Traffic with lane changing

globals [
  loop-counter
  roads
  lane-ycord
  west-lane-one
  west-lane-two
  east-lane-one
  east-lane-two
  max-speed-limit
  min-speed-limit
  lead-car
  lead-car-moves
  prev-xcor
  prev-ycor
  car-ahead
]

breed [ dividers divider ]
breed [ cars car ]


cars-own [
  speed        
  lane
  previous-x        
  agressive?   
]

to setup
  clear-all
  setup-display
  set max-speed-limit 1
  set min-speed-limit 0
  setup-cars
  watch lead-car
  reset-ticks
end 

to go
  ask lead-car [ set prev-xcor xcor  set prev-ycor ycor ]
  cars-drive
  tick
  ask lead-car [ set lead-car-moves (lead-car-moves + distancexy prev-xcor prev-ycor) ]
;  plot-data
end 

to cars-drive
  ask cars [
    ifelse (any? vehicles-directly-ahead) [
      let new-lane try-change-lane
      if (new-lane = nobody) [ ; couldn't change lane
        set speed [ speed ] of vehicle-directly-ahead
        slow-down ] ; so slow down 
    ] [
      speed-up ; else speed up
    ]
    forward speed
  ]
end 

to-report try-change-lane
  if (divider?) [
    report nobody ; no lane changing allowed
  ]
  let dist abs(previous-x - xcor)
  if (dist > 0 and dist < 5) [
    report nobody ; make a car that just changed lane wait before going back
  ]
  if (not agressive?) [
    report nobody
  ]
  let open-patch change-to-fast-lane
  if (open-patch != nobody) [
    report open-patch
  ]
  report change-to-slow-lane
end 

to-report change-to-fast-lane
  let y 0
  let on-left patch-left-and-ahead 90 2
  ask on-left [
    set y abs(pycor)
  ]
  if (y = 2 and not any? cars-on on-left) [
    set previous-x xcor
    set label (label + 1)
    move-to on-left
    report on-left
  ]
  report nobody
end 

to-report change-to-slow-lane
  let y 0
  let on-right patch-right-and-ahead 90 2
  ask on-right [
    set y abs(pycor)
  ]
  if (y = 4 and not any? cars-on on-right) [
    set previous-x xcor
    set label (label + 1)
    move-to on-right
    report on-right
  ]
  report nobody
end 

to-report vehicles-directly-ahead
  ifelse (agressive?) [
    report cars-on patch-ahead 1  
  ] [
    report (turtle-set (cars-on patch-ahead 1) (cars-on patch-ahead buffer))  
  ]
end 

to-report vehicle-directly-ahead
  report one-of vehicles-directly-ahead
end 

to setup-cars 
  set-default-shape turtles "car-west"
  set west-lane-one 2
  set west-lane-two 4
  setup-traffic 270 west-lane-one west-lane-two
  
  set east-lane-one -2
  set east-lane-two -4
  set-default-shape turtles "car-east"
  setup-traffic 90 east-lane-one east-lane-two
  
  set lead-car one-of cars
  ask lead-car [ 
    set color red
    if (not divider?) [
      set agressive? true
      set label 0
    ]
  ]
end 

to setup-traffic [ direction fast-lane slow-lane ]
  create-cars total-cars [
    set color one-of [ 5 27 36 45 55 65 75 85 95 105 115 125 135 ] ; skip red
    set heading direction
    ifelse ((random 2) = 0) [ 
      set lane-ycord fast-lane
    ] [ 
      set lane-ycord slow-lane
    ]
    setxy random-xcor lane-ycord  
    
    set agressive? false
    if (not divider?) [
      set previous-x max-pxcor
      if ((random 5) = 0) [ ; roughly 1 in 5 get to be lane changers
        set agressive? true
        set label 0
      ]
    ]

    set speed 0.1 + random-float 0.9
;    set speed random max-speed-limit

    avoid-collision
    ;locate-empty-road-spot
  ]
end 

to avoid-collision
  set loop-counter (loop-counter + 1)
  let max-iterations 100
;  let cars-near (turtle-set (turtles-on patch-ahead 1) (turtles-here) (turtles-on patch-ahead -1))
;  if any? other cars-near [ 
  if any? other cars-here [
    forward random 3
    if (loop-counter < 100) [
      avoid-collision
    ]
  ]
end 

to locate-empty-road-spot
  move-to one-of roads with [ not any? turtles-on self ]
end 

to speed-up  ; car procedure
  ifelse speed >= (max-speed-limit + random-float .2)
    [ set speed max-speed-limit ]
    [ set speed speed + car-acceleration ]
end 

to slow-down  ; car procedure
  set speed (speed - car-deceleration)
  if speed < min-speed-limit [ 
    set speed min-speed-limit 
  ]
end 

to setup-display
  setup-median
  setup-dividers
  setup-grass
end 

to setup-median
  ask patches [ 
    if (pycor = 0) 
    [ set pcolor yellow ]
  ]
end 

to setup-dividers
  let c max-pycor / 2
  setup-divider c
  setup-divider (- c)
end 

to setup-divider [ y ]
  create-dividers 1 [
    set shape "line"
    set color white   ; lanes on California roads are white
    setxy min-pxcor y ; start on the far left
    set heading 90    ; draw towards the right
  ]
  let line-length 2   ; default
  let line-spacing 1  ; default
  if (divider?) [     ; user can choose if cars are allowed to change lanes
    set line-length 1
    set line-spacing 0
  ]
  ; ask dividers [
  ;   paint-line line-length line-spacing
  ;   while [ xcor > min-pxcor ] [
  ;     paint-line line-length line-spacing
  ;   ]  
  ; ]
  ; this is cleaner than the above
  repeat (world-width / (line-length + line-spacing)) [
    ask dividers [
      paint-line line-length line-spacing
    ]
  ]
  ask dividers [ die ] ; don't need the line painting agents any longer
end 

to paint-line [ line-length line-spacing ] 
  pen-down
  forward line-length
  pen-up
  forward line-spacing
end 

to setup-grass
  ask patches [
    if (pycor > (max-pycor - 1) or pycor < (min-pycor + 1))
    [ set pcolor green ]
  ]
end