module.js

async function redirectModule(moduleOptions) {
  const defaults = {
    rules: [],
    onDecode: (req, res, next) => decodeURI(req.url),
    onDecodeError: (error, req, res, next) => next(error)
  }

  const options = {
    ...defaults,
    ...await parseOptions(this.options.redirect),
    ...await parseOptions(moduleOptions)
  }

  if (this.options.mode === 'spa') {
    return this.extendRoutes((routes) => {
      options.rules.forEach((route) => {
        routes.push({
          path: route.path || route.from,
          redirect: route.redirect || route.to
        })
      })
    })
  }

  options.rules = options.rules.map(rule => ({ ...rule, from: new RegExp(rule.from) }))

  const middleware = require('./middleware.js')(options)
  this.addServerMiddleware(middleware)
}

async function parseOptions(options) {
  if (typeof options === 'function') {
    options = await options()
  }

  if (Object.keys(options).length === 0) {
    return []
  }

  if (Array.isArray(options)) {
    return { rules: options }
  }

  if (typeof options.rules === 'function') {
    options.rules = await options.rules()
  }

  if (options.rules && !Array.isArray(options.rules)) {
    options.rules = [options.rules]
  }

  return options
}

module.exports = redirectModule
module.exports.meta = require('../package.json')