From 41a94d07f00f53d4624205fa4b23553a11e305dc Mon Sep 17 00:00:00 2001
From: Rigel Kent <sendmemail@rigelk.eu>
Date: Sat, 11 Apr 2020 15:58:44 +0200
Subject: Refactor from-now pipe to display the two most significant intervals

---
 client/src/app/shared/angular/from-now.pipe.ts | 89 +++++++++++++++++++-------
 1 file changed, 66 insertions(+), 23 deletions(-)

(limited to 'client/src/app/shared')

diff --git a/client/src/app/shared/angular/from-now.pipe.ts b/client/src/app/shared/angular/from-now.pipe.ts
index 3a9a76411..c3c0efbfc 100644
--- a/client/src/app/shared/angular/from-now.pipe.ts
+++ b/client/src/app/shared/angular/from-now.pipe.ts
@@ -1,5 +1,6 @@
 import { Pipe, PipeTransform } from '@angular/core'
 import { I18n } from '@ngx-translate/i18n-polyfill'
+import { findIndex } from 'lodash-es'
 
 // Thanks: https://stackoverflow.com/questions/3177836/how-to-format-time-since-xxx-e-g-4-minutes-ago-similar-to-stack-exchange-site
 @Pipe({ name: 'myFromNow' })
@@ -10,31 +11,73 @@ export class FromNowPipe implements PipeTransform {
   transform (arg: number | Date | string) {
     const argDate = new Date(arg)
     const seconds = Math.floor((Date.now() - argDate.getTime()) / 1000)
+    let intervals = [
+      {
+        unit: 31536000, // 1 year
+        singular: (i: number) => this.i18n('{{i}} year', { i }),
+        plural: (i: number) => this.i18n('{{i}} years', { i })
+      },
+      {
+        unit: 2592000, // 1 month
+        max: 11,
+        singular: (i: number) => this.i18n('{{i}} month', { i }),
+        plural: (i: number) => this.i18n('{{i}} months', { i })
+      },
+      {
+        unit: 604800, // 1 week
+        max: 3,
+        singular: (i: number) => this.i18n('{{i}} week', { i }),
+        plural: (i: number) => this.i18n('{{i}} weeks', { i })
+      },
+      {
+        unit: 86400, // 1 day
+        max: 6,
+        singular: (i: number) => this.i18n('{{i}} day', { i }),
+        plural: (i: number) => this.i18n('{{i}} days', { i })
+      },
+      {
+        unit: 3600, // 1 hour
+        max: 23,
+        singular: (i: number) => this.i18n('{{i}} hour', { i }),
+        plural: (i: number) => this.i18n('{{i}} hours', { i })
+      },
+      {
+        unit: 60, // 1 min
+        max: 59,
+        singular: (i: number) => this.i18n('{{i}} min', { i }),
+        plural: (i: number) => this.i18n('{{i}} min', { i })
+      }
+    ]
+      .map(i => ({ ...i, interval: Math.floor(seconds / i.unit) })) // absolute interval
+      .map((i, index, array) => ({ // interval relative to remainder
+        ...i,
+        interval: index === 0
+          ? i.interval
+          : Math.floor((seconds - array[index - 1].interval * array[index - 1].unit) / i.unit)
+      }))
+      .map(i => ({ // value, interval put in its translated text wrt max value
+        ...i,
+        value: (i.interval > 1
+          ? i.plural
+          : i.singular
+        )(Math.min(i.max, i.interval)) // respect the max value
+      }))
 
-    let interval = Math.floor(seconds / 31536000)
-    if (interval > 1) {
-      return this.i18n('{{interval}} years ago', { interval })
-    }
-
-    interval = Math.floor(seconds / 2592000)
-    if (interval > 1) return this.i18n('{{interval}} months ago', { interval })
-    if (interval === 1) return this.i18n('{{interval}} month ago', { interval })
-
-    interval = Math.floor(seconds / 604800)
-    if (interval > 1) return this.i18n('{{interval}} weeks ago', { interval })
-    if (interval === 1) return this.i18n('{{interval}} week ago', { interval })
+    // only keep the first two intervals with enough seconds to be considered
+    const big_interval_index = findIndex(intervals, i => i.interval >= 1)
+    intervals = intervals
+      .slice(big_interval_index, big_interval_index + 2)
+      .filter(i => i.interval >= 1)
 
-    interval = Math.floor(seconds / 86400)
-    if (interval > 1) return this.i18n('{{interval}} days ago', { interval })
-    if (interval === 1) return this.i18n('{{interval}} day ago', { interval })
-
-    interval = Math.floor(seconds / 3600)
-    if (interval > 1) return this.i18n('{{interval}} hours ago', { interval })
-    if (interval === 1) return this.i18n('{{interval}} hour ago', { interval })
-
-    interval = Math.floor(seconds / 60)
-    if (interval >= 1) return this.i18n('{{interval}} min ago', { interval })
+    if (intervals.length === 0) {
+      return this.i18n('just now')
+    }
 
-    return this.i18n('{{interval}} sec ago', { interval: Math.max(0, seconds) })
+    return intervals.length == 1
+      ? this.i18n('{{interval}} ago', { interval: intervals[0].value })
+      : this.i18n('{{big_interval}} {{small_interval}} ago', { 
+          big_interval: intervals[0].value,
+          small_interval: intervals[1].value
+        })
   }
 }
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