import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { registerWorkerGuard } from "./guard.ts";
import { WorktreeAgentParameters, type ProgressReporter } from "./types.ts";
import { runWorker } from "./worker.ts";
import { isParentClean, prepareWorktree } from "./worktree.ts";

function shellQuote(value: string): string {
  return `'${value.replace(/'/g, `'"'"'`)}'`;
}

export default function worktreeAgentExtension(pi: ExtensionAPI) {
  const workerRoot = process.env.PI_WORKTREE_ROOT;
  if (process.env.PI_WORKTREE_AGENT === "1" && workerRoot) {
    registerWorkerGuard(pi, workerRoot);
    return;
  }

  pi.registerTool({
    name: "run_issue_in_worktree",
    label: "Run issue in worktree",
    description:
      "Create an isolated Git worktree for a retrieved Linear issue and run a child Pi agent there. " +
      "Call this only after retrieving and understanding the Linear issue. The call remains active until the child finishes.",
    promptSnippet: "Run a retrieved Linear issue in an isolated Git worktree using a child Pi agent",
    promptGuidelines: [
      "Use run_issue_in_worktree only after retrieving the Linear issue, then let the child agent perform all repository modifications.",
      "When run_issue_in_worktree is active, do not modify files in the parent checkout.",
    ],
    parameters: WorktreeAgentParameters,

    async execute(_toolCallId, params, signal, onUpdate, ctx) {
      const report: ProgressReporter = (message, details) => {
        onUpdate?.({ content: [{ type: "text", text: message }], details });
      };

      const worktree = await prepareWorktree(pi, ctx.cwd, params, report);
      const workerReport = await runWorker({
        input: params,
        worktree,
        model: ctx.model,
        thinkingLevel: pi.getThinkingLevel(),
        signal,
        report,
      });

      const parentClean = await isParentClean(pi, worktree.repoRoot);
      const resumeCommand =
        `cd ${shellQuote(worktree.worktreePath)} && ` +
        'PI_WORKTREE_AGENT=1 PI_WORKTREE_ROOT="$PWD" pi -c';
      const parentWarning = parentClean
        ? ""
        : "\n\nWARNING: The parent working tree is no longer clean; inspect it before continuing.";

      return {
        content: [
          {
            type: "text",
            text:
              `Child Pi finished in ${worktree.worktreePath}.\n` +
              `Branch: ${worktree.branchName}\n` +
              `Resume: ${resumeCommand}\n\n${workerReport}${parentWarning}`,
          },
        ],
        details: {
          phase: "complete",
          branchName: worktree.branchName,
          worktreePath: worktree.worktreePath,
          parentClean,
          resumeCommand,
          workerReport,
        },
      };
    },
  });
}