//
//

use std::time::Duration;
use std::error::Error;
use std::sync::atomic::{AtomicU32, Ordering};
use std::collections::HashMap;
use futures_util::{StreamExt};
use reqwest::Client;
use reqwest::header::{HeaderName, HeaderMap};

static REQUEST_COUNTER: AtomicU32 = AtomicU32::new(0);

#[derive(Debug, Clone, serde::Serialize)]
pub struct StreamResponse {
  request_id: u32,
  status: u16,
  status_text: String,
  headers: HashMap<String, String>
}

#[derive(Clone, serde::Serialize)]
pub struct EndPayload {
  request_id: u32,
  status: u16,
}

#[derive(Clone, serde::Serialize)]
pub struct ChunkPayload {
  request_id: u32,
  chunk: bytes::Bytes,
}

#[tauri::command]
pub async fn stream_fetch(
  window: tauri::Window,
  method: String,
  url: String,
  headers: HashMap<String, String>,
  body: Vec<u8>,
) -> Result<StreamResponse, String> {

  let event_name = "stream-response";
  let request_id = REQUEST_COUNTER.fetch_add(1, Ordering::SeqCst);

  let mut _headers = HeaderMap::new();
  for (key, value) in &headers {
    _headers.insert(key.parse::<HeaderName>().unwrap(), value.parse().unwrap());
  }

  // println!("method: {:?}", method);
  // println!("url: {:?}", url);
  // println!("headers: {:?}", headers);
  // println!("headers: {:?}", _headers);

  let method = method.parse::<reqwest::Method>().map_err(|err| format!("failed to parse method: {}", err))?;
  let client = Client::builder()
    .default_headers(_headers)
    .redirect(reqwest::redirect::Policy::limited(3))
    .connect_timeout(Duration::new(3, 0))
    .build()
    .map_err(|err| format!("failed to generate client: {}", err))?;

  let mut request = client.request(
    method.clone(),
    url.parse::<reqwest::Url>().map_err(|err| format!("failed to parse url: {}", err))?
  );

  if method == reqwest::Method::POST || method == reqwest::Method::PUT || method == reqwest::Method::PATCH {
    let body = bytes::Bytes::from(body);
    // println!("body: {:?}", body);
    request = request.body(body);
  }

  // println!("client: {:?}", client);
  // println!("request: {:?}", request);

  let response_future = request.send();

  let res = response_future.await;
  let response = match res {
    Ok(res) => {
      // get response and emit to client
      let mut headers = HashMap::new();
      for (name, value) in res.headers() {
        headers.insert(
          name.as_str().to_string(),
          std::str::from_utf8(value.as_bytes()).unwrap().to_string()
        );
      }
      let status = res.status().as_u16();

      tauri::async_runtime::spawn(async move {
        let mut stream = res.bytes_stream();

        while let Some(chunk) = stream.next().await {
          match chunk {
            Ok(bytes) => {
              // println!("chunk: {:?}", bytes);
              if let Err(e) = window.emit(event_name, ChunkPayload{ request_id, chunk: bytes }) {
                println!("Failed to emit chunk payload: {:?}", e);
              }
            }
            Err(err) => {
              println!("Error chunk: {:?}", err);
            }
          }
        }
        if let Err(e) = window.emit(event_name, EndPayload{ request_id, status: 0 }) {
          println!("Failed to emit end payload: {:?}", e);
        }
      });

      StreamResponse {
        request_id,
        status,
        status_text: "OK".to_string(),
        headers,
      }
    }
    Err(err) => {
      let error: String = err.source()
        .map(|e| e.to_string())
        .unwrap_or_else(|| "Unknown error occurred".to_string());
      println!("Error response: {:?}", error);
      tauri::async_runtime::spawn( async move {
        if let Err(e) = window.emit(event_name, ChunkPayload{ request_id, chunk: error.into() }) {
          println!("Failed to emit chunk payload: {:?}", e);
        }
        if let Err(e) = window.emit(event_name, EndPayload{ request_id, status: 0 }) {
          println!("Failed to emit end payload: {:?}", e);
        }
      });
      StreamResponse {
        request_id,
        status: 599,
        status_text: "Error".to_string(),
        headers: HashMap::new(),
      }
    }
  };
  // println!("Response: {:?}", response);
  Ok(response)
}