copilot.ts

import { Installation } from "opencode/installation"
import { ModelsDev } from "opencode/provider/models"

const TOKEN_HEADER = "x-copilot-token"
const BASE_URL = "https://api.githubcopilot.com"

function detect(url: string, init?: RequestInit) {
  try {
    const body = typeof init?.body === "string" ? JSON.parse(init.body) : init?.body

    // Completions API
    if (body?.messages && url.includes("completions")) {
      const last = body.messages[body.messages.length - 1]
      return {
        vision: body.messages.some(
          (msg: any) => Array.isArray(msg.content) && msg.content.some((part: any) => part.type === "image_url"),
        ),
        agent: last?.role !== "user",
      }
    }

    // Responses API
    if (body?.input) {
      const last = body.input[body.input.length - 1]
      return {
        vision: body.input.some(
          (item: any) => Array.isArray(item?.content) && item.content.some((part: any) => part.type === "input_image"),
        ),
        agent: last?.role !== "user",
      }
    }

    // Messages API
    if (body?.messages) {
      const last = body.messages[body.messages.length - 1]
      const hasNonTool = Array.isArray(last?.content) && last.content.some((part: any) => part?.type !== "tool_result")
      return {
        vision: body.messages.some(
          (item: any) =>
            Array.isArray(item?.content) &&
            item.content.some(
              (part: any) =>
                part?.type === "image" ||
                (part?.type === "tool_result" &&
                  Array.isArray(part?.content) &&
                  part.content.some((nested: any) => nested?.type === "image")),
            ),
        ),
        agent: !(last?.role === "user" && hasNonTool),
      }
    }
  } catch {}
  return { vision: false, agent: false }
}

export async function copilotFetch(request: RequestInfo | URL, init?: RequestInit) {
  const incoming = (init?.headers ?? {}) as Record<string, string>
  const token = incoming[TOKEN_HEADER]
  if (!token) return fetch(request, init)

  const url = request instanceof URL ? request.href : request.toString()
  const { vision, agent } = detect(url, init)

  const headers: Record<string, string> = {
    "x-initiator": agent ? "agent" : "user",
    ...incoming,
    "User-Agent": `opencode/${Installation.VERSION}`,
    Authorization: `Bearer ${token}`,
    "Openai-Intent": "conversation-edits",
  }
  if (vision) headers["Copilot-Vision-Request"] = "true"

  delete headers[TOKEN_HEADER]
  delete headers["x-api-key"]
  delete headers["authorization"]

  return fetch(request, { ...init, headers })
}

export { TOKEN_HEADER, BASE_URL }

export async function models() {
  const data = await ModelsDev.get()
  return data["github-copilot"]?.models ?? {}
}