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

class interface
	HEALTH_SYSTEM

create 
	make
			-- Initialize an empty system.
		ensure
				patients.is_empty
				medications.is_empty
				pr.is_empty
				di.is_empty
				dpr.is_empty
				not warn

feature -- Access

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

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

	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)
		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))

	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
		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)

	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
		ensure -- from ANY
			symmetric: Result implies other ~ Current
			consistent: standard_is_equal (other) implies Result

	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)
		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))

	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
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
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

	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
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
	
feature -- Duplication

	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)
		ensure -- from ANY
			is_equal: Current ~ other

	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
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

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

	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)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

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

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

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

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

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

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

	add_interaction (m1, m2: MEDICATION)
			-- Add an interaction between 'm1' and 'm2'.
		require
				m1 /= Void and then m2 /= Void
				m1 /= m2
		ensure
			dangerous_interactions_extended: di ~ (old di.deep_twin).extended (mm ([m1, m2])).extended (mm ([m2, m1]))

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

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

	add_to_prescription (p1: PATIENT; m1: MEDICATION)
			-- Add a prescription of 'm1' to 'p1'.
		require
				p1 /= Void and m1 /= Void
		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)

	remove_from_prescription (p1: PATIENT; m1: MEDICATION)
			-- Remove prescription of 'm1' to 'p1'.
		require
				p1 /= Void and m1 /= Void
		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
	
feature -- Constructor

	make
			-- Initialize an empty system.
		ensure
				patients.is_empty
				medications.is_empty
				pr.is_empty
				di.is_empty
				dpr.is_empty
				not warn
	
feature -- Output

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

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

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class

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

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
	
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
	
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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