" Keys and date formats for return value of s:Timestamp()
let s:formats = {
\ 'human': '%a, %d %b %Y %T %Z',
\ 'machine': '%Y-%m-%dT%H:%M:%S.000Z',
\}
" Get UTC timestamp string dictionary with layout in s:formats
function! s:Timestamp(time) abort
" Force UTC, recording previous timezone, if any
if exists('$TZ')
let tz = $TZ
endif
let $TZ = 'UTC'
" Get current time
let time = localtime()
" Fill out timestamp dictionary
let timestamp = {}
for key in keys(s:formats)
let timestamp[key] = strftime(s:formats[key], time)
endfor
" Clear UTC and restore previous timezone, if any
unlet $TZ
if exists('tz')
let $TZ = tz
endif
" Return filled-out timestamp dictionary
return timestamp
endfunction
" Define timestamp prefix string
let s:prefix = 'Last updated: '
" Define pattern to match date timestamps; no ZALGO, please
let s:pattern = '\m\C'
\.s:prefix
\.''
" Update a timestamp
function! html#timestamp#Update() abort
" Do nothing if the buffer hasn't been modified
if !&modified
return
endif
" Find the first occurrence of the timestamp pattern, bail if none
let lnum = search(s:pattern, 'nw')
if !lnum
return
endif
" Get timestamp dictionary
let timestamp = s:Timestamp(localtime())
" Fill out updated timestamp string with dictionary values
let update = s:prefix
\.''
" Apply the updated timestamp
let line = getline(lnum)
let line = substitute(line, s:pattern, update, '')
call setline(lnum, line)
endfunction