# @name    Fuel Prices
# @desc    Cheapest nearby price, brand and street for one fuel type (tankerkoenig.de)
# @author  Hank_the_Tank / Claude
# @version 1.5
# @config  apikey text   "API key"      default="YOUR-API-KEY" help="Free key from creativecommons.tankerkoenig.de"
# @config  lat    text   "Latitude"     default="52.5200"
# @config  lon    text   "Longitude"    default="13.4050"
# @config  radius number "Radius"       default=5 min=1 max=25 unit=km
# @config  fuel   select "Fuel"         default=diesel options=diesel,e5,e10
# @config  every  number "Refresh"      default=10 min=5 max=60 unit=min
# @config  tint   color  "Price color"  default=#00FF00
# @config  icon   text   "Icon ID"      default=""

import string
import json

class FuelPrice
  var url, find                # request URL and search needle, built from settings
  var ic, tint                  # icon name and price colour
  var price, brand, street       # last known values for the cheapest station
  var label                       # the [text, color] pieces draw() paints
  var period, ticks, in_flight     # loop() pacing

  def fmt()                      # builds the coloured display pieces
    if self.price == nil return [["...", 0x666666]] end
    var b = self.brand == nil ? "" : self.brand
    var s = self.street == nil ? "" : self.street
    return [[string.format("%.3f", self.price) + "€", self.tint],
            [" | " + b + " | " + s, 0xFFFFFF]]
  end

  def init()
    self.ic = store.get("icon")
    self.tint = store.get("tint")
    self.url = "https://creativecommons.tankerkoenig.de/json/list.php?lat=" +
               store.get("lat") + "&lng=" + store.get("lon") +
               "&rad=" + str(store.get("radius")) + "&sort=price&type=" +
               store.get("fuel") + "&apikey=" + store.get("apikey")
    self.find = "{\"id\":\""     # start of the first (cheapest) station object
    self.period = store.get("every") * 60   # loop() runs ~1x/s
    self.price = store.get("price")         # survive a reboot
    self.brand = store.get("brand")
    self.street = store.get("street")
    self.label = self.fmt()
    self.ticks = 0
    self.in_flight = false
  end

  def on_body(body, status)
    self.in_flight = false
    if body == nil
      log("FuelPrices: no data (status " + str(status) + ") - check API key / coordinates")
      return
    end
    var mp = re.search("\"price\":([0-9]+\\.[0-9]+)", body)
    if mp == nil return end
    var p = num(mp[1])
    if p == nil return end
    var mb = re.search("\"brand\":\"([^\"]*)\"", body)
    var ms = re.search("\"street\":\"([^\"]*)\"", body)
    # re-wrap each raw JSON string piece and let json.load decode escapes (umlauts etc.)
    self.price = p
    self.brand = mb == nil ? "" : json.load("[\"" + mb[1] + "\"]")[0]
    self.street = ms == nil ? "" : json.load("[\"" + ms[1] + "\"]")[0]
    self.label = self.fmt()                 # rebuild the coloured line
    store.set("price", p)                   # only keep it once it is good
    store.set("brand", self.brand)
    store.set("street", self.street)
  end

  def loop()
    if self.ticks <= 0
      self.ticks = self.period
      if !self.in_flight
        self.in_flight = true
        http.get(self.url, / b, st -> self.on_body(b, st),
                 {'find': self.find, 'keep': 480})
      end
    end
    self.ticks -= 1
  end

  def draw()
    clear()
    if !icon(self.ic, 0, 0)                 # no icon set, or unknown to the device
      rect_fill(2, 1, 4, 6, 0x555555)        # fallback: a small pump shape
      rect_fill(1, 0, 2, 1, 0x555555)
      line(6, 2, 7, 2, 0x555555)
      line(7, 2, 7, 5, 0x555555)
    end
    scroll_text(9, 6, width() - 9, self.label, 0xFFFFFF)
  end

  def on_button(btn)
    if btn == "select" self.ticks = 0 end   # force an immediate refresh
  end
end

return FuelPrice()

These icons belong on the device, in /ICONS. Each one is at most 32×8 pixels — shown here magnified, at their real proportions.