// Where the plugin's own files live. The host config dir resolution mirrors the SDK's `configDir`
// (`@punktfunk/host` does not re-export it) so we always land in the same place the host and runner
// use; the plugin owns a `rom-manager/` subtree under it (design §9), created 0700.
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { fileURLToPath } from "node:url";

/** The host's config dir — the same resolution the host and SDK use. */
export const hostConfigDir = (): string => {
	const explicit = process.env.PUNKTFUNK_CONFIG_DIR;
	if (explicit) return explicit;
	if (process.platform === "win32") {
		const base = process.env.ProgramData ?? process.env.APPDATA ?? ".";
		return path.join(base, "punktfunk");
	}
	const base =
		process.env.XDG_CONFIG_HOME ?? path.join(os.homedir(), ".config");
	return path.join(base, "punktfunk");
};

/**
 * This plugin's private directory: `<config_dir>/plugin-state/rom-manager`.
 *
 * The state lives under `plugin-state/`, not straight under the config dir, because the managed
 * runner is de-privileged on Windows (`NT AUTHORITY\LocalService`) and the config dir is locked
 * read-only there — `punktfunk-host plugins enable` grants the runner write on exactly
 * `plugin-state`. (Mirrors `@punktfunk/host`'s `pluginStateDir`; reimplemented locally like
 * `hostConfigDir`, since we don't want to gate on an SDK version bump.) On Linux the runner owns
 * the config dir, so the same path is writable with no special step.
 */
export const pluginDir = (): string =>
	path.join(hostConfigDir(), "plugin-state", "rom-manager");

/** The pre-0.2.1 location (`<config_dir>/rom-manager`), migrated away from on first run (state.ts). */
export const legacyPluginDir = (): string =>
	path.join(hostConfigDir(), "rom-manager");

/** `<config_dir>/rom-manager/config.json` — operator-editable, atomic-written. */
export const configPath = (): string => path.join(pluginDir(), "config.json");

/** `<config_dir>/rom-manager/cache.json` — disposable derived state (art verdicts, detection, fingerprint). */
export const cachePath = (): string => path.join(pluginDir(), "cache.json");

/**
 * Locate the built SPA directory (`dist/ui`) at runtime. The package ships as ONE self-contained bundle
 * (`dist/index.js`) so it installs from the Gitea registry with no external deps — which means
 * `import.meta.url` can be `dist/index.js` (bundled) or `dist/server/index.js` (unbundled dev). We walk
 * up from the calling module looking for a `ui/index.html`, so both layouts resolve. `fromUrl` is the
 * caller's `import.meta.url`.
 */
export const resolveUiDir = (fromUrl: string): string => {
	let dir = path.dirname(fileURLToPath(fromUrl));
	for (let i = 0; i < 6; i++) {
		for (const cand of [path.join(dir, "ui"), path.join(dir, "dist", "ui")]) {
			try {
				if (fs.existsSync(path.join(cand, "index.html"))) return cand;
			} catch {
				// keep walking
			}
		}
		const parent = path.dirname(dir);
		if (parent === dir) break;
		dir = parent;
	}
	// Fallback to the bundled layout (dist/index.js → dist/ui) even if unbuilt.
	return path.join(path.dirname(fileURLToPath(fromUrl)), "ui");
};