Assignment_4 03

note
    description : "ZVV information system."

class
    APPLICATION

create
    execute

feature {NONE} -- Initialization

    execute
            -- Run application.
        do
            read_data
            if not read_error then
                Io.new_line
                print ("Eligible for discount: ")
                print (gets_discount)
            end
        end

feature -- Access

    birth_date: DATE
            -- Birth date.

    current_date: DATE
            -- Current date.

    date_duration: DATE_DURATION
            -- Difference between dates

    home: STRING
            -- Home postal code.

    work: STRING
            -- Work postal code.

    age: INTEGER
            -- Age (difference in years between today's date and `birth_date').
        require
            birth_date_exists: birth_date /= Void
        do
            create current_date.make_now
            create date_duration.make (0, 0, 0)
            date_duration := current_date.relative_duration (birth_date)
            Result := date_duration.days_count
        end

feature -- Status report

    valid_postal_code (pc: STRING): BOOLEAN
            -- Is `pc' a valid postal code in Switzerland?
        do
            Result := ((pc /= void) and then (pc.is_natural = true) and then (pc.count = 4))
        end

    in_zurich_canton (pc: STRING): BOOLEAN
            -- Is postal code `pc' inside the canton of Zurich?
        require
            valid_code: valid_postal_code (pc)
        do
            Result := pc [1] = '8'
        end

    in_zurich_city (pc: STRING): BOOLEAN
            -- Is postal code `pc' inside the city of Zurich?
        require
            valid_code: valid_postal_code (pc)
        do
            Result := ((pc [1] = '8') and (pc [2] = '0'))
        end

    gets_discount: BOOLEAN
            -- Is a customer with the current `birth_date', `home' and `work' eligible for a discounted seasonal ticket?
        require
            birth_date_exists: birth_date /= Void
            valid_home_code: valid_postal_code (home)
            valid_work_code: valid_postal_code (work)
        do
            if 25 >= (age/365.25) then
                Result := true
            elseif (in_zurich_city (home) = true) and (in_zurich_city (work) = false) then
                Result := true
            elseif (in_zurich_city (work) = true) and (in_zurich_canton (home) = true) and (in_zurich_city (home) = false) then
                Result := true
            else
                Result := false
            end
        end

feature {NONE} -- Implementation

    read_error: BOOLEAN
            -- Did an error occur while reading user data?

    read_data
            -- Read user input.
        local
            date_format: STRING
        do
            date_format := "[0]dd/[0]mm/yyyy"
            print ("Enter birth date as dd/mm/yyyy: ")
            Io.read_line
            if not (create {DATE_VALIDITY_CHECKER}).date_valid (Io.last_string, date_format) then
                print ("Invalid date")
                read_error := True
            else
                create birth_date.make_from_string (Io.last_string, date_format)
            end

            if not read_error then
                print ("Enter home postal code: ")
                Io.read_line
                home := Io.last_string.twin
                if not valid_postal_code (home)  then
                    print ("Invalid postal code")
                    read_error := True
                end
            end

            if not read_error then
                print ("Enter work postal code: ")
                Io.read_line
                work := Io.last_string.twin
                if not valid_postal_code (work)  then
                    print ("Invalid postal code")
                    read_error := True
                end
            end
        end
end