import fs from 'fs'
import path from 'path'
import chalk from 'chalk'
import { createServer, ViteDevServer } from '..'
import { createDebugger, normalizePath } from '../utils'
import { ModuleNode } from './moduleGraph'
import { Update } from 'types/hmrPayload'
import { CLIENT_DIR } from '../constants'
import { RollupError } from 'rollup'
import { prepareError } from './middlewares/error'
import match from 'minimatch'
import { Server } from 'http'
import { isCSSRequest } from '../plugins/css'

export const debugHmr = createDebugger('vite:hmr')

const normalizedClientDir = normalizePath(CLIENT_DIR)

export interface HmrOptions {
  protocol?: string
  host?: string
  port?: number
  clientPort?: number
  path?: string
  timeout?: number
  overlay?: boolean
  server?: Server
}

export interface HmrContext {
  file: string
  timestamp: number
  modules: Array<ModuleNode>
  read: () => string | Promise<string>
  server: ViteDevServer
}

function getShortName(file: string, root: string) {
  return file.startsWith(root + '/') ? path.posix.relative(root, file) : file
}

export async function handleHMRUpdate(
  file: string,
  server: ViteDevServer
): Promise<any> {
  const { ws, config, moduleGraph } = server
  const shortFile = getShortName(file, config.root)

  const isConfig = file === config.configFile
  const isConfigDependency = config.configFileDependencies.some(
    (name) => file === path.resolve(name)
  )
  const isEnv = config.inlineConfig.envFile !== false && file.endsWith('.env')
  if (isConfig || isConfigDependency || isEnv) {
    // auto restart server
    debugHmr(`[config change] ${chalk.dim(shortFile)}`)
    config.logger.info(
      chalk.green(
        `${path.relative(process.cwd(), file)} changed, restarting server...`
      ),
      { clear: true, timestamp: true }
    )
    await restartServer(server)
    return
  }

  debugHmr(`[file change] ${chalk.dim(shortFile)}`)

  // (dev only) the client itself cannot be hot updated.
  if (file.startsWith(normalizedClientDir)) {
    ws.send({
      type: 'full-reload',
      path: '*'
    })
    return
  }

  const mods = moduleGraph.getModulesByFile(file)

  // check if any plugin wants to perform custom HMR handling
  const timestamp = Date.now()
  const hmrContext: HmrContext = {
    file,
    timestamp,
    modules: mods ? [...mods] : [],
    read: () => readModifiedFile(file),
    server
  }

  for (const plugin of config.plugins) {
    if (plugin.handleHotUpdate) {
      const filteredModules = await plugin.handleHotUpdate(hmrContext)
      if (filteredModules) {
        hmrContext.modules = filteredModules
      }
    }
  }

  if (!hmrContext.modules.length) {
    // html file cannot be hot updated
    if (file.endsWith('.html')) {
      config.logger.info(chalk.green(`page reload `) + chalk.dim(shortFile), {
        clear: true,
        timestamp: true
      })
      ws.send({
        type: 'full-reload',
        path: config.server.middlewareMode
          ? '*'
          : '/' + normalizePath(path.relative(config.root, file))
      })
    } else {
      // loaded but not in the module graph, probably not js
      debugHmr(`[no modules matched] ${chalk.dim(shortFile)}`)
    }
    return
  }

  updateModules(shortFile, hmrContext.modules, timestamp, server)
}

function updateModules(
  file: string,
  modules: ModuleNode[],
  timestamp: number,
  { config, ws }: ViteDevServer
) {
  const updates: Update[] = []
  const invalidatedModules = new Set<ModuleNode>()
  let needFullReload = false

  for (const mod of modules) {
    invalidate(mod, timestamp, invalidatedModules)
    if (needFullReload) {
      continue
    }

    const boundaries = new Set<{
      boundary: ModuleNode
      acceptedVia: ModuleNode
    }>()
    const hasDeadEnd = propagateUpdate(mod, timestamp, boundaries)
    if (hasDeadEnd) {
      needFullReload = true
      continue
    }

    updates.push(
      ...[...boundaries].map(({ boundary, acceptedVia }) => ({
        type: `${boundary.type}-update` as Update['type'],
        timestamp,
        path: boundary.url,
        acceptedPath: acceptedVia.url
      }))
    )
  }

  if (needFullReload) {
    config.logger.info(chalk.green(`page reload `) + chalk.dim(file), {
      clear: true,
      timestamp: true
    })
    ws.send({
      type: 'full-reload'
    })
  } else {
    config.logger.info(
      updates
        .map(({ path }) => chalk.green(`hmr update `) + chalk.dim(path))
        .join('\n'),
      { clear: true, timestamp: true }
    )
    ws.send({
      type: 'update',
      updates
    })
  }
}

export async function handleFileAddUnlink(
  file: string,
  server: ViteDevServer,
  isUnlink = false
): Promise<void> {
  const modules = [...(server.moduleGraph.getModulesByFile(file) ?? [])]
  if (isUnlink && file in server._globImporters) {
    delete server._globImporters[file]
  } else {
    for (const i in server._globImporters) {
      const { module, importGlobs } = server._globImporters[i]
      for (const { base, pattern } of importGlobs) {
        if (match(file, pattern) || match(path.relative(base, file), pattern)) {
          modules.push(module)
          // We use `onFileChange` to invalidate `module.file` so that subsequent `ssrLoadModule()`
          // calls get fresh glob import results with(out) the newly added(/removed) `file`.
          server.moduleGraph.onFileChange(module.file!)
          break
        }
      }
    }
  }
  if (modules.length > 0) {
    updateModules(
      getShortName(file, server.config.root),
      modules,
      Date.now(),
      server
    )
  }
}

function propagateUpdate(
  node: ModuleNode,
  timestamp: number,
  boundaries: Set<{
    boundary: ModuleNode
    acceptedVia: ModuleNode
  }>,
  currentChain: ModuleNode[] = [node]
): boolean /* hasDeadEnd */ {
  if (node.isSelfAccepting) {
    boundaries.add({
      boundary: node,
      acceptedVia: node
    })

    // additionally check for CSS importers, since a PostCSS plugin like
    // Tailwind JIT may register any file as a dependency to a CSS file.
    for (const importer of node.importers) {
      if (isCSSRequest(importer.url) && !currentChain.includes(importer)) {
        propagateUpdate(
          importer,
          timestamp,
          boundaries,
          currentChain.concat(importer)
        )
      }
    }

    return false
  }

  if (!node.importers.size) {
    return true
  }
  
  // #3716, #3913
  // For a non-CSS file, if all of its importers are CSS files (registered via
  // PostCSS plugins) it should be considered a dead end and force full reload.
  if (
    !isCSSRequest(node.url) &&
    [...node.importers].every((i) => isCSSRequest(i.url))
  ) {
    return true
  }

  for (const importer of node.importers) {
    const subChain = currentChain.concat(importer)
    if (importer.acceptedHmrDeps.has(node)) {
      boundaries.add({
        boundary: importer,
        acceptedVia: node
      })
      continue
    }

    if (currentChain.includes(importer)) {
      // circular deps is considered dead end
      return true
    }

    if (propagateUpdate(importer, timestamp, boundaries, subChain)) {
      return true
    }
  }
  return false
}

function invalidate(mod: ModuleNode, timestamp: number, seen: Set<ModuleNode>) {
  if (seen.has(mod)) {
    return
  }
  seen.add(mod)
  mod.lastHMRTimestamp = timestamp
  mod.transformResult = null
  mod.ssrModule = null
  mod.ssrTransformResult = null
  mod.importers.forEach((importer) => {
    if (!importer.acceptedHmrDeps.has(mod)) {
      invalidate(importer, timestamp, seen)
    }
  })
}

export function handlePrunedModules(
  mods: Set<ModuleNode>,
  { ws }: ViteDevServer
): void {
  // update the disposed modules' hmr timestamp
  // since if it's re-imported, it should re-apply side effects
  // and without the timestamp the browser will not re-import it!
  const t = Date.now()
  mods.forEach((mod) => {
    mod.lastHMRTimestamp = t
    debugHmr(`[dispose] ${chalk.dim(mod.file)}`)
  })
  ws.send({
    type: 'prune',
    paths: [...mods].map((m) => m.url)
  })
}

const enum LexerState {
  inCall,
  inSingleQuoteString,
  inDoubleQuoteString,
  inTemplateString,
  inArray
}

/**
 * Lex import.meta.hot.accept() for accepted deps.
 * Since hot.accept() can only accept string literals or array of string
 * literals, we don't really need a heavy @babel/parse call on the entire source.
 *
 * @returns selfAccepts
 */
export function lexAcceptedHmrDeps(
  code: string,
  start: number,
  urls: Set<{ url: string; start: number; end: number }>
): boolean {
  let state: LexerState = LexerState.inCall
  // the state can only be 2 levels deep so no need for a stack
  let prevState: LexerState = LexerState.inCall
  let currentDep: string = ''

  function addDep(index: number) {
    urls.add({
      url: currentDep,
      start: index - currentDep.length - 1,
      end: index + 1
    })
    currentDep = ''
  }

  for (let i = start; i < code.length; i++) {
    const char = code.charAt(i)
    switch (state) {
      case LexerState.inCall:
      case LexerState.inArray:
        if (char === `'`) {
          prevState = state
          state = LexerState.inSingleQuoteString
        } else if (char === `"`) {
          prevState = state
          state = LexerState.inDoubleQuoteString
        } else if (char === '`') {
          prevState = state
          state = LexerState.inTemplateString
        } else if (/\s/.test(char)) {
          continue
        } else {
          if (state === LexerState.inCall) {
            if (char === `[`) {
              state = LexerState.inArray
            } else {
              // reaching here means the first arg is neither a string literal
              // nor an Array literal (direct callback) or there is no arg
              // in both case this indicates a self-accepting module
              return true // done
            }
          } else if (state === LexerState.inArray) {
            if (char === `]`) {
              return false // done
            } else if (char === ',') {
              continue
            } else {
              error(i)
            }
          }
        }
        break
      case LexerState.inSingleQuoteString:
        if (char === `'`) {
          addDep(i)
          if (prevState === LexerState.inCall) {
            // accept('foo', ...)
            return false
          } else {
            state = prevState
          }
        } else {
          currentDep += char
        }
        break
      case LexerState.inDoubleQuoteString:
        if (char === `"`) {
          addDep(i)
          if (prevState === LexerState.inCall) {
            // accept('foo', ...)
            return false
          } else {
            state = prevState
          }
        } else {
          currentDep += char
        }
        break
      case LexerState.inTemplateString:
        if (char === '`') {
          addDep(i)
          if (prevState === LexerState.inCall) {
            // accept('foo', ...)
            return false
          } else {
            state = prevState
          }
        } else if (char === '$' && code.charAt(i + 1) === '{') {
          error(i)
        } else {
          currentDep += char
        }
        break
      default:
        throw new Error('unknown import.meta.hot lexer state')
    }
  }
  return false
}

function error(pos: number) {
  const err = new Error(
    `import.meta.accept() can only accept string literals or an ` +
      `Array of string literals.`
  ) as RollupError
  err.pos = pos
  throw err
}

// vitejs/vite#610 when hot-reloading Vue files, we read immediately on file
// change event and sometimes this can be too early and get an empty buffer.
// Poll until the file's modified time has changed before reading again.
async function readModifiedFile(file: string): Promise<string> {
  const content = fs.readFileSync(file, 'utf-8')
  if (!content) {
    const mtime = fs.statSync(file).mtimeMs
    await new Promise((r) => {
      let n = 0
      const poll = async () => {
        n++
        const newMtime = fs.statSync(file).mtimeMs
        if (newMtime !== mtime || n > 10) {
          r(0)
        } else {
          setTimeout(poll, 10)
        }
      }
      setTimeout(poll, 10)
    })
    return fs.readFileSync(file, 'utf-8')
  } else {
    return content
  }
}

async function restartServer(server: ViteDevServer) {
  // @ts-ignore
  global.__vite_start_time = Date.now()
  let newServer = null
  try {
    newServer = await createServer(server.config.inlineConfig)
  } catch (err) {
    server.ws.send({
      type: 'error',
      err: prepareError(err)
    })
    return
  }

  await server.close()
  for (const key in newServer) {
    if (key !== 'app') {
      // @ts-ignore
      server[key] = newServer[key]
    }
  }
  if (!server.config.server.middlewareMode) {
    await server.listen(undefined, true)
  } else {
    server.config.logger.info('server restarted.', { timestamp: true })
  }
}