import { existsSync } from "node:fs";
import { dirname, join } from "node:path";
import { fileURLToPath } from "node:url";

/**
 * Absolute filesystem path to the bundled Javy binary for this
 * platform. `@suaveplan/wasm-compiler-javy` calls this to locate the
 * binary it spawns via `child_process.spawnSync` — the postinstall
 * script places the binary at this exact path after verifying its
 * SHA-256.
 *
 * Throws if the binary is missing (the postinstall step failed or was
 * skipped via `JAVY_SKIP_DOWNLOAD=1` without a follow-up seed). The
 * caller is expected to surface this as a structured error.
 */
export function getJavyBinary(): string {
    const here = dirname(fileURLToPath(import.meta.url));
    // dist/index.js → ../bin/<name>
    const candidate = join(here, "..", "bin", "javy");
    if (!existsSync(candidate)) {
        // src/index.ts → ../bin/<name> (when running from src under bun)
        const fallback = join(here, "..", "bin", "javy");
        if (existsSync(fallback)) return fallback;
        throw new Error(
            "@suaveplan/javy-cli-linux-x64: binary not found at " +
                candidate +
                " — did postinstall run? (set JAVY_SKIP_DOWNLOAD=1 only with a manual seed)"
        );
    }
    return candidate;
}

/** Platform triple this wrapper serves. */
export const JAVY_PLATFORM = "linux-x64" as const;

/** Pinned Javy upstream version this wrapper installs. */
export const JAVY_VERSION = "v8.1.1" as const;