//shack/Eselkalk: initial commit

This commit tries to calculate the dates of shack-plena.

1 files changed, 57 insertions, 0 deletions

diff --git a/shack/Eselkalk/index.js b/shack/Eselkalk/index.js
new file mode 100644
index 00000000..f64e0605
--- /dev/null
+++ b/shack/Eselkalk/index.js
@@ -0,0 +1,57 @@
+//
+// node //shack/Eselkalk DATE
+//
+// where DATE ∈ [YYYY[-MM]], defaulting to the current YYYY-MM
+//
+
+range = process.argv[2] ||
+    JSON.parse(JSON.stringify(new Date())).slice(0, '....-..'.length)
+
+function dates(date) {
+  var year = date.getFullYear()
+  var month = date.getMonth()
+
+  var i = new Date([year, (month < 9 ? '0' : '') + (month + 1)].join('-'))
+
+  var days = []
+  var next_day = 4;
+  for (
+      ; i.getMonth() === month
+      ; i = new Date(+i + 24 * 60 * 60 * 1000)) {
+    if (i.getDay() === next_day) {
+      next_day = next_day === 3 ? 4 : 3
+      if (next_day === 3) {
+        var next_4day = new Date(+i + 7 * 24 * 60 * 60 * 1000)
+        if (next_4day.getMonth() !== month) {
+          i = new Date(+i - 24 * 60 * 60 * 1000)
+          next_4day = 4
+        }
+      }
+      days.push(new Date(+i + (20 * 60 + i.getTimezoneOffset()) * 60 * 1000))
+      while (i.getDay() !== 0) {
+        i = new Date(+i + 24 * 60 * 60 * 1000)
+      }
+    }
+  }
+
+  return days
+}
+
+
+result = []
+
+// TODO if (/^....-..-..$/.test(range)) { ... }
+if (/^....-..$/.test(range)) {
+  result = dates(new Date(range))
+}
+else if (/^....$/.test(range)) {
+  ['01','02','03','04','05','06','07','08','09','10','11','12'
+  ].forEach(function (i) {
+    result = result.concat(dates(new Date([range, i].join('-'))))
+  })
+}
+else {
+  throw new Error('You are made of stupid! ' + range)
+}
+
+console.log(JSON.stringify(result, null, 2))