export { _randomBytes as randomBytes } from './platform/random'

const b64urlAvailable = Buffer.isEncoding('base64url')

/**
 * Check if two buffers are equal
 *
 * @param a  First buffer
 * @param b  Second buffer
 */
export function buffersEqual(a: Buffer, b: Buffer): boolean {
    if (a.length !== b.length) return false

    for (let i = 0; i < a.length; i++) {
        if (a[i] !== b[i]) return false
    }

    return true
}

/**
 * Copy a buffer
 *
 * @param buf  Buffer to copy
 * @param start  Start offset
 * @param end  End offset
 */
export function cloneBuffer(buf: Buffer, start = 0, end = buf.length): Buffer {
    const ret = Buffer.alloc(end - start)
    buf.copy(ret, 0, start, end)

    return ret
}

/**
 * Parse url-safe base64 string
 *
 * @param str  String to parse
 */
export function parseUrlSafeBase64(str: string): Buffer {
    if (b64urlAvailable) {
        return Buffer.from(str, 'base64url')
    }

    str = str.replace(/-/g, '+').replace(/_/g, '/')
    while (str.length % 4) str += '='

    return Buffer.from(str, 'base64')
}

/**
 * Convert a buffer to url-safe base64 string
 *
 * @param buf  Buffer to convert
 */
export function encodeUrlSafeBase64(buf: Buffer): string {
    if (b64urlAvailable) {
        return buf.toString('base64url')
    }

    return buf.toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/g, '')
}