Adds OpenAI customModel settings field and adds logic to support it

Closes gitkraken#3223

package.json

@@ -3321,7 +3321,8 @@
 							"gpt-3.5-turbo",
 							"gpt-3.5-turbo-16k",
 							"gpt-3.5-turbo-0613",
-							"gpt-3.5-turbo-1106"
+							"gpt-3.5-turbo-1106",
+							"custom"
 						],
 						"enumDescriptions": [
 							"GPT-4 Turbo (Latest)",
@@ -3334,7 +3335,8 @@
 							"GPT-3.5 Turbo",
 							"GPT-3.5 Turbo 16k",
 							"GPT-3.5 Turbo (June 13)",
-							"GPT-3.5 Turbo (Nov 6)"
+							"GPT-3.5 Turbo (Nov 6)",
+							"Custom"
 						],
 						"markdownDescription": "Specifies the OpenAI model to use for GitLens' experimental AI features",
 						"scope": "window",
@@ -3346,7 +3348,17 @@
 							"null"
 						],
 						"default": null,
-						"markdownDescription": "Specifies a custom URL to use for access to an OpenAI model via Azure. Azure URLs should be in the following format: https://{your-resource-name}.openai.azure.com/openai/deployments/{deployment-id}/chat/completions?api-version={api-version}",
+						"markdownDescription": "Specifies a custom URL to use for access to an OpenAI-compatible API. URLs could be in any format as long as the API responds in the same way as OpenAI. eg: https://{serverHost}/v1/chat/completions \n\nAzure URLs should be in the following format: https://{your-resource-name}.openai.azure.com/openai/deployments/{deployment-id}/chat/completions?api-version={api-version}",
+						"scope": "window",
+						"order": 102
+					},
+					"gitlens.ai.experimental.openai.customModel": {
+						"type": [
+							"string",
+							"null"
+						],
+						"default": null,
+						"markdownDescription": "Specifies a custom model to use with an OpenAI-compatible API. Only used when the OpenAI model is set to 'Custom'.",
 						"scope": "window",
 						"order": 102
 					},

src/ai/aiProviderService.ts

@@ -218,7 +218,7 @@ async function confirmAIProviderToS(provider: AIProvider, storage: Storage): Pro
 	return false;
 }
 
-export function getMaxCharacters(model: OpenAIModels | AnthropicModels, outputLength: number): number {
+export function getMaxCharacters(model: OpenAIModels | AnthropicModels | string, outputLength: number): number {
 	const tokensPerCharacter = 3.1;
 
 	let tokens;

src/ai/openaiProvider.ts

@@ -25,7 +25,7 @@ export class OpenAIProvider implements AIProvider<'openai'> {
 		return configuration.get('ai.experimental.openai.url') || 'https://api.openai.com/v1/chat/completions';
 	}
 
-	private async getOrChooseModel(): Promise<OpenAIModels | undefined> {
+	private async getOrChooseModel(): Promise<OpenAIModels | string | undefined> {
 		const model = this.model;
 		if (model != null) return model;
 
@@ -40,7 +40,14 @@ export class OpenAIProvider implements AIProvider<'openai'> {
 		const apiKey = await getApiKey(this.container.storage);
 		if (apiKey == null) return undefined;
 
-		const model = await this.getOrChooseModel();
+		let model = await this.getOrChooseModel();
+		if (model == null) return undefined;
+
+		if (model === 'custom') {
+			const customModel = configuration.get('ai.experimental.openai.customModel') || '';
+			model = customModel ? `${customModel}` : undefined;
+		}
+		// Might need to notify the user that they need to set a custom model name
 		if (model == null) return undefined;
 
 		let retries = 0;
@@ -88,6 +95,7 @@ Follow the user's instructions carefully, don't repeat yourself, don't include t
 			};
 
 			const rsp = await this.fetch(apiKey, request);
+
 			if (!rsp.ok) {
 				if (rsp.status === 404) {
 					throw new Error(
@@ -135,7 +143,14 @@ Follow the user's instructions carefully, don't repeat yourself, don't include t
 		const apiKey = await getApiKey(this.container.storage);
 		if (apiKey == null) return undefined;
 
-		const model = await this.getOrChooseModel();
+		let model = await this.getOrChooseModel();
+		if (model == null) return undefined;
+
+		if (model === 'custom') {
+			const customModel = configuration.get('ai.experimental.openai.customModel') || '';
+			model = customModel ? `${customModel}` : undefined;
+		}
+		// Might need to notify the user that they need to set a custom model name
 		if (model == null) return undefined;
 
 		let retries = 0;
@@ -302,10 +317,11 @@ export type OpenAIModels =
 	| 'gpt-3.5-turbo-1106'
 	| 'gpt-3.5-turbo'
 	| 'gpt-3.5-turbo-16k'
-	| 'gpt-3.5-turbo-0613';
+	| 'gpt-3.5-turbo-0613'
+	| 'custom';
 
 interface OpenAIChatCompletionRequest {
-	model: OpenAIModels;
+	model: OpenAIModels | string;
 	messages: { role: 'system' | 'user' | 'assistant'; content: string }[];
 	temperature?: number;
 	top_p?: number;

src/config.ts

@@ -15,6 +15,7 @@ export interface Config {
 			readonly openai: {
 				readonly model: OpenAIModels | null;
 				readonly url: string | null;
+				readonly customModel: string | null;
 			};
 			readonly anthropic: {
 				readonly model: AnthropicModels | null;

src/quickpicks/aiModelPicker.ts

@@ -22,6 +22,7 @@ export async function showAIModelPicker(provider?: AIProviders): Promise<ModelQu
 		{ label: 'OpenAI', description: 'GPT-4', provider: 'openai', model: 'gpt-4' },
 		{ label: 'OpenAI', description: 'GPT-4 32k', provider: 'openai', model: 'gpt-4-32k' },
 		{ label: 'OpenAI', description: 'GPT-3.5 Turbo', provider: 'openai', model: 'gpt-3.5-turbo-1106' },
+		{ label: 'OpenAI', description: 'Custom', provider: 'openai', model: 'custom' },
 		{ label: 'Anthropic', kind: QuickPickItemKind.Separator },
 		{ label: 'Anthropic', description: 'Claude 3 Opus', provider: 'anthropic', model: 'claude-3-opus-20240229' },
 		{