From f06321dea2738e339f83c8cc08e9fa829e0da0d4 Mon Sep 17 00:00:00 2001
From: Terry Truong <terry06890@gmail.com>
Date: Sat, 15 Oct 2022 12:56:01 +1100
Subject: Fix more bugs due to not excluding 0 CE

---
 src/components/TimeLine.vue |  9 +++++++++
 src/lib.ts                  | 12 ++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/components/TimeLine.vue b/src/components/TimeLine.vue
index 0c0e6d6..8301dba 100644
--- a/src/components/TimeLine.vue
+++ b/src/components/TimeLine.vue
@@ -414,6 +414,8 @@ function zoomTimeline(zoomRatio: number){
 			newStartOffset /= oldUnitsPerNew;
 			newEndOffset /= oldUnitsPerNew;
 			// Shift starting and ending points to align with new scale
+				// Note: There is some distortion due to not accounting for no year 0 CE here
+					// But the result seems tolerable, and resolving it adds a fair bit of code complexity
 			let newStartSubUnits =
 				(scale.value == DAY_SCALE) ? getDaysInMonth(newStart.year, newStart.month) :
 				(scale.value == MONTH_SCALE) ? 12 :
@@ -455,6 +457,13 @@ function zoomTimeline(zoomRatio: number){
 			} else {
 				newStart.year = Math.floor(newStart.year / newScale) * newScale;
 				newEnd.year = Math.floor(newEnd.year / newScale) * newScale;
+				// Account for no 0 CE
+				if (newStart.year == 0){
+					newStart.year = 1;
+				}
+				if (newEnd.year == 0){
+					newEnd.year = 1;
+				}
 			}
 			//
 			scaleIdx.value -= 1;
diff --git a/src/lib.ts b/src/lib.ts
index e3d0cfc..bd454bc 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -216,12 +216,16 @@ export function stepDate(date: HistDate, scale: number, {forward=true, count=1,
 			let newYear;
 			if (forward){
 				newYear = newDate.year + scale;
-				if (newDate.year < 0 && newYear >= 0){ // If different sign, account for there being no 0 CE
-					newYear += 1;
+				if (newYear == 0){ // Account for there being no 0 CE
+					newYear = 1;
+				} else if (newDate.year == 1 && scale > 1){
+					newYear -= 1;
 				}
 			} else {
 				newYear = newDate.year - scale;
-				if (newDate.year > 0 && newYear <= 0){
+				if (newYear == 0 && scale > 1){
+					newYear = 1;
+				} else if (newDate.year == 1){
 					newYear -= 1;
 				}
 			}
@@ -236,7 +240,7 @@ export function inDateScale(date: HistDate, scale: number): boolean {
 	} else if (scale == MONTH_SCALE){
 		return date.day == 1;
 	} else {
-		return date.year % scale == 0 && date.month == 1 && date.day == 1;
+		return (date.year == 1 || date.year % scale == 0) && date.month == 1 && date.day == 1;
 	}
 }
 export function getScaleRatio(scale: number, scale2: number){
-- 
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