night-and-day

A vim theme scheduler. Divide your day into as many intervals as you like, assigning each interval its own theme.

Intervals can be defined using absolute time (HH:MM) or sun-relative time (portions of day/night based on local sunrise/sunset times).

installation

If you don't have a preferred approach to plugin management, consider trying vim-plug, which can be installed with:

curl -fLo ~/.vim/autoload/plug.vim --create-dirs \
    https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim

To install night-and-day via vim-plug, add the following to the top of your vimrc:

call plug#begin('~/.vim/plugged')
Plug 'nightsense/night-and-day'
call plug#end()

Then, within vim, run PlugUpdate.

configuration

Add a "nested list" containing your settings to vimrc, like so:

let g:nd_themes = [
  \ ['4:00',  'base16-default-light', 'light' ],
  \ ['11:00', 'solarized',            'light' ],
  \ ['18:00', 'solarized',            'dark'  ],
  \ ]

column 1: the start time for each theme in H:MM/HH:MM format (valid range: 0:00-23:59)
- arrange your list in chronological order
column 2: the name of each theme (as used by the vim command colorscheme)
column 3: the background state for each theme (either light or dark)

All three columns are required for each entry in the list.

The above sample configuration, which reflects the world map image at the top of this readme, will activate:

base16-default-light 4-11AM
solarized (light background) 11AM-6PM
solarized (dark background) 6PM-4AM

sun-relative times

In addition to absolute times, you can set times relative to sunrise/sunset.

let g:nd_themes = [
  \ ['sunrise+0',   'base16-default-light', 'light' ],
  \ ['sunrise+1/2', 'solarized',            'light' ],
  \ ['sunset+0',    'solarized',            'dark'  ],
  \ ]
let g:nd_latitude = '50'
let g:nd_timeshift = '74'

sun-relative times are specified with the prefix sunrise+ or sunset+
the + refers to the period following the solar event in question: the daylight period after sunrise, the darkness period after sunset
the number after +, which must be either 0 or a fraction with value less than 1, denotes how far the start time should be extended into the following period

Thus, sunrise+0 denotes the moment of sunrise, while sunrise+1/3 denotes the moment one third into the daylight period. At sunrise+1/2, known as "solar noon", the sun reaches its highest point in the sky. The opposite time, sunset+1/2, is "solar midnight".

The above sample configuration will activate:

base16-default-light from sunrise to halfway through the day (solar noon)
solarized (light background) from solar noon until sunset
solarized (dark background) from sunset until sunrise (the entire darkness period)

Note that the above configuration also features two new variables. The first, g:nd_latitude, is mandatory when using sun-relative time. Indeed, the presence of this variable in vimrc is the trigger that activates sun-relative time; in order to switch back to absolute time, simply remove it.

There are 23 permitted latitude values; choose the one nearest you.

region	permitted values for `g:nd_latitude`
north temperate	`30` `40` `45` `50` `55` `57.5` `60` `62.5` `65`
tropics	`-20` `-10` `0` `10` `20`
south temperate	`-65` `-62.5` `-60` `-57.5` `-55` `-50` `-45` `-40` `-30`

The second additional variable, g:nd_timeshift, is optional, though appropriate for most users. This variable specifies an offset (in minutes, positive or negative) for sunrise/sunset times to be shifted. An offset is necessary to account for one's longitudinal position within a timezone, as well as daylight saving time (if applicable).

The simplest way to determine the appropriate value for g:nd_timeshift is to start vim with the following configuration:

let g:nd_themes = [
  \ ['sunrise+0', 'default', 'light' ],
  \ ['sunset+0',  'default', 'light' ],
  \ ]
let g:nd_latitude = 'LL'
let g:nd_timeshift = '0'

...where LL is the value closest to your current latitude. Then, from the vim command line, run :call NdSchedule(). This will print your theme schedule, including the precise times being used for sun-relative timings.

Next, get today's exact sunrise/sunset times via an online search. (With something like "[YOUR LOCATION] sunrise sunset", Google will likely give you the information in one of those answer boxes.) Finally, set nd_timeshift to the appropriate value to get accurate sunrise/sunset times. Relaunch vim and run :call NdSchedule() again to confirm the offset.

If your region features daylight saving time (DST) for part of the year, you can take care of the adjustment automatically by wrapping g:nd_timeshift in an "if statement". For instance, to activate DST for March through September:
if strftime("%m") > 2 && strftime("%m") < 10
  let g:nd_timeshift = '67'
else
  let g:nd_timeshift = '7'
endif

status line themes

To add airline themes to your schedule, activate airline support with let g:nd_airline = 1 and add the theme names as the fourth item on each line, like so:

Note: this example requires vim-airline-themes to be installed, in addition to vim-airline.

let g:nd_themes = [
  \ ['07:00', 'solarized', 'light', 'solarized' ],
  \ ['08:00', 'solarized', 'dark' , 'solarized' ],
  \ ]
let g:nd_airline = 1

For lightline themes:

Note: this example requires lightline.vim to be installed.

let g:nd_themes = [
  \ ['07:00', 'base16-default-light', 'light' , 'Tomorrow' ],
  \ ['08:00', 'base16-default-dark',  'dark'  , 'Tomorrow_Night'  ],
  \ ]
let g:nd_lightline = 1

notes

This plugin incorporates the vim-colorscheme-switcher by xolox.

Map image courtesy of Wikimedia Commons.

The sunrise/sunset timetables were obtained from the "year" spreadsheet provided by the US National Oceanic & Atmospheric Administration.