setupContext.js

import fs from 'fs'
import url from 'url'
import os from 'os'
import path from 'path'
import crypto from 'crypto'
import chokidar from 'chokidar'
import postcss from 'postcss'
import hash from 'object-hash'
import dlv from 'dlv'
import selectorParser from 'postcss-selector-parser'
import LRU from 'quick-lru'
import normalizePath from 'normalize-path'

import transformThemeValue from '../../util/transformThemeValue'
import parseObjectStyles from '../../util/parseObjectStyles'
import getModuleDependencies from '../../lib/getModuleDependencies'
import prefixSelector from '../../util/prefixSelector'

import resolveConfig from '../../../resolveConfig'

import corePlugins from '../corePlugins'
import isPlainObject from '../../util/isPlainObject'
import escapeClassName from '../../util/escapeClassName'

import nameClass from '../../util/nameClass'
import { coerceValue } from '../../util/pluginUtils'

import * as sharedState from './sharedState'

let contextMap = sharedState.contextMap
let configContextMap = sharedState.configContextMap
let contextSourcesMap = sharedState.contextSourcesMap
let env = sharedState.env

// Earmarks a directory for our touch files.
// If the directory already exists we delete any existing touch files,
// invalidating any caches associated with them.
const touchDir =
  env.TAILWIND_TOUCH_DIR || path.join(os.homedir() || os.tmpdir(), '.tailwindcss', 'touch')

if (!sharedState.env.TAILWIND_DISABLE_TOUCH) {
  if (fs.existsSync(touchDir)) {
    for (let file of fs.readdirSync(touchDir)) {
      try {
        fs.unlinkSync(path.join(touchDir, file))
      } catch (_err) {}
    }
  } else {
    fs.mkdirSync(touchDir, { recursive: true })
  }
}

// This is used to trigger rebuilds. Just updating the timestamp
// is significantly faster than actually writing to the file (10x).

function touch(filename) {
  let time = new Date()

  try {
    fs.utimesSync(filename, time, time)
  } catch (err) {
    fs.closeSync(fs.openSync(filename, 'w'))
  }
}

function isObject(value) {
  return typeof value === 'object' && value !== null
}

function isEmpty(obj) {
  return Object.keys(obj).length === 0
}

function isString(value) {
  return typeof value === 'string' || value instanceof String
}

function toPath(value) {
  if (Array.isArray(value)) {
    return value
  }

  let inBrackets = false
  let parts = []
  let chunk = ''

  for (let i = 0; i < value.length; i++) {
    let char = value[i]
    if (char === '[') {
      inBrackets = true
      parts.push(chunk)
      chunk = ''
      continue
    }
    if (char === ']' && inBrackets) {
      inBrackets = false
      parts.push(chunk)
      chunk = ''
      continue
    }
    if (char === '.' && !inBrackets && chunk.length > 0) {
      parts.push(chunk)
      chunk = ''
      continue
    }
    chunk = chunk + char
  }

  if (chunk.length > 0) {
    parts.push(chunk)
  }

  return parts
}

function resolveConfigPath(pathOrConfig) {
  // require('tailwindcss')({ theme: ..., variants: ... })
  if (isObject(pathOrConfig) && pathOrConfig.config === undefined && !isEmpty(pathOrConfig)) {
    return null
  }

  // require('tailwindcss')({ config: 'custom-config.js' })
  if (
    isObject(pathOrConfig) &&
    pathOrConfig.config !== undefined &&
    isString(pathOrConfig.config)
  ) {
    return path.resolve(pathOrConfig.config)
  }

  // require('tailwindcss')({ config: { theme: ..., variants: ... } })
  if (
    isObject(pathOrConfig) &&
    pathOrConfig.config !== undefined &&
    isObject(pathOrConfig.config)
  ) {
    return null
  }

  // require('tailwindcss')('custom-config.js')
  if (isString(pathOrConfig)) {
    return path.resolve(pathOrConfig)
  }

  // require('tailwindcss')
  for (const configFile of ['./tailwind.config.js', './tailwind.config.cjs']) {
    try {
      const configPath = path.resolve(configFile)
      fs.accessSync(configPath)
      return configPath
    } catch (err) {}
  }

  return null
}

let configPathCache = new LRU({ maxSize: 100 })

// Get the config object based on a path
function getTailwindConfig(configOrPath) {
  let userConfigPath = resolveConfigPath(configOrPath)

  if (sharedState.env.TAILWIND_DISABLE_TOUCH) {
    if (userConfigPath !== null) {
      let [prevConfig, prevConfigHash, prevDeps, prevModified] =
        configPathCache.get(userConfigPath) || []

      let newDeps = getModuleDependencies(userConfigPath).map((dep) => dep.file)

      let modified = false
      let newModified = new Map()
      for (let file of newDeps) {
        let time = fs.statSync(file).mtimeMs
        newModified.set(file, time)
        if (!prevModified || !prevModified.has(file) || time > prevModified.get(file)) {
          modified = true
        }
      }

      // It hasn't changed (based on timestamps)
      if (!modified) {
        return [prevConfig, userConfigPath, prevConfigHash, prevDeps]
      }

      // It has changed (based on timestamps), or first run
      for (let file of newDeps) {
        delete require.cache[file]
      }
      let newConfig = resolveConfig(require(userConfigPath))
      let newHash = hash(newConfig)
      configPathCache.set(userConfigPath, [newConfig, newHash, newDeps, newModified])
      return [newConfig, userConfigPath, newHash, newDeps]
    }

    // It's a plain object, not a path
    let newConfig = resolveConfig(
      configOrPath.config === undefined ? configOrPath : configOrPath.config
    )

    return [newConfig, null, hash(newConfig), []]
  }

  if (userConfigPath !== null) {
    let [prevConfig, prevModified = -Infinity, prevConfigHash] =
      configPathCache.get(userConfigPath) || []
    let modified = fs.statSync(userConfigPath).mtimeMs

    // It hasn't changed (based on timestamp)
    if (modified <= prevModified) {
      return [prevConfig, userConfigPath, prevConfigHash]
    }

    // It has changed (based on timestamp), or first run
    delete require.cache[userConfigPath]
    let newConfig = resolveConfig(require(userConfigPath))
    let newHash = hash(newConfig)
    configPathCache.set(userConfigPath, [newConfig, modified, newHash])
    return [newConfig, userConfigPath, newHash]
  }

  // It's a plain object, not a path
  let newConfig = resolveConfig(
    configOrPath.config === undefined ? configOrPath : configOrPath.config
  )

  return [newConfig, null, hash(newConfig)]
}

let fileModifiedMap = new Map()

function trackModified(files) {
  let changed = false

  for (let file of files) {
    if (!file) continue

    let pathname = url.parse(file).pathname
    let newModified = fs.statSync(decodeURIComponent(pathname)).mtimeMs

    if (!fileModifiedMap.has(file) || newModified > fileModifiedMap.get(file)) {
      changed = true
    }

    fileModifiedMap.set(file, newModified)
  }

  return changed
}

function generateTouchFileName() {
  let chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
  let randomChars = ''
  let randomCharsLength = 12
  let bytes = null

  try {
    bytes = crypto.randomBytes(randomCharsLength)
  } catch (_error) {
    bytes = crypto.pseudoRandomBytes(randomCharsLength)
  }

  for (let i = 0; i < randomCharsLength; i++) {
    randomChars += chars[bytes[i] % chars.length]
  }

  return path.join(touchDir, `touch-${process.pid}-${randomChars}`)
}

function rebootWatcher(context) {
  if (env.TAILWIND_DISABLE_TOUCH) {
    return
  }

  if (context.touchFile === null) {
    context.touchFile = generateTouchFileName()
    touch(context.touchFile)
  }

  if (env.TAILWIND_MODE === 'build') {
    return
  }

  if (
    env.TAILWIND_MODE === 'watch' ||
    (env.TAILWIND_MODE === undefined && env.NODE_ENV === 'development')
  ) {
    Promise.resolve(context.watcher ? context.watcher.close() : null).then(() => {
      context.watcher = chokidar.watch([...context.candidateFiles, ...context.configDependencies], {
        ignoreInitial: true,
      })

      context.watcher.on('add', (file) => {
        context.changedFiles.add(path.resolve('.', file))
        touch(context.touchFile)
      })

      context.watcher.on('change', (file) => {
        // If it was a config dependency, touch the config file to trigger a new context.
        // This is not really that clean of a solution but it's the fastest, because we
        // can do a very quick check on each build to see if the config has changed instead
        // of having to get all of the module dependencies and check every timestamp each
        // time.
        if (context.configDependencies.has(file)) {
          for (let dependency of context.configDependencies) {
            delete require.cache[require.resolve(dependency)]
          }
          touch(context.configPath)
        } else {
          context.changedFiles.add(path.resolve('.', file))
          touch(context.touchFile)
        }
      })

      context.watcher.on('unlink', (file) => {
        // Touch the config file if any of the dependencies are deleted.
        if (context.configDependencies.has(file)) {
          for (let dependency of context.configDependencies) {
            delete require.cache[require.resolve(dependency)]
          }
          touch(context.configPath)
        }
      })
    })
  }
}

function insertInto(list, value, { before = [] } = {}) {
  before = [].concat(before)

  if (before.length <= 0) {
    list.push(value)
    return
  }

  let idx = list.length - 1
  for (let other of before) {
    let iidx = list.indexOf(other)
    if (iidx === -1) continue
    idx = Math.min(idx, iidx)
  }

  list.splice(idx, 0, value)
}

function parseStyles(styles) {
  if (!Array.isArray(styles)) {
    return parseStyles([styles])
  }

  return styles.flatMap((style) => {
    let isNode = !Array.isArray(style) && !isPlainObject(style)
    return isNode ? style : parseObjectStyles(style)
  })
}

function getClasses(selector) {
  let parser = selectorParser((selectors) => {
    let allClasses = []
    selectors.walkClasses((classNode) => {
      allClasses.push(classNode.value)
    })
    return allClasses
  })
  return parser.transformSync(selector)
}

function extractCandidates(node) {
  let classes = node.type === 'rule' ? getClasses(node.selector) : []

  if (node.type === 'atrule') {
    node.walkRules((rule) => {
      classes = [...classes, ...getClasses(rule.selector)]
    })
  }

  return classes
}

function withIdentifiers(styles) {
  return parseStyles(styles).flatMap((node) => {
    let nodeMap = new Map()
    let candidates = extractCandidates(node)

    // If this isn't "on-demandable", assign it a universal candidate.
    if (candidates.length === 0) {
      return [['*', node]]
    }

    return candidates.map((c) => {
      if (!nodeMap.has(node)) {
        nodeMap.set(node, node)
      }
      return [c, nodeMap.get(node)]
    })
  })
}

function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offsets }) {
  function getConfigValue(path, defaultValue) {
    return path ? dlv(tailwindConfig, path, defaultValue) : tailwindConfig
  }

  function applyConfiguredPrefix(selector) {
    return prefixSelector(tailwindConfig.prefix, selector)
  }

  function prefixIdentifier(identifier, options) {
    if (identifier === '*') {
      return '*'
    }

    if (!options.respectPrefix) {
      return identifier
    }

    if (typeof context.tailwindConfig.prefix === 'function') {
      return prefixSelector(context.tailwindConfig.prefix, `.${identifier}`).substr(1)
    }

    return context.tailwindConfig.prefix + identifier
  }

  return {
    addVariant(variantName, applyThisVariant, options = {}) {
      insertInto(variantList, variantName, options)
      variantMap.set(variantName, applyThisVariant)
    },
    postcss,
    prefix: applyConfiguredPrefix,
    e: escapeClassName,
    config: getConfigValue,
    theme(path, defaultValue) {
      const [pathRoot, ...subPaths] = toPath(path)
      const value = getConfigValue(['theme', pathRoot, ...subPaths], defaultValue)
      return transformThemeValue(pathRoot)(value)
    },
    corePlugins: (path) => {
      if (Array.isArray(tailwindConfig.corePlugins)) {
        return tailwindConfig.corePlugins.includes(path)
      }

      return getConfigValue(['corePlugins', path], true)
    },
    variants: (path, defaultValue) => {
      if (Array.isArray(tailwindConfig.variants)) {
        return tailwindConfig.variants
      }

      return getConfigValue(['variants', path], defaultValue)
    },
    addBase(base) {
      for (let [identifier, rule] of withIdentifiers(base)) {
        let prefixedIdentifier = prefixIdentifier(identifier, {})
        let offset = offsets.base++

        if (!context.candidateRuleMap.has(prefixedIdentifier)) {
          context.candidateRuleMap.set(prefixedIdentifier, [])
        }

        context.candidateRuleMap
          .get(prefixedIdentifier)
          .push([{ sort: offset, layer: 'base' }, rule])
      }
    },
    addComponents(components, options) {
      let defaultOptions = {
        variants: [],
        respectPrefix: true,
        respectImportant: false,
        respectVariants: true,
      }

      options = Object.assign(
        {},
        defaultOptions,
        Array.isArray(options) ? { variants: options } : options
      )

      for (let [identifier, rule] of withIdentifiers(components)) {
        let prefixedIdentifier = prefixIdentifier(identifier, options)
        let offset = offsets.components++

        if (!context.candidateRuleMap.has(prefixedIdentifier)) {
          context.candidateRuleMap.set(prefixedIdentifier, [])
        }

        context.candidateRuleMap
          .get(prefixedIdentifier)
          .push([{ sort: offset, layer: 'components', options }, rule])
      }
    },
    addUtilities(utilities, options) {
      let defaultOptions = {
        variants: [],
        respectPrefix: true,
        respectImportant: true,
        respectVariants: true,
      }

      options = Object.assign(
        {},
        defaultOptions,
        Array.isArray(options) ? { variants: options } : options
      )

      for (let [identifier, rule] of withIdentifiers(utilities)) {
        let prefixedIdentifier = prefixIdentifier(identifier, options)
        let offset = offsets.utilities++

        if (!context.candidateRuleMap.has(prefixedIdentifier)) {
          context.candidateRuleMap.set(prefixedIdentifier, [])
        }

        context.candidateRuleMap
          .get(prefixedIdentifier)
          .push([{ sort: offset, layer: 'utilities', options }, rule])
      }
    },
    matchUtilities: function (utilities, options) {
      let defaultOptions = {
        variants: [],
        respectPrefix: true,
        respectImportant: true,
        respectVariants: true,
      }

      options = { ...defaultOptions, ...options }

      let offset = offsets.utilities++

      for (let identifier in utilities) {
        let prefixedIdentifier = prefixIdentifier(identifier, options)
        let rule = utilities[identifier]

        function wrapped(modifier) {
          let { type = 'any' } = options
          let value = coerceValue(type, modifier, options.values)

          if (value === undefined) {
            return []
          }

          let includedRules = []
          let ruleSets = []
            .concat(
              rule(value, {
                includeRules(rules) {
                  includedRules.push(...rules)
                },
              })
            )
            .filter(Boolean)
            .map((declaration) => ({
              [nameClass(identifier, modifier)]: declaration,
            }))

          return [...includedRules, ...ruleSets]
        }

        let withOffsets = [{ sort: offset, layer: 'utilities', options }, wrapped]

        if (!context.candidateRuleMap.has(prefixedIdentifier)) {
          context.candidateRuleMap.set(prefixedIdentifier, [])
        }

        context.candidateRuleMap.get(prefixedIdentifier).push(withOffsets)
      }
    },
  }
}

function extractVariantAtRules(node) {
  node.walkAtRules((atRule) => {
    if (['responsive', 'variants'].includes(atRule.name)) {
      extractVariantAtRules(atRule)
      atRule.before(atRule.nodes)
      atRule.remove()
    }
  })
}

function collectLayerPlugins(root) {
  let layerPlugins = []

  root.each((node) => {
    if (node.type === 'atrule' && ['responsive', 'variants'].includes(node.name)) {
      node.name = 'layer'
      node.params = 'utilities'
    }
  })

  // Walk @layer rules and treat them like plugins
  root.walkAtRules('layer', (layerNode) => {
    extractVariantAtRules(layerNode)

    if (layerNode.params === 'base') {
      for (let node of layerNode.nodes) {
        layerPlugins.push(function ({ addBase }) {
          addBase(node, { respectPrefix: false })
        })
      }
    } else if (layerNode.params === 'components') {
      for (let node of layerNode.nodes) {
        layerPlugins.push(function ({ addComponents }) {
          addComponents(node, { respectPrefix: false })
        })
      }
    } else if (layerNode.params === 'utilities') {
      for (let node of layerNode.nodes) {
        layerPlugins.push(function ({ addUtilities }) {
          addUtilities(node, { respectPrefix: false })
        })
      }
    }
  })

  return layerPlugins
}

function registerPlugins(tailwindConfig, plugins, context) {
  let variantList = []
  let variantMap = new Map()
  let offsets = {
    base: 0n,
    components: 0n,
    utilities: 0n,
  }

  let pluginApi = buildPluginApi(tailwindConfig, context, {
    variantList,
    variantMap,
    offsets,
  })

  for (let plugin of plugins) {
    if (Array.isArray(plugin)) {
      for (let pluginItem of plugin) {
        pluginItem(pluginApi)
      }
    } else {
      plugin(pluginApi)
    }
  }

  let highestOffset = ((args) => args.reduce((m, e) => (e > m ? e : m)))([
    offsets.base,
    offsets.components,
    offsets.utilities,
  ])
  let reservedBits = BigInt(highestOffset.toString(2).length)

  context.layerOrder = {
    base: (1n << reservedBits) << 0n,
    components: (1n << reservedBits) << 1n,
    utilities: (1n << reservedBits) << 2n,
  }

  reservedBits += 3n
  context.variantOrder = variantList.reduce(
    (map, variant, i) => map.set(variant, (1n << BigInt(i)) << reservedBits),
    new Map()
  )

  context.minimumScreen = [...context.variantOrder.values()].shift()

  // Build variantMap
  for (let [variantName, variantFunction] of variantMap.entries()) {
    let sort = context.variantOrder.get(variantName)
    context.variantMap.set(variantName, [sort, variantFunction])
  }
}

function cleanupContext(context) {
  if (context.watcher) {
    context.watcher.close()
  }
}

// Retrieve an existing context from cache if possible (since contexts are unique per
// source path), or set up a new one (including setting up watchers and registering
// plugins) then return it
export default function setupContext(configOrPath) {
  return (result, root) => {
    let foundTailwind = false

    root.walkAtRules('tailwind', () => {
      foundTailwind = true
    })

    let sourcePath = result.opts.from
    let [
      tailwindConfig,
      userConfigPath,
      tailwindConfigHash,
      configDependencies,
    ] = getTailwindConfig(configOrPath)
    let isConfigFile = userConfigPath !== null

    let contextDependencies = new Set(
      sharedState.env.TAILWIND_DISABLE_TOUCH ? configDependencies : []
    )

    // If there are no @tailwind rules, we don't consider this CSS file or it's dependencies
    // to be dependencies of the context. Can reuse the context even if they change.
    // We may want to think about `@layer` being part of this trigger too, but it's tough
    // because it's impossible for a layer in one file to end up in the actual @tailwind rule
    // in another file since independent sources are effectively isolated.
    if (foundTailwind) {
      contextDependencies.add(sourcePath)
      for (let message of result.messages) {
        if (message.type === 'dependency') {
          contextDependencies.add(message.file)
        }
      }
    }

    if (sharedState.env.TAILWIND_DISABLE_TOUCH) {
      for (let file of configDependencies) {
        result.messages.push({
          type: 'dependency',
          plugin: 'tailwindcss-jit',
          parent: result.opts.from,
          file,
        })
      }
    } else {
      if (isConfigFile) {
        contextDependencies.add(userConfigPath)
      }
    }

    let contextDependenciesChanged = trackModified([...contextDependencies])

    process.env.DEBUG && console.log('Source path:', sourcePath)

    if (!contextDependenciesChanged) {
      // If this file already has a context in the cache and we don't need to
      // reset the context, return the cached context.
      if (isConfigFile && contextMap.has(sourcePath)) {
        return contextMap.get(sourcePath)
      }

      // If the config used already exists in the cache, return that.
      if (configContextMap.has(tailwindConfigHash)) {
        let context = configContextMap.get(tailwindConfigHash)
        contextSourcesMap.get(context).add(sourcePath)
        contextMap.set(sourcePath, context)
        return context
      }
    }

    // If this source is in the context map, get the old context.
    // Remove this source from the context sources for the old context,
    // and clean up that context if no one else is using it. This can be
    // called by many processes in rapid succession, so we check for presence
    // first because the first process to run this code will wipe it out first.
    if (contextMap.has(sourcePath)) {
      let oldContext = contextMap.get(sourcePath)
      if (contextSourcesMap.has(oldContext)) {
        contextSourcesMap.get(oldContext).delete(sourcePath)
        if (contextSourcesMap.get(oldContext).size === 0) {
          contextSourcesMap.delete(oldContext)
          cleanupContext(oldContext)
        }
      }
    }

    process.env.DEBUG && console.log('Setting up new context...')

    let context = {
      changedFiles: new Set(),
      ruleCache: new Set(),
      watcher: null,
      scannedContent: false,
      touchFile: null,
      classCache: new Map(),
      applyClassCache: new Map(),
      notClassCache: new Set(),
      postCssNodeCache: new Map(),
      candidateRuleMap: new Map(),
      configPath: userConfigPath,
      tailwindConfig: tailwindConfig,
      configDependencies: new Set(),
      candidateFiles: (Array.isArray(tailwindConfig.purge)
        ? tailwindConfig.purge
        : tailwindConfig.purge.content
      ).map((path) => normalizePath(path)),
      variantMap: new Map(),
      stylesheetCache: null,
      fileModifiedMap: new Map(),
    }

    // ---

    // Update all context tracking state

    configContextMap.set(tailwindConfigHash, context)
    contextMap.set(sourcePath, context)

    if (!contextSourcesMap.has(context)) {
      contextSourcesMap.set(context, new Set())
    }

    contextSourcesMap.get(context).add(sourcePath)

    // ---

    if (isConfigFile && !sharedState.env.TAILWIND_DISABLE_TOUCH) {
      for (let dependency of getModuleDependencies(userConfigPath)) {
        if (dependency.file === userConfigPath) {
          continue
        }

        context.configDependencies.add(dependency.file)
      }
    }

    rebootWatcher(context)

    let corePluginList = Object.entries(corePlugins)
      .map(([name, plugin]) => {
        if (!tailwindConfig.corePlugins.includes(name)) {
          return null
        }

        return plugin
      })
      .filter(Boolean)

    let userPlugins = tailwindConfig.plugins.map((plugin) => {
      if (plugin.__isOptionsFunction) {
        plugin = plugin()
      }

      return typeof plugin === 'function' ? plugin : plugin.handler
    })

    let layerPlugins = collectLayerPlugins(root)

    // TODO: This is a workaround for backwards compatibility, since custom variants
    // were historically sorted before screen/stackable variants.
    let beforeVariants = [corePlugins['pseudoClassVariants']]
    let afterVariants = [
      corePlugins['directionVariants'],
      corePlugins['reducedMotionVariants'],
      corePlugins['darkVariants'],
      corePlugins['screenVariants'],
    ]

    registerPlugins(
      context.tailwindConfig,
      [...corePluginList, ...beforeVariants, ...userPlugins, ...afterVariants, ...layerPlugins],
      context
    )

    return context
  }
}