From 0f0c8a11115f6f41c4338df9e2b71e5a40b49b02 Mon Sep 17 00:00:00 2001
From: Johan Walles <johan.walles@gmail.com>
Date: Mon, 15 Jul 2019 18:46:53 +0200
Subject: [PATCH] Don't highlight files with unsupported file extensions

---
 m/reader.go      | 42 ++++++++++++++++++++++++++++++++++++------
 m/reader_test.go |  4 ----
 moar.go          |  2 ++
 3 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/m/reader.go b/m/reader.go
index 2b35fad..718058b 100644
--- a/m/reader.go
+++ b/m/reader.go
@@ -9,6 +9,7 @@ import (
 	"os/exec"
 	"path"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"sync"
 )
@@ -157,15 +158,44 @@ func NewReaderFromCommand(filename string, filterCommand ...string) (*Reader, er
 }
 
 func _CanHighlight(filename string) bool {
-	ext := filepath.Ext(filename)
-	if len(ext) == 0 {
+	extension := filepath.Ext(filename)
+	if len(extension) <= 1 {
+		// No extension or a single "."
 		return false
 	}
 
-	// FIXME: Check file extension vs "highlight --list-scripts=langs" before
-	// calling highlight, otherwise files with unsupported extensions (like
-	// .log) get messed upp.
-	return true
+	// Remove leading dot from the extension
+	extension = extension[1:]
+
+	// Check file extension vs "highlight --list-scripts=langs" before calling
+	// highlight, otherwise files with unsupported extensions (like .log) get
+	// messed upp.
+	highlight := exec.Command("highlight", "--list-scripts=langs")
+	outBytes, err := highlight.CombinedOutput()
+	if err != nil {
+		return false
+	}
+
+	extensionMatcher := regexp.MustCompile("[^() ]+")
+
+	outString := string(outBytes)
+	outLines := strings.Split(outString, "\n")
+	for _, line := range outLines {
+		parts := strings.Split(line, ": ")
+		if len(parts) < 2 {
+			continue
+		}
+
+		// Pick out all extensions from this line
+		for _, supportedExtension := range extensionMatcher.FindAllString(parts[1], -1) {
+			if extension == supportedExtension {
+				return true
+			}
+		}
+	}
+
+	// No match
+	return false
 }
 
 // NewReaderFromFilename creates a new file reader
diff --git a/m/reader_test.go b/m/reader_test.go
index 99c23b6..ec6cbfb 100644
--- a/m/reader_test.go
+++ b/m/reader_test.go
@@ -127,10 +127,8 @@ func TestGetLines(t *testing.T) {
 			continue
 		}
 		if err := reader._Wait(); err != nil {
-			/* FIXME: Re-enable this and fix the error that it uncovers
 			t.Errorf("Error reading file <%s>: %s", file, err.Error())
 			continue
-			*/
 		}
 
 		_TestGetLines(t, reader)
@@ -168,9 +166,7 @@ func TestStatusText(t *testing.T) {
 		panic(err)
 	}
 	if err := testMe._Wait(); err != nil {
-		/* FIXME: Re-enable this and fix the problem it uncovers:
 		panic(err)
-		*/
 	}
 
 	statusText := testMe.GetLines(0, 0).statusText
diff --git a/moar.go b/moar.go
index 492b844..7cbc9e5 100644
--- a/moar.go
+++ b/moar.go
@@ -47,6 +47,8 @@ func main() {
 	printVersion := flag.Bool("version", false, "Prints the moar version number")
 
 	// FIXME: Support --help
+	// FIXME: Have --help warn / explain if highlight is not installed
+	// FIXME: Have --help explain how to make moar your default pager
 
 	// FIXME: Support --no-highlight