src/types/openai.ts

/**
 * OpenAI API types for /v1/chat/completions compatibility
 */
import { z } from "zod";

// --- Request ---

const ContentPartSchema = z.object({
  type: z.string(),
  text: z.string().optional(),
}).passthrough();

export const ChatMessageSchema = z.object({
  role: z.enum(["system", "developer", "user", "assistant", "tool", "function"]),
  content: z.union([z.string(), z.array(ContentPartSchema)]).nullable().optional(),
  name: z.string().optional(),
  // New format: tool_calls (array, on assistant messages)
  tool_calls: z.array(z.object({
    id: z.string(),
    type: z.literal("function"),
    function: z.object({
      name: z.string(),
      arguments: z.string(),
    }),
  })).optional(),
  tool_call_id: z.string().optional(),
  // Legacy format: function_call (single object, on assistant messages)
  function_call: z.object({
    name: z.string(),
    arguments: z.string(),
  }).optional(),
});

export const ChatCompletionRequestSchema = z.object({
  model: z.string(),
  messages: z.array(ChatMessageSchema).min(1),
  stream: z.boolean().optional().default(false),
  n: z.number().optional().default(1),
  temperature: z.number().optional(),
  top_p: z.number().optional(),
  max_tokens: z.number().optional(),
  presence_penalty: z.number().optional(),
  frequency_penalty: z.number().optional(),
  stop: z.union([z.string(), z.array(z.string())]).optional(),
  user: z.string().optional(),
  // Codex-specific extensions
  reasoning_effort: z.enum(["low", "medium", "high", "xhigh"]).optional(),
  service_tier: z.enum(["fast", "flex"]).nullable().optional(),
  // New tool format (accepted for compatibility, not forwarded to Codex)
  tools: z.array(z.object({
    type: z.literal("function"),
    function: z.object({
      name: z.string(),
      description: z.string().optional(),
      parameters: z.record(z.unknown()).optional(),
    }),
  })).optional(),
  tool_choice: z.union([
    z.enum(["none", "auto", "required"]),
    z.object({ type: z.literal("function"), function: z.object({ name: z.string() }) }),
  ]).optional(),
  parallel_tool_calls: z.boolean().optional(),
  // Structured output format (JSON mode / JSON Schema)
  response_format: z.object({
    type: z.enum(["text", "json_object", "json_schema"]),
    json_schema: z.object({
      name: z.string(),
      schema: z.record(z.unknown()),
      strict: z.boolean().optional(),
    }).optional(),
  }).optional(),
  // Legacy function format (accepted for compatibility, not forwarded to Codex)
  functions: z.array(z.object({
    name: z.string(),
    description: z.string().optional(),
    parameters: z.record(z.unknown()).optional(),
  })).optional(),
  function_call: z.union([
    z.enum(["none", "auto"]),
    z.object({ name: z.string() }),
  ]).optional(),
});

export type ChatMessage = z.infer<typeof ChatMessageSchema>;
export type ChatCompletionRequest = z.infer<typeof ChatCompletionRequestSchema>;

// --- Response (non-streaming) ---

export interface ChatCompletionToolCall {
  id: string;
  type: "function";
  function: {
    name: string;
    arguments: string;
  };
}

export interface ChatCompletionChoice {
  index: number;
  message: {
    role: "assistant";
    content: string | null;
    reasoning_content?: string | null;
    tool_calls?: ChatCompletionToolCall[];
  };
  finish_reason: "stop" | "length" | "tool_calls" | "function_call" | null;
}

export interface ChatCompletionUsage {
  prompt_tokens: number;
  completion_tokens: number;
  total_tokens: number;
  prompt_tokens_details?: {
    cached_tokens?: number;
  };
  completion_tokens_details?: {
    reasoning_tokens?: number;
  };
}

export interface ChatCompletionResponse {
  id: string;
  object: "chat.completion";
  created: number;
  model: string;
  choices: ChatCompletionChoice[];
  usage: ChatCompletionUsage;
}

// --- Response (streaming) ---

export interface ChatCompletionChunkToolCall {
  index: number;
  id?: string;
  type?: "function";
  function?: {
    name?: string;
    arguments?: string;
  };
}

export interface ChatCompletionChunkDelta {
  role?: "assistant";
  content?: string | null;
  reasoning_content?: string | null;
  tool_calls?: ChatCompletionChunkToolCall[];
}

export interface ChatCompletionChunkChoice {
  index: number;
  delta: ChatCompletionChunkDelta;
  finish_reason: "stop" | "length" | "tool_calls" | "function_call" | null;
}

export interface ChatCompletionChunk {
  id: string;
  object: "chat.completion.chunk";
  created: number;
  model: string;
  choices: ChatCompletionChunkChoice[];
  usage?: ChatCompletionUsage | null;
}

// --- Error ---

export interface OpenAIErrorBody {
  error: {
    message: string;
    type: string;
    param: string | null;
    code: string | null;
  };
}

// --- Models ---

export interface OpenAIModel {
  id: string;
  object: "model";
  created: number;
  owned_by: string;
}

export interface OpenAIModelList {
  object: "list";
  data: OpenAIModel[];
}