]
			-- Type of current object
			-- (type of which it is a direct instance)
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			generating_type_not_void: Result /= Void
		end

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			generator_not_void: Result /= Void
			generator_not_empty: not Result.is_empty
		end
	
feature -- Comparison

	frozen deep_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_deep_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			shallow_implies_deep: standard_equal (a, b) implies Result
			both_or_none_void: (a = Void) implies (Result = (b = Void))
			same_type: (Result and (a /= Void)) implies (b /= Void and then a.same_type (b))
			symmetric: Result implies deep_equal (b, a)
		end

	frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b))
		end

	frozen is_deep_equal (other: HEALTH_SYSTEM): BOOLEAN
			-- Are Current and other attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			shallow_implies_deep: standard_is_equal (other) implies Result
			same_type: Result implies same_type (other)
			symmetric: Result implies other.is_deep_equal (Current)
		end

	is_equal (other: HEALTH_SYSTEM): BOOLEAN
			-- Is other attached to an object considered
			-- equal to current object?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			symmetric: Result implies other ~ Current
			consistent: standard_is_equal (other) implies Result
		end

	frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.standard_is_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b))
		end

	frozen standard_is_equal (other: HEALTH_SYSTEM): BOOLEAN
			-- Is other attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
		end
	
feature -- Status report

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of other (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		end

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of other?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
		end
	
feature -- Duplication

	frozen clone (other: detachable ANY): like other
		obsolete "Use `twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- equal to other
			--
			-- For non-void other, clone calls copy;
			-- to change copying/cloning semantics, redefine copy.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.twin
			end
		ensure -- from ANY
			instance_free: class
			equal: Result ~ other
		end

	copy (other: HEALTH_SYSTEM)
			-- Update current object using fields of object attached
			-- to other, so as to yield equal objects.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		external
			"built_in"
		ensure -- from ANY
			is_equal: Current ~ other
		end

	frozen deep_clone (other: detachable ANY): like other
		obsolete "Use `deep_twin' instead. [2017-05-31]"
			-- Void if other is void: otherwise, new object structure
			-- recursively duplicated from the one attached to other
			-- (from ANY)
		do
			if other /= Void then
				Result := other.deep_twin
			end
		ensure -- from ANY
			instance_free: class
			deep_equal: deep_equal (other, Result)
		end

	frozen deep_copy (other: HEALTH_SYSTEM)
			-- Effect equivalent to that of:
			--		copy (other . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		do
			copy (other.deep_twin)
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)
		end

	frozen deep_twin: HEALTH_SYSTEM
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)
		end

	frozen standard_clone (other: detachable ANY): like other
		obsolete "Use `standard_twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.standard_twin
			end
		ensure -- from ANY
			instance_free: class
			equal: standard_equal (Result, other)
		end

	frozen standard_copy (other: HEALTH_SYSTEM)
			-- Copy every field of other onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		external
			"built_in"
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)
		end

	frozen standard_twin: HEALTH_SYSTEM
			-- New object field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)
		end

	frozen twin: HEALTH_SYSTEM
			-- New object equal to Current
			-- twin calls copy; to change copying/twinning semantics, redefine copy.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result ~ Current
		end
	
feature -- Basic operations

	frozen as_attached: attached HEALTH_SYSTEM
		obsolete "Remove calls to this feature. [2017-05-31]"
			-- Attached version of Current.
			-- (Can be used during transitional period to convert
			-- non-void-safe classes to void-safe ones.)
			-- (from ANY)
		do
			Result := Current
		end

	frozen default: detachable HEALTH_SYSTEM
			-- Default value of object's type
			-- (from ANY)
		do
		end

	frozen default_pointer: POINTER
			-- Default value of type POINTER
			-- (Avoid the need to write p.default for
			-- some p of type POINTER.)
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)
		do
		end

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end
	
feature -- Commands

	add_interaction (m1, m2: MEDICATION)
			-- Add an interaction between 'm1' and 'm2'.
		require
				m1 /= Void and then m2 /= Void
				m1 /= m2
		local
			rs: SET [MEDICATION]
			p: PATIENT
		do
			di.extend (mm ([m1, m2]))
			di.extend (mm ([m2, m1]))
			across
				pr as c
			loop
				p := c.item.first
				rs := pr.image (p)
				if rs.has (m1) and rs.has (m2) then
					dpr.extend (pi ([p, m1 |-> m2]))
					dpr.extend (pi ([p, m2 |-> m1]))
					warn := True
				end
			end
		ensure
			dangerous_interactions_extended: di ~ (old di.deep_twin).extended (mm ([m1, m2])).extended (mm ([m2, m1]))
		end

	add_medication (m: MEDICATION)
			-- Add medication 'm' into the system.
		require
				m /= Void and then not medications.has (m)
		do
			medications.extend (m)
		ensure
				medications.count = old medications.count + 1
				medications ~ (old medications.deep_twin).extended (m)
		end

	add_patient (p: PATIENT)
			-- Add patient 'p' into the system.
		require
				p /= Void and then not patients.has (p)
		do
			patients.extend (p)
		ensure
				patients.count = old patients.count + 1
				patients ~ (old patients.deep_twin).extended (p)
		end

	add_to_prescription (p1: PATIENT; m1: MEDICATION)
			-- Add a prescription of 'm1' to 'p1'.
		require
				p1 /= Void and m1 /= Void
		local
			p: PATIENT
			m2: MEDICATION
		do
			pr.extend (pm ([p1, m1]))
			across
				pr as c
			loop
				p := c.item.first
				m2 := c.item.second
				if di.has (mm ([m1, m2])) then
					dpr.extend (pi ([p, m1 |-> m2]))
					dpr.extend (pi ([p, m2 |-> m1]))
					warn := True
				end
			end
		ensure
			interactions_stay_intact: di ~ old di.deep_twin
			prescriptions_extended: pr ~ (old pr.deep_twin).extended (pm ([p1, m1]))
			dangerous_prescriptions_report_updated: across
					patients as patient
				all
					across
						medications as med_1
					all
						across
							medications as med_2
						all
							dpr.has (pi ([patient.item, med_1.item |-> med_2.item])) = ((old dpr.deep_twin).has (pi ([patient.item, med_1.item |-> med_2.item])) or else (p1 ~ patient.item and across
								medications as med
							some
								di.has (mm ([med.item, m1])) and pr.has (pm ([p1, med.item])) and pr.has (pm ([p1, m1])) and (m1 |-> med.item ~ med_1.item |-> med_2.item or else m1 |-> med.item ~ med_2.item |-> med_1.item)
							end))
						end
					end
				end
			warning_for_supervisor_reset: warn = across
					(old pr.deep_twin).domain as patient
				some
					across
						(old pr.deep_twin).image (patient.item) as med
					some
						di.has (mm ([med.item, m1]))
					end
				end or else (old warn)
		end

	remove_from_prescription (p1: PATIENT; m1: MEDICATION)
			-- Remove prescription of 'm1' to 'p1'.
		require
				p1 /= Void and m1 /= Void
		local
			m: MEDICATION
		do
			pr.subtract (pm ([p1, m1]))
			across
				pr as c
			loop
				m := c.item.second
				if dpr.has (pi ([p1, m1 |-> m])) then
					dpr.subtract (pi ([p1, m1 |-> m]))
					dpr.subtract (pi ([p1, m |-> m1]))
				end
			end
		ensure
			prescription_removed: pr ~ (old pr.deep_twin).subtracted (pm ([p1, m1]))
			dangerous_prescriptions_report_updated: across
					medications as med
				all
					not (dpr.has (pi ([p1, med.item |-> m1])) or else dpr.has (pi ([p1, m1 |-> med.item])))
				end
		end
	
feature -- Constructor

	make
			-- Initialize an empty system.
		do
			create patients.make_empty
			create medications.make_empty
			create pr.make_empty
			create di.make_empty
			create dpr.make_empty
			warn := False
		ensure
				patients.is_empty
				medications.is_empty
				pr.is_empty
				di.is_empty
				dpr.is_empty
				not warn
		end
	
feature -- Output

	Io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		once
			create Result
			Result.set_output_default
		ensure -- from ANY
			instance_free: class
			io_not_void: Result /= Void
		end

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		do
			Result := tagged_out
		ensure -- from ANY
			out_not_void: Result /= Void
		end

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		do
			if o /= Void then
				Io.put_string (o.out)
			end
		ensure -- from ANY
			instance_free: class
		end

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			tagged_out_not_void: Result /= Void
		end
	
feature -- Platform

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		once
			create Result
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
		end
	
feature {NONE} -- Retrieval

	frozen internal_correct_mismatch
			-- Called from runtime to perform a proper dynamic dispatch on correct_mismatch
			-- from MISMATCH_CORRECTOR.
			-- (from ANY)
		local
			l_msg: STRING_8
			l_exc: EXCEPTIONS
		do
			if attached {MISMATCH_CORRECTOR} Current as l_corrector then
				l_corrector.correct_mismatch
			else
				create l_msg.make_from_string ("Mismatch: ")
				create l_exc
				l_msg.append (generating_type.name)
				l_exc.raise_retrieval_exception (l_msg)
			end
		end
	
feature -- State Attributes

	di: REL [MEDICATION, MEDICATION]
			-- dangerous interactions

	dpr: REL [PATIENT, INTERACTION]
			-- dangerous prescriptions report

	medications: SET [MEDICATION]
			-- set of medications

	patients: SET [PATIENT]
			-- set of patients

	pr: REL [PATIENT, MEDICATION]
			-- prescriptions

	warn: BOOLEAN
			-- warning signal for the system supervisor
	
feature {NONE} -- Workaround to avoid using convert

	mm (t: TUPLE [MEDICATION, MEDICATION]): PAIR [MEDICATION, MEDICATION]
		do
			create Result.make_from_tuple (t)
		end

	pi (t: TUPLE [PATIENT, INTERACTION]): PAIR [PATIENT, INTERACTION]
		do
			create Result.make_from_tuple (t)
		end

	pm (t: TUPLE [PATIENT, MEDICATION]): PAIR [PATIENT, MEDICATION]
		do
			create Result.make_from_tuple (t)
		end
	
invariant
	symmetry: across
			medications as m1
		all
			across
				medications as m2
			all
				di.has (mm ([m1.item, m2.item])) = di.has (mm ([m2.item, m1.item]))
			end
		end
	irreflexivity: across
			medications as m1
		all
			not di.has (mm ([m1.item, m1.item]))
		end
	dangerous_prescriptions_reported: across
			medications as m1
		all
			across
				medications as m2
			all
				across
					patients as p1
				all
					(di.has (mm ([m1.item, m2.item])) and pr.has (pm ([p1.item, m1.item])) and pr.has (pm ([p1.item, m2.item]))) = dpr.image (p1.item).has (m1.item |-> m2.item)
				end
			end
		end

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

end -- class HEALTH_SYSTEM

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