import { customAlphabet } from 'nanoid'

/** Base62 alphabet: `_` and `-` excluded so the prefix separator stays unambiguous. */
const segment = customAlphabet('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz', 24)

/**
 * Generates a prefixed resource id (`{prefix}_{24 base62 chars}`, ~143 bits).
 *
 * @param prefix - The resource-type prefix (e.g. `usr`, `org`).
 * @returns The generated id.
 */
export function generate(prefix: string): string {
  return `${prefix}_${random()}`
}

/**
 * Generates the random segment of an id (24 base62 chars) without a prefix,
 * for ids composing extra parts (e.g. `wh_{timestamp}_{random}`).
 *
 * @returns The generated segment.
 */
export function random(): string {
  return segment()
}

/**
 * Generates a time-prefixed resource id (`{prefix}_{epoch ms}_{24 base62
 * chars}`). The epoch-ms is zero-padded to 15 digits (headroom past the year
 * 5138) so lexical id order is chronological, letting newest-first lists page
 * by keyset on the id alone.
 *
 * @param prefix - The resource-type prefix (e.g. `wh`, `ftr`).
 * @param now - The timestamp to embed.
 * @returns The generated id.
 */
export function generateSortable(prefix: string, now: Date = new Date()): string {
  return `${prefix}_${now.getTime().toString().padStart(15, '0')}_${random()}`
}