#![doc = include_str!("../README.md")]
use reqwest;
use lazy_static::lazy_static;
use anyhow::{anyhow, Result};
use futures_util::StreamExt;
use futures_util::stream::Stream;

pub extern crate futures_util;

lazy_static! {
    static ref BASE_URL: reqwest::Url = reqwest::Url::parse("https://api.openai.com/v1/models").unwrap();
}

/// This is the main interface to interact with the api.
pub struct Client {
    req_client: reqwest::Client,
}


/// See <https://platform.openai.com/docs/api-reference/models>.
pub mod models;

/// See <https://platform.openai.com/docs/api-reference/chat>.
pub mod chat;

/// See <https://platform.openai.com/docs/api-reference/completions>.
pub mod completions;

impl Client {

    /// Create a new client.
    /// This will automatically build a [reqwest::Client] used internally.
    pub fn new(api_key: &str) -> Client {
        use reqwest::header;

        // Create the header map
        let mut headers = header::HeaderMap::new();
        let mut key_headervalue = header::HeaderValue::from_str(&format!("Bearer {api_key}")).unwrap();
        key_headervalue.set_sensitive(true);
        headers.insert(header::AUTHORIZATION, key_headervalue);
        let req_client = reqwest::ClientBuilder::new().default_headers(headers).build().unwrap();

        Client {
            req_client,
        }
    }

    /// Lists the currently available models, and provides basic information about each one such as the owner and availability.
    /// 
    /// ```no_run
    /// # let api_key = "";
    /// # tokio_test::block_on(async {
    /// let client = openai_rust::Client::new(api_key);
    /// let models = client.list_models().await.unwrap();
    /// # })
    /// ```
    /// 
    /// See <https://platform.openai.com/docs/api-reference/models/list>.
    pub async fn list_models(&self) -> Result<Vec<models::Model>, anyhow::Error> {
        let mut url = BASE_URL.clone();
        url.set_path("/v1/models");

        let res = self.req_client.get(url).send().await?;

        if res.status() == 200 {
            Ok(res.json::<models::ListModelsResponse>().await?.data)
        } else {
            Err(anyhow!(res.text().await?))
        }
    }

    /// Given a chat conversation, the model will return a chat completion response.
    /// 
    /// See <https://platform.openai.com/docs/api-reference/chat>.
    /// ```no_run
    /// # use tokio_test;
    /// # tokio_test::block_on(async {
    /// # use openai_rust;
    /// # let api_key = "";
    /// let client = openai_rust::Client::new(api_key);
    /// let args = openai_rust::chat::ChatArguments::new("gpt-3.5-turbo", vec![
    ///    openai_rust::chat::Message {
    ///        role: "user".to_owned(),
    ///        content: "Hello GPT!".to_owned(),
    ///    }
    /// ]);
    /// let res = client.create_chat(args).await.unwrap();
    /// println!("{}", res.choices[0].message.content);
    /// # })
    /// ```
    pub async fn create_chat(&self, args: chat::ChatArguments) -> Result<chat::ChatResponse, anyhow::Error>  {
        let mut url = BASE_URL.clone();
        url.set_path("/v1/chat/completions");

        let res = self.req_client.post(url).json(&args).send().await?;

        if res.status() == 200 {
            Ok(res.json::<chat::ChatResponse>().await?)
        } else {
            Err(anyhow!(res.text().await?))
        }  
    }

    /// Like [Client::create_chat] but with streaming.
    /// 
    /// See <https://platform.openai.com/docs/api-reference/chat>.
    /// 
    /// This method will return a stream. Calling [next](StreamExt::next) on it will return a vector of [chat::stream::ChatResponseEvent]s.
    /// 
    /// ```no_run
    /// # use tokio_test;
    /// # tokio_test::block_on(async {
    /// # use openai_rust;
    /// # use std::io::Write;
    /// # let client = openai_rust::Client::new("");
    /// # let args = openai_rust::chat::ChatArguments::new("gpt-3.5-turbo", vec![
    /// #    openai_rust::chat::Message {
    /// #        role: "user".to_owned(),
    /// #        content: "Hello GPT!".to_owned(),
    /// #    }
    /// # ]);
    /// use openai_rust::futures_util::StreamExt;
    /// let mut res = client.create_chat_stream(args).await.unwrap();
    /// while let Some(events) = res.next().await {
    ///     for event in events.unwrap() {
    ///         print!("{}", event.choices[0].delta.content.as_ref().unwrap_or(&"".to_owned()));
    ///         std::io::stdout().flush().unwrap();
    ///     }
    /// }
    /// # })
    /// ```
    /// 
    pub async fn create_chat_stream(
        &self,
        args: chat::ChatArguments,
    ) -> Result<impl Stream<Item = Result<Vec<chat::stream::ChatResponseEvent>>>> {
        let mut url = BASE_URL.clone();
        url.set_path("/v1/chat/completions");

        // Enable streaming
        let mut args = args;
        args.stream = Some(true);

        let res = self.req_client.post(url).json(&args).send().await?;

        if res.status() == 200 {
            let stream = res.bytes_stream();
            let stream = stream.map(chat::stream::deserialize_chat_events);
            Ok(stream)
        } else {
            Err(anyhow!(res.text().await?))
        }
    }

    /// Creates a completion for the provided prompt and parameters
    /// 
    /// ```no_run
    /// # use openai_rust;
    /// # use tokio_test;
    /// # tokio_test::block_on(async {
    /// # let api_key = "";
    /// let c = openai_rust::Client::new(api_key);
    /// let args = openai_rust::completions::CompletionArguments::new("text-davinci-003", "The quick brown fox".to_owned());
    /// println!("{}", c.create_completion(args).await.unwrap().choices[0].text);
    /// # })
    /// ```
    pub async fn create_completion(&self, args: completions::CompletionArguments) -> Result<completions::CompletionResponse> {
        let mut url = BASE_URL.clone();
        url.set_path("/v1/completions");

        let res = self.req_client.post(url).json(&args).send().await?;

        if res.status() == 200 {
            Ok(res.json::<completions::CompletionResponse>().await?)
        } else {
            Err(anyhow!(res.text().await?))
        }  
    }
}