import * as FS from 'node:fs';
import * as PATH from 'node:path';
import { configDir } from './config.ts';

// What atcli remembers between runs that is neither a setting nor a secret:
// where a watch got to (--resume), and the newest item seen in each listing
// (--new). One small JSON file beside the config, keyed by account and by
// what was listed; it is safe to delete, which only forgets.

function stateFile(): string {
    return PATH.join(configDir(), 'state.json');
}

function readAll(): Record<string, string> {
    try {
        return JSON.parse(FS.readFileSync(stateFile(), 'utf-8')) as Record<string, string>;
    } catch {
        return {};
    }
}

export function readState(key: string): string | undefined {
    return readAll()[key];
}

export function writeState(key: string, value: string): void {
    const state = readAll();
    if (state[key] === value) return;
    state[key] = value;
    FS.mkdirSync(PATH.dirname(stateFile()), { recursive: true, mode: 0o700 });
    const temp = `${stateFile()}.${process.pid}.tmp`;
    FS.writeFileSync(temp, `${JSON.stringify(state, null, 2)}\n`, { mode: 0o600 });
    FS.renameSync(temp, stateFile());
}

/** Forget what is remembered for keys starting with `prefix`; all of it without one. Returns how many. */
export function clearState(prefix = ''): number {
    const state = readAll();
    const gone = Object.keys(state).filter((key) => key.startsWith(prefix));
    if (!gone.length) return 0;
    for (const key of gone) delete state[key];
    FS.mkdirSync(PATH.dirname(stateFile()), { recursive: true, mode: 0o700 });
    FS.writeFileSync(stateFile(), `${JSON.stringify(state, null, 2)}\n`, { mode: 0o600 });
    return gone.length;
}