From 1c978b7cce8e141abb28858583708a59d480c4e7 Mon Sep 17 00:00:00 2001
From: Onne <onne@onnlucky.com>
Date: Sat, 20 Jul 2024 10:20:52 +0200
Subject: [PATCH] Fix last point of line charts. And small other fixes to line
 charts. (#21235)

* Fixes last point of graphs.

Especially for items that don't often change state, the last state could
be essentially be ignored for quite a while, using the average of the
last series of entries instead.

Also for detailed graphs, the initial values could be off, because the
initial last value would be computed on bad data, resulting in NaN.

And no longer adds a double entry at end if graph has only one point.
---
 src/panels/lovelace/common/graph/coordinates.ts | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/panels/lovelace/common/graph/coordinates.ts b/src/panels/lovelace/common/graph/coordinates.ts
index 56f5251965..02226d2bab 100644
--- a/src/panels/lovelace/common/graph/coordinates.ts
+++ b/src/panels/lovelace/common/graph/coordinates.ts
@@ -22,9 +22,15 @@ const calcPoints = (
   let xRatio = width / (hours - (detail === 1 ? 1 : 0));
   xRatio = isFinite(xRatio) ? xRatio : width;
 
-  const first = history.filter(Boolean)[0];
+  let first = history.filter(Boolean)[0];
+  if (detail > 1) {
+    first = first.filter(Boolean)[0];
+  }
   let last = [average(first), lastValue(first)];
 
+  const getY = (value: number): number =>
+    height + strokeWidth / 2 - (value - min) / yRatio;
+
   const getCoords = (item: any[], i: number, offset = 0, depth = 1) => {
     if (depth > 1 && item) {
       return item.forEach((subItem, index) =>
@@ -37,8 +43,7 @@ const calcPoints = (
     if (item) {
       last = [average(item), lastValue(item)];
     }
-    const y =
-      height + strokeWidth / 2 - ((item ? last[0] : last[1]) - min) / yRatio;
+    const y = getY(item ? last[0] : last[1]);
     return coords.push([x, y]);
   };
 
@@ -46,11 +51,7 @@ const calcPoints = (
     getCoords(history[i], i, 0, detail);
   }
 
-  if (coords.length === 1) {
-    coords[1] = [width, coords[0][1]];
-  }
-
-  coords.push([width, coords[coords.length - 1][1]]);
+  coords.push([width, getY(last[1])]);
   return coords;
 };