From 57fd6a640aaee223adaa174ad5d1fb82f496a878 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Wiedemann?= <jerome@wnetworks.org>
Date: Sun, 31 Jan 2021 17:22:27 +0000
Subject: [PATCH] feat(group_by): Add new `diff` function

---
 README.md              |  1 +
 src/graphEntry.ts      | 10 ++++++++++
 src/types-config-ti.ts |  2 +-
 src/types-config.ts    |  2 +-
 4 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index ab137a2..12b7d83 100644
--- a/README.md
+++ b/README.md
@@ -183,6 +183,7 @@ The card stricly validates all the options available (but not for the `apex_conf
 | `sum` | v1.0.0 | Will return the sum of all the states in each bucket |
 | `median` | v1.0.0 | Will return the median of all the states in each bucket |
 | `delta` | v1.0.0 | Will return the delta between the biggest and smallest state in each bucket |
+| `diff` | MEXT_VERSION | Will return the difference between the last and the first entry in the bucket |
 
 ### `chart_type` Options
 
diff --git a/src/graphEntry.ts b/src/graphEntry.ts
index 10075b0..74828bb 100644
--- a/src/graphEntry.ts
+++ b/src/graphEntry.ts
@@ -63,6 +63,7 @@ export default class GraphEntry {
       sum: this._sum,
       median: this._median,
       delta: this._delta,
+      diff: this._diff,
     };
     this._index = index;
     this._cache = cache;
@@ -377,6 +378,15 @@ export default class GraphEntry {
     return max === null || min === null ? null : max - min;
   }
 
+  private _diff(items: EntityCachePoints): number | null {
+    const first = this._first(items);
+    const last = this._last(items);
+    if (first === null || last === null) {
+      return null;
+    }
+    return last - first;
+  }
+
   private _filterNulls(items: EntityCachePoints): EntityCachePoints {
     return items.filter((item) => item[1] !== null);
   }
diff --git a/src/types-config-ti.ts b/src/types-config-ti.ts
index 037536d..1f265ec 100644
--- a/src/types-config-ti.ts
+++ b/src/types-config-ti.ts
@@ -58,7 +58,7 @@ export const ChartCardPrettyTime = t.union(t.lit('millisecond'), t.lit('second')
 
 export const GroupByFill = t.union(t.lit('null'), t.lit('last'), t.lit('zero'));
 
-export const GroupByFunc = t.union(t.lit('raw'), t.lit('avg'), t.lit('min'), t.lit('max'), t.lit('last'), t.lit('first'), t.lit('sum'), t.lit('median'), t.lit('delta'));
+export const GroupByFunc = t.union(t.lit('raw'), t.lit('avg'), t.lit('min'), t.lit('max'), t.lit('last'), t.lit('first'), t.lit('sum'), t.lit('median'), t.lit('delta'), t.lit('diff'));
 
 export const ChartCardHeaderExternalConfig = t.iface([], {
   "show": t.opt("boolean"),
diff --git a/src/types-config.ts b/src/types-config.ts
index b89ff2b..a5d1d05 100644
--- a/src/types-config.ts
+++ b/src/types-config.ts
@@ -54,7 +54,7 @@ export type ChartCardPrettyTime = 'millisecond' | 'second' | 'minute' | 'hour' |
 
 export type GroupByFill = 'null' | 'last' | 'zero';
 
-export type GroupByFunc = 'raw' | 'avg' | 'min' | 'max' | 'last' | 'first' | 'sum' | 'median' | 'delta';
+export type GroupByFunc = 'raw' | 'avg' | 'min' | 'max' | 'last' | 'first' | 'sum' | 'median' | 'delta' | 'diff';
 
 export interface ChartCardHeaderExternalConfig {
   show?: boolean;