/**
 * LiveTurn — the minimal machine-edit ingress (spec §6.2): one @cline/sdk
 * Agent turn on the built-in `claude-code` provider, which rides the
 * operator's local Claude Code Pro/Max login — the extension holds NO
 * credentials of any kind (INV-8). vscode-free; the editSelection command
 * (extension.ts) feeds the result into the applyAgentEdit seam (INV-9).
 *
 * Like src/cline.ts: @cline/sdk is ESM-only, loaded via dynamic import(),
 * never bundled (esbuild keeps it external).
 */

import type { TurnProgressSnapshot } from "./turnProgress";
import { createTurnProgressState, reduceTurnProgress } from "./turnProgress";

export interface EditTurnResult {
  replacement: string;
  model: string;
  /** the SDK run id — recorded as provenance sessionId. */
  sessionId: string;
}

/**
 * Options for runEditTurn. Both new fields are purely additive observability /
 * control over the existing turn (INV-44): `onProgress` streams reduced progress
 * snapshots out; `signal` cancels the turn in. Neither touches the result path,
 * and neither pulls `vscode` into this module (INV-43 — `AbortSignal` is a web
 * standard, the progress snapshot is a domain type).
 */
export interface RunEditTurnOptions {
  modelId?: string;
  onProgress?: (snapshot: TurnProgressSnapshot) => void;
  signal?: AbortSignal;
}

const SYSTEM_PROMPT = [
  "You are a precise text editor embedded in VS Code.",
  "You will be given a piece of text and an instruction.",
  "Respond with ONLY the edited replacement text — no explanation, no preamble,",
  "no markdown code fences. Preserve the original's leading/trailing whitespace",
  "unless the instruction says otherwise.",
].join(" ");

/**
 * Strip a wrapping markdown code fence if the model added one anyway.
 * If `selectedText` itself was fence-wrapped (i.e. the user's selection was a
 * fenced block), the model mirroring that format is correct — return
 * `outputText` unchanged so the fence is preserved.
 */
export function extractReplacement(outputText: string, selectedText: string): string {
  const fencePattern = /^\s*```[^\n]*\n[\s\S]*?\n?```\s*$/;
  if (fencePattern.test(selectedText)) return outputText;
  const m = outputText.match(/^\s*```[^\n]*\n([\s\S]*?)\n?```\s*$/);
  return m ? m[1] : outputText;
}

export async function runEditTurn(
  instruction: string,
  selectedText: string,
  opts?: RunEditTurnOptions,
): Promise<EditTurnResult> {
  const sdk = await import("@cline/sdk");
  const modelId = opts?.modelId ?? "sonnet";
  const agent = new sdk.Agent({
    providerId: "claude-code",
    modelId,
    systemPrompt: SYSTEM_PROMPT,
    // The claude-code provider spawns the bundled `claude` CLI. On macOS, when
    // that process is launched from inside VS Code it performs IDE auto-connect,
    // which shells out to `osascript` (`tell application …`) to identify/activate
    // the editor — raising the macOS "control other applications" (Apple Events)
    // permission prompt (#59). We only consume the turn's text result and never
    // use the IDE connection, so we disable it: `CLAUDE_CODE_AUTO_CONNECT_IDE=0`
    // hard-returns out of the auto-connect path in the binary, and
    // `CLAUDE_CODE_IDE_SKIP_AUTO_INSTALL=1` skips the extension-install deep link.
    // Seeding with the full `process.env` keeps the default inheritance intact
    // (login under HOME, proxy/CA vars) — we only add the two switches. The
    // provider forwards `options.env` into the spawned child (verified end to end
    // through @cline/sdk → ai-sdk-provider-claude-code → @anthropic-ai/claude-agent-sdk).
    options: {
      env: {
        ...process.env,
        CLAUDE_CODE_AUTO_CONNECT_IDE: "0",
        CLAUDE_CODE_IDE_SKIP_AUTO_INSTALL: "1",
      },
    },
  });

  // Stream reduced progress snapshots out (INV-44 additive) and wire cancellation
  // in via the AbortSignal (INV-47). agent.subscribe returns its unsubscribe fn.
  let state = createTurnProgressState();
  const unsubscribe = opts?.onProgress
    ? agent.subscribe((event) => {
        const next = reduceTurnProgress(state, event);
        state = next.state;
        // Observability must never affect the result (INV-44): a throwing relay
        // is swallowed, not allowed to propagate into the SDK and fail the turn.
        if (next.snapshot) {
          try {
            opts.onProgress!(next.snapshot);
          } catch {
            /* progress is best-effort */
          }
        }
      })
    : undefined;
  const onAbort = () => agent.abort();
  opts?.signal?.addEventListener("abort", onAbort);

  try {
    // A signal already aborted before the turn starts can't be honored by
    // agent.abort() (the SDK's AbortController isn't created until run()), so
    // short-circuit to the same aborted outcome the call site reflects (INV-47).
    if (opts?.signal?.aborted) {
      throw new Error("claude-code turn aborted: cancelled before start");
    }
    const result = await agent.run(
      `<instruction>\n${instruction}\n</instruction>\n<text>\n${selectedText}\n</text>`,
    );
    // The SDK's AgentRunResult.status union is "completed" | "aborted" | "failed"
    // (@cline/shared agent.d.ts) — "completed" is the success status. An aborted
    // turn (user cancel) falls into this throw; the call site reflects "cancelled".
    if (result.status !== "completed") {
      throw new Error(
        `claude-code turn ${result.status}: ${result.error?.message ?? "unknown error"} ` +
          "(is Claude Code installed and signed in?)",
      );
    }
    return { replacement: extractReplacement(result.outputText, selectedText), model: modelId, sessionId: result.runId };
  } finally {
    unsubscribe?.();
    opts?.signal?.removeEventListener("abort", onAbort);
  }
}