index.ts

/* eslint-disable @typescript-eslint/no-explicit-any */
/* eslint-disable @typescript-eslint/no-unused-vars */
import type {
  RouteConfig as RouteConfigBase,
  ZodContentObject,
  ZodMediaTypeObject,
  ZodRequestBody,
} from '@asteasolutions/zod-to-openapi'
import {
  OpenAPIRegistry,
  OpenApiGeneratorV3,
  OpenApiGeneratorV31,
  extendZodWithOpenApi,
} from '@asteasolutions/zod-to-openapi'
import { zValidator } from '@hono/zod-validator'
import { Hono } from 'hono'
import type {
  Context,
  Env,
  Handler,
  Input,
  MiddlewareHandler,
  Schema,
  ToSchema,
  TypedResponse,
  ValidationTargets,
} from 'hono'
import type { MergePath, MergeSchemaPath } from 'hono/types'
import type { JSONParsed, JSONValue, RemoveBlankRecord, SimplifyDeepArray } from 'hono/utils/types'
import type {
  ClientErrorStatusCode,
  InfoStatusCode,
  RedirectStatusCode,
  ServerErrorStatusCode,
  StatusCode,
  SuccessStatusCode,
} from 'hono/utils/http-status'
import { mergePath } from 'hono/utils/url'
import type { ZodError, ZodSchema } from 'zod'
import { ZodType, z } from 'zod'

type MaybePromise<T> = Promise<T> | T

export type RouteConfig = RouteConfigBase & {
  middleware?: MiddlewareHandler | MiddlewareHandler[]
}

type RequestTypes = {
  body?: ZodRequestBody
  params?: ZodType
  query?: ZodType
  cookies?: ZodType
  headers?: ZodType | ZodType[]
}

type IsJson<T> = T extends string
  ? T extends `application/${infer Start}json${infer _End}`
    ? Start extends '' | `${string}+` | `vnd.${string}+`
      ? 'json'
      : never
    : never
  : never

type IsForm<T> = T extends string
  ? T extends
      | `multipart/form-data${infer _Rest}`
      | `application/x-www-form-urlencoded${infer _Rest}`
    ? 'form'
    : never
  : never

type ReturnJsonOrTextOrResponse<
  ContentType,
  Content,
  Status extends keyof StatusCodeRangeDefinitions | StatusCode
> = ContentType extends string
  ? ContentType extends `application/${infer Start}json${infer _End}`
    ? Start extends '' | `${string}+` | `vnd.${string}+`
      ? TypedResponse<
          SimplifyDeepArray<Content> extends JSONValue
            ? JSONValue extends SimplifyDeepArray<Content>
              ? never
              : JSONParsed<Content>
            : never,
          ExtractStatusCode<Status>,
          'json'
        >
      : never
    : ContentType extends `text/plain${infer _Rest}`
    ? TypedResponse<Content, ExtractStatusCode<Status>, 'text'>
    : Response
  : never

type RequestPart<R extends RouteConfig, Part extends string> = Part extends keyof R['request']
  ? R['request'][Part]
  : {}

type HasUndefined<T> = undefined extends T ? true : false

type InputTypeBase<
  R extends RouteConfig,
  Part extends string,
  Type extends keyof ValidationTargets
> = R['request'] extends RequestTypes
  ? RequestPart<R, Part> extends ZodType
    ? {
        in: {
          [K in Type]: HasUndefined<ValidationTargets[K]> extends true
            ? {
                [K2 in keyof z.input<RequestPart<R, Part>>]?: z.input<RequestPart<R, Part>>[K2]
              }
            : {
                [K2 in keyof z.input<RequestPart<R, Part>>]: z.input<RequestPart<R, Part>>[K2]
              }
        }
        out: { [K in Type]: z.output<RequestPart<R, Part>> }
      }
    : {}
  : {}

type InputTypeJson<R extends RouteConfig> = R['request'] extends RequestTypes
  ? R['request']['body'] extends ZodRequestBody
    ? R['request']['body']['content'] extends ZodContentObject
      ? IsJson<keyof R['request']['body']['content']> extends never
        ? {}
        : R['request']['body']['content'][keyof R['request']['body']['content']] extends Record<
            'schema',
            ZodSchema<any>
          >
        ? {
            in: {
              json: z.input<
                R['request']['body']['content'][keyof R['request']['body']['content']]['schema']
              >
            }
            out: {
              json: z.output<
                R['request']['body']['content'][keyof R['request']['body']['content']]['schema']
              >
            }
          }
        : {}
      : {}
    : {}
  : {}

type InputTypeForm<R extends RouteConfig> = R['request'] extends RequestTypes
  ? R['request']['body'] extends ZodRequestBody
    ? R['request']['body']['content'] extends ZodContentObject
      ? IsForm<keyof R['request']['body']['content']> extends never
        ? {}
        : R['request']['body']['content'][keyof R['request']['body']['content']] extends Record<
            'schema',
            ZodSchema<any>
          >
        ? {
            in: {
              form: z.input<
                R['request']['body']['content'][keyof R['request']['body']['content']]['schema']
              >
            }
            out: {
              form: z.output<
                R['request']['body']['content'][keyof R['request']['body']['content']]['schema']
              >
            }
          }
        : {}
      : {}
    : {}
  : {}

type InputTypeParam<R extends RouteConfig> = InputTypeBase<R, 'params', 'param'>
type InputTypeQuery<R extends RouteConfig> = InputTypeBase<R, 'query', 'query'>
type InputTypeHeader<R extends RouteConfig> = InputTypeBase<R, 'headers', 'header'>
type InputTypeCookie<R extends RouteConfig> = InputTypeBase<R, 'cookies', 'cookie'>

type ExtractContent<T> = T extends {
  [K in keyof T]: infer A
}
  ? A extends Record<'schema', ZodSchema>
    ? z.infer<A['schema']>
    : never
  : never

type StatusCodeRangeDefinitions = {
  '1XX': InfoStatusCode
  '2XX': SuccessStatusCode
  '3XX': RedirectStatusCode
  '4XX': ClientErrorStatusCode
  '5XX': ServerErrorStatusCode
}
type RouteConfigStatusCode = keyof StatusCodeRangeDefinitions | StatusCode
type ExtractStatusCode<T extends RouteConfigStatusCode> = T extends keyof StatusCodeRangeDefinitions
  ? StatusCodeRangeDefinitions[T]
  : T
type DefinedStatusCodes<R extends RouteConfig> = keyof R['responses'] & RouteConfigStatusCode
export type RouteConfigToTypedResponse<R extends RouteConfig> =
  | {
      [Status in DefinedStatusCodes<R>]: undefined extends R['responses'][Status]['content']
        ? TypedResponse<{}, ExtractStatusCode<Status>, string>
        : ReturnJsonOrTextOrResponse<
            keyof R['responses'][Status]['content'],
            ExtractContent<R['responses'][Status]['content']>,
            Status
          >
    }[DefinedStatusCodes<R>]
  | ('default' extends keyof R['responses']
      ? undefined extends R['responses']['default']['content']
        ? TypedResponse<{}, Exclude<StatusCode, ExtractStatusCode<DefinedStatusCodes<R>>>, string>
        : ReturnJsonOrTextOrResponse<
            keyof R['responses']['default']['content'],
            ExtractContent<R['responses']['default']['content']>,
            Exclude<StatusCode, ExtractStatusCode<DefinedStatusCodes<R>>>
          >
      : never)

export type Hook<T, E extends Env, P extends string, R> = (
  result: { target: keyof ValidationTargets } & (
    | {
        success: true
        data: T
      }
    | {
        success: false
        error: ZodError
      }
  ),
  c: Context<E, P>
) => R

type ConvertPathType<T extends string> = T extends `${infer Start}/{${infer Param}}${infer Rest}`
  ? `${Start}/:${Param}${ConvertPathType<Rest>}`
  : T

export type OpenAPIHonoOptions<E extends Env> = {
  defaultHook?: Hook<any, E, any, any>
}
type HonoInit<E extends Env> = ConstructorParameters<typeof Hono>[0] & OpenAPIHonoOptions<E>

/**
 * Turns `T | T[] | undefined` into `T[]`
 */
type AsArray<T> = T extends undefined // TODO move to utils?
  ? []
  : T extends any[]
  ? T
  : [T]

/**
 * Like simplify but recursive
 */
export type DeepSimplify<T> = {
  // TODO move to utils?
  [KeyType in keyof T]: T[KeyType] extends Record<string, unknown>
    ? DeepSimplify<T[KeyType]>
    : T[KeyType]
} & {}

/**
 * Helper to infer generics from {@link MiddlewareHandler}
 */
export type OfHandlerType<T extends MiddlewareHandler> = T extends MiddlewareHandler<
  infer E,
  infer P,
  infer I
>
  ? {
      env: E
      path: P
      input: I
    }
  : never

/**
 * Reduce a tuple of middleware handlers into a single
 * handler representing the composition of all
 * handlers.
 */
export type MiddlewareToHandlerType<M extends MiddlewareHandler<any, any, any>[]> = M extends [
  infer First,
  infer Second,
  ...infer Rest
]
  ? First extends MiddlewareHandler<any, any, any>
    ? Second extends MiddlewareHandler<any, any, any>
      ? Rest extends MiddlewareHandler<any, any, any>[] // Ensure Rest is an array of MiddlewareHandler
        ? MiddlewareToHandlerType<
            [
              MiddlewareHandler<
                DeepSimplify<OfHandlerType<First>['env'] & OfHandlerType<Second>['env']>, // Combine envs
                OfHandlerType<First>['path'], // Keep path from First
                OfHandlerType<First>['input'] // Keep input from First
              >,
              ...Rest
            ]
          >
        : never
      : never
    : never
  : M extends [infer Last]
  ? Last // Return the last remaining handler in the array
  : never

type RouteMiddlewareParams<R extends RouteConfig> = OfHandlerType<
  MiddlewareToHandlerType<AsArray<R['middleware']>>
>

export type RouteConfigToEnv<R extends RouteConfig> = RouteMiddlewareParams<R> extends never
  ? Env
  : RouteMiddlewareParams<R>['env']

export type RouteHandler<
  R extends RouteConfig,
  E extends Env = RouteConfigToEnv<R>,
  I extends Input = InputTypeParam<R> &
    InputTypeQuery<R> &
    InputTypeHeader<R> &
    InputTypeCookie<R> &
    InputTypeForm<R> &
    InputTypeJson<R>,
  P extends string = ConvertPathType<R['path']>
> = Handler<
  E,
  P,
  I,
  // If response type is defined, only TypedResponse is allowed.
  R extends {
    responses: {
      [statusCode: number]: {
        content: {
          [mediaType: string]: ZodMediaTypeObject
        }
      }
    }
  }
    ? MaybePromise<RouteConfigToTypedResponse<R>>
    : MaybePromise<RouteConfigToTypedResponse<R>> | MaybePromise<Response>
>

export type RouteHook<
  R extends RouteConfig,
  E extends Env = RouteConfigToEnv<R>,
  I extends Input = InputTypeParam<R> &
    InputTypeQuery<R> &
    InputTypeHeader<R> &
    InputTypeCookie<R> &
    InputTypeForm<R> &
    InputTypeJson<R>,
  P extends string = ConvertPathType<R['path']>
> = Hook<
  I,
  E,
  P,
  RouteConfigToTypedResponse<R> | Response | Promise<Response> | void | Promise<void>
>

type OpenAPIObjectConfig = Parameters<
  InstanceType<typeof OpenApiGeneratorV3>['generateDocument']
>[0]

export type OpenAPIObjectConfigure<E extends Env, P extends string> =
  | OpenAPIObjectConfig
  | ((context: Context<E, P>) => OpenAPIObjectConfig)

export class OpenAPIHono<
  E extends Env = Env,
  S extends Schema = {},
  BasePath extends string = '/'
> extends Hono<E, S, BasePath> {
  openAPIRegistry: OpenAPIRegistry
  defaultHook?: OpenAPIHonoOptions<E>['defaultHook']

  constructor(init?: HonoInit<E>) {
    super(init)
    this.openAPIRegistry = new OpenAPIRegistry()
    this.defaultHook = init?.defaultHook
  }

  /**
   *
   * @param {RouteConfig} route - The route definition which you create with `createRoute()`.
   * @param {Handler} handler - The handler. If you want to return a JSON object, you should specify the status code with `c.json()`.
   * @param {Hook} hook - Optional. The hook method defines what it should do after validation.
   * @example
   * app.openapi(
   *   route,
   *   (c) => {
   *     // ...
   *     return c.json(
   *       {
   *         age: 20,
   *         name: 'Young man',
   *       },
   *       200 // You should specify the status code even if it's 200.
   *     )
   *   },
   *  (result, c) => {
   *    if (!result.success) {
   *      return c.json(
   *        {
   *          code: 400,
   *          message: 'Custom Message',
   *        },
   *        400
   *      )
   *    }
   *  }
   *)
   */
  openapi = <
    R extends RouteConfig,
    I extends Input = InputTypeParam<R> &
      InputTypeQuery<R> &
      InputTypeHeader<R> &
      InputTypeCookie<R> &
      InputTypeForm<R> &
      InputTypeJson<R>,
    P extends string = ConvertPathType<R['path']>
  >(
    { middleware: routeMiddleware, ...route }: R,
    handler: Handler<
      // use the env from the middleware if it's defined
      R['middleware'] extends MiddlewareHandler[] | MiddlewareHandler
        ? RouteMiddlewareParams<R>['env'] & E
        : E,
      P,
      I,
      // If response type is defined, only TypedResponse is allowed.
      R extends {
        responses: {
          [statusCode: number]: {
            content: {
              [mediaType: string]: ZodMediaTypeObject
            }
          }
        }
      }
        ? MaybePromise<RouteConfigToTypedResponse<R>>
        : MaybePromise<RouteConfigToTypedResponse<R>> | MaybePromise<Response>
    >,
    hook:
      | Hook<
          I,
          E,
          P,
          R extends {
            responses: {
              [statusCode: number]: {
                content: {
                  [mediaType: string]: ZodMediaTypeObject
                }
              }
            }
          }
            ? MaybePromise<RouteConfigToTypedResponse<R>> | undefined
            : MaybePromise<RouteConfigToTypedResponse<R>> | MaybePromise<Response> | undefined
        >
      | undefined = this.defaultHook
  ): OpenAPIHono<
    E,
    S & ToSchema<R['method'], MergePath<BasePath, P>, I, RouteConfigToTypedResponse<R>>,
    BasePath
  > => {
    this.openAPIRegistry.registerPath(route)

    const validators: MiddlewareHandler[] = []

    if (route.request?.query) {
      const validator = zValidator('query', route.request.query as any, hook as any)
      validators.push(validator as any)
    }

    if (route.request?.params) {
      const validator = zValidator('param', route.request.params as any, hook as any)
      validators.push(validator as any)
    }

    if (route.request?.headers) {
      const validator = zValidator('header', route.request.headers as any, hook as any)
      validators.push(validator as any)
    }

    if (route.request?.cookies) {
      const validator = zValidator('cookie', route.request.cookies as any, hook as any)
      validators.push(validator as any)
    }

    const bodyContent = route.request?.body?.content

    if (bodyContent) {
      for (const mediaType of Object.keys(bodyContent)) {
        if (!bodyContent[mediaType]) {
          continue
        }
        const schema = (bodyContent[mediaType] as ZodMediaTypeObject)['schema']
        if (!(schema instanceof ZodType)) {
          continue
        }
        if (isJSONContentType(mediaType)) {
          const validator = zValidator('json', schema, hook as any)
          if (route.request?.body?.required) {
            validators.push(validator)
          } else {
            const mw: MiddlewareHandler = async (c, next) => {
              if (c.req.header('content-type')) {
                if (isJSONContentType(c.req.header('content-type')!)) {
                  return await validator(c, next)
                }
              }
              c.req.addValidatedData('json', {})
              await next()
            }
            validators.push(mw)
          }
        }
        if (isFormContentType(mediaType)) {
          const validator = zValidator('form', schema, hook as any)
          if (route.request?.body?.required) {
            validators.push(validator)
          } else {
            const mw: MiddlewareHandler = async (c, next) => {
              if (c.req.header('content-type')) {
                if (isFormContentType(c.req.header('content-type')!)) {
                  return await validator(c, next)
                }
              }
              c.req.addValidatedData('form', {})
              await next()
            }
            validators.push(mw)
          }
        }
      }
    }

    const middleware = routeMiddleware
      ? Array.isArray(routeMiddleware)
        ? routeMiddleware
        : [routeMiddleware]
      : []

    this.on(
      [route.method],
      route.path.replaceAll(/\/{(.+?)}/g, '/:$1'),
      ...middleware,
      ...validators,
      handler
    )
    return this
  }

  getOpenAPIDocument = (
    config: OpenAPIObjectConfig
  ): ReturnType<typeof generator.generateDocument> => {
    const generator = new OpenApiGeneratorV3(this.openAPIRegistry.definitions)
    const document = generator.generateDocument(config)
    // @ts-expect-error the _basePath is a private property
    return this._basePath ? addBasePathToDocument(document, this._basePath) : document
  }

  getOpenAPI31Document = (
    config: OpenAPIObjectConfig
  ): ReturnType<typeof generator.generateDocument> => {
    const generator = new OpenApiGeneratorV31(this.openAPIRegistry.definitions)
    const document = generator.generateDocument(config)
    // @ts-expect-error the _basePath is a private property
    return this._basePath ? addBasePathToDocument(document, this._basePath) : document
  }

  doc = <P extends string>(
    path: P,
    configure: OpenAPIObjectConfigure<E, P>
  ): OpenAPIHono<E, S & ToSchema<'get', P, {}, {}>, BasePath> => {
    return this.get(path, (c) => {
      const config = typeof configure === 'function' ? configure(c) : configure
      try {
        const document = this.getOpenAPIDocument(config)
        return c.json(document)
      } catch (e: any) {
        return c.json(e, 500)
      }
    }) as any
  }

  doc31 = <P extends string>(
    path: P,
    configure: OpenAPIObjectConfigure<E, P>
  ): OpenAPIHono<E, S & ToSchema<'get', P, {}, {}>, BasePath> => {
    return this.get(path, (c) => {
      const config = typeof configure === 'function' ? configure(c) : configure
      try {
        const document = this.getOpenAPI31Document(config)
        return c.json(document)
      } catch (e: any) {
        return c.json(e, 500)
      }
    }) as any
  }

  route<
    SubPath extends string,
    SubEnv extends Env,
    SubSchema extends Schema,
    SubBasePath extends string
  >(
    path: SubPath,
    app: Hono<SubEnv, SubSchema, SubBasePath>
  ): OpenAPIHono<E, MergeSchemaPath<SubSchema, MergePath<BasePath, SubPath>> & S, BasePath>
  route<SubPath extends string>(path: SubPath): Hono<E, RemoveBlankRecord<S>, BasePath>
  route<
    SubPath extends string,
    SubEnv extends Env,
    SubSchema extends Schema,
    SubBasePath extends string
  >(
    path: SubPath,
    app?: Hono<SubEnv, SubSchema, SubBasePath>
  ): OpenAPIHono<E, MergeSchemaPath<SubSchema, MergePath<BasePath, SubPath>> & S, BasePath> {
    const pathForOpenAPI = path.replaceAll(/:([^\/]+)/g, '{$1}')
    super.route(path, app as any)

    if (!(app instanceof OpenAPIHono)) {
      return this as any
    }

    app.openAPIRegistry.definitions.forEach((def) => {
      switch (def.type) {
        case 'component':
          return this.openAPIRegistry.registerComponent(def.componentType, def.name, def.component)

        case 'route':
          return this.openAPIRegistry.registerPath({
            ...def.route,
            path: mergePath(pathForOpenAPI, def.route.path),
          })

        case 'webhook':
          return this.openAPIRegistry.registerWebhook({
            ...def.webhook,
            path: mergePath(pathForOpenAPI, def.webhook.path),
          })

        case 'schema':
          return this.openAPIRegistry.register(def.schema._def.openapi._internal.refId, def.schema)

        case 'parameter':
          return this.openAPIRegistry.registerParameter(
            def.schema._def.openapi._internal.refId,
            def.schema
          )

        default: {
          const errorIfNotExhaustive: never = def
          throw new Error(`Unknown registry type: ${errorIfNotExhaustive}`)
        }
      }
    })

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    return this as any
  }

  basePath<SubPath extends string>(path: SubPath): OpenAPIHono<E, S, MergePath<BasePath, SubPath>> {
    return new OpenAPIHono({ ...(super.basePath(path) as any), defaultHook: this.defaultHook })
  }
}

type RoutingPath<P extends string> = P extends `${infer Head}/{${infer Param}}${infer Tail}`
  ? `${Head}/:${Param}${RoutingPath<Tail>}`
  : P

export const createRoute = <P extends string, R extends Omit<RouteConfig, 'path'> & { path: P }>(
  routeConfig: R
) => {
  const route = {
    ...routeConfig,
    getRoutingPath(): RoutingPath<R['path']> {
      return routeConfig.path.replaceAll(/\/{(.+?)}/g, '/:$1') as RoutingPath<P>
    },
  }
  return Object.defineProperty(route, 'getRoutingPath', { enumerable: false })
}

extendZodWithOpenApi(z)
export { extendZodWithOpenApi, z }

function addBasePathToDocument(document: Record<string, any>, basePath: string) {
  const updatedPaths: Record<string, any> = {}

  Object.keys(document.paths).forEach((path) => {
    updatedPaths[mergePath(basePath, path)] = document.paths[path]
  })

  return {
    ...document,
    paths: updatedPaths,
  }
}

function isJSONContentType(contentType: string) {
  return /^application\/([a-z-\.]+\+)?json/.test(contentType)
}

function isFormContentType(contentType: string) {
  return (
    contentType.startsWith('multipart/form-data') ||
    contentType.startsWith('application/x-www-form-urlencoded')
  )
}