// currencyConvert — convert an amount between currencies using a live rate.
//
// Demonstrates: outbound HTTP with the framework-provided `HttpClient`,
// reading the JSON response (`yield* response.json`), transforming it, and a
// typed error status when the upstream can't answer (422). Uses a public,
// no-key FX endpoint so it runs out of the box.
//
//   curl -X POST http://localhost:8910/ -d '{"from":"USD","to":"EUR","amount":42}'

import { Effect, Schema } from 'effect'
import { HttpClient, HttpClientRequest } from '@effect/platform'
import { defineServerless, ServerlessHttpError } from '@voltro/serverless'

const CODE = Schema.String.pipe(Schema.pattern(/^[A-Za-z]{3}$/))

export default defineServerless({
  name: 'currency-convert',
  method: 'POST',
  input: Schema.Struct({
    from: CODE,
    to: CODE,
    amount: Schema.Number.pipe(Schema.greaterThanOrEqualTo(0)),
  }),
  output: Schema.Struct({
    from: Schema.String,
    to: Schema.String,
    amount: Schema.Number,
    rate: Schema.Number,
    result: Schema.Number,
  }),
  runtime: { memoryMb: 128, timeoutSeconds: 10 },
  handler: ({ from, to, amount }, _ctx) =>
    Effect.gen(function* () {
      const base = from.toUpperCase()
      const quote = to.toUpperCase()
      const http = yield* HttpClient.HttpClient
      const response = yield* http.execute(HttpClientRequest.get(`https://open.er-api.com/v6/latest/${base}`))
      const body = (yield* response.json) as { rates?: Record<string, number> }
      const rate = body.rates?.[quote]
      if (typeof rate !== 'number') {
        return yield* Effect.fail(
          new ServerlessHttpError({ status: 422, message: 'unknown-currency', detail: `no rate ${base}->${quote}` }),
        )
      }
      return { from: base, to: quote, amount, rate, result: Math.round(amount * rate * 100) / 100 }
    }),
})