#!/usr/bin/env node
/**
 * pi-coding-agent bridge (stdio JSON).
 *
 * Input (stdin):
 * {
 *   "workspace": "/abs/path",
 *   "model": "claude-sonnet-4-5",
 *   "prompt": "...",
 *   "targets": ["docs/RD-UN.md"]
 * }
 *
 * Output (stdout, last line JSON): 同 cursor-bridge / opencode-bridge 协议
 *
 * 设计：与 cursor-bridge / opencode-bridge 完全相同的协议层。
 *
 * 调用的 pi 命令：
 *   workspace: --tools read,write,edit --approve
 *   reasoning: --no-tools，不加载扩展
 *   未知 tool_profile 直接失败，不退回读写工具
 *
 * 工作目录：Go 端 cmd.Dir 设（pi 没有 --cwd flag；node 桥 spawn 时再覆盖一次）
 *
 * 完成信号：
 *   - agent_settled  → 成功（"最稳妥" 标志，自动重试/队列全走完才算）
 *   - agent_error    → 失败
 *   - turn_end       → 单轮结束，不一定等于整体任务完成
 */
import { spawn } from "node:child_process";
import { readFileSync, existsSync } from "node:fs";
import { resolve, relative, isAbsolute } from "node:path";
import { buildPiLaunchArgs } from "../../deploy/pi-agent/pi-args.mjs";

async function readStdin() {
  const chunks = [];
  for await (const chunk of process.stdin) {
    chunks.push(chunk);
  }
  return Buffer.concat(chunks).toString("utf8");
}

function fail(reason, extra = {}, stderr = "") {
  process.stdout.write(
    JSON.stringify({
      ok: false,
      patches: [],
      fallback_reason: reason,
      stderr: stderr ? stderr.slice(0, 400) : undefined,
      ...extra,
    }) + "\n",
  );
  process.exit(0);
}

function safeRel(workspace, target) {
  const abs = isAbsolute(target) ? target : resolve(workspace, target);
  const rel = relative(workspace, abs);
  if (!rel || rel.startsWith("..") || isAbsolute(rel)) {
    return null;
  }
  return rel.replace(/\\/g, "/");
}

async function main() {
  let req;
  try {
    const raw = await readStdin();
    req = JSON.parse(raw);
  } catch (e) {
    fail("invalid_json: " + (e && e.message ? e.message : String(e)));
    return;
  }

  const workspace = req.workspace;
  const model = req.model || process.env.PI_AGENT_MODEL || "claude-sonnet-4-5";
  const provider = req.provider || process.env.PI_AGENT_PROVIDER || "anthropic";
  const prompt = req.prompt || "";
  const targets = Array.isArray(req.targets) ? req.targets : [];

  if (!workspace || !existsSync(workspace)) {
    fail("workspace_missing");
    return;
  }
  if (!prompt.trim()) {
    fail("prompt_empty");
    return;
  }

  const allowed = new Set();
  for (const t of targets) {
    const rel = safeRel(workspace, t);
    if (rel) allowed.add(rel);
  }
  if (allowed.size === 0) {
    fail("no_targets");
    return;
  }

  // 1. spawn pi --mode rpc
  const piBin = process.env.PI_AGENT_BIN || "pi";
  const sysPromptFile = process.env.PI_AGENT_SYSTEM_PROMPT_FILE || "INSTRUCTIONS.md";
  const absSysPrompt = resolve(workspace, sysPromptFile);
  let args;
  try {
    args = buildPiLaunchArgs({
      toolProfile: req.tool_profile,
      provider,
      model,
      systemPromptFile: existsSync(absSysPrompt) ? sysPromptFile : "",
      workspaceTools: "read,write,edit",
    });
  } catch (e) {
    if (e && e.code === "UNKNOWN_TOOL_PROFILE") {
      fail("unknown_tool_profile");
      return;
    }
    throw e;
  }

  const env = { ...process.env };
  env.PI_AGENT_MODEL = model;
  env.PI_AGENT_PROVIDER = provider;

  let agentId = "";
  let runId = "";
  let lastErr = "";
  let succeeded = false;

  try {
    const child = spawn(piBin, args, {
      cwd: workspace,
      env,
      stdio: ["pipe", "pipe", "pipe"],
    });

    // 2. 写 JSONL prompt 命令到 stdin
    const cmdId = "req-" + Date.now();
    child.stdin.write(
      JSON.stringify({
        id: cmdId,
        type: "prompt",
        message: prompt,
      }) + "\n",
    );

    // 3. 按行解析 ndjson 事件流
    let buf = "";
    child.stdout.on("data", (chunk) => {
      buf += chunk.toString("utf8");
      let nl;
      while ((nl = buf.indexOf("\n")) >= 0) {
        const line = buf.slice(0, nl).trim();
        buf = buf.slice(nl + 1);
        if (!line) continue;
        let ev;
        try { ev = JSON.parse(line); } catch { continue; }
        if (!ev || typeof ev !== "object") continue;
        const t = ev.type || "";
        if (t === "session" && ev.id) {
          agentId = ev.id;
        }
        if (t === "agent_settled") {
          succeeded = true;
          // agent_settled 表示任务真正结束；关闭 stdin 让 pi 退出
          child.stdin.end();
        }
        if (t === "agent_error") {
          lastErr = ev.error?.message || ev.message || "agent_error";
        }
      }
    });

    let stderrBuf = "";
    child.stderr.on("data", (chunk) => {
      stderrBuf += chunk.toString("utf8");
      lastErr = (stderrBuf + " " + lastErr).slice(-400);
    });

    await new Promise((resolveDone) => {
      child.on("close", () => resolveDone());
      child.on("error", (err) => {
        lastErr = err && err.message ? err.message : String(err);
        resolveDone();
      });
    });
  } catch (e) {
    fail("startup_or_run: " + (e && e.message ? e.message : String(e)));
    return;
  }

  if (!succeeded) {
    fail(lastErr || "agent_not_settled", { agent_id: agentId, run_id: runId }, lastErr);
    return;
  }

  // 4. 读 workspace 内目标文件
  const patches = [];
  for (const rel of allowed) {
    const abs = resolve(workspace, rel);
    if (!existsSync(abs)) continue;
    const content = readFileSync(abs, "utf8");
    patches.push({ rel_path: rel, content });
  }

  if (patches.length === 0) {
    fail("empty_patches", { agent_id: agentId, run_id: runId });
    return;
  }

  process.stdout.write(
    JSON.stringify({
      ok: true,
      agent_id: agentId,
      run_id: runId,
      patches,
      fallback_reason: "",
    }) + "\n",
  );
}

main().catch((e) => {
  fail("unhandled: " + (e && e.message ? e.message : String(e)));
});