Use existing analyzer module for language detction for highlighting

Thanks @lafriks for pointing out we can reuse existing code for more reliable language detection here.

go.sum

@@ -288,6 +288,7 @@ github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymF
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/ethantkoenig/rupture v0.0.0-20181029165146-c3b3b810dc77 h1:ZLWiTTzTUBb0WEXUxobYI/RxULIzOoIP7pgfDd4p1cw=
 github.com/ethantkoenig/rupture v0.0.0-20181029165146-c3b3b810dc77/go.mod h1:MkKY/CB98aVE4VxO63X5vTQKUgcn+3XP15LMASe3lYs=
 github.com/facebookgo/ensure v0.0.0-20160127193407-b4ab57deab51 h1:0JZ+dUmQeA8IIVUMzysrX4/AKuQwWhV2dYQuPZdvdSQ=
 github.com/facebookgo/ensure v0.0.0-20160127193407-b4ab57deab51/go.mod h1:Yg+htXGokKKdzcwhuNDwVvN+uBxDGXJ7G/VN1d8fa64=
@@ -655,6 +656,7 @@ github.com/jackc/puddle v0.0.0-20190413234325-e4ced69a3a2b/go.mod h1:m4B5Dj62Y0f
 github.com/jackc/puddle v0.0.0-20190608224051-11cab39313c9/go.mod h1:m4B5Dj62Y0fbyuIc15OsIqK0+JU8nkqQjsgx7dvjSWk=
 github.com/jackc/puddle v1.1.0/go.mod h1:m4B5Dj62Y0fbyuIc15OsIqK0+JU8nkqQjsgx7dvjSWk=
 github.com/jarcoal/httpmock v0.0.0-20180424175123-9c70cfe4a1da/go.mod h1:ks+b9deReOc7jgqp+e7LuFiCBH6Rm5hL32cLcEAArb4=
+github.com/jaytaylor/html2text v0.0.0-20200412013138-3577fbdbcff7 h1:g0fAGBisHaEQ0TRq1iBvemFRf+8AEWEmBESSiWB3Vsc=
 github.com/jaytaylor/html2text v0.0.0-20200412013138-3577fbdbcff7/go.mod h1:CVKlgaMiht+LXvHG173ujK6JUhZXKb2u/BQtjPDIvyk=
 github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 h1:BQSFePA1RWJOlocH6Fxy8MmwDt+yVQYULKfN0RoTN8A=
 github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99/go.mod h1:1lJo3i6rXxKeerYnT8Nvf0QmHCRC1n8sfWVwXF2Frvo=
@@ -684,6 +686,7 @@ github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7V
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/karrick/godirwalk v1.8.0/go.mod h1:H5KPZjojv4lE+QYImBI8xVtrBRgYrIVsaRPx4tDPEn4=
 github.com/karrick/godirwalk v1.10.3/go.mod h1:RoGL9dQei4vP9ilrpETWE8CLOZ1kiN0LhBygSwrAsHA=
+github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNUXsshfwJMBgNA0RU6/i7WVaAegv3PtuIHPMs=
 github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/kevinburke/ssh_config v0.0.0-20190725054713-01f96b0aa0cd h1:Coekwdh0v2wtGp9Gmz1Ze3eVRAWJMLokvN3QjdzCHLY=
 github.com/kevinburke/ssh_config v0.0.0-20190725054713-01f96b0aa0cd/go.mod h1:CT57kijsi8u/K/BOFA39wgDQJ9CxiF4nAY/ojJ6r6mM=
@@ -1025,6 +1028,7 @@ github.com/spf13/viper v1.7.0 h1:xVKxvI7ouOI5I+U9s2eeiUfMaWBVoXA3AWskkrqK0VM=
 github.com/spf13/viper v1.7.0/go.mod h1:8WkrPz2fc9jxqZNCJI/76HCieCp4Q8HaLFoCha5qpdg=
 github.com/spf13/viper v1.7.1 h1:pM5oEahlgWv/WnHXpgbKz7iLIxRf65tye2Ci+XFK5sk=
 github.com/spf13/viper v1.7.1/go.mod h1:8WkrPz2fc9jxqZNCJI/76HCieCp4Q8HaLFoCha5qpdg=
+github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf h1:pvbZ0lM0XWPBqUKqFU8cmavspvIl9nulOYwdy6IFRRo=
 github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf/go.mod h1:RJID2RhlZKId02nZ62WenDCkgHFerpIOmW0iT7GKmXM=
 github.com/steveyen/gtreap v0.1.0 h1:CjhzTa274PyJLJuMZwIzCO1PfC00oRa8d1Kc78bFXJM=
 github.com/steveyen/gtreap v0.1.0/go.mod h1:kl/5J7XbrOmlIbYIXdRHDDE5QxHqpk0cmkT7Z4dM9/Y=
@@ -1069,6 +1073,7 @@ github.com/unknwon/com v1.0.1/go.mod h1:tOOxU81rwgoCLoOVVPHb6T/wt8HZygqH5id+GNnl
 github.com/unknwon/i18n v0.0.0-20190805065654-5c6446a380b6/go.mod h1:+5rDk6sDGpl3azws3O+f+GpFSyN9GVr0K8cvQLQM2ZQ=
 github.com/unknwon/i18n v0.0.0-20200823051745-09abd91c7f2c h1:679/gJXwrsHC3RATr0YYjZvDMJPYN7W9FGSGNoLmKxM=
 github.com/unknwon/i18n v0.0.0-20200823051745-09abd91c7f2c/go.mod h1:+5rDk6sDGpl3azws3O+f+GpFSyN9GVr0K8cvQLQM2ZQ=
+github.com/unknwon/paginater v0.0.0-20200328080006-042474bd0eae h1:ihaXiJkaca54IaCSnEXtE/uSZOmPxKZhDfVLrzZLFDs=
 github.com/unknwon/paginater v0.0.0-20200328080006-042474bd0eae/go.mod h1:1fdkY6xxl6ExVs2QFv7R0F5IRZHKA8RahhB9fMC9RvM=
 github.com/urfave/cli v1.20.0/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijbERA=
 github.com/urfave/cli v1.22.1/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=

modules/highlight/highlight.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 	"sync"
 
+	"code.gitea.io/gitea/modules/analyze"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"github.com/alecthomas/chroma/formatters/html"
@@ -117,12 +118,11 @@ func File(numLines int, fileName string, code []byte) map[int]string {
 		fileName = "test." + val
 	}
 
-	lexer := lexers.Match(fileName)
+	language := analyze.GetCodeLanguage(fileName, code)
+
+	lexer := lexers.Get(language)
 	if lexer == nil {
-		lexer = lexers.Analyse(string(code))
-		if lexer == nil {
-			lexer = lexers.Fallback
-		}
+		lexer = lexers.Fallback
 	}
 
 	iterator, err := lexer.Tokenise(nil, string(code))