/* Lifted from BlackBeltTechnology/pi-model-proxy@179d450, MIT licensed.
 * See model-proxy/convert/UPSTREAM.md for divergences.
 */
import type { OpenAIMessage, OpenAIContentPart, OpenAITool } from "./types.js";

/**
 * Convert an array of OpenAI messages into a pi-ai Context
 * (systemPrompt + messages array).
 *
 * Returns generic objects compatible with pi-ai's Message types.
 */
export function convertOpenAIMessages(openaiMessages: OpenAIMessage[]): { systemPrompt?: string; messages: any[] } {
  let systemPrompt: string | undefined;
  const messages: any[] = [];

  for (const msg of openaiMessages) {
    if (msg.role === "system") {
      const text = extractText(msg.content);
      systemPrompt = systemPrompt ? `${systemPrompt}\n${text}` : text;
      continue;
    }
    if (msg.role === "user") {
      messages.push(convertUserMessage(msg));
      continue;
    }
    if (msg.role === "assistant") {
      messages.push(convertAssistantMessage(msg));
      continue;
    }
    if (msg.role === "tool") {
      messages.push(convertToolResult(msg));
      continue;
    }
  }

  return { systemPrompt, messages };
}

export function convertOpenAITools(tools: OpenAITool[]): any[] {
  return tools.map((t) => ({
    name: t.function.name,
    description: t.function.description || "",
    parameters: t.function.parameters || { type: "object", properties: {} },
  }));
}

function convertUserMessage(msg: OpenAIMessage): any {
  return {
    role: "user",
    content: convertUserContent(msg.content),
    timestamp: Date.now(),
  };
}

function convertAssistantMessage(msg: OpenAIMessage): any {
  const content: any[] = [];
  if (msg.content) {
    const text = extractText(msg.content);
    if (text) content.push({ type: "text", text });
  }
  if (msg.tool_calls) {
    for (const tc of msg.tool_calls) {
      content.push({
        type: "toolCall",
        id: tc.id,
        name: tc.function.name,
        arguments: tryParseJSON(tc.function.arguments),
      });
    }
  }
  return {
    role: "assistant",
    content,
    api: "openai-completions",
    provider: "proxy",
    model: "proxy",
    usage: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, totalTokens: 0, cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 } },
    stopReason: "stop",
    timestamp: Date.now(),
  };
}

function convertToolResult(msg: OpenAIMessage): any {
  return {
    role: "toolResult",
    toolCallId: msg.tool_call_id || "",
    toolName: msg.name || "",
    content: [{ type: "text", text: typeof msg.content === "string" ? msg.content : JSON.stringify(msg.content) }],
    isError: false,
    timestamp: Date.now(),
  };
}

function convertUserContent(content: string | OpenAIContentPart[] | null): string | any[] {
  if (!content) return "";
  if (typeof content === "string") return content;
  const parts: any[] = [];
  for (const part of content) {
    if (part.type === "text" && part.text) {
      parts.push({ type: "text", text: part.text });
    } else if (part.type === "image_url" && part.image_url?.url) {
      const match = part.image_url.url.match(/^data:([^;]+);base64,(.+)$/);
      if (match) {
        parts.push({ type: "image", mimeType: match[1], data: match[2] });
      }
    }
  }
  return parts.length === 1 && parts[0].type === "text" ? parts[0].text : parts;
}

function extractText(content: string | OpenAIContentPart[] | null): string {
  if (!content) return "";
  if (typeof content === "string") return content;
  return content.filter((p) => p.type === "text").map((p) => p.text!).join("");
}

function tryParseJSON(s: string): Record<string, any> {
  try { return JSON.parse(s); } catch { return {}; }
}