import { APIGatewayProxyHandler } from 'aws-lambda'

import debug from 'debug'

import buildRunner from './runner'

import { safeStringify } from './static/safe-json'

import { validateAPIGatewayProxyEvent } from './validations/event'

const log = debug('app:handler')

export const handler: APIGatewayProxyHandler = async (event) => {

// handle the preflight request (OPTIONS method withot req body) automatically sent by the browser before making a CORS request (e.g., POST)

if (event.httpMethod === 'OPTIONS') return ok({})

const validatedEvent = validateAPIGatewayProxyEvent(event)

if (validatedEvent.isError()) return badRequest(validatedEvent.value)

const body = validatedEvent.value

try {

const run = buildRunner(body.lang, body.options)

const treeViewerData = await run(body.functionData)

if (treeViewerData.isError())

return unprocessableEntity(treeViewerData.value.reason)

return ok(treeViewerData.value)

} catch (e) {

log('Unexpected error: %O', e)

return internalServerError('Internal server error')

}

}

const ok = (body: any) => result(200, body)

const badRequest = (reason: string) => result(400, { reason })

const unprocessableEntity = (reason: string) => result(422, { reason })

const internalServerError = (reason: string) => result(500, { reason })

const result = (statusCode: number, body: Record<string, any>) => ({

statusCode,

body: safeStringify(body),

headers: {

"Access-Control-Allow-Origin": "*",

"Access-Control-Allow-Methods": "OPTIONS,GET,POST,PUT,DELETE",

"Access-Control-Allow-Headers": "Content-Type",

},

})