From a7dd95107eac65e10e2f9380e92da89a661106d5 Mon Sep 17 00:00:00 2001
From: Ned Palacios <npdoesmc@gmail.com>
Date: Sat, 25 Nov 2023 23:28:24 +0800
Subject: [PATCH] fix: inconsistencies in line number issue in output_gen.go

---
 output_gen.go | 23 ++++++++++++++++-------
 source.go     | 12 ++++++++++--
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/output_gen.go b/output_gen.go
index 1557225..3ffd274 100644
--- a/output_gen.go
+++ b/output_gen.go
@@ -85,7 +85,7 @@ func (gen *OutputGenerator) Generate(cd *ContextData, explain *ExplainGenerator,
 			startRow = uint32(cd.MainError.ErrorNode.StartPos.Line)
 		}
 
-		startLines := doc.LinesAt(int(startRow)-1, int(startRow)+1)
+		startLines := doc.LinesAt(int(startRow)-1, int(startRow))
 		endLines := doc.LinesAt(min(int(startRow)+1, doc.TotalLines()), doc.TotalLines())
 		arrowLength := int(cd.MainError.Nearest.EndByte() - cd.MainError.Nearest.StartByte())
 		if arrowLength == 0 {
@@ -136,9 +136,15 @@ func (gen *OutputGenerator) Generate(cd *ContextData, explain *ExplainGenerator,
 
 				if len(step.Fixes) != 0 {
 					descriptionBuilder := &strings.Builder{}
+
+					// get the start and end line after applying the diff
 					startLine := step.Fixes[0].StartPosition.Line
 					afterLine := step.Fixes[0].EndPosition.Line
 
+					// get the original start and end line
+					origStartLine := step.Fixes[0].StartPosition.Line
+					origAfterLine := step.Fixes[0].EndPosition.Line
+
 					for fIdx, fix := range step.Fixes {
 						diffPosition = diffPosition.addNoCheck(editedDoc.Apply(Changeset{
 							NewText:  fix.NewText,
@@ -146,8 +152,11 @@ func (gen *OutputGenerator) Generate(cd *ContextData, explain *ExplainGenerator,
 							EndPos:   fix.EndPosition,
 						}.Add(diffPosition)))
 
-						startLine = min(startLine, fix.StartPosition.Line)
-						afterLine = max(afterLine, fix.EndPosition.Line)
+						origStartLine = min(origStartLine, fix.StartPosition.Line)
+						origAfterLine = max(origAfterLine, fix.EndPosition.Line)
+
+						startLine = min(startLine, fix.StartPosition.Line+diffPosition.Line)
+						afterLine = max(afterLine, fix.EndPosition.Line+diffPosition.Line)
 
 						if len(fix.Description) != 0 {
 							if fIdx < len(step.Fixes)-1 {
@@ -159,21 +168,21 @@ func (gen *OutputGenerator) Generate(cd *ContextData, explain *ExplainGenerator,
 					}
 
 					gen.writeln("```diff")
-					gen.writeLines(editedDoc.LinesAt(startLine-2, startLine)...)
+					gen.writeLines(editedDoc.LinesAt(startLine-2, startLine-1)...)
 
-					original := editedDoc.LinesAt(startLine+1, afterLine)
+					original := editedDoc.LinesAt(origStartLine, origAfterLine)
 					for _, origLine := range original {
 						gen.write("- ")
 						gen.writeln(origLine)
 					}
 
-					modified := editedDoc.ModifiedLinesAt(startLine+1, afterLine)
+					modified := editedDoc.ModifiedLinesAt(startLine, afterLine)
 					for _, modifiedLine := range modified {
 						gen.write("+ ")
 						gen.writeln(modifiedLine)
 					}
 
-					gen.writeLines(editedDoc.LinesAt(afterLine+1, min(afterLine+3, editedDoc.TotalLines()))...)
+					gen.writeLines(editedDoc.LinesAt(origAfterLine+1, min(origAfterLine+2, editedDoc.TotalLines()))...)
 					gen.writeln("```")
 					if descriptionBuilder.Len() != 0 {
 						gen.writeln(descriptionBuilder.String())
diff --git a/source.go b/source.go
index 5944c98..61aa8a9 100644
--- a/source.go
+++ b/source.go
@@ -15,6 +15,10 @@ type Position struct {
 	Index  int
 }
 
+func (pos Position) IsInBetween(loc Location) bool {
+	return pos.Index >= loc.StartPos.Index && pos.Index <= loc.EndPos.Index
+}
+
 func (pos Position) Add(pos2 Position) Position {
 	return Position{
 		Line:   max(pos.Line+pos2.Line, 0),
@@ -48,6 +52,10 @@ type Location struct {
 	EndPos   Position
 }
 
+func (loc Location) IsWithin(other Location) bool {
+	return loc.StartPos.IsInBetween(other) && loc.EndPos.IsInBetween(other)
+}
+
 func (loc Location) Point() sitter.Point {
 	return sitter.Point{
 		Row:    uint32(loc.StartPos.Line),
@@ -307,10 +315,10 @@ func linesAt(list []string, from int, to int) []string {
 	} else if from > 0 && to == len(list) {
 		return list[from:]
 	} else if from == 0 && to < len(list) {
-		return list[:to]
+		return list[:to+1]
 	}
 
-	return list[from:to]
+	return list[from : to+1]
 }
 
 func (doc *EditableDocument) ModifiedLinesAt(from int, to int) []string {