Add DeepSeek to the list of providers

src/api/providers/deepseek.ts

@@ -0,0 +1,116 @@
+import { Anthropic } from "@anthropic-ai/sdk"
+import OpenAI from "openai"
+import { ApiHandlerOptions, ModelInfo, deepSeekModels, deepSeekDefaultModelId } from "../../shared/api"
+import { ApiHandler } from "../index"
+import { ApiStream } from "../transform/stream"
+
+export class DeepSeekHandler implements ApiHandler {
+	private options: ApiHandlerOptions
+	private client: OpenAI
+
+	constructor(options: ApiHandlerOptions) {
+		this.options = options
+		if (!options.deepSeekApiKey) {
+			throw new Error("DeepSeek API key is required. Please provide it in the settings.")
+		}
+		this.client = new OpenAI({
+			baseURL: this.options.deepSeekBaseUrl ?? "https://api.deepseek.com/v1",
+			apiKey: this.options.deepSeekApiKey,
+		})
+	}
+
+	async *createMessage(systemPrompt: string, messages: Anthropic.Messages.MessageParam[]): ApiStream {
+		// Convert messages to simple format that DeepSeek expects
+		const formattedMessages = messages.map(msg => {
+			if (typeof msg.content === "string") {
+				return { role: msg.role, content: msg.content }
+			}
+			// For array content, concatenate text parts
+			return {
+				role: msg.role,
+				content: msg.content.reduce((acc, part) => {
+					if (part.type === "text") {
+						return acc + part.text
+					}
+					return acc
+				}, "")
+			}
+		})
+
+		const openAiMessages: OpenAI.Chat.ChatCompletionMessageParam[] = [
+			{ role: "system", content: systemPrompt },
+			...formattedMessages,
+		]
+		const modelInfo = deepSeekModels[this.options.deepSeekModelId as keyof typeof deepSeekModels] || deepSeekModels[deepSeekDefaultModelId]
+		
+		const contextWindow = modelInfo.contextWindow || 64_000
+		const getTokenCount = (content: string) => Math.ceil(content.length * 0.3)
+
+		// Always keep system prompt
+		const systemMsg = openAiMessages[0]
+		let availableTokens = contextWindow - getTokenCount(typeof systemMsg.content === 'string' ? systemMsg.content : '')
+		
+		// Start with most recent messages and work backwards
+		const userMessages = openAiMessages.slice(1).reverse()
+		const includedMessages = []
+		let truncated = false
+
+		for (const msg of userMessages) {
+			const content = typeof msg.content === 'string' ? msg.content : ''
+			const tokens = getTokenCount(content)
+			
+			if (tokens <= availableTokens) {
+				includedMessages.unshift(msg)
+				availableTokens -= tokens
+			} else {
+				truncated = true
+				break
+			}
+		}
+
+		if (truncated) {
+			yield {
+				type: 'text',
+				text: '(Note: Some earlier messages were truncated to fit within the model\'s context window)\n\n'
+			}
+		}
+
+		const requestOptions: OpenAI.Chat.ChatCompletionCreateParamsStreaming = {
+			model: this.options.deepSeekModelId ?? "deepseek-chat",
+			messages: [systemMsg, ...includedMessages],
+			temperature: 0,
+			stream: true,
+			max_tokens: modelInfo.maxTokens,
+		}
+
+		if (this.options.includeStreamOptions ?? true) {
+			requestOptions.stream_options = { include_usage: true }
+		}
+
+		const stream = await this.client.chat.completions.create(requestOptions)
+		for await (const chunk of stream) {
+			const delta = chunk.choices[0]?.delta
+			if (delta?.content) {
+				yield {
+					type: "text",
+					text: delta.content,
+				}
+			}
+			if (chunk.usage) {
+				yield {
+					type: "usage",
+					inputTokens: chunk.usage.prompt_tokens || 0,
+					outputTokens: chunk.usage.completion_tokens || 0,
+				}
+			}
+		}
+	}
+
+	getModel(): { id: string; info: ModelInfo } {
+		const modelId = this.options.deepSeekModelId ?? deepSeekDefaultModelId
+		return {
+			id: modelId,
+			info: deepSeekModels[modelId as keyof typeof deepSeekModels] || deepSeekModels[deepSeekDefaultModelId],
+		}
+	}
+}