use std::{sync::Arc, time::Duration};

use crate::{
    pict::{Details, Extension, Images, Upload, Uploads},
    Error,
};
use actix_web::{body::BodyStream, http::StatusCode, web, HttpRequest, HttpResponse};
use awc::Client;
use url::Url;

pub(crate) static VALID_SIZES: &[u16] = &[80, 160, 320, 640, 1080, 2160];

pub(crate) struct Connection {
    upstream: Url,
    client: Client,
}

impl std::fmt::Debug for Connection {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Connection")
            .field("upstream", &self.upstream.as_str())
            .field("client", &"Client")
            .finish()
    }
}

impl Connection {
    pub(crate) fn new(upstream: Url, client: Client) -> Self {
        Connection { upstream, client }
    }

    #[tracing::instrument(skip_all)]
    pub(crate) async fn claim(&self, upload: Upload) -> Result<Images, Error> {
        let mut attempts = 0;
        const CLAIM_ATTEMPT_LIMIT: usize = 10;
        loop {
            match self.client.get(self.claim_url(&upload)).send().await {
                Ok(mut res) => {
                    match res.status() {
                        StatusCode::OK => {
                            return res
                                .json::<Images>()
                                .await
                                .map_err(|_| UploadError::Json.into());
                        }
                        StatusCode::NO_CONTENT => {
                            // continue
                        }
                        _ => {
                            let images =
                                res.json::<Images>().await.map_err(|_| UploadError::Json)?;

                            let code = images.code().unwrap_or("uknown-error").to_string();
                            let msg = images.msg().to_string();

                            return Err(UploadError::UploadFailure(code, msg).into());
                        }
                    }
                }
                Err(_) => {
                    attempts += 1;

                    if attempts > CLAIM_ATTEMPT_LIMIT {
                        return Err(UploadError::Status.into());
                    }

                    tokio::time::sleep(Duration::from_secs(1)).await;
                    // continue
                }
            }
        }
    }

    #[tracing::instrument(skip_all)]
    pub(crate) async fn thumbnail(
        &self,
        size: u16,
        file: &str,
        extension: Extension,
        req: &HttpRequest,
    ) -> Result<HttpResponse, Error> {
        if !VALID_SIZES.contains(&size) {
            return Err(UploadError::Size(size).into());
        }

        self.proxy(self.thumbnail_url(size, file, extension), req)
            .await
    }

    #[tracing::instrument(skip_all)]
    pub(crate) async fn image(&self, file: &str, req: &HttpRequest) -> Result<HttpResponse, Error> {
        self.proxy(self.image_url(file), req).await
    }

    #[tracing::instrument(skip_all)]
    pub(crate) async fn details(&self, file: &str) -> Result<Details, Error> {
        let mut response = self
            .client
            .get(self.details_url(file))
            .send()
            .await
            .map_err(|e| UploadError::Request(Arc::from(e.to_string())))?;

        if !response.status().is_success() {
            return Err(UploadError::Status.into());
        }

        response.json().await.map_err(|_| UploadError::Json.into())
    }

    #[tracing::instrument(skip_all)]
    pub(crate) async fn upload(
        &self,
        req: &HttpRequest,
        body: web::Payload,
    ) -> Result<Uploads, Error> {
        let client_request = self.client.request_from(self.upload_url(), req.head());

        let mut client_request = if let Some(addr) = req.head().peer_addr {
            client_request.append_header(("X-Forwarded-For", addr.to_string()))
        } else {
            client_request
        };

        client_request.headers_mut().remove("Accept-Encoding");

        let mut res = client_request
            .send_stream(body)
            .await
            .map_err(|e| UploadError::Request(Arc::from(e.to_string())))?;

        let uploads = res.json::<Uploads>().await.map_err(|_| UploadError::Json)?;

        Ok(uploads)
    }

    #[tracing::instrument(skip_all)]
    pub(crate) async fn delete(&self, file: &str, token: &str) -> Result<(), Error> {
        let res = self
            .client
            .delete(self.delete_url(file, token))
            .send()
            .await
            .map_err(|e| UploadError::Request(Arc::from(e.to_string())))?;

        if !res.status().is_success() {
            return Err(UploadError::Status.into());
        }

        Ok(())
    }

    fn claim_url(&self, upload: &Upload) -> String {
        let mut url = self.upstream.clone();
        url.set_path("/image/backgrounded/claim");
        url.set_query(Some(&format!("upload_id={}", upload.id())));

        url.to_string()
    }

    fn upload_url(&self) -> String {
        let mut url = self.upstream.clone();
        url.set_path("/image/backgrounded");

        url.to_string()
    }

    fn thumbnail_url(&self, size: u16, file: &str, extension: Extension) -> String {
        let mut url = self.upstream.clone();
        url.set_path(&format!("/image/process.{extension}"));
        url.set_query(Some(&format!("src={file}&resize={size}")));

        url.to_string()
    }

    fn image_url(&self, file: &str) -> String {
        let mut url = self.upstream.clone();
        url.set_path(&format!("/image/original/{file}"));

        url.to_string()
    }

    fn details_url(&self, file: &str) -> String {
        let mut url = self.upstream.clone();
        url.set_path(&format!("/image/details/original/{file}"));

        url.to_string()
    }

    fn delete_url(&self, file: &str, token: &str) -> String {
        let mut url = self.upstream.clone();
        url.set_path(&format!("/image/delete/{token}/{file}"));

        url.to_string()
    }

    #[tracing::instrument(skip_all)]
    async fn proxy(&self, url: String, req: &HttpRequest) -> Result<HttpResponse, Error> {
        let client_request = self.client.request_from(url, req.head());
        let client_request = if let Some(addr) = req.head().peer_addr {
            client_request.append_header(("X-Forwarded-For", addr.to_string()))
        } else {
            client_request
        };

        let res = client_request
            .no_decompress()
            .send()
            .await
            .map_err(|e| UploadError::Request(Arc::from(e.to_string())))?;

        let mut client_res = HttpResponse::build(res.status());

        for (name, value) in res.headers().iter().filter(|(h, _)| *h != "connection") {
            client_res.append_header((name.clone(), value.clone()));
        }

        Ok(client_res.body(BodyStream::new(res)))
    }
}

#[derive(Clone, Debug, thiserror::Error)]
pub(crate) enum UploadError {
    #[error("There was an error making the upstream request: {0}")]
    Request(Arc<str>),

    #[error("There was an error parsing the upstream response")]
    Json,

    #[error("Request returned bad HTTP status")]
    Status,

    #[error("Request failed with {0}: {1}")]
    UploadFailure(String, String),

    #[error("Requested size {0} is invalid")]
    Size(u16),
}