I realised I had an ical file of all my appointments from the period I used Google Calendar from January 2008 when I started as an independent consultant, until February 2020 when I switched to the calendar in my company’s NextCloud.
I never search through that file even though I sometimes wonder what I did at a certain moment in that period. After a nudge by Martijn Aslander who wrote on a community platform we both frequent about back filling his daily activities into Obisidian for instance based on his photos of a day through the years in his archive, I thought to import that ical file and turn it into day logs listing my appointments for a date.

I tried to find some ready made parsers or libraries I could use in PHP, but most I could find is aimed at importing a live calendar rather than an archived file, and none of them were aimed at creating an output of that file in a different format. Looking at the ical file I realised that making my own simple parser should be easy enough.

I write a small PHP script that reads the ical file line by line until it finds one that says BEGIN:VEVENT. Then it reads the lines until it finds the closing line END:VEVENT. It then interprets the information between those lines, lifting out the date, location, name and description, while ignoring any other information.
After each event it finds, it writes to a file ‘Daylog [date].md’ in a folder ./year/month (creating the file or appending the event as a new line if the file exists). It uses the format I use for my current Day logs.
Let it repeat until it processed all 4.714 events in my calendar from 2008 to 2020.

A screenshot of all the folders with Daylogs created from 2008-2020

Screenshot of the newly created Daylog for 20 February 2008, based on the appointments I had that day, taken from the calendar archive. This one mentions a preparatory meeting for the open GovCamp I helped organise that year in June, which kicked off my work in open data since then.