import cp, { type ChildProcess } from 'node:child_process'
import logger from '@wdio/logger'

import { download as downloadDriver } from './install.js'
import { hasAccess, parseParams } from './utils.js'
import { DEFAULT_HOSTNAME } from './constants.js'
import type { GeckodriverParameters } from './types.js'

const log = logger('geckodriver')

export async function start (params: GeckodriverParameters): Promise<ChildProcess> {
    const { cacheDir, customGeckoDriverPath, spawnOpts = {}, geckoDriverVersion, ...startArgs } = params
    let geckoDriverPath = customGeckoDriverPath || process.env.GECKODRIVER_PATH
    if (!geckoDriverPath) {
        geckoDriverPath = await downloadDriver(geckoDriverVersion, cacheDir)
    }

    if (!(await hasAccess(geckoDriverPath))) {
        throw new Error('Failed to access Geckodriver, was it installed successfully?')
    }

    startArgs.host = startArgs.host || DEFAULT_HOSTNAME

    // By default, Geckodriver uses port 9222.
    // Users may specify a custom port for individual runs, but they need to modify it for each worker.
    // For other cases, to enable parallel instances, we need to set the port to 0 (random).
    // Otherwise, all instances will attempt to connect to the default port and fail.
    // If both --connect-existing and --websocket-port are used together, an error is thrown.
    // However, if --connect-existing is not used and --websocket-port is not specified, the websocketPort is set to 0.
    if (startArgs.connectExisting && startArgs.websocketPort) {
        throw new Error(
            'Cannot use --connect-existing and --websocket-port together'
        )
    } else if (!startArgs.connectExisting && !startArgs.websocketPort) {
        startArgs.websocketPort = 0
    }

    const args = parseParams(startArgs)
    log.info(`Starting Geckodriver at ${geckoDriverPath} with params: ${args.join(' ')}`)
    const child = cp.spawn(geckoDriverPath, args, spawnOpts)
    return new Promise<ChildProcess>((resolve, reject) => {
        child.once('spawn', () => resolve(child))
        child.once('error', (err) => reject(new Error(`Failed to start Geckodriver: ${err.message}`)))
    })
}

export const download = downloadDriver
export * from './types.js'