Add syntax highlighting

Using chroma. Still a few TODOs to investigate later, but this works for
now.

Closes #24.

go.mod

@@ -6,6 +6,7 @@ require (
 	buf.build/gen/go/bufbuild/registry/connectrpc/go v1.16.0-20240327205414-2f1854093b57.1
 	buf.build/gen/go/bufbuild/registry/protocolbuffers/go v1.33.0-20240327205414-2f1854093b57.1
 	connectrpc.com/connect v1.16.0
+	github.com/alecthomas/chroma/v2 v2.13.0
 	github.com/bufbuild/httplb v0.1.0
 	github.com/charmbracelet/bubbles v0.18.0
 	github.com/charmbracelet/bubbletea v0.25.0
@@ -19,6 +20,7 @@ require (
 	github.com/atotto/clipboard v0.1.4 // indirect
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
 	github.com/containerd/console v1.0.4-0.20230313162750-1ae8d489ac81 // indirect
+	github.com/dlclark/regexp2 v1.11.0 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.18 // indirect
 	github.com/mattn/go-localereader v0.0.1 // indirect

go.sum

@@ -6,6 +6,12 @@ buf.build/gen/go/bufbuild/registry/protocolbuffers/go v1.33.0-20240327205414-2f1
 buf.build/gen/go/bufbuild/registry/protocolbuffers/go v1.33.0-20240327205414-2f1854093b57.1/go.mod h1:Cw3zAf/W6/Y6BxHo6RWlVCE9FeNnbcL8Fq45qalol2I=
 connectrpc.com/connect v1.16.0 h1:rdtfQjZ0OyFkWPTegBNcH7cwquGAN1WzyJy80oFNibg=
 connectrpc.com/connect v1.16.0/go.mod h1:XpZAduBQUySsb4/KO5JffORVkDI4B6/EYPi7N8xpNZw=
+github.com/alecthomas/assert/v2 v2.6.0 h1:o3WJwILtexrEUk3cUVal3oiQY2tfgr/FHWiz/v2n4FU=
+github.com/alecthomas/assert/v2 v2.6.0/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
+github.com/alecthomas/chroma/v2 v2.13.0 h1:VP72+99Fb2zEcYM0MeaWJmV+xQvz5v5cxRHd+ooU1lI=
+github.com/alecthomas/chroma/v2 v2.13.0/go.mod h1:BUGjjsD+ndS6eX37YgTchSEG+Jg9Jv1GiZs9sqPqztk=
+github.com/alecthomas/repr v0.4.0 h1:GhI2A8MACjfegCPVq9f1FLvIBS+DrQ2KQBFZP1iFzXc=
+github.com/alecthomas/repr v0.4.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
 github.com/atotto/clipboard v0.1.4 h1:EH0zSVneZPSuFR11BlR9YppQTVDbh5+16AmcJi4g1z4=
 github.com/atotto/clipboard v0.1.4/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
 github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiErDT4WkJ2k=
@@ -22,10 +28,14 @@ github.com/containerd/console v1.0.4-0.20230313162750-1ae8d489ac81 h1:q2hJAaP1k2
 github.com/containerd/console v1.0.4-0.20230313162750-1ae8d489ac81/go.mod h1:YynlIjWYF8myEu6sdkwKIvGQq+cOckRm6So2avqoYAk=
 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/dlclark/regexp2 v1.11.0 h1:G/nrcoOa7ZXlpoa/91N3X7mM3r8eIlMBBJZvsz/mxKI=
+github.com/dlclark/regexp2 v1.11.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
+github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
 github.com/jdx/go-netrc v1.0.0 h1:QbLMLyCZGj0NA8glAhxUpf1zDg6cxnWgMBbjq40W0gQ=
 github.com/jdx/go-netrc v1.0.0/go.mod h1:Gh9eFQJnoTNIRHXl2j5bJXA1u84hQWJWgGh569zF3v8=
 github.com/jonboulle/clockwork v0.4.0 h1:p4Cf1aMWXnXAUh8lVfewRBx1zaTSYKrKMF2g3ST4RZ4=

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"encoding/base64"
 	"fmt"
@@ -13,6 +14,9 @@ import (
 	modulev1 "buf.build/gen/go/bufbuild/registry/protocolbuffers/go/buf/registry/module/v1"
 	ownerv1 "buf.build/gen/go/bufbuild/registry/protocolbuffers/go/buf/registry/owner/v1"
 	"connectrpc.com/connect"
+	"github.com/alecthomas/chroma/v2/formatters"
+	"github.com/alecthomas/chroma/v2/lexers"
+	"github.com/alecthomas/chroma/v2/styles"
 	"github.com/bufbuild/httplb"
 	"github.com/charmbracelet/bubbles/help"
 	"github.com/charmbracelet/bubbles/key"
@@ -470,11 +474,6 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.commitsTable, cmd = m.commitsTable.Update(msg)
 	case modelStateBrowsingCommitContents:
 		m.commitFilesTable, cmd = m.commitFilesTable.Update(msg)
-		for _, file := range m.currentCommitFiles {
-			if file.Path == m.commitFilesTable.SelectedRow()[0] {
-				m.fileViewport.SetContent(string(file.Content))
-			}
-		}
 	case modelStateBrowsingCommitFileContents:
 		m.fileViewport, cmd = m.fileViewport.Update(msg)
 	case modelStateSearching:
@@ -512,6 +511,20 @@ func (m model) View() string {
 	case modelStateLoadingCommitContents:
 		view = m.spinner.View()
 	case modelStateBrowsingCommitContents, modelStateBrowsingCommitFileContents:
+		selectedFileName := m.commitFilesTable.SelectedRow()[0]
+		var fileContents string
+		for _, file := range m.currentCommitFiles {
+			if file.Path == selectedFileName {
+				fileContents = string(file.Content)
+				break
+			}
+		}
+		highlightedFile, err := highlightFile(selectedFileName, fileContents)
+		if err != nil {
+			// TODO: Log and use the unhighlighted file contents?
+			return fmt.Sprintf("highlighting selected file %s: %s", selectedFileName, err)
+		}
+		m.fileViewport.SetContent(highlightedFile)
 		fileView := m.fileViewport.View()
 		if m.state == modelStateBrowsingCommitFileContents {
 			fileViewStyle := lipgloss.NewStyle().
@@ -661,3 +674,38 @@ func getUserTokenFromNetrc(hostname string) (username string, token string, err
 	token = parsedNetrc.Machine(hostname).Get("password")
 	return username, token, nil
 }
+
+func highlightFile(filename, fileContents string) (string, error) {
+	// TODO: There are only a few filetypes that can actually exist in a module:
+	// - Licenses
+	// - README (markdown/text(?))
+	// - protobuf
+	lexer := lexers.Match(filename)
+	if lexer == nil {
+		// This happens for LICENSE files.
+		lexer = lexers.Fallback
+	}
+	// TODO: Make this configurable?
+	// Probably not ;)
+	style := styles.Get("algol_nu")
+	if style == nil {
+		style = styles.Fallback
+	}
+	// TODO: This seemingly works on my terminal, but we may need
+	// to select a different one based on terminal type.
+	// I think we should be able to figure that out from
+	// tea/termenv, somehow.
+	formatter := formatters.TTY256
+	if formatter == nil {
+		formatter = formatters.Fallback
+	}
+	iterator, err := lexer.Tokenise(nil, fileContents)
+	if err != nil {
+		return "", fmt.Errorf("tokenizing file: %w", err)
+	}
+	var buffer bytes.Buffer
+	if err := formatter.Format(&buffer, style, iterator); err != nil {
+		return "", fmt.Errorf("formatting file: %w", err)
+	}
+	return buffer.String(), nil
+}