next.js/packages/next/src/server/request/params.ts

import type { WorkStore } from '../app-render/work-async-storage.external'
import type { FallbackRouteParams } from './fallback-params'

import { ReflectAdapter } from '../web/spec-extension/adapters/reflect'
import {
  throwToInterruptStaticGeneration,
  postponeWithTracking,
  trackSynchronousRequestDataAccessInDev,
} from '../app-render/dynamic-rendering'

import {
  workUnitAsyncStorage,
  type PrerenderStore,
  type PrerenderStorePPR,
  type PrerenderStoreLegacy,
  type PrerenderStoreModern,
} from '../app-render/work-unit-async-storage.external'
import { InvariantError } from '../../shared/lib/invariant-error'
import {
  describeStringPropertyAccess,
  wellKnownProperties,
} from '../../shared/lib/utils/reflect-utils'
import { makeHangingPromise } from '../dynamic-rendering-utils'
import { createDedupedByCallsiteServerErrorLoggerDev } from '../create-deduped-by-callsite-server-error-logger'
import { scheduleImmediate } from '../../lib/scheduler'
import { dynamicAccessAsyncStorage } from '../app-render/dynamic-access-async-storage.external'

export type ParamValue = string | Array<string> | undefined
export type Params = Record<string, ParamValue>

/**
 * In this version of Next.js the `params` prop passed to Layouts, Pages, and other Segments is a Promise.
 * However to facilitate migration to this new Promise type you can currently still access params directly on the Promise instance passed to these Segments.
 * The `UnsafeUnwrappedParams` type is available if you need to temporarily access the underlying params without first awaiting or `use`ing the Promise.
 *
 * In a future version of Next.js the `params` prop will be a plain Promise and this type will be removed.
 *
 * Typically instances of `params` can be updated automatically to be treated as a Promise by a codemod published alongside this Next.js version however if you
 * have not yet run the codemod of the codemod cannot detect certain instances of `params` usage you should first try to refactor your code to await `params`.
 *
 * If refactoring is not possible but you still want to be able to access params directly without typescript errors you can cast the params Promise to this type
 *
 * ```tsx
 * type Props = { params: Promise<{ id: string }>}
 *
 * export default async function Layout(props: Props) {
 *  const directParams = (props.params as unknown as UnsafeUnwrappedParams<typeof props.params>)
 *  return ...
 * }
 * ```
 *
 * This type is marked deprecated to help identify it as target for refactoring away.
 *
 * @deprecated
 */
export type UnsafeUnwrappedParams<P> =
  P extends Promise<infer U> ? Omit<U, 'then' | 'status' | 'value'> : never

export function createParamsFromClient(
  underlyingParams: Params,
  workStore: WorkStore
) {
  const workUnitStore = workUnitAsyncStorage.getStore()
  if (workUnitStore) {
    switch (workUnitStore.type) {
      case 'prerender':
      case 'prerender-client':
      case 'prerender-ppr':
      case 'prerender-legacy':
        return createPrerenderParams(underlyingParams, workStore, workUnitStore)
      case 'cache':
      case 'private-cache':
      case 'unstable-cache':
        throw new InvariantError(
          'createParamsFromClient should not be called in cache contexts.'
        )
      case 'request':
        break
      default:
        workUnitStore satisfies never
    }
  }
  return createRenderParams(underlyingParams, workStore)
}

// generateMetadata always runs in RSC context so it is equivalent to a Server Page Component
export type CreateServerParamsForMetadata = typeof createServerParamsForMetadata
export const createServerParamsForMetadata = createServerParamsForServerSegment

// routes always runs in RSC context so it is equivalent to a Server Page Component
export function createServerParamsForRoute(
  underlyingParams: Params,
  workStore: WorkStore
) {
  const workUnitStore = workUnitAsyncStorage.getStore()
  if (workUnitStore) {
    switch (workUnitStore.type) {
      case 'prerender':
      case 'prerender-client':
      case 'prerender-ppr':
      case 'prerender-legacy':
        return createPrerenderParams(underlyingParams, workStore, workUnitStore)
      case 'cache':
      case 'private-cache':
      case 'unstable-cache':
        throw new InvariantError(
          'createServerParamsForRoute should not be called in cache contexts.'
        )
      case 'request':
        break
      default:
        workUnitStore satisfies never
    }
  }
  return createRenderParams(underlyingParams, workStore)
}

export function createServerParamsForServerSegment(
  underlyingParams: Params,
  workStore: WorkStore
): Promise<Params> {
  const workUnitStore = workUnitAsyncStorage.getStore()
  if (workUnitStore) {
    switch (workUnitStore.type) {
      case 'prerender':
      case 'prerender-client':
      case 'prerender-ppr':
      case 'prerender-legacy':
        return createPrerenderParams(underlyingParams, workStore, workUnitStore)
      case 'cache':
      case 'private-cache':
      case 'unstable-cache':
        throw new InvariantError(
          'createServerParamsForServerSegment should not be called in cache contexts.'
        )
      case 'request':
        break
      default:
        workUnitStore satisfies never
    }
  }
  return createRenderParams(underlyingParams, workStore)
}

export function createPrerenderParamsForClientSegment(
  underlyingParams: Params
): Promise<Params> {
  const workUnitStore = workUnitAsyncStorage.getStore()
  if (workUnitStore) {
    switch (workUnitStore.type) {
      case 'prerender':
      case 'prerender-client':
        const fallbackParams = workUnitStore.fallbackRouteParams
        if (fallbackParams) {
          for (let key in underlyingParams) {
            if (fallbackParams.has(key)) {
              // This params object has one or more fallback params, so we need
              // to consider the awaiting of this params object "dynamic". Since
              // we are in cacheComponents mode we encode this as a promise that never
              // resolves.
              return makeHangingPromise(workUnitStore.renderSignal, '`params`')
            }
          }
        }
        break
      case 'cache':
      case 'private-cache':
      case 'unstable-cache':
        throw new InvariantError(
          'createPrerenderParamsForClientSegment should not be called in cache contexts.'
        )
      case 'prerender-ppr':
      case 'prerender-legacy':
      case 'request':
        break
      default:
        workUnitStore satisfies never
    }
  }
  // We're prerendering in a mode that does not abort. We resolve the promise without
  // any tracking because we're just transporting a value from server to client where the tracking
  // will be applied.
  return Promise.resolve(underlyingParams)
}

function createPrerenderParams(
  underlyingParams: Params,
  workStore: WorkStore,
  prerenderStore: PrerenderStore
): Promise<Params> {
  switch (prerenderStore.type) {
    case 'prerender':
    case 'prerender-client': {
      const fallbackParams = prerenderStore.fallbackRouteParams
      if (fallbackParams) {
        for (const key in underlyingParams) {
          if (fallbackParams.has(key)) {
            // This params object has one or more fallback params, so we need
            // to consider the awaiting of this params object "dynamic". Since
            // we are in cacheComponents mode we encode this as a promise that never
            // resolves.
            return makeHangingParams(underlyingParams, prerenderStore)
          }
        }
      }
      break
    }
    case 'prerender-ppr': {
      const fallbackParams = prerenderStore.fallbackRouteParams
      if (fallbackParams) {
        for (const key in underlyingParams) {
          if (fallbackParams.has(key)) {
            return makeErroringExoticParams(
              underlyingParams,
              fallbackParams,
              workStore,
              prerenderStore
            )
          }
        }
      }
      break
    }
    case 'prerender-legacy':
      break
    default:
      prerenderStore satisfies never
  }

  if (process.env.__NEXT_CACHE_COMPONENTS) {
    return makeUntrackedParams(underlyingParams)
  } else {
    return makeUntrackedExoticParams(underlyingParams)
  }
}

function createRenderParams(
  underlyingParams: Params,
  workStore: WorkStore
): Promise<Params> {
  if (process.env.NODE_ENV === 'development' && !workStore.isPrefetchRequest) {
    if (process.env.__NEXT_CACHE_COMPONENTS) {
      return makeDynamicallyTrackedParamsWithDevWarnings(
        underlyingParams,
        workStore
      )
    }

    return makeDynamicallyTrackedExoticParamsWithDevWarnings(
      underlyingParams,
      workStore
    )
  } else {
    if (process.env.__NEXT_CACHE_COMPONENTS) {
      return makeUntrackedParams(underlyingParams)
    }

    return makeUntrackedExoticParams(underlyingParams)
  }
}

interface CacheLifetime {}
const CachedParams = new WeakMap<CacheLifetime, Promise<Params>>()

const fallbackParamsProxyHandler: ProxyHandler<Promise<Params>> = {
  get: function get(target, prop, receiver) {
    if (prop === 'then' || prop === 'catch' || prop === 'finally') {
      const originalMethod = ReflectAdapter.get(target, prop, receiver)

      return {
        [prop]: (...args: unknown[]) => {
          const store = dynamicAccessAsyncStorage.getStore()

          if (store) {
            store.abortController.abort(
              new Error(`Accessed fallback \`params\` during prerendering.`)
            )
          }

          return new Proxy(
            originalMethod.apply(target, args),
            fallbackParamsProxyHandler
          )
        },
      }[prop]
    }

    return ReflectAdapter.get(target, prop, receiver)
  },
}

function makeHangingParams(
  underlyingParams: Params,
  prerenderStore: PrerenderStoreModern
): Promise<Params> {
  const cachedParams = CachedParams.get(underlyingParams)
  if (cachedParams) {
    return cachedParams
  }

  const promise = new Proxy(
    makeHangingPromise<Params>(prerenderStore.renderSignal, '`params`'),
    fallbackParamsProxyHandler
  )

  CachedParams.set(underlyingParams, promise)

  return promise
}

function makeErroringExoticParams(
  underlyingParams: Params,
  fallbackParams: FallbackRouteParams,
  workStore: WorkStore,
  prerenderStore: PrerenderStorePPR | PrerenderStoreLegacy
): Promise<Params> {
  const cachedParams = CachedParams.get(underlyingParams)
  if (cachedParams) {
    return cachedParams
  }

  const augmentedUnderlying = { ...underlyingParams }

  // We don't use makeResolvedReactPromise here because params
  // supports copying with spread and we don't want to unnecessarily
  // instrument the promise with spreadable properties of ReactPromise.
  const promise = Promise.resolve(augmentedUnderlying)
  CachedParams.set(underlyingParams, promise)

  Object.keys(underlyingParams).forEach((prop) => {
    if (wellKnownProperties.has(prop)) {
      // These properties cannot be shadowed because they need to be the
      // true underlying value for Promises to work correctly at runtime
    } else {
      if (fallbackParams.has(prop)) {
        Object.defineProperty(augmentedUnderlying, prop, {
          get() {
            const expression = describeStringPropertyAccess('params', prop)
            // In most dynamic APIs we also throw if `dynamic = "error"` however
            // for params is only dynamic when we're generating a fallback shell
            // and even when `dynamic = "error"` we still support generating dynamic
            // fallback shells
            // TODO remove this comment when cacheComponents is the default since there
            // will be no `dynamic = "error"`
            if (prerenderStore.type === 'prerender-ppr') {
              // PPR Prerender (no cacheComponents)
              postponeWithTracking(
                workStore.route,
                expression,
                prerenderStore.dynamicTracking
              )
            } else {
              // Legacy Prerender
              throwToInterruptStaticGeneration(
                expression,
                workStore,
                prerenderStore
              )
            }
          },
          enumerable: true,
        })
        Object.defineProperty(promise, prop, {
          get() {
            const expression = describeStringPropertyAccess('params', prop)
            // In most dynamic APIs we also throw if `dynamic = "error"` however
            // for params is only dynamic when we're generating a fallback shell
            // and even when `dynamic = "error"` we still support generating dynamic
            // fallback shells
            // TODO remove this comment when cacheComponents is the default since there
            // will be no `dynamic = "error"`
            if (prerenderStore.type === 'prerender-ppr') {
              // PPR Prerender (no cacheComponents)
              postponeWithTracking(
                workStore.route,
                expression,
                prerenderStore.dynamicTracking
              )
            } else {
              // Legacy Prerender
              throwToInterruptStaticGeneration(
                expression,
                workStore,
                prerenderStore
              )
            }
          },
          set(newValue) {
            Object.defineProperty(promise, prop, {
              value: newValue,
              writable: true,
              enumerable: true,
            })
          },
          enumerable: true,
          configurable: true,
        })
      } else {
        ;(promise as any)[prop] = underlyingParams[prop]
      }
    }
  })

  return promise
}

function makeUntrackedExoticParams(underlyingParams: Params): Promise<Params> {
  const cachedParams = CachedParams.get(underlyingParams)
  if (cachedParams) {
    return cachedParams
  }

  // We don't use makeResolvedReactPromise here because params
  // supports copying with spread and we don't want to unnecessarily
  // instrument the promise with spreadable properties of ReactPromise.
  const promise = Promise.resolve(underlyingParams)
  CachedParams.set(underlyingParams, promise)

  Object.keys(underlyingParams).forEach((prop) => {
    if (wellKnownProperties.has(prop)) {
      // These properties cannot be shadowed because they need to be the
      // true underlying value for Promises to work correctly at runtime
    } else {
      ;(promise as any)[prop] = underlyingParams[prop]
    }
  })

  return promise
}

function makeUntrackedParams(underlyingParams: Params): Promise<Params> {
  const cachedParams = CachedParams.get(underlyingParams)
  if (cachedParams) {
    return cachedParams
  }

  const promise = Promise.resolve(underlyingParams)
  CachedParams.set(underlyingParams, promise)

  return promise
}

function makeDynamicallyTrackedExoticParamsWithDevWarnings(
  underlyingParams: Params,
  store: WorkStore
): Promise<Params> {
  const cachedParams = CachedParams.get(underlyingParams)
  if (cachedParams) {
    return cachedParams
  }

  // We don't use makeResolvedReactPromise here because params
  // supports copying with spread and we don't want to unnecessarily
  // instrument the promise with spreadable properties of ReactPromise.
  const promise = new Promise<Params>((resolve) =>
    scheduleImmediate(() => resolve(underlyingParams))
  )

  const proxiedProperties = new Set<string>()
  const unproxiedProperties: Array<string> = []

  Object.keys(underlyingParams).forEach((prop) => {
    if (wellKnownProperties.has(prop)) {
      // These properties cannot be shadowed because they need to be the
      // true underlying value for Promises to work correctly at runtime
      unproxiedProperties.push(prop)
    } else {
      proxiedProperties.add(prop)
      ;(promise as any)[prop] = underlyingParams[prop]
    }
  })

  const proxiedPromise = new Proxy(promise, {
    get(target, prop, receiver) {
      if (typeof prop === 'string') {
        if (
          // We are accessing a property that was proxied to the promise instance
          proxiedProperties.has(prop)
        ) {
          const expression = describeStringPropertyAccess('params', prop)
          syncIODev(store.route, expression)
        }
      }
      return ReflectAdapter.get(target, prop, receiver)
    },
    set(target, prop, value, receiver) {
      if (typeof prop === 'string') {
        proxiedProperties.delete(prop)
      }
      return ReflectAdapter.set(target, prop, value, receiver)
    },
    ownKeys(target) {
      const expression = '`...params` or similar expression'
      syncIODev(store.route, expression, unproxiedProperties)
      return Reflect.ownKeys(target)
    },
  })

  CachedParams.set(underlyingParams, proxiedPromise)
  return proxiedPromise
}

// Similar to `makeDynamicallyTrackedExoticParamsWithDevWarnings`, but just
// logging the sync access without actually defining the params on the promise.
function makeDynamicallyTrackedParamsWithDevWarnings(
  underlyingParams: Params,
  store: WorkStore
): Promise<Params> {
  const cachedParams = CachedParams.get(underlyingParams)
  if (cachedParams) {
    return cachedParams
  }

  // We don't use makeResolvedReactPromise here because params
  // supports copying with spread and we don't want to unnecessarily
  // instrument the promise with spreadable properties of ReactPromise.
  const promise = new Promise<Params>((resolve) =>
    scheduleImmediate(() => resolve(underlyingParams))
  )

  const proxiedProperties = new Set<string>()
  const unproxiedProperties: Array<string> = []

  Object.keys(underlyingParams).forEach((prop) => {
    if (wellKnownProperties.has(prop)) {
      // These properties cannot be shadowed because they need to be the
      // true underlying value for Promises to work correctly at runtime
      unproxiedProperties.push(prop)
    } else {
      proxiedProperties.add(prop)
    }
  })

  const proxiedPromise = new Proxy(promise, {
    get(target, prop, receiver) {
      if (typeof prop === 'string') {
        if (
          // We are accessing a property that was proxied to the promise instance
          proxiedProperties.has(prop)
        ) {
          const expression = describeStringPropertyAccess('params', prop)
          warnForSyncAccess(store.route, expression)
        }
      }
      return ReflectAdapter.get(target, prop, receiver)
    },
    set(target, prop, value, receiver) {
      if (typeof prop === 'string') {
        proxiedProperties.delete(prop)
      }
      return ReflectAdapter.set(target, prop, value, receiver)
    },
    ownKeys(target) {
      const expression = '`...params` or similar expression'
      warnForIncompleteEnumeration(store.route, expression, unproxiedProperties)
      return Reflect.ownKeys(target)
    },
  })

  CachedParams.set(underlyingParams, proxiedPromise)
  return proxiedPromise
}

function syncIODev(
  route: string | undefined,
  expression: string,
  missingProperties?: Array<string>
) {
  const workUnitStore = workUnitAsyncStorage.getStore()
  if (workUnitStore) {
    switch (workUnitStore.type) {
      case 'request':
        if (workUnitStore.prerenderPhase === true) {
          // When we're rendering dynamically in dev, we need to advance out of
          // the Prerender environment when we read Request data synchronously.
          trackSynchronousRequestDataAccessInDev(workUnitStore)
        }
        break
      case 'prerender':
      case 'prerender-client':
      case 'prerender-ppr':
      case 'prerender-legacy':
      case 'cache':
      case 'private-cache':
      case 'unstable-cache':
        break
      default:
        workUnitStore satisfies never
    }
  }
  // In all cases we warn normally
  if (missingProperties && missingProperties.length > 0) {
    warnForIncompleteEnumeration(route, expression, missingProperties)
  } else {
    warnForSyncAccess(route, expression)
  }
}

const warnForSyncAccess = createDedupedByCallsiteServerErrorLoggerDev(
  createParamsAccessError
)

const warnForIncompleteEnumeration =
  createDedupedByCallsiteServerErrorLoggerDev(createIncompleteEnumerationError)

function createParamsAccessError(
  route: string | undefined,
  expression: string
) {
  const prefix = route ? `Route "${route}" ` : 'This route '
  return new Error(
    `${prefix}used ${expression}. ` +
      `\`params\` should be awaited before using its properties. ` +
      `Learn more: https://nextjs.org/docs/messages/sync-dynamic-apis`
  )
}

function createIncompleteEnumerationError(
  route: string | undefined,
  expression: string,
  missingProperties: Array<string>
) {
  const prefix = route ? `Route "${route}" ` : 'This route '
  return new Error(
    `${prefix}used ${expression}. ` +
      `\`params\` should be awaited before using its properties. ` +
      `The following properties were not available through enumeration ` +
      `because they conflict with builtin property names: ` +
      `${describeListOfPropertyNames(missingProperties)}. ` +
      `Learn more: https://nextjs.org/docs/messages/sync-dynamic-apis`
  )
}

function describeListOfPropertyNames(properties: Array<string>) {
  switch (properties.length) {
    case 0:
      throw new InvariantError(
        'Expected describeListOfPropertyNames to be called with a non-empty list of strings.'
      )
    case 1:
      return `\`${properties[0]}\``
    case 2:
      return `\`${properties[0]}\` and \`${properties[1]}\``
    default: {
      let description = ''
      for (let i = 0; i < properties.length - 1; i++) {
        description += `\`${properties[i]}\`, `
      }
      description += `, and \`${properties[properties.length - 1]}\``
      return description
    }
  }
}