import consola from "consola"
import { getProxyForUrl } from "proxy-from-env"
import { Agent, ProxyAgent, setGlobalDispatcher, type Dispatcher } from "undici"

export function initProxyFromEnv(): void {
  if (typeof Bun !== "undefined") return

  try {
    const direct = new Agent()
    const proxies = new Map<string, ProxyAgent>()

    // We only need a minimal dispatcher that implements `dispatch` at runtime.
    // Typing the object as `Dispatcher` forces TypeScript to require many
    // additional methods. Instead, keep a plain object and cast when passing
    // to `setGlobalDispatcher`.
    const dispatcher = {
      dispatch(
        options: Dispatcher.DispatchOptions,
        handler: Dispatcher.DispatchHandler,
      ) {
        try {
          const origin =
            typeof options.origin === "string" ?
              new URL(options.origin)
            : (options.origin as URL)
          const get = getProxyForUrl as unknown as (
            u: string,
          ) => string | undefined
          const raw = get(origin.toString())
          const proxyUrl = raw && raw.length > 0 ? raw : undefined
          if (!proxyUrl) {
            consola.debug(`HTTP proxy bypass: ${origin.hostname}`)
            return (direct as unknown as Dispatcher).dispatch(options, handler)
          }
          let agent = proxies.get(proxyUrl)
          if (!agent) {
            agent = new ProxyAgent(proxyUrl)
            proxies.set(proxyUrl, agent)
          }
          let label = proxyUrl
          try {
            const u = new URL(proxyUrl)
            label = `${u.protocol}//${u.host}`
          } catch {
            /* noop */
          }
          consola.debug(`HTTP proxy route: ${origin.hostname} via ${label}`)
          return (agent as unknown as Dispatcher).dispatch(options, handler)
        } catch {
          return (direct as unknown as Dispatcher).dispatch(options, handler)
        }
      },
      close() {
        return direct.close()
      },
      destroy() {
        return direct.destroy()
      },
    }

    setGlobalDispatcher(dispatcher as unknown as Dispatcher)
    consola.debug("HTTP proxy configured from environment (per-URL)")
  } catch (err) {
    consola.debug("Proxy setup skipped:", err)
  }
}