// Copyright 2021 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

use futures_util::TryStreamExt;
use serde::{ser::Serializer, Serialize};
use tauri::{
    command,
    plugin::{Builder as PluginBuilder, TauriPlugin},
    Runtime, Window,
};
use tokio::{
    fs::File,
    io::{AsyncWriteExt, BufWriter},
};
use tokio_util::codec::{BytesCodec, FramedRead};

use read_progress_stream::ReadProgressStream;

use std::{collections::HashMap, sync::Mutex};

type Result<T> = std::result::Result<T, Error>;

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error(transparent)]
    Io(#[from] std::io::Error),
    #[error(transparent)]
    Request(#[from] reqwest::Error),
    #[error("{0}")]
    ContentLength(String),
}

impl Serialize for Error {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(self.to_string().as_ref())
    }
}

#[derive(Clone, Serialize)]
struct ProgressPayload {
    id: u32,
    progress: u64,
    total: u64,
}

#[command]
async fn download<R: Runtime>(
    window: Window<R>,
    id: u32,
    url: &str,
    file_path: &str,
    headers: HashMap<String, String>,
) -> Result<u32> {
    let client = reqwest::Client::new();

    let mut request = client.get(url);
    // Loop trought the headers keys and values
    // and add them to the request object.
    for (key, value) in headers {
        request = request.header(&key, value);
    }

    let response = request.send().await?;
    let total = response.content_length().unwrap_or(0);

    let mut file = BufWriter::new(File::create(file_path).await?);
    let mut stream = response.bytes_stream();

    let mut i = 0;
    let mut temp_progress = 0;

    while let Some(chunk) = stream.try_next().await? {
        i = i + 1;
        file.write_all(&chunk).await?;
        temp_progress = temp_progress + chunk.len();
        if i >= 10 {
            window
                .emit(
                    "download://progress",
                    ProgressPayload {
                        id,
                        progress: temp_progress as u64,
                        total,
                    },
                )
                .unwrap(); // TODO: remove the unwrap again.
            i = 0;
            temp_progress = 0;
        }
    }
    if i < 10 {
        window
            .emit(
                "download://progress",
                ProgressPayload {
                    id,
                    progress: temp_progress as u64,
                    total,
                },
            )
            .unwrap(); // TODO: remove the unwrap again.
    }
    file.flush().await?;

    Ok(id)
}

#[command]
async fn upload<R: Runtime>(
    window: Window<R>,
    id: u32,
    url: &str,
    file_path: &str,
    headers: HashMap<String, String>,
) -> Result<serde_json::Value> {
    // Read the file
    let file = File::open(file_path).await?;

    // Create the request and attach the file to the body
    let client = reqwest::Client::new();
    let mut request = client.post(url).body(file_to_body(id, window, file));

    // Loop trought the headers keys and values
    // and add them to the request object.
    for (key, value) in headers {
        request = request.header(&key, value);
    }

    let response = request.send().await?;

    response.json().await.map_err(Into::into)
}

fn file_to_body<R: Runtime>(id: u32, window: Window<R>, file: File) -> reqwest::Body {
    let stream = FramedRead::new(file, BytesCodec::new()).map_ok(|r| r.freeze());
    let window = Mutex::new(window);
    reqwest::Body::wrap_stream(ReadProgressStream::new(
        stream,
        Box::new(move |progress, total| {
            let _ = window.lock().unwrap().emit(
                "upload://progress",
                ProgressPayload {
                    id,
                    progress,
                    total,
                },
            );
        }),
    ))
}

pub fn init<R: Runtime>() -> TauriPlugin<R> {
    PluginBuilder::new("upload")
        .invoke_handler(tauri::generate_handler![download, upload])
        .build()
}