export type DankFlags = {
    dankPort?: number
    esbuildPort?: number
    logHttp: boolean
    minify: boolean
    noDankUI: boolean
    production: boolean
}

export function resolveFlags(
    mode: 'build' | 'preview' | 'serve',
): Readonly<DankFlags> {
    const withHttp = mode !== 'build'
    const isDevBuildMode = mode === 'serve'
    const isOptInProduction = isProductionBuild()
    return Object.freeze({
        dankPort: withHttp ? resolveDankPort() : undefined,
        esbuildPort: withHttp ? resolveEsbuildPort() : undefined,
        logHttp: withHttp && willLogHttp(),
        minify: !isDevBuildMode || isOptInProduction || willMinify(),
        noDankUI: resolveNoDankUI(),
        production: !isDevBuildMode || isOptInProduction,
    })
}

// `dank build` will minify sources and append git release tag to build tag
// `dank serve` will pre-bundle with service worker and minify
const isProductionBuild = () =>
    process.env.PRODUCTION === 'true' || process.argv.includes('--production')

// `dank serve` port for frontend webserver
function resolveDankPort(): number | undefined {
    if (process.env.DANK_PORT?.length) {
        return parsePortEnvVar('DANK_PORT')
    }
}

// `dank serve` port for esbuild bundler integration
function resolveEsbuildPort(): number | undefined {
    if (process.env.ESBUILD_PORT?.length) {
        return parsePortEnvVar('ESBUILD_PORT')
    }
}

function resolveNoDankUI(): boolean {
    if (process.env.DANK_UI === '0' || process.env.DANK_UI === 'false') {
        return true
    }
    return process.argv.includes('--no-dank-ui')
}

function parsePortEnvVar(name: string): number {
    const port = parseInt(process.env[name]!, 10)
    if (isNaN(port)) {
        throw Error(`env var ${name}=${port} must be a valid port number`)
    } else {
        return port
    }
}

const willMinify = () =>
    process.env.MINIFY === 'true' || process.argv.includes('--minify')

// `dank serve` will print http access logs to console
const willLogHttp = () =>
    process.env.LOG_HTTP === 'true' || process.argv.includes('--log-http')