import { constants } from "node:fs";
import { open, realpath } from "node:fs/promises";
import { createHash, randomUUID } from "node:crypto";
import { homedir } from "node:os";
import { basename, dirname, join, resolve } from "node:path";
import type { OpencodeRuntimeAdapter } from "../runtime/opencode.js";
import { SANDBOX_GID, SANDBOX_UID } from "../runtime/conversationWorkspace.js";
import { openArtifactDirectory } from "../mcp/artifact-files.js";

export const nativeToolOutputDirectory = () => resolve(
  process.env.XDG_DATA_HOME ?? join(homedir(), ".local", "share"), "opencode", "tool-output",
);

// Only native truncation metadata from this session authorizes a source file.
// Text supplied by the model or a tool response is never an ownership proof.
export async function stageSessionToolOutputs(
  command: string, workspace: string, sessionId: string,
  messages: Awaited<ReturnType<OpencodeRuntimeAdapter["messages"]>>,
) {
  const sources = new Set<string>();
  const root = nativeToolOutputDirectory();
  for (const message of messages) for (const part of message.parts) {
    if (part.type !== "tool" || part.state.status !== "completed") continue;
    const metadata = part.state.metadata;
    const path = metadata?.outputPath;
    if (metadata?.truncated === true && typeof path === "string" && command.includes(path)
        && dirname(path) === root && /^tool_[a-zA-Z0-9]+$/.test(basename(path))) sources.add(path);
  }
  if (!sources.size) return [];
  const canonicalRoot = await realpath(root);
  const directory = await openArtifactDirectory(workspace, sessionId);
  const files: Array<{ source_path: string; relative_path: string; shell_path: string; size: number; sha256: string }> = [];
  let remaining = 128 * 1024 * 1024;
  try {
    for (const path of sources) {
      if (await realpath(path) !== join(canonicalRoot, basename(path))) throw new Error("Unsafe tool output path");
      const source = await open(path, constants.O_RDONLY | constants.O_NOFOLLOW);
      let bytes: Buffer;
      try {
        const stat = await source.stat();
        if (!stat.isFile() || stat.size > remaining) throw new Error("Tool output staging budget exceeded");
        bytes = await source.readFile();
        if (bytes.length > remaining) throw new Error("Tool output staging budget exceeded");
        remaining -= bytes.length;
      } finally { await source.close(); }
      const filename = `tool-output-${randomUUID()}.txt`;
      const destination = await open(`/proc/self/fd/${directory.fd}/${filename}`,
        constants.O_WRONLY | constants.O_CREAT | constants.O_EXCL | constants.O_NOFOLLOW, 0o600);
      try {
        await destination.writeFile(bytes);
        if (typeof process.getuid === "function" && process.getuid() === 0) await destination.chown(SANDBOX_UID, SANDBOX_GID);
      } finally { await destination.close(); }
      files.push({ source_path: path, relative_path: `files/${filename}`, shell_path: filename, size: bytes.length,
        sha256: createHash("sha256").update(bytes).digest("hex") });
    }
  } finally { await directory.close(); }
  return files;
}