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Mini Api Builder
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type URLSearchParamsInit = ConstructorParameters<typeof URLSearchParams>[0]; | |
type ApiFormatMap = { | |
arrayBuffer: ArrayBuffer; | |
text: string; | |
json: object; | |
formData: FormData; | |
blob: Blob; | |
stream: ReadableStream<Uint8Array>; | |
response: Response; | |
}; | |
type ApiFormat = keyof ApiFormatMap; | |
type ApiResponseType<T extends ApiFormat> = { | |
responseType?: T; | |
}; | |
type ApiQuery = { | |
query?: URLSearchParamsInit; | |
}; | |
type ApiDefaults<T extends ApiFormat> = RequestInit & ApiResponseType<T> & ApiQuery; | |
type ApiCallOptions<T extends ApiFormat> = RequestInit & ApiResponseType<T> & ApiQuery; | |
type ApiBuilder<T extends ApiFormat> = { | |
[key: string]: ApiBuilder<T>; | |
(firstArg: string | number, ...extraPaths: (string | number)[]): ApiBuilder<T>; | |
(): Promise<ApiFormatMap[T]>; | |
<O extends ApiFormat = T>(callOptions: ApiCallOptions<O>): Promise<ApiFormatMap[O]>; | |
}; | |
export function createApi<T extends ApiFormat = 'response'>( | |
url: string, | |
defaults?: ApiDefaults<T>, | |
): ApiBuilder<T> { | |
const internalTarget = (() => {}) as unknown as ApiBuilder<T>; | |
const responseModifier = (callOptions?: ApiCallOptions<ApiFormat>) => { | |
const responseType: ApiFormat | undefined = callOptions?.responseType ?? defaults?.responseType; | |
switch (responseType) { | |
case 'json': | |
return (res: Response) => res.json(); | |
case 'text': | |
return (res: Response) => res.text(); | |
case 'arrayBuffer': | |
return (res: Response) => res.arrayBuffer(); | |
case 'formData': | |
return (res: Response) => res.formData(); | |
case 'blob': | |
return (res: Response) => res.blob(); | |
case 'stream': | |
return (res: Response) => res.body; | |
case 'response': | |
default: | |
return (res: Response) => res; | |
} | |
}; | |
const parseUrl = (callOptions?: ApiCallOptions<ApiFormat>): string => { | |
const parsedUrl: URL = new URL(url); | |
if (!!defaults?.query) { | |
new URLSearchParams(defaults.query).forEach((value, key) => | |
parsedUrl.searchParams.set(key, value), | |
); | |
} | |
if (!!callOptions?.query) { | |
new URLSearchParams(callOptions.query).forEach((value, key) => | |
parsedUrl.searchParams.set(key, value), | |
); | |
} | |
return parsedUrl.toString(); | |
}; | |
const parseHeadersInit = (callHeaders?: HeadersInit): Headers | HeadersInit | undefined => { | |
if (!defaults?.headers) { | |
return callHeaders; | |
} | |
if (!callHeaders) { | |
return defaults.headers; | |
} | |
const headers = new Headers(defaults.headers); | |
for (const [name, value] of new Headers(callHeaders)) { | |
headers.set(name, value); | |
} | |
return headers; | |
}; | |
const parseRequestInit = (callOptions?: ApiCallOptions<ApiFormat>): RequestInit | undefined => { | |
if (!defaults) { | |
if (!callOptions) return; | |
const { query: _1, responseType: _2, ...requestInit } = callOptions; | |
return requestInit; | |
} | |
if (!callOptions) { | |
const { query: _1, responseType: _2, ...requestInit } = defaults; | |
return requestInit; | |
} | |
const { query: _1, responseType: _2, ...requestInitOptions } = callOptions; | |
const { query: _3, responseType: _4, ...requestInitDefaults } = defaults; | |
const headers = parseHeadersInit(callOptions.headers); | |
return { | |
...requestInitDefaults, | |
...requestInitOptions, | |
headers, | |
}; | |
}; | |
const p = (url: string): ApiBuilder<T> => | |
new Proxy(internalTarget, { | |
get(_target, key: string) { | |
return p(`${url}/${key}`); | |
}, | |
apply(_target, _thisArg, args: (string | number | ApiCallOptions<ApiFormat>)[]) { | |
// () => Promise<T> | |
if (args.length === 0) { | |
const modifier = responseModifier(); | |
return fetch(parseUrl(), parseRequestInit()).then(modifier); | |
} | |
// (callOptions) => Promise<T or O> | |
if (typeof args[0] === 'object' && args[0] !== null) { | |
const options: ApiCallOptions<ApiFormat> = args[0]; | |
const modifier = responseModifier(options); | |
return fetch(parseUrl(options), parseRequestInit(options)).then(modifier); | |
} | |
// (...paths) => ApiBuilder<T> | |
return p(`${url}/${args.join('/')}`); | |
}, | |
}); | |
return p(url); | |
} |
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