import { execFile } from "node:child_process";

import { parseCanonicalKeymap } from "./canonical-parser.js";
import type { ResolvedReadlineProfile } from "./profile-loader.js";
import { parseReadlineVariables } from "./variables.js";

const INSERT_MARKER = "__PI_VI_INSERT__";
const VARIABLES_MARKER = "__PI_VI_VARIABLES__";

export type BashRunner = (
  executable: string,
  arguments_: readonly string[],
) => Promise<{ stdout: string }>;

const defaultRunner: BashRunner = (executable, arguments_) =>
  new Promise((resolve, reject) => {
    execFile(
      executable,
      [...arguments_],
      {
        encoding: "utf8",
        env: { ...process.env, BASH_ENV: "", ENV: "" },
        maxBuffer: 4 * 1024 * 1024,
        timeout: 5000,
      },
      (error, stdout) => {
        if (error !== null) reject(new Error(error.message, { cause: error }));
        else resolve({ stdout });
      },
    );
  });

/** Ask Bash/Readline to resolve includes, conditionals, variables, and macros. */
export async function loadBashResolvedInputrc(
  base: ResolvedReadlineProfile,
  inputrcPath: string,
  run: BashRunner = defaultRunner,
): Promise<ResolvedReadlineProfile> {
  const script = [
    "set -o vi",
    'bind -f "$1"',
    "bind -m vi-command -p",
    `printf '\\n${INSERT_MARKER}\\n'`,
    "bind -m vi-insertion -p",
    `printf '\\n${VARIABLES_MARKER}\\n'`,
    "bind -v",
  ].join("; ");
  const { stdout } = await run(base.metadata.bash.executable, [
    "--noprofile",
    "--norc",
    "-c",
    script,
    "pi-vi",
    inputrcPath,
  ]);
  const insertMarker = `\n${INSERT_MARKER}\n`;
  const variablesMarker = `\n${VARIABLES_MARKER}\n`;
  const insertIndex = stdout.indexOf(insertMarker);
  const variablesIndex = stdout.indexOf(variablesMarker);
  if (insertIndex < 0 || variablesIndex < insertIndex)
    throw new Error("Bash inputrc dump omitted a section marker");
  return {
    ...base,
    viCommand: parseCanonicalKeymap("vi-command", stdout.slice(0, insertIndex)),
    viInsert: parseCanonicalKeymap(
      "vi-insert",
      stdout.slice(insertIndex + insertMarker.length, variablesIndex),
    ),
    variables: parseReadlineVariables(
      stdout.slice(variablesIndex + variablesMarker.length),
    ),
  };
}