// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

//! Upload files from disk to a remote server over HTTP.
//!
//! Download files from a remote HTTP server to disk.

#![doc(
    html_logo_url = "https://github.com/tauri-apps/tauri/raw/dev/app-icon.png",
    html_favicon_url = "https://github.com/tauri-apps/tauri/raw/dev/app-icon.png"
)]

mod transfer_stats;
use transfer_stats::TransferStats;

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

use read_progress_stream::ReadProgressStream;

use std::collections::HashMap;

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),
    #[error("request failed with status code {0}: {1}")]
    HttpErrorCode(u16, 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)]
#[serde(rename_all = "camelCase")]
struct ProgressPayload {
    progress: u64,
    progress_total: u64,
    total: u64,
    transfer_speed: u64,
}

#[command]
async fn download(
    url: String,
    file_path: String,
    headers: HashMap<String, String>,
    body: Option<String>,
    on_progress: Channel<ProgressPayload>,
) -> Result<()> {
    tokio::spawn(async move {
        let client = reqwest::Client::new();
        let mut request = if let Some(body) = body {
            client.post(&url).body(body)
        } else {
            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?;
        if !response.status().is_success() {
            return Err(Error::HttpErrorCode(
                response.status().as_u16(),
                response.text().await.unwrap_or_default(),
            ));
        }
        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 stats = TransferStats::default();
        while let Some(chunk) = stream.try_next().await? {
            file.write_all(&chunk).await?;
            stats.record_chunk_transfer(chunk.len());
            let _ = on_progress.send(ProgressPayload {
                progress: chunk.len() as u64,
                progress_total: stats.total_transferred,
                total,
                transfer_speed: stats.transfer_speed,
            });
        }
        file.flush().await?;
        Ok(())
    })
    .await
    .map_err(|e| Error::Io(std::io::Error::other(e.to_string())))?
}

#[command]
async fn upload(
    url: String,
    file_path: String,
    headers: HashMap<String, String>,
    on_progress: Channel<ProgressPayload>,
) -> Result<String> {
    tokio::spawn(async move {
        // Read the file
        let file = File::open(&file_path).await?;
        let file_len = file.metadata().await.unwrap().len();

        // Create the request and attach the file to the body
        let client = reqwest::Client::new();
        let mut request = client
            .post(&url)
            .header(reqwest::header::CONTENT_LENGTH, file_len)
            .body(file_to_body(on_progress, file, file_len));

        // Loop through 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?;
        if response.status().is_success() {
            response.text().await.map_err(Into::into)
        } else {
            Err(Error::HttpErrorCode(
                response.status().as_u16(),
                response.text().await.unwrap_or_default(),
            ))
        }
    })
    .await
    .map_err(|e| Error::Io(std::io::Error::other(e.to_string())))?
}

fn file_to_body(channel: Channel<ProgressPayload>, file: File, file_len: u64) -> reqwest::Body {
    let stream = FramedRead::new(file, BytesCodec::new()).map_ok(|r| r.freeze());

    let mut stats = TransferStats::default();
    reqwest::Body::wrap_stream(ReadProgressStream::new(
        stream,
        Box::new(move |progress, _total| {
            stats.record_chunk_transfer(progress as usize);
            let _ = channel.send(ProgressPayload {
                progress,
                progress_total: stats.total_transferred,
                total: file_len,
                transfer_speed: stats.transfer_speed,
            });
        }),
    ))
}

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

#[cfg(test)]
mod tests {
    use super::*;
    use mockito::{self, Mock, Server, ServerGuard};
    use tauri::ipc::InvokeResponseBody;
    struct MockedServer {
        _server: ServerGuard,
        url: String,
        mocked_endpoint: Mock,
    }

    #[tokio::test]
    async fn should_error_on_download_if_status_not_success() {
        let mocked_server = spawn_server_mocked(400).await;
        let result = download_file(mocked_server.url).await;
        mocked_server.mocked_endpoint.assert();
        assert!(result.is_err());
    }

    #[tokio::test]
    async fn should_download_file_successfully() {
        let mocked_server = spawn_server_mocked(200).await;
        let result = download_file(mocked_server.url).await;
        mocked_server.mocked_endpoint.assert();
        assert!(
            result.is_ok(),
            "failed to download file: {}",
            result.unwrap_err()
        );
    }

    #[tokio::test]
    async fn should_error_on_upload_if_status_not_success() {
        let mocked_server = spawn_upload_server_mocked(500).await;
        let result = upload_file(mocked_server.url).await;
        mocked_server.mocked_endpoint.assert();
        assert!(result.is_err());
        match result.unwrap_err() {
            Error::HttpErrorCode(status, _) => assert_eq!(status, 500),
            _ => panic!("Expected HttpErrorCode error"),
        }
    }

    #[tokio::test]
    async fn should_error_on_upload_if_file_not_found() {
        let mocked_server = spawn_upload_server_mocked(200).await;
        let file_path = "/nonexistent/file.txt".to_string();
        let headers = HashMap::new();
        let sender: Channel<ProgressPayload> =
            Channel::new(|msg: InvokeResponseBody| -> tauri::Result<()> {
                let _ = msg;
                Ok(())
            });

        let result = upload(mocked_server.url, file_path, headers, sender).await;
        assert!(result.is_err());
        match result.unwrap_err() {
            Error::Io(_) => {}
            _ => panic!("Expected IO error for missing file"),
        }
    }

    #[tokio::test]
    async fn should_upload_file_successfully() {
        let mocked_server = spawn_upload_server_mocked(200).await;
        let result = upload_file(mocked_server.url).await;
        mocked_server.mocked_endpoint.assert();
        assert!(
            result.is_ok(),
            "failed to upload file: {}",
            result.unwrap_err()
        );
        let response_body = result.unwrap();
        assert_eq!(response_body, "upload successful");
    }

    async fn download_file(url: String) -> Result<()> {
        let file_path = concat!(env!("CARGO_MANIFEST_DIR"), "/test/test.txt").to_string();
        let headers = HashMap::new();
        let sender: Channel<ProgressPayload> =
            Channel::new(|msg: InvokeResponseBody| -> tauri::Result<()> {
                let _ = msg;
                Ok(())
            });
        download(url, file_path, headers, None, sender).await
    }

    async fn upload_file(url: String) -> Result<String> {
        let file_path = concat!(env!("CARGO_MANIFEST_DIR"), "/test/test.txt").to_string();
        let headers = HashMap::new();
        let sender: Channel<ProgressPayload> =
            Channel::new(|msg: InvokeResponseBody| -> tauri::Result<()> {
                let _ = msg;
                Ok(())
            });
        upload(url, file_path, headers, sender).await
    }

    async fn spawn_server_mocked(return_status: usize) -> MockedServer {
        let mut _server = Server::new_async().await;
        let path = "/mock_test";
        let mock = _server
            .mock("GET", path)
            .with_status(return_status)
            .with_body("mocked response body")
            .create_async()
            .await;

        let url = _server.url() + path;
        MockedServer {
            _server,
            url,
            mocked_endpoint: mock,
        }
    }

    async fn spawn_upload_server_mocked(return_status: usize) -> MockedServer {
        let mut _server = Server::new_async().await;
        let path = "/upload_test";
        let mock = _server
            .mock("POST", path)
            .with_status(return_status)
            .with_body("upload successful")
            .match_header("content-length", "20")
            .create_async()
            .await;

        let url = _server.url() + path;
        MockedServer {
            _server,
            url,
            mocked_endpoint: mock,
        }
    }
}
