@nuxtjs/tailwindcss/lib/module.js

const { join, resolve, relative } = require('path')
const { pathExists } = require('fs-extra')
const defu = require('defu')
const clearModule = require('clear-module')

const logger = require('./logger')
const defaultTailwindConfig = require('./files/tailwind.config.js')

module.exports = async function (moduleOptions) {
  const { nuxt, addTemplate } = this
  const options = defu.arrayFn(moduleOptions, nuxt.options.tailwindcss, {
    configPath: 'tailwind.config.js',
    cssPath: join(nuxt.options.dir.assets, 'css', 'tailwind.css'),
    exposeConfig: false,
    config: defaultTailwindConfig(nuxt.options),
    ui: nuxt.options.dev
  })

  const configPath = nuxt.resolver.resolveAlias(options.configPath)
  const cssPath = nuxt.resolver.resolveAlias(options.cssPath)

  // Include CSS file in project css
  if (await pathExists(cssPath)) {
    logger.info(`Using Tailwind CSS from ~/${relative(nuxt.options.srcDir, cssPath)}`)
    nuxt.options.css.unshift(cssPath)
  } else {
    nuxt.options.css.unshift(resolve(__dirname, 'files', 'tailwind.css'))
  }

  // Get and extend the Tailwind config
  let tailwindConfig = {}
  if (await pathExists(configPath)) {
    clearModule(configPath)
    tailwindConfig = require(configPath)
    logger.info(`Merging Tailwind config from ~/${relative(this.options.srcDir, configPath)}`)
  }
  // Merge with our default purgecss default
  tailwindConfig = defu.arrayFn(tailwindConfig, options.config)

  // Watch the Tailwind config file to restart the server
  /* istanbul ignore if */
  if (nuxt.options.dev) {
    nuxt.options.watch.push(configPath)
  }
  // This hooks is called only for `nuxt dev` and `nuxt build` commands
  nuxt.hook('build:before', async () => {
    // Fix issue with postCSS that needs process.env.NODE_ENV
    /* istanbul ignore if */
    if (!nuxt.options.dev && !process.env.NODE_ENV) {
      process.env.NODE_ENV = 'production'
    }
    /*
    ** Set PostCSS config
    */
    const { postcss } = nuxt.options.build

    postcss.preset.stage = 1 // see https://tailwindcss.com/docs/using-with-preprocessors#future-css-features
    postcss.plugins = postcss.plugins || {}

    // Let modules extend the tailwind config
    await nuxt.callHook('tailwindcss:config', tailwindConfig)

    /* istanbul ignore if */
    if (Array.isArray(postcss.plugins)) {
      logger.error('Array syntax for postcss plugins is not supported with v3. Please use the object syntax: https://nuxtjs.org/guides/configuration-glossary/configuration-build#postcss')
    } else if (typeof postcss.plugins === 'object') {
      postcss.plugins.tailwindcss = tailwindConfig
    }

    /*
    ** Add /_tailwind UI
    */
    /* istanbul ignore if */
    if (nuxt.options.dev) {
      // add layout
      const layout = resolve(__dirname, 'ui', 'layouts', 'tw.vue')
      this.addLayout(layout, 'tw')
      // add page
      const page = resolve(__dirname, 'ui', 'pages', 'index.vue')

      // register page
      this.extendRoutes((routes) => {
        routes.unshift({
          name: '_tailwind',
          path: '/_tailwind',
          component: page
        })
      })
      const url = nuxt.server.listeners ? nuxt.server.listeners[0].url : '/'
      logger.info(`Tailwind Colors available on ${url}_tailwind`)
    }
    /*
    ** Expose resolved tailwind config as an alias
    ** https://tailwindcss.com/docs/configuration/#referencing-in-javascript
    */
    if (nuxt.options.dev || options.exposeConfig) {
      // Resolve config
      const resolveConfig = require('tailwindcss/resolveConfig')
      const resolvedConfig = resolveConfig(tailwindConfig)

      // Render as a json file in buildDir
      addTemplate({
        src: resolve(__dirname, 'templates/tailwind.config.json'),
        fileName: 'tailwind.config.json',
        options: { config: resolvedConfig }
      })

      // Alias to ~tailwind.config
      nuxt.options.alias['~tailwind.config'] =
        resolve(nuxt.options.buildDir, 'tailwind.config.json')

      // Force chunk creation for long term caching
      const { cacheGroups } = nuxt.options.build.optimization.splitChunks
      cacheGroups.tailwindConfig = {
        test: /tailwind\.config/,
        chunks: 'all',
        priority: 10,
        name: true
      }
    }
  })
}

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