The plan implicitly defines different segments of the GPX track. I mean those defined by the different :daily-plans in the plan definition. There should be a way to display these segments, for example with a different color.
This should be possible using leaflet-gpx line styling facility.
Another option could be to just split the GPX into multiple GPX tracks, according to start and end kilometers they should represent

Explain the features usable in a Clerk notebook

At the moment kilometers in a day calculation is solely based on the average speed parameter provided by the user.
For example:

(defn kilometers-in-a-day [day-plan average-speed]
  (reduce + (map #(* (:length %) average-speed)
                 (filter #(= (:type %) :ride)
                         (:activities day-plan)))))

I should switch to a different structure that allows more flexibility.
For example, a generator of couples (hour, speed) instead of a constant average speed.
This way, one can produce different generator functions according to different models.
One model would be the existing constant average speed.
Another model could take into account the elevation to apply a <1 multiplier to the provided average speed.
Another model could use another parameter like the Watt expressed by the cyclist, to combine it with other parameters (some suggested "bumpiness")

This way, at least, the visualization will be readable even if the user switches to dark mode

Calculating a diagram is slow. I suspect I am calling points (which reads and parse a XML file)`` too many times

When used standalone

(let [elevation (gpx/elevation gpx-resource)]
  (clerk/html
   [:svg {:width 600 :height 200}
    (diagram/elevation-diagram {:elevation elevation
                                :from 0
                                :to 400
                                :viewbox [0 0 600 200]})]))

but, when used in a plan diagram

(clerk/html
 (diagram/plan->diagram plan-start-19))

For reference, here the elevation chart displayed by Komoot for the same GPX file

This is important, because it would enable a better composition of viewers

They do, but then the map is invisible

Places where the information should be visible

• Plan diagram
• Map marker popups
• Elevation diagram

There are too many arbitrary constants in the code (especially in diagram.clj

• Elevation diagrams
• Maps (saved for later)

For example, to have separate maps showing different days from the plan.
E.g.

(clerk/with-viewer leaflet/leaflet-gpx-detail
  {:plan a-certain-plan
    :day "day 1" ; the same label used in a plan
  })

leaflet/leaflet-gpx-viewer currently requires to specify a point to center the map.

(clerk/with-viewer leaflet/leaflet-gpx-viewer
  {:gpx "https://stefanorodighiero.net/misc/VG-2024_400k_lake_provvis.gpx"
   ;; :gpx-content gpx-content
   :center [45.478431 11.439041]
   :markers (plan/points-at-daily-kilometers
             gpx-resource
             plan-start-19)
   :zoom 9})

It should not be a task of the user

The popups placed on the maps require to specify a lot of information, and that information is directly in the code composing the map.

                                            (doseq [pp (:markers value)]
                                              (.bindPopup
                                               (.addTo (.marker js/L (clj->js [(:lat pp) (:lon pp)])) @m)
                                               (str "<small>"
                                                    "<strong>" (:label pp) "</strong>"
                                                    "<br />"
                                                    (.floor js/Math (:kilometers pp))
                                                    " km / ("
                                                    (.floor js/Math (:cumulative-distance pp))
                                                    " km) ▲ "
                                                    (.floor js/Math (:elevation pp))
                                                    "</small>")))))

It should be instead provided by the user, for example as a popup-message attribute.
This way markerts could be also used when not providing a plan.

When updating a plan (and saving the file) after loading the notebook for the first time, an error occurs:

More precisely, to reproduce:

• in a notebook, bind (def) a plan to a symbol
• use the plan with leaflet/leaflet-gpx-viewer
• so far so good
• but if you change the definition in the def expression, the error occurs
• if the literal for the plan is instead passed directly to leaflet/leaflet-gpx-viewer, no error

The last point is surprising, because I thought it would have been the same, either updating a data definition, or updating directly the viewer invocation.

There's already a GPX referernce in the plan anyway.

This would allow to use the metadata notation to apply viewers to plans
(when also #22 is closed)

It would be nice to display the GPX data on an actual map, and highlight the different segments in the plan

Todo

• Display maps
  • Passing a GPX file content as a string
  • Passing a GPX file as a URL
• Display multiple maps on the same notebook
• Automatically center the map usign the GPX data
• Resolve unstability issues: sometimes the notebook displays a "Invalid module" error, that spontaneusly goes away when reloading the page