chore: getting ready for calendar

.gitignore

@@ -41,3 +41,4 @@ luac.out
 
 .tests
 
+Session.vim

lua/obs/calendar.lua

@@ -0,0 +1,71 @@
+local popup = require "plenary.popup"
+
+local function get_date()
+    return os.date "%x"
+end
+
+local function get_full_month_name()
+    return os.date "%B"
+end
+
+local function get_full_year()
+    return os.date "%Y"
+end
+
+local function get_full_weekday_name()
+    return os.date "%A"
+end
+
+local function get_day()
+    return os.date "%d"
+end
+
+local function get_days_in_month(month, year)
+    local days_in_month = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+    local d = days_in_month[month]
+
+    -- check for leap year
+    if month == 2 then
+        if year % 4 == 0 then
+            if year % 100 == 0 then
+                if year % 400 == 0 then
+                    d = 29
+                end
+            else
+                d = 29
+            end
+        end
+    end
+    return d
+end
+
+local function create_calendar()
+    local width = 60
+    local height = 10
+    local borderchars =
+        { "─", "│", "─", "│", "╭", "╮", "╯", "╰" }
+    local bufnr = vim.api.nvim_create_buf(false, false)
+
+    local win_id, win = popup.create(bufnr, {
+        title = "Obs.nvim Calendar",
+        highlight = "ObsNvimCalendarWindow",
+        line = math.floor(((vim.o.lines - height) / 2) - 1),
+        col = math.floor((vim.o.columns - width) / 2),
+        minwidth = width,
+        minheight = height,
+        borderchars = borderchars,
+    })
+
+    vim.api.nvim_win_set_option(
+        win.border.win_id,
+        "winhl",
+        "Normal:ObsNvimCalendarBorder"
+    )
+
+    return {
+        bufnr = bufnr,
+        win_id = win_id,
+    }
+end
+
+create_calendar()