display.jl

import Base: show

const tab = "   "

function show(io::IO, engine::Engine, depth::Integer = 0)
    if get(io, :compact, false)
        print(io, "Engine($(name(engine)))")
    else
        println(io, tab^depth, "engine:")
        depth += 1
        println(io, tab^depth, "name   = ", name(engine))
        println(io, tab^depth, "thrust = ", thrust(engine))    
        println(io, tab^depth, "Isp    = ", Isp(engine))
    end
end

function show(io::IO, tank::Tank, depth::Integer = 0)
    if get(io, :compact, false)
        print(io, "Tank($(tank.dry_mass))")
    else
        println(io, tab^depth, "tank:")
        depth += 1
        println(io, tab^depth, "dry   = ", tank.dry_mass)
        println(io, tab^depth, "total = ", tank.total_mass)
    end
end

function print_stage(io::IO, rocket::Rocket, depth::Number)
    println(io, tab^depth, "throttle   = ", rocket.throttle)
    println(io, tab^depth, "propellant = ", rocket.propellant)
    
    println(io)
    show(io, rocket.tank, depth)
    println(io)  

    show(io, rocket.engine, depth)
    println(io)  
end

function print_stage(io::IO, payload::Payload, depth::Number)
    println(io, tab^depth, payload)
    println(io)    
end

function show(io::IO, payload::Payload, depth::Number)
    print(io, tab^depth, payload)
end

function show(io::IO, ship::SpaceVehicle)
    if get(io, :compact, false)
        print(io, "SpaceVehicle($(position(ship)), $(velocity(ship)))")
    else
        println(io, "position = ", position(ship))
        println(io, "velocity = ", velocity(ship))
        println(io)
		stages = collect(ship)
        for i in length(stages):-1:1
            println(io, "stage ", i, ": ")
            print_stage(io, stages[i], 1)
        end
    end
end

function show(io::IO, r::Rocket, depth::Integer = 0)
    if get(io, :compact, false)
        print(io, "Rocket($(r.throttle), $(r.propellant))")
    else
        println(io, tab^depth, "Rocket:")
    
        depth += 1
        println(io, tab^depth, "throttle   = ", r.throttle)
        println(io, tab^depth, "propellant = ", r.propellant)    
        println(io)
    
        show(io, r.tank, depth)
        println(io)
        show(io, r.engine, depth)
        println(io)
    
        println(io, tab^depth , "Payload:")
        show(io, r.payload, depth + 1)
    end
end