// aiComplete — a one-shot LLM completion at the edge.
//
// Demonstrates: calling a third-party API that needs a SECRET (the key lives in
// `ctx.env`, never in the bundle), an optional input field, reading the JSON
// response, and mapping an upstream failure to a 502. Uses the OpenAI
// chat-completions shape; point it at any compatible endpoint via OPENAI_BASE_URL.
//
//   OPENAI_API_KEY=sk-... voltro serverless dev functions/aiComplete.serverless.ts
//   curl -X POST http://localhost:8910/ -d '{"prompt":"Name three primary colors."}'

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

export default defineServerless({
  name: 'ai-complete',
  method: 'POST',
  input: Schema.Struct({
    prompt: Schema.String.pipe(Schema.minLength(1), Schema.maxLength(4000)),
    system: Schema.optional(Schema.String),
  }),
  output: Schema.Struct({ text: Schema.String }),
  runtime: { memoryMb: 256, timeoutSeconds: 30 },
  handler: ({ prompt, system }, ctx) =>
    Effect.gen(function* () {
      const apiKey = ctx.env.OPENAI_API_KEY
      if (!apiKey) {
        return yield* Effect.fail(
          new ServerlessHttpError({ status: 503, message: 'ai-not-configured', detail: 'Set OPENAI_API_KEY.' }),
        )
      }
      const baseUrl = ctx.env.OPENAI_BASE_URL ?? 'https://api.openai.com'
      const model = ctx.env.OPENAI_MODEL ?? 'gpt-4o-mini'

      const http = yield* HttpClient.HttpClient
      const request = HttpClientRequest.post(`${baseUrl}/v1/chat/completions`).pipe(
        HttpClientRequest.setHeader('authorization', `Bearer ${apiKey}`),
        HttpClientRequest.bodyUnsafeJson({
          model,
          max_tokens: 400,
          messages: [
            ...(system ? [{ role: 'system', content: system }] : []),
            { role: 'user', content: prompt },
          ],
        }),
      )

      const response = yield* http.execute(request)
      if (response.status >= 400) {
        const detail = yield* response.text
        return yield* Effect.fail(new ServerlessHttpError({ status: 502, message: 'ai-call-failed', detail }))
      }
      const body = (yield* response.json) as {
        choices?: ReadonlyArray<{ message?: { content?: string } }>
      }
      return { text: body.choices?.[0]?.message?.content ?? '' }
    }),
})