#!/usr/bin/env bun
/**
 * move.ts
 * -------
 * Entry point for the `move` CLI.
 *
 * Thin shim that ties the four logic modules together:
 *   - `cli.ts`         parses and validates `process.argv`.
 *   - `configFile.ts`  loads and validates the JSON config file.
 *   - `config.ts`      holds defaults and the layered `resolveConfig` overlay.
 *   - `keeper.ts`      owns the synthetic-activity sweep and idle-watch loop.
 *
 * Order of operations:
 *   1. Parse CLI args. Bad input -> stderr + usage hint, exit 2.
 *   2. `--help` / `--version` short-circuit before any I/O or mouse work.
 *   3. Load + validate the config file (default XDG path, or `--config
 *      <path>` if supplied). Validation failures share the exit-2 path.
 *   4. Resolve the full `Config` (CLI > file > DEFAULT_CONFIG) — verbose
 *      lives inside `Config` and is layered with the same precedence as
 *      the numeric fields.
 *   5. Run keeper. Any unhandled rejection exits 1.
 *
 * Runtime: Bun (uses `@nut-tree-fork/nut-js` via `keeper.ts`). The shebang
 * above lets this file run as a real CLI once linked via `bun link`.
 */

import { parseCliArgs, printHelp, VERSION } from "./cli.ts";
import type { ParsedCliArgs } from "./cli.ts";
import { resolveConfig } from "./config.ts";
import type { ConfigOverrides } from "./config.ts";
import { loadConfigFile } from "./configFile.ts";
import { runKeeper } from "./keeper.ts";

/**
 * Print a user-error message and exit 2. Used for anything that comes from
 * invalid input: unknown CLI flags, bad numbers, malformed or missing
 * config files, unresolvable default paths. The accompanying "Try 'move
 * --help'" pointer is appropriate for these cases.
 *
 * Returns `never` so callers can invoke it without TypeScript flagging
 * "variable might be undefined" downstream.
 */
function failUser(err: unknown): never {
    const msg: string = err instanceof Error ? err.message : String(err);
    process.stderr.write(`move: ${msg}\nTry 'move --help' for more information.\n`);
    process.exit(2);
}

/**
 * Print a runtime-failure message and exit 1. Used for anything the user
 * couldn't have prevented from the command line: nut.js errors, missing
 * Accessibility permission on macOS, unexpected exceptions from the
 * keeper loop. Prefers the stack trace when available since these failures
 * usually need a developer to interpret.
 */
function failRuntime(err: unknown): never {
    const detail: string = err instanceof Error ? (err.stack ?? err.message) : String(err);
    process.stderr.write(`move: runtime error: ${detail}\n`);
    process.exit(1);
}

let cliArgs: ParsedCliArgs;
try {
    cliArgs = parseCliArgs();
} catch (err: unknown) {
    failUser(err);
}

if (cliArgs.help) {
    // printHelp() resolves defaultConfigPath(), which can throw CliError
    // when neither $XDG_CONFIG_HOME nor $HOME is set.
    try {
        printHelp();
    } catch (err: unknown) {
        failUser(err);
    }
    process.exit(0);
}
if (cliArgs.version) {
    process.stdout.write(`move ${VERSION}\n`);
    process.exit(0);
}

let fileOverrides: ConfigOverrides | null;
try {
    fileOverrides = loadConfigFile(cliArgs.config);
} catch (err: unknown) {
    failUser(err);
}

const cliOverrides: ConfigOverrides = {
    moveInterval:  cliArgs.moveInterval,
    checkInterval: cliArgs.checkInterval,
    stepDelay:     cliArgs.stepDelay,
    stepCount:     cliArgs.stepCount,
    verbose:       cliArgs.verbose,
};

const config = resolveConfig(fileOverrides, cliOverrides);

runKeeper(config).catch(failRuntime);