filters: add wrap utility written in go

I had started writing this as an awk script but quickly got stuck with
obscure code which did not even work properly. I jumped the gun and re
did it in go. Bonus, we will not have MacOS's 1987 BSD awk issues. On
the other hand, instead of a 20.0K awk script, we now have a 2.2M static
go binary. If this makes people scream, I challenge them to do that with
BSD awk :)

Basically, this takes text from stdin or from a file and wraps long
lines on word boundaries. It takes care of not breaking up email quotes
nor list items (numbered as well). Also, it is conservative by default
and only wraps long lines and lines that end with a space (indicating
a format=flowed message).

If the AERC_SUBJECT environment variable is defined and contains the
word PATCH, the text is not modified at all (i.e. wrap behaves as
cat(1)).

There are a few command line options to control behavior:

  Usage of ./wrap:
    -f string
          read from file instead of stdin
    -l int
          minimum percentage of letters in a line to be considered
          a paragaph (default 50)
    -r    reflow all paragraphs even if no trailing space
    -w int
          preferred wrap margin (default 80)

Update docs, makefile and default config file with examples.

Add a torture test to ensure it works as expected.

Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>

1 files changed, 212 insertions, 0 deletions

diff --git a/filters/wrap_test.go b/filters/wrap_test.go
new file mode 100644
index 00000000..f8d82cbe
--- /dev/null
+++ b/filters/wrap_test.go
@@ -0,0 +1,212 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"testing"
+)
+
+type vector struct {
+	name   string
+	in     string
+	out    string
+	width  int
+	reflow bool
+	ratio  int
+}
+
+var vectors = []vector{
+	{
+		name: "simple",
+		in: `long line that exceeds margin by many words
+`,
+		width:  30,
+		reflow: false,
+		ratio:  50,
+		out: `long line that exceeds margin
+by many words
+`,
+	},
+	{
+		name: "two-paragraphs",
+		in: `this is one long paragraph
+this is another long one
+`,
+		width:  20,
+		reflow: false,
+		ratio:  50,
+		out: `this is one long
+paragraph
+this is another
+long one
+`,
+	},
+	{
+		name: "reflow",
+		in: `this is one long paragraph
+this is another long one
+`,
+		width:  20,
+		reflow: true,
+		ratio:  50,
+		out: `this is one long
+paragraph this is
+another long one
+`,
+	},
+	{
+		name: "quotes",
+		in: `Let's play with quotes:
+
+>> Hi there how are you doing?
+> Great thanks
+
+How rude.
+
+>> Fantastic. Let's go wrap some words.
+`,
+		width:  20,
+		reflow: false,
+		ratio:  50,
+		out: `Let's play with
+quotes:
+
+>> Hi there how are
+>> you doing?
+> Great thanks
+
+How rude.
+
+>> Fantastic. Let's
+>> go wrap some
+>> words.
+`,
+	},
+	{
+		name: "ascii-art",
+		in: `This is a nice drawing, isn't it?
+
++-------------------+
+|      foobaz       |
++-------------------+
+          |
+          |
++-------------------+
+|      foobar       |
++-------------------+
+`,
+		width:  15,
+		ratio:  50,
+		reflow: true,
+		out: `This is a nice
+drawing, isn't
+it?
+
++-------------------+
+|      foobaz       |
++-------------------+
+          |
+          |
++-------------------+
+|      foobar       |
++-------------------+
+`,
+	},
+	{
+		name: "list-items",
+		in: `Shopping list:
+
+  -  milk
+  -  chocolate
+  -  cookies (please, with nuts)
+`,
+		width:  20,
+		reflow: false,
+		ratio:  50,
+		out: `Shopping list:
+
+  -  milk
+  -  chocolate
+  -  cookies
+     (please, with
+     nuts)
+`,
+	},
+	{
+		name: "list-items-reflow",
+		in: `Shopping list:
+
+  *  milk
+  *  chocolate
+  *  cookies
+     (please,
+     with nuts)
+`,
+		width:  100,
+		reflow: true,
+		ratio:  30,
+		out: `Shopping list:
+
+  *  milk
+  *  chocolate
+  *  cookies (please, with nuts)
+`,
+	},
+	{
+		name: "long-url",
+		in: `Please follow this ugly link:
+http://foobaz.org/xapapzolmkdmldfk-fldskjflsk-cisjoij/onoes.jsp?xxx=2&yyy=3
+`,
+		width:  20,
+		reflow: true,
+		ratio:  50,
+		out: `Please follow this
+ugly link:
+http://foobaz.org/xapapzolmkdmldfk-fldskjflsk-cisjoij/onoes.jsp?xxx=2&yyy=3
+`,
+	},
+	{
+		name:   "format=flowed",
+		in:     "Oh, \nI'm \nso \nhip \nI \nuse \nformat=flowed.\n",
+		width:  30,
+		reflow: false,
+		ratio:  50,
+		out:    "Oh, I'm so hip I use\nformat=flowed.\n",
+	},
+	{
+		name: "non-ascii",
+		in: `Lorem ççççç ççççç ççç ççççç çç ççç ççççç çççççççç ççç çç ççççç ççççççççççç ççççç
+
+Lorem жжжжж жжжжж жжж жжжжж жж жжж жжжжж жжжжжжжж жжж жж жжжжж жжжжжжжжжжж жжжжж жжжжжжжж
+`,
+		width:  40,
+		reflow: false,
+		ratio:  50,
+		out: `Lorem ççççç ççççç ççç ççççç çç ççç
+ççççç çççççççç ççç çç ççççç ççççççççççç
+ççççç
+
+Lorem жжжжж жжжжж жжж жжжжж жж жжж
+жжжжж жжжжжжжж жжж жж жжжжж жжжжжжжжжжж
+жжжжж жжжжжжжж
+`,
+	},
+}
+
+func TestWrap(t *testing.T) {
+	for _, vec := range vectors {
+		t.Run(vec.name, func(t *testing.T) {
+			r := bytes.NewReader([]byte(vec.in))
+			var buf bytes.Buffer
+			err := wrap(r, &buf, vec.width, vec.reflow, vec.ratio)
+			if err != nil && !errors.Is(err, io.EOF) {
+				t.Fatalf("[%s]: %v", vec.name, err)
+			}
+			if buf.String() != vec.out {
+				t.Errorf("[%s] invalid format:\n%q\nexpected\n%q",
+					vec.name, buf.String(), vec.out)
+			}
+		})
+	}
+}