Allow the copilot to run on unrecognized languages

Author: intitni

Core/Sources/CopilotService/CopilotRequest.swift

@@ -11,7 +11,7 @@ struct CopilotDoc: Codable {
     var path: String
     var uri: String
     var relativePath: String
-    var languageId: LanguageIdentifier
+    var languageId: CopilotLanguage
     var position: Position
     /// Buffer version. Not sure what this is for, not sure how to get it
     var version: Int = 0

Core/Sources/CopilotService/CopilotService.swift

@@ -156,8 +156,8 @@ public final class CopilotSuggestionService: CopilotBaseService, CopilotSuggesti
         usesTabsForIndentation: Bool,
         ignoreSpaceOnlySuggestions: Bool
     ) async throws -> [CopilotCompletion] {
-        guard let languageId = languageIdentifierFromFileURL(fileURL) else { return [] }
-
+        let languageId = languageIdentifierFromFileURL(fileURL)
+        
         let relativePath = {
             let filePath = fileURL.path
             let rootPath = projectRootURL.path

Core/Sources/CopilotService/LanguageIdentifierFromFilePath.swift

@@ -1,6 +1,33 @@
 import Foundation
 import LanguageServerProtocol
 
+public enum CopilotLanguage: RawRepresentable, Codable {
+    case builtIn(LanguageIdentifier)
+    case plaintext
+    case other(String)
+
+    public var rawValue: String {
+        switch self {
+        case let .builtIn(language):
+            return language.rawValue
+        case .plaintext:
+            return "plaintext"
+        case let .other(language):
+            return language
+        }
+    }
+
+    public init?(rawValue: String) {
+        if let language = LanguageIdentifier(rawValue: rawValue) {
+            self = .builtIn(language)
+        } else if rawValue == "txt" || rawValue.isEmpty {
+            self = .plaintext
+        } else {
+            self = .other(rawValue)
+        }
+    }
+}
+
 extension LanguageIdentifier {
     /// Copied from https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [MIT]
     var fileExtensions: [String] {
@@ -219,7 +246,10 @@ let fileExtensionToLanguageId = {
     return dict
 }()
 
-public func languageIdentifierFromFileURL(_ fileURL: URL) -> LanguageIdentifier? {
+public func languageIdentifierFromFileURL(_ fileURL: URL) -> CopilotLanguage {
     let fileExtension = fileURL.pathExtension
-    return fileExtensionToLanguageId[fileExtension]
+    if let builtIn = fileExtensionToLanguageId[fileExtension] {
+        return .builtIn(builtIn)
+    }
+    return .init(rawValue: fileExtension) ?? .plaintext
 }

Core/Sources/Service/SuggestionCommandHandler/WindowBaseCommandHandler.swift

@@ -230,7 +230,7 @@ struct WindowBaseCommandHandler: SuggestionCommandHandler {
         Task {
             try? await service.send(
                 content: """
-                ```\(codeLanguage?.rawValue ?? "")
+                ```\(codeLanguage.rawValue)
                 \(removeContinuousSpaces(from: code))
                 ```
                 """,
@@ -278,7 +278,7 @@ struct WindowBaseCommandHandler: SuggestionCommandHandler {
             return """
             \(language.isEmpty ? "" : "You must always reply in \(language)")
             You are a senior programmer, you will answer my questions concisely about the code below, or modify it according to my requests. When you receive a modification request, reply with the modified code in a code block.
-            ```\(codeLanguage?.rawValue ?? "")
+            ```\(codeLanguage.rawValue)
             \(removeContinuousSpaces(from: code))
             ```
             """

Core/Sources/Service/Workspace.swift

@@ -14,8 +14,7 @@ final class Filespace {
     }
 
     let fileURL: URL
-    private(set) lazy var language: String = languageIdentifierFromFileURL(fileURL)?
-        .rawValue ?? "plaintext"
+    private(set) lazy var language: String = languageIdentifierFromFileURL(fileURL).rawValue
     var suggestions: [CopilotCompletion] = [] {
         didSet { lastSuggestionUpdateTime = Environment.now() }
     }