import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import {
  findProjectVenv,
  ensureSharedVenv,
  activateVenv,
  getActiveVenv,
  getSharedVenvPath,
} from "./venv.js";

export default function (pi: ExtensionAPI) {
  pi.on("session_start", async (_event, ctx) => {
    // 1. Respect existing VIRTUAL_ENV — user already activated something
    if (process.env.VIRTUAL_ENV) {
      return;
    }

    // 2. Discover project venv in cwd
    const projectVenv = findProjectVenv(ctx.cwd);
    if (projectVenv) {
      activateVenv(projectVenv);
      return;
    }

    // 3. Fall back to shared venv
    try {
      const sharedVenv = await ensureSharedVenv();
      if (sharedVenv) {
        activateVenv(sharedVenv);
      }
    } catch (err: any) {
      const msg = err?.message ?? String(err);
      ctx.ui.notify(
        `pi-pyvenv: venv initialization failed. ${msg} Fix: install python3-venv (e.g. sudo apt install python3-venv)`,
        "warning"
      );
    }
  });

  pi.registerCommand("pyvenv", {
    description: "Show or manage the Python virtual environment",
    handler: async (args, ctx) => {
      const arg = args.trim();

      if (arg === "recreate") {
        const sharedPath = getSharedVenvPath();
        if (!getActiveVenv()?.startsWith(sharedPath)) {
          ctx.ui.notify("Only the shared fallback venv can be recreated.", "warning");
          return;
        }

        const ok = await ctx.ui.confirm(
          "Recreate shared venv?",
          `Delete ${sharedPath} and rebuild it?`
        );
        if (!ok) return;

        const { rm } = await import("node:fs/promises");
        try {
          await rm(sharedPath, { recursive: true, force: true });
          ctx.ui.notify("Shared venv deleted. Rebuilding...", "info");
        } catch (e: any) {
          ctx.ui.notify(`Failed to delete venv: ${e.message}`, "error");
          return;
        }

        const rebuilt = await ensureSharedVenv();
        if (rebuilt) {
          activateVenv(rebuilt);
          ctx.ui.notify(`Shared venv rebuilt: ${rebuilt}`, "info");
        } else {
          ctx.ui.notify("No Python interpreter found to rebuild shared venv.", "error");
        }
        return;
      }

      if (arg === "" || arg === "status") {
        const active = getActiveVenv();
        if (!active) {
          ctx.ui.notify("No Python venv is active.", "warning");
        } else {
          ctx.ui.notify(`Python venv: ${active}`, "info");
        }
        return;
      }

      ctx.ui.notify(
        `Unknown pyvenv command: "${arg}". Try "status" or "recreate".`,
        "warning"
      );
    },
  });
}