From 361dc3e6d9cd9d70c1d68c3ea889b35dc78b49aa Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Fri, 9 Aug 2024 18:01:26 +0900
Subject: [PATCH 01/11] fix(viewport): fix height calculation method

---
 go.mod                    |  4 ++++
 go.sum                    | 10 ++++++++++
 viewport/viewport.go      | 16 ++++++++++++++-
 viewport/viewport_test.go | 41 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 viewport/viewport_test.go

diff --git a/go.mod b/go.mod
index 4d7b1bbcf..52e57dbb3 100644
--- a/go.mod
+++ b/go.mod
@@ -15,6 +15,7 @@ require (
 	github.com/muesli/termenv v0.15.2
 	github.com/rivo/uniseg v0.4.7
 	github.com/sahilm/fuzzy v0.1.1
+	github.com/stretchr/testify v1.9.0
 )
 
 require (
@@ -22,14 +23,17 @@ require (
 	github.com/charmbracelet/x/input v0.1.0 // indirect
 	github.com/charmbracelet/x/term v0.1.1 // indirect
 	github.com/charmbracelet/x/windows v0.1.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
 	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-localereader v0.0.1 // indirect
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
 	golang.org/x/sync v0.7.0 // indirect
 	golang.org/x/sys v0.20.0 // indirect
 	golang.org/x/text v0.3.8 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index 41f2d1d22..a5ffa50ad 100644
--- a/go.sum
+++ b/go.sum
@@ -18,6 +18,8 @@ github.com/charmbracelet/x/term v0.1.1 h1:3cosVAiPOig+EV4X9U+3LDgtwwAoEzJjNdwbXD
 github.com/charmbracelet/x/term v0.1.1/go.mod h1:wB1fHt5ECsu3mXYusyzcngVWWlu1KKUmmLhfgr/Flxw=
 github.com/charmbracelet/x/windows v0.1.0 h1:gTaxdvzDM5oMa/I2ZNF7wN78X/atWemG9Wph7Ika2k4=
 github.com/charmbracelet/x/windows v0.1.0/go.mod h1:GLEO/l+lizvFDBPLIOk+49gdX49L9YWMB5t+DZd0jkQ=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f h1:Y/CXytFA4m6baUTXGLOoWe4PQhGxaX0KpnayAqC48p4=
@@ -38,11 +40,15 @@ github.com/muesli/cancelreader v0.2.2 h1:3I4Kt4BQjOR54NavqnDogx/MIoWBFa0StPA8ELU
 github.com/muesli/cancelreader v0.2.2/go.mod h1:3XuTXfFS2VjM+HTLZY9Ak0l6eUKfijIfMUZ4EgX0QYo=
 github.com/muesli/termenv v0.15.2 h1:GohcuySI0QmI3wN8Ok9PtKGkgkFIk7y6Vpb5PvrY+Wo=
 github.com/muesli/termenv v0.15.2/go.mod h1:Epx+iuz8sNs7mNKhxzH4fWXGNpZwUaJKRS1noLXviQ8=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/sahilm/fuzzy v0.1.1 h1:ceu5RHF8DGgoi+/dR5PsECjCDH1BE3Fnmpo7aVXOdRA=
 github.com/sahilm/fuzzy v0.1.1/go.mod h1:VFvziUEIMCrT6A6tw2RFIXPXXmzXbOsSHF0DOI8ZK9Y=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e h1:JVG44RsyaB9T2KIHavMF/ppJZNG9ZpyihvCd0w101no=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e/go.mod h1:RbqR21r5mrJuqunuUZ/Dhy/avygyECGrLceyNeo4LiM=
 golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561 h1:MDc5xs78ZrZr3HMQugiXOAkSZtfTpbJLDr/lwfgO53E=
@@ -54,3 +60,7 @@ golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.3.8 h1:nAL+RVCQ9uMn3vJZbV+MRnydTJFPf8qqY42YiA6MrqY=
 golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/viewport/viewport.go b/viewport/viewport.go
index e0a4cc33f..e56b77775 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -111,7 +111,8 @@ func (m *Model) SetContent(s string) {
 // maxYOffset returns the maximum possible value of the y-offset based on the
 // viewport's content and set height.
 func (m Model) maxYOffset() int {
-	return max(0, len(m.lines)-m.Height)
+	linesHeight := countHeightBasedOnWidth(m.lines, m.Width)
+	return max(0, linesHeight-m.Height)
 }
 
 // visibleLines returns the lines that should currently be visible in the
@@ -403,3 +404,16 @@ func max(a, b int) int {
 	}
 	return b
 }
+
+func countHeightBasedOnWidth(lines []string, width int) int {
+	h := 0
+	for _, line := range lines {
+		if len(line) <= width {
+			h++
+			continue
+		}
+		h += int(math.Ceil(float64(len(line)) / float64(width)))
+	}
+
+	return h
+}
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
new file mode 100644
index 000000000..02d69eaa3
--- /dev/null
+++ b/viewport/viewport_test.go
@@ -0,0 +1,41 @@
+package viewport
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_countHeightBasedOnWidth(t *testing.T) {
+	t.Parallel()
+	tests := map[string]struct {
+		lines []string
+		width int
+		want  int
+	}{
+		"Empty lines": {
+			lines: []string{},
+			width: 0,
+			want:  0,
+		},
+		"Lines within width": {
+			lines: []string{"123", "123"},
+			width: 5,
+			want:  2,
+		},
+		"Lines over width": {
+			lines: []string{"1234567890", "123"},
+			width: 5,
+			want:  3,
+		},
+	}
+
+	for name, tt := range tests {
+		tt := tt
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			got := countHeightBasedOnWidth(tt.lines, tt.width)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}

From ee209540653a51302b2bf394e5b737d18e6c9d7e Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Wed, 14 Aug 2024 09:53:21 +0900
Subject: [PATCH 02/11] fixup! fix(viewport): fix height calculation method

---
 go.mod                    |  4 ----
 go.sum                    | 10 ----------
 viewport/viewport_test.go |  6 +++---
 3 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/go.mod b/go.mod
index 52e57dbb3..4d7b1bbcf 100644
--- a/go.mod
+++ b/go.mod
@@ -15,7 +15,6 @@ require (
 	github.com/muesli/termenv v0.15.2
 	github.com/rivo/uniseg v0.4.7
 	github.com/sahilm/fuzzy v0.1.1
-	github.com/stretchr/testify v1.9.0
 )
 
 require (
@@ -23,17 +22,14 @@ require (
 	github.com/charmbracelet/x/input v0.1.0 // indirect
 	github.com/charmbracelet/x/term v0.1.1 // indirect
 	github.com/charmbracelet/x/windows v0.1.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
 	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-localereader v0.0.1 // indirect
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
 	golang.org/x/sync v0.7.0 // indirect
 	golang.org/x/sys v0.20.0 // indirect
 	golang.org/x/text v0.3.8 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index a5ffa50ad..41f2d1d22 100644
--- a/go.sum
+++ b/go.sum
@@ -18,8 +18,6 @@ github.com/charmbracelet/x/term v0.1.1 h1:3cosVAiPOig+EV4X9U+3LDgtwwAoEzJjNdwbXD
 github.com/charmbracelet/x/term v0.1.1/go.mod h1:wB1fHt5ECsu3mXYusyzcngVWWlu1KKUmmLhfgr/Flxw=
 github.com/charmbracelet/x/windows v0.1.0 h1:gTaxdvzDM5oMa/I2ZNF7wN78X/atWemG9Wph7Ika2k4=
 github.com/charmbracelet/x/windows v0.1.0/go.mod h1:GLEO/l+lizvFDBPLIOk+49gdX49L9YWMB5t+DZd0jkQ=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f h1:Y/CXytFA4m6baUTXGLOoWe4PQhGxaX0KpnayAqC48p4=
@@ -40,15 +38,11 @@ github.com/muesli/cancelreader v0.2.2 h1:3I4Kt4BQjOR54NavqnDogx/MIoWBFa0StPA8ELU
 github.com/muesli/cancelreader v0.2.2/go.mod h1:3XuTXfFS2VjM+HTLZY9Ak0l6eUKfijIfMUZ4EgX0QYo=
 github.com/muesli/termenv v0.15.2 h1:GohcuySI0QmI3wN8Ok9PtKGkgkFIk7y6Vpb5PvrY+Wo=
 github.com/muesli/termenv v0.15.2/go.mod h1:Epx+iuz8sNs7mNKhxzH4fWXGNpZwUaJKRS1noLXviQ8=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/sahilm/fuzzy v0.1.1 h1:ceu5RHF8DGgoi+/dR5PsECjCDH1BE3Fnmpo7aVXOdRA=
 github.com/sahilm/fuzzy v0.1.1/go.mod h1:VFvziUEIMCrT6A6tw2RFIXPXXmzXbOsSHF0DOI8ZK9Y=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e h1:JVG44RsyaB9T2KIHavMF/ppJZNG9ZpyihvCd0w101no=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e/go.mod h1:RbqR21r5mrJuqunuUZ/Dhy/avygyECGrLceyNeo4LiM=
 golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561 h1:MDc5xs78ZrZr3HMQugiXOAkSZtfTpbJLDr/lwfgO53E=
@@ -60,7 +54,3 @@ golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.3.8 h1:nAL+RVCQ9uMn3vJZbV+MRnydTJFPf8qqY42YiA6MrqY=
 golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index 02d69eaa3..dc200cedd 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -2,8 +2,6 @@ package viewport
 
 import (
 	"testing"
-
-	"github.com/stretchr/testify/assert"
 )
 
 func Test_countHeightBasedOnWidth(t *testing.T) {
@@ -35,7 +33,9 @@ func Test_countHeightBasedOnWidth(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 			got := countHeightBasedOnWidth(tt.lines, tt.width)
-			assert.Equal(t, tt.want, got)
+			if tt.want != got {
+				t.Errorf("expected %v, got %v", tt.want, got)
+			}
 		})
 	}
 }

From eaff7e7f766cb409f425cdbf6177f54d0a733e06 Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Sun, 25 Aug 2024 23:47:13 +0900
Subject: [PATCH 03/11] fix the panic caused by incorrect usage of lines

---
 viewport/viewport.go      | 31 ++++++++++++++++++++-----------
 viewport/viewport_test.go | 38 ++++++++++++++++++++++----------------
 2 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index e56b77775..ae044c22c 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -111,7 +111,7 @@ func (m *Model) SetContent(s string) {
 // maxYOffset returns the maximum possible value of the y-offset based on the
 // viewport's content and set height.
 func (m Model) maxYOffset() int {
-	linesHeight := countHeightBasedOnWidth(m.lines, m.Width)
+	linesHeight := len(linesToActualDisplayedLines(m.lines, m.Width))
 	return max(0, linesHeight-m.Height)
 }
 
@@ -119,9 +119,11 @@ func (m Model) maxYOffset() int {
 // viewport.
 func (m Model) visibleLines() (lines []string) {
 	if len(m.lines) > 0 {
+		actualDisplayedLines := linesToActualDisplayedLines(m.lines, m.Width)
 		top := max(0, m.YOffset)
-		bottom := clamp(m.YOffset+m.Height, top, len(m.lines))
-		lines = m.lines[top:bottom]
+		bottom := clamp(m.YOffset+m.Height, top, len(actualDisplayedLines))
+
+		lines = actualDisplayedLines[top:bottom]
 	}
 	return lines
 }
@@ -192,7 +194,7 @@ func (m *Model) LineDown(n int) (lines []string) {
 	// Gather lines to send off for performance scrolling.
 	bottom := clamp(m.YOffset+m.Height, 0, len(m.lines))
 	top := clamp(m.YOffset+m.Height-n, 0, bottom)
-	return m.lines[top:bottom]
+	return linesToActualDisplayedLines(m.lines, m.Width)[top:bottom]
 }
 
 // LineUp moves the view down by the given number of lines. Returns the new
@@ -209,7 +211,7 @@ func (m *Model) LineUp(n int) (lines []string) {
 	// Gather lines to send off for performance scrolling.
 	top := max(0, m.YOffset)
 	bottom := clamp(m.YOffset+n, 0, m.maxYOffset())
-	return m.lines[top:bottom]
+	return linesToActualDisplayedLines(m.lines, m.Width)[top:bottom]
 }
 
 // TotalLineCount returns the total number of lines (both hidden and visible) within the viewport.
@@ -405,15 +407,22 @@ func max(a, b int) int {
 	return b
 }
 
-func countHeightBasedOnWidth(lines []string, width int) int {
-	h := 0
+// linesToActualDisplayedLines converts lines to the actual lines considering window width.
+// If there is a line that is longer than the width, it will be displayed in multiple lines.
+// For more details: https://github.com/charmbracelet/bubbles/pull/578
+// If you want to know actual behavior of this function, please check out the unit tests.
+func linesToActualDisplayedLines(lines []string, width int) []string {
+	var actual []string
 	for _, line := range lines {
 		if len(line) <= width {
-			h++
+			actual = append(actual, line)
 			continue
 		}
-		h += int(math.Ceil(float64(len(line)) / float64(width)))
+		for width < len(line) {
+			actual = append(actual, line[:width])
+			line = line[width:]
+		}
+		actual = append(actual, line)
 	}
-
-	return h
+	return actual
 }
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index dc200cedd..47cb2bcbd 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -4,27 +4,27 @@ import (
 	"testing"
 )
 
-func Test_countHeightBasedOnWidth(t *testing.T) {
+func Test_linesToActualDisplayedLines(t *testing.T) {
 	t.Parallel()
 	tests := map[string]struct {
 		lines []string
 		width int
-		want  int
+		want  []string
 	}{
-		"Empty lines": {
+		"empty slice": {
 			lines: []string{},
-			width: 0,
-			want:  0,
+			width: 3,
+			want:  []string{},
 		},
-		"Lines within width": {
-			lines: []string{"123", "123"},
-			width: 5,
-			want:  2,
+		"all lines are within width": {
+			lines: []string{"aaa", "bbb", "ccc"},
+			width: 3,
+			want:  []string{"aaa", "bbb", "ccc"},
 		},
-		"Lines over width": {
-			lines: []string{"1234567890", "123"},
-			width: 5,
-			want:  3,
+		"some lines exceeds width": {
+			lines: []string{"aaaaaa", "bbbbbbbb", "ccc"},
+			width: 3,
+			want:  []string{"aaa", "aaa", "bbb", "bbb", "bb", "ccc"},
 		},
 	}
 
@@ -32,9 +32,15 @@ func Test_countHeightBasedOnWidth(t *testing.T) {
 		tt := tt
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
-			got := countHeightBasedOnWidth(tt.lines, tt.width)
-			if tt.want != got {
-				t.Errorf("expected %v, got %v", tt.want, got)
+			got := linesToActualDisplayedLines(tt.lines, tt.width)
+
+			if len(got) != len(tt.want) {
+				t.Errorf("expected len is %d but got %d", len(tt.want), len(got))
+			}
+			for i := range tt.want {
+				if tt.want[i] != got[i] {
+					t.Errorf("expected %s but got %s", tt.want[i], got[i])
+				}
 			}
 		})
 	}

From 5e1cef42305edf5507e316dbda2cb3b5cd6cef18 Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Mon, 26 Aug 2024 00:44:25 +0900
Subject: [PATCH 04/11] fix ScrollPercent

---
 viewport/viewport.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index ae044c22c..dea456008 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -87,12 +87,14 @@ func (m Model) PastBottom() bool {
 
 // ScrollPercent returns the amount scrolled as a float between 0 and 1.
 func (m Model) ScrollPercent() float64 {
-	if m.Height >= len(m.lines) {
+	actualDisplayedLength := len(linesToActualDisplayedLines(m.lines, m.Width))
+
+	if m.Height >= actualDisplayedLength {
 		return 1.0
 	}
 	y := float64(m.YOffset)
 	h := float64(m.Height)
-	t := float64(len(m.lines))
+	t := float64(actualDisplayedLength)
 	v := y / (t - h)
 	return math.Max(0.0, math.Min(1.0, v))
 }

From 8d78f89c0e24b391a85190869eceda8ce4a5d1fa Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Mon, 26 Aug 2024 01:02:49 +0900
Subject: [PATCH 05/11] rename the function and variables

---
 viewport/viewport.go      | 22 +++++++++++-----------
 viewport/viewport_test.go |  2 +-
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index dea456008..19245daad 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -87,14 +87,14 @@ func (m Model) PastBottom() bool {
 
 // ScrollPercent returns the amount scrolled as a float between 0 and 1.
 func (m Model) ScrollPercent() float64 {
-	actualDisplayedLength := len(linesToActualDisplayedLines(m.lines, m.Width))
+	actuallyDisplayedLength := len(linesToActuallyDisplayedLines(m.lines, m.Width))
 
-	if m.Height >= actualDisplayedLength {
+	if m.Height >= actuallyDisplayedLength {
 		return 1.0
 	}
 	y := float64(m.YOffset)
 	h := float64(m.Height)
-	t := float64(actualDisplayedLength)
+	t := float64(actuallyDisplayedLength)
 	v := y / (t - h)
 	return math.Max(0.0, math.Min(1.0, v))
 }
@@ -113,7 +113,7 @@ func (m *Model) SetContent(s string) {
 // maxYOffset returns the maximum possible value of the y-offset based on the
 // viewport's content and set height.
 func (m Model) maxYOffset() int {
-	linesHeight := len(linesToActualDisplayedLines(m.lines, m.Width))
+	linesHeight := len(linesToActuallyDisplayedLines(m.lines, m.Width))
 	return max(0, linesHeight-m.Height)
 }
 
@@ -121,11 +121,11 @@ func (m Model) maxYOffset() int {
 // viewport.
 func (m Model) visibleLines() (lines []string) {
 	if len(m.lines) > 0 {
-		actualDisplayedLines := linesToActualDisplayedLines(m.lines, m.Width)
+		actuallyDisplayedLines := linesToActuallyDisplayedLines(m.lines, m.Width)
 		top := max(0, m.YOffset)
-		bottom := clamp(m.YOffset+m.Height, top, len(actualDisplayedLines))
+		bottom := clamp(m.YOffset+m.Height, top, len(actuallyDisplayedLines))
 
-		lines = actualDisplayedLines[top:bottom]
+		lines = actuallyDisplayedLines[top:bottom]
 	}
 	return lines
 }
@@ -196,7 +196,7 @@ func (m *Model) LineDown(n int) (lines []string) {
 	// Gather lines to send off for performance scrolling.
 	bottom := clamp(m.YOffset+m.Height, 0, len(m.lines))
 	top := clamp(m.YOffset+m.Height-n, 0, bottom)
-	return linesToActualDisplayedLines(m.lines, m.Width)[top:bottom]
+	return linesToActuallyDisplayedLines(m.lines, m.Width)[top:bottom]
 }
 
 // LineUp moves the view down by the given number of lines. Returns the new
@@ -213,7 +213,7 @@ func (m *Model) LineUp(n int) (lines []string) {
 	// Gather lines to send off for performance scrolling.
 	top := max(0, m.YOffset)
 	bottom := clamp(m.YOffset+n, 0, m.maxYOffset())
-	return linesToActualDisplayedLines(m.lines, m.Width)[top:bottom]
+	return linesToActuallyDisplayedLines(m.lines, m.Width)[top:bottom]
 }
 
 // TotalLineCount returns the total number of lines (both hidden and visible) within the viewport.
@@ -409,11 +409,11 @@ func max(a, b int) int {
 	return b
 }
 
-// linesToActualDisplayedLines converts lines to the actual lines considering window width.
+// linesToActuallyDisplayedLines converts lines to the lines actually displayed considering window width.
 // If there is a line that is longer than the width, it will be displayed in multiple lines.
 // For more details: https://github.com/charmbracelet/bubbles/pull/578
 // If you want to know actual behavior of this function, please check out the unit tests.
-func linesToActualDisplayedLines(lines []string, width int) []string {
+func linesToActuallyDisplayedLines(lines []string, width int) []string {
 	var actual []string
 	for _, line := range lines {
 		if len(line) <= width {
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index 47cb2bcbd..a94cf3e0a 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -32,7 +32,7 @@ func Test_linesToActualDisplayedLines(t *testing.T) {
 		tt := tt
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
-			got := linesToActualDisplayedLines(tt.lines, tt.width)
+			got := linesToActuallyDisplayedLines(tt.lines, tt.width)
 
 			if len(got) != len(tt.want) {
 				t.Errorf("expected len is %d but got %d", len(tt.want), len(got))

From eb7b9d5a0e1ffe012be413ca4445a9b91fdf033f Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Mon, 26 Aug 2024 10:35:51 +0900
Subject: [PATCH 06/11] fix: use actual lines in `SetContent`

`GoToBottom()` should be called when the offset exceeds the number of
actual lines, not the number of content lines.
---
 viewport/viewport.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index 19245daad..4a62623fd 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -105,7 +105,7 @@ func (m *Model) SetContent(s string) {
 	s = strings.ReplaceAll(s, "\r\n", "\n") // normalize line endings
 	m.lines = strings.Split(s, "\n")
 
-	if m.YOffset > len(m.lines)-1 {
+	if m.YOffset > len(linesToActuallyDisplayedLines(m.lines, m.Width))-1 {
 		m.GotoBottom()
 	}
 }

From 6f9f512c617447b7d23eb52ee8ac1af2803426b7 Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Mon, 26 Aug 2024 16:01:17 +0900
Subject: [PATCH 07/11] fix: the test function's name

---
 viewport/viewport_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index a94cf3e0a..d7cdbfda7 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -4,7 +4,7 @@ import (
 	"testing"
 )
 
-func Test_linesToActualDisplayedLines(t *testing.T) {
+func Test_linesToActuallyDisplayedLines(t *testing.T) {
 	t.Parallel()
 	tests := map[string]struct {
 		lines []string

From a3e0450b7e45b79a8a5c6bc6c3df9283e0631311 Mon Sep 17 00:00:00 2001
From: bashbunni <bunni@bashbunni.dev>
Date: Sat, 7 Sep 2024 09:01:13 -0700
Subject: [PATCH 08/11] refactor(viewport): clarify naming for wrapped lines

---
 viewport/viewport.go      | 37 +++++++++++++++++--------------------
 viewport/viewport_test.go |  4 ++--
 2 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index 4a62623fd..1f60ec19e 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -87,14 +87,14 @@ func (m Model) PastBottom() bool {
 
 // ScrollPercent returns the amount scrolled as a float between 0 and 1.
 func (m Model) ScrollPercent() float64 {
-	actuallyDisplayedLength := len(linesToActuallyDisplayedLines(m.lines, m.Width))
+	wrappedLines := len(wrap(m.lines, m.Width))
 
-	if m.Height >= actuallyDisplayedLength {
+	if m.Height >= wrappedLines {
 		return 1.0
 	}
 	y := float64(m.YOffset)
 	h := float64(m.Height)
-	t := float64(actuallyDisplayedLength)
+	t := float64(wrappedLines)
 	v := y / (t - h)
 	return math.Max(0.0, math.Min(1.0, v))
 }
@@ -105,7 +105,7 @@ func (m *Model) SetContent(s string) {
 	s = strings.ReplaceAll(s, "\r\n", "\n") // normalize line endings
 	m.lines = strings.Split(s, "\n")
 
-	if m.YOffset > len(linesToActuallyDisplayedLines(m.lines, m.Width))-1 {
+	if m.YOffset > len(wrap(m.lines, m.Width))-1 {
 		m.GotoBottom()
 	}
 }
@@ -113,7 +113,7 @@ func (m *Model) SetContent(s string) {
 // maxYOffset returns the maximum possible value of the y-offset based on the
 // viewport's content and set height.
 func (m Model) maxYOffset() int {
-	linesHeight := len(linesToActuallyDisplayedLines(m.lines, m.Width))
+	linesHeight := len(wrap(m.lines, m.Width))
 	return max(0, linesHeight-m.Height)
 }
 
@@ -121,11 +121,11 @@ func (m Model) maxYOffset() int {
 // viewport.
 func (m Model) visibleLines() (lines []string) {
 	if len(m.lines) > 0 {
-		actuallyDisplayedLines := linesToActuallyDisplayedLines(m.lines, m.Width)
+		wrappedLines := wrap(m.lines, m.Width)
 		top := max(0, m.YOffset)
-		bottom := clamp(m.YOffset+m.Height, top, len(actuallyDisplayedLines))
+		bottom := clamp(m.YOffset+m.Height, top, len(wrappedLines))
 
-		lines = actuallyDisplayedLines[top:bottom]
+		lines = wrappedLines[top:bottom]
 	}
 	return lines
 }
@@ -196,7 +196,7 @@ func (m *Model) LineDown(n int) (lines []string) {
 	// Gather lines to send off for performance scrolling.
 	bottom := clamp(m.YOffset+m.Height, 0, len(m.lines))
 	top := clamp(m.YOffset+m.Height-n, 0, bottom)
-	return linesToActuallyDisplayedLines(m.lines, m.Width)[top:bottom]
+	return wrap(m.lines, m.Width)[top:bottom]
 }
 
 // LineUp moves the view down by the given number of lines. Returns the new
@@ -213,7 +213,7 @@ func (m *Model) LineUp(n int) (lines []string) {
 	// Gather lines to send off for performance scrolling.
 	top := max(0, m.YOffset)
 	bottom := clamp(m.YOffset+n, 0, m.maxYOffset())
-	return linesToActuallyDisplayedLines(m.lines, m.Width)[top:bottom]
+	return wrap(m.lines, m.Width)[top:bottom]
 }
 
 // TotalLineCount returns the total number of lines (both hidden and visible) within the viewport.
@@ -409,22 +409,19 @@ func max(a, b int) int {
 	return b
 }
 
-// linesToActuallyDisplayedLines converts lines to the lines actually displayed considering window width.
-// If there is a line that is longer than the width, it will be displayed in multiple lines.
-// For more details: https://github.com/charmbracelet/bubbles/pull/578
-// If you want to know actual behavior of this function, please check out the unit tests.
-func linesToActuallyDisplayedLines(lines []string, width int) []string {
-	var actual []string
+// wrap returns lines wrapped to the given width.
+func wrap(lines []string, width int) []string {
+	var out []string
 	for _, line := range lines {
 		if len(line) <= width {
-			actual = append(actual, line)
+			out = append(out, line)
 			continue
 		}
 		for width < len(line) {
-			actual = append(actual, line[:width])
+			out = append(out, line[:width])
 			line = line[width:]
 		}
-		actual = append(actual, line)
+		out = append(out, line)
 	}
-	return actual
+	return out
 }
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index d7cdbfda7..3993a3c8a 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -4,7 +4,7 @@ import (
 	"testing"
 )
 
-func Test_linesToActuallyDisplayedLines(t *testing.T) {
+func TestWrap(t *testing.T) {
 	t.Parallel()
 	tests := map[string]struct {
 		lines []string
@@ -32,7 +32,7 @@ func Test_linesToActuallyDisplayedLines(t *testing.T) {
 		tt := tt
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
-			got := linesToActuallyDisplayedLines(tt.lines, tt.width)
+			got := wrap(tt.lines, tt.width)
 
 			if len(got) != len(tt.want) {
 				t.Errorf("expected len is %d but got %d", len(tt.want), len(got))

From ac3e89b62cf14c6161ef12d511bdcc6933e76d28 Mon Sep 17 00:00:00 2001
From: bashbunni <bunni@bashbunni.dev>
Date: Sat, 7 Sep 2024 10:19:16 -0700
Subject: [PATCH 09/11] refactor(test): wrap words when possible

---
 viewport/viewport.go      | 18 +++++++++---------
 viewport/viewport_test.go | 11 +++++++----
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index 1f60ec19e..539457ccb 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -7,6 +7,7 @@ import (
 	"github.com/charmbracelet/bubbles/key"
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/x/ansi"
 )
 
 // New returns a new model with the given width and height as well as default
@@ -413,15 +414,14 @@ func max(a, b int) int {
 func wrap(lines []string, width int) []string {
 	var out []string
 	for _, line := range lines {
-		if len(line) <= width {
-			out = append(out, line)
-			continue
-		}
-		for width < len(line) {
-			out = append(out, line[:width])
-			line = line[width:]
-		}
-		out = append(out, line)
+		// word wrap lines
+		wrapWords := ansi.Wordwrap(line, width, "")
+		// wrap lines (handles lines that could not be word wrapped)
+		wrap := ansi.Hardwrap(wrapWords, width, true)
+		// split string by new lines
+		wrapLines := strings.Split(strings.TrimSpace(wrap), "\n")
+
+		out = append(out, wrapLines...)
 	}
 	return out
 }
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index 3993a3c8a..0dc797462 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -26,20 +26,23 @@ func TestWrap(t *testing.T) {
 			width: 3,
 			want:  []string{"aaa", "aaa", "bbb", "bbb", "bb", "ccc"},
 		},
+		"full sentence exceeding width": {
+			lines: []string{"hello bob, I like yogurt in the mornings."},
+			width: 12,
+			want:  []string{"hello bob, I", "like yogurt", "in the", "mornings."},
+		},
 	}
 
 	for name, tt := range tests {
-		tt := tt
 		t.Run(name, func(t *testing.T) {
-			t.Parallel()
 			got := wrap(tt.lines, tt.width)
 
 			if len(got) != len(tt.want) {
-				t.Errorf("expected len is %d but got %d", len(tt.want), len(got))
+				t.Fatalf("expected len is %d but got %d", len(tt.want), len(got))
 			}
 			for i := range tt.want {
 				if tt.want[i] != got[i] {
-					t.Errorf("expected %s but got %s", tt.want[i], got[i])
+					t.Fatalf("expected %s but got %s", tt.want[i], got[i])
 				}
 			}
 		})

From 6ba0f57d3ed1da0f3bcecccc83d0e20815753173 Mon Sep 17 00:00:00 2001
From: bashbunni <bunni@bashbunni.dev>
Date: Sat, 7 Sep 2024 20:42:47 -0700
Subject: [PATCH 10/11] fix(viewport): do not allow YOffset to exceed its max

---
 viewport/viewport.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index 539457ccb..05e93ae19 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -298,6 +298,10 @@ func (m Model) updateAsModel(msg tea.Msg) (Model, tea.Cmd) {
 	var cmd tea.Cmd
 
 	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		if m.PastBottom() {
+			m.SetYOffset(m.maxYOffset())
+		}
 	case tea.KeyMsg:
 		switch {
 		case key.Matches(msg, m.KeyMap.PageDown):

From d8159865dcb527b829da87c916895767c936c5ea Mon Sep 17 00:00:00 2001
From: kyu08 <49891479+kyu08@users.noreply.github.com>
Date: Sat, 12 Oct 2024 13:23:17 +0900
Subject: [PATCH 11/11] fix(viewport): remove `strings.TrimSpace`

---
 viewport/viewport.go      | 2 +-
 viewport/viewport_test.go | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index 05e93ae19..332134b05 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -423,7 +423,7 @@ func wrap(lines []string, width int) []string {
 		// wrap lines (handles lines that could not be word wrapped)
 		wrap := ansi.Hardwrap(wrapWords, width, true)
 		// split string by new lines
-		wrapLines := strings.Split(strings.TrimSpace(wrap), "\n")
+		wrapLines := strings.Split(wrap, "\n")
 
 		out = append(out, wrapLines...)
 	}
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index 0dc797462..636163719 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -31,6 +31,11 @@ func TestWrap(t *testing.T) {
 			width: 12,
 			want:  []string{"hello bob, I", "like yogurt", "in the", "mornings."},
 		},
+		"whitespace of head of line is preserved": {
+			lines: []string{" aaa", "bbb", "ccc"},
+			width: 5,
+			want:  []string{" aaa", "bbb", "ccc"},
+		},
 	}
 
 	for name, tt := range tests {
@@ -42,7 +47,7 @@ func TestWrap(t *testing.T) {
 			}
 			for i := range tt.want {
 				if tt.want[i] != got[i] {
-					t.Fatalf("expected %s but got %s", tt.want[i], got[i])
+					t.Fatalf("expected %q but got %q", tt.want[i], got[i])
 				}
 			}
 		})