Trendsetting

globals [color-mode] ;; 0 = default, 1 = source, 2 = times heard, 3 = popularity

turtles-own [popularity trendy? trend-setter? interest-category trend-category trend-source times-heard]
;; popularity is a number value representing the degree of each turtle
;; trendy? is a boolean that is true if the person follows the trend
;; trend-setter? is a boolean that is true if the person is seeded the trend (i.e. the overall trend-starter)
;; interest-category is an integer representing the type of things the person is interested in
;; trend-category is an integer that represents the inherent type of thing a trend is 
;; (corresponds with same values as interest-category) if the person is carrying a trend.
;; trend-source tells whether the turtle followed a trend from a friend, from the media, or both.
;; times-heard counts how many times a turtle has heard a meme

patches-own [category]
;; category is an integer that represents the inherent type of thing a trend is 
;; (corresponds with same values as trend-category of a person)

;; Create people and links.

to setup
  ca
  set color-mode 0 ;; default
  create-turtles population [
    set shape "person"
    set color blue ;; default "no-trend" color is blue
    setxy random-xcor random-ycor
    set interest-category random 10 ;; an "interest type" corresponding to one of 0-9
    set trend-category -1 ;; -1 corresponds with "no trend"
    set times-heard 0
  ]
  repeat population [
    ask one-of turtles [
      create-link-with one-of other turtles
    ]
  ]
  ask turtles [
    set popularity count my-links
  ]
  ask patches [
    set category -1 ;; -1 corresponds with "no trend", i.e. this patch is not a TV
  ]
  reset-ticks
end 

;; seed a trend to one random person

to seed-trend
  ask one-of turtles [
    set color red
    set trendy? true
    set trend-setter? true
    set trend-category interest-category ;; trend is given a "type" corresponding to the turtle's interest
    set times-heard 1
    set size 1.5 ;; distinguish the trend-setter
  ]
end 

;; run the model

to go
  ask turtles with [trendy? = true][ ;; ask the trendy turtles to spread the trend
    spread-trend
  ]
  ;; if media is turned on, every  ticks a TV will flash in a patch with a turtle on it.
  if media?[
    if ticks mod (media-frequency / 2) = 0 [
      ask one-of patches with [count turtles-here > 0] [
        media-trend
      ]
    ]
    if ticks mod media-frequency = 0 [
      ask patches with [pcolor = white][
        set category -1
        set pcolor black
      ]
    ]
  ]
  recolor
  tick
end 

;; spreading the trend

to spread-trend
  let target nobody
  set target one-of link-neighbors
  if target != nobody [
    ask target [
      ;; diff represents the difference between the turtle's interest category and the category of the trend.
      ;; the smaller the difference, the higher the probability that the trend will be passed to that turtle.
      ;; (i.e. if difference = 0, random number is chosen between 0 and 9. if difference = 9, random number is chosen between 0 and 99
      let diff (interest-category - [trend-category] of myself)
      if 0 = random (10 * (1 + (abs diff))) [
        set color red
        set trendy? true
        ;; if the turtle has already adopted the trend from media, 
        ;; leave it be. otherwise, set its source to "friend"
        if trend-source != "media" [
          set trend-source "friend"
        ]
        set trend-category [trend-category] of myself
      ]
      set times-heard times-heard + 1
    ]
    ;; if a trend spreads between 2 turtles, turn the link between them red
    ask links [
      if all? both-ends [trendy? = true]
        [ ifelse color-mode = 0 or color-mode = 1
          [set color red]
          [ifelse color-mode = 2
            [set color blue]
            [set color 83]
          ]
        ]
    ]
  ]
end 

;; when media? is true, patches run this procedure, representing TV-watching.
;; assume that a turtle will accept a trend regardless of category with media exposure

to media-trend
  set pcolor white ;; the turtle watches TV
  ;; the TV broadcasts the current trend
  set category [trend-category] of one-of turtles with [trend-setter? = true]
  let watcher one-of turtles-here
  if watcher != nobody [
    ask watcher[
      set color red
      set trendy? true
      set times-heard times-heard + 1
      ;; if the turtle has already adopted the trend from a friend, 
      ;; leave it be. otherwise, set its source to "media"
      if trend-source != "friend" [
        set trend-source "media"
      ]
      set trend-category [category] of myself     
    ]
  ]
end 
  
;; procedure to recolor to the default scheme -- color-mode = 0

to recolor-default
  ask turtles [
    ifelse trendy? = true
      [set color red]
      [set color blue]
  ]
  ask patches with [category = -1] [set pcolor black]
  ask links with [color = 83 or color = blue] [set color red]
end 

;; procedure to recolor to show source (friend vs media) -- color-mode = 1

to recolor-by-source
  ask patches with [category = -1] [set pcolor black]
  ask turtles with [trend-source = "media"] [set color yellow]
  ask turtles with [trend-source = "friend"] [set color red]
  ask turtles with [trend-source = 0] [set color blue]
  ask links with [color = 83 or color = blue] [set color red]
end 

;; procedure to recolor to display the number of times heard -- color-mode = 2

to recolor-by-times-heard
  ask patches with [category = -1] [set pcolor 3]
  ask turtles [set color scale-color green times-heard 0 world-width * 2]
  ask links with [color = red or color = 83] [set color blue]
end 

;; procedure to recolor to show popularity levels -- color-mode = 3

to recolor-by-popularity
  ask patches with [category = -1] [set pcolor 3]
  ask turtles [set color scale-color violet popularity 0 world-width * 2]
  ask links with [color = red or color = blue] [set color 83]
end 

;; procedure to recolor while the "go" function is running

to recolor
  ifelse color-mode = 0
    [recolor-default]
    [ ifelse color-mode = 1
      [recolor-by-source]
      [ifelse color-mode = 2
        [recolor-by-times-heard]
        [recolor-by-popularity]
      ]
    ]
end