EDIT: the previous version of this ticket was to output a full train schedule, but that's not the plan anymore. Instead, core will directly output something akin to a space-time chart, as that's the end goal here. It won't be directly an image, rather some csv/json that can be used to build it.

What we need to have

We'll generally want to have a 2D space with distance on one axis and time on the other. We'll first log every relevant data, and then see how it can be plotted (probably in a notebook)

Required:

• Train head position
• When each zone is occupied
• By which train (with an ID that isn't specific to OSRD)

Nice to have:

• Train tail position
• Head / tail positions of other trains (that directly show up on the tracks)
• When the new train needs each zone to be free
• Path data: zones, signals, routes
• Train speed at each location
• Maximum speed at each location
• Temporary speed limits?
• Engineering allowance ranges

Implementation plan (draft):

We'll generate some JSON data during post-processing, with every relevant data we can fetch. At first we'll dump it into a file, eventually it should be uploaded to the object storage.

Easy to get:

• Train head / tail position
• When each zone is occupied by a different train
• Path data
• Speed, max speed, temporary speed limits
• Engineering allowance range

ID of other trains: we'll need to attach some metadata to the "cached timetables". It shouldn't be too tricky. -> Turns out we also need to add that data to the requirement endpoint response. Still doable.

When the train needs each zone to be free: we'll need to dig into what is now private / hidden behind abstract interfaces. It can be done, but the result may not be very nice (in terms of implementation) -> We can just plot the requirements in front of the trains (as it should be), no issue there.

Head/tail position of other trains: we just don't have the information there.