openrouter_client

import gleam/http
import gleam/http/request
import gleam/httpc
import gleam/json.{array, object, string}
import gleam/list
import gleam/option
import gleam/result
import openrouter_client/internal.{
  HttpRequestError, Misc, decode_openrouter_response,
}

pub type Client {
  Client(api_key: String, model: String, system_prompt: option.Option(String))
}

/// Create a new Openrouter client
/// Takes in the api key, a model name and a optional system prompt
pub fn new(api_key: String, model: String, system_prompt: option.Option(String)) {
  Client(api_key, model, system_prompt)
}

pub fn send(client: Client, prompt: String) {
  use base_req <- result.try(
    request.to("https://openrouter.ai/api/v1/chat/completions")
    |> result.map_error(fn(_) { Misc }),
  )

  let req =
    base_req
    |> request.set_body(openrouter_request_to_json_string(
      client.model,
      client.system_prompt,
      prompt,
    ))
    |> request.set_method(http.Post)
    |> request.set_header("content-type", "application/json")
    |> request.set_header("Authorization", "Bearer " <> client.api_key)

  use resp <- result.try(
    httpc.send(req)
    |> result.map_error(fn(_) {
      HttpRequestError("Could not make request to OpenRouter")
    }),
  )

  decode_openrouter_response(resp.body)
}

fn openrouter_request_to_json_string(model, system_prompt, prompt) {
  let messages = case system_prompt {
    option.Some(system_prompt) -> {
      [[#("role", string("system")), #("content", string(system_prompt))]]
    }
    option.None -> {
      []
    }
  }

  let messages =
    messages
    |> list.append([[#("role", string("user")), #("content", string(prompt))]])

  object([
    #("model", string(model)),
    #("messages", array(messages, of: json.object)),
  ])
  |> json.to_string
}