/** @file Shared utility functions. */
import * as fs from 'node:fs'
import * as path from 'node:path'
import process from 'node:process'

/**
 * Get the environment variable value.
 *
 * @param name - The name of the environment variable.
 * @returns The value of the environment variable.
 * @throws {Error} If the environment variable is not set.
 */
export function requireEnv(name: string) {
    return (
        process.env[name] ??
        (() => {
            throw Error(`Missing ${name} environment variable.`)
        })()
    )
}

/**
 * Read the path from environment variable and resolve it.
 *
 * @param name - The name of the environment variable.
 * @returns The resolved path.
 * @throws {Error} If the environment variable is not set.
 */
export function requireEnvResolvedPath(name: string) {
    return path.resolve(requireEnv(name))
}

/**
 * Read the path from environment variable and resolve it. Verify that it exists.
 *
 * @param name - The name of the environment variable.
 * @returns The resolved path.
 * @throws {Error} If the environment variable is not set or path does not exist.
 */
export function requireEnvPathExist(name: string) {
    const value = requireEnv(name)
    if (fs.existsSync(value)) {
        return value
    } else {
        throw Error(`File with path ${value} read from environment variable ${name} is missing.`)
    }
}