kpx 0.0.1

use std::{
    io::{self, Read, Write},
    path::{Path, PathBuf},
};

use tracing::{info, instrument, trace};

#[cfg(windows)]
use std::ffi::OsString;

#[cfg(windows)]
use named_pipe::PipeClient;

#[cfg(unix)]
use std::os::unix::net::UnixStream;

/// Basic transport abstraction over the KeePassXC IPC channel.
pub trait Transport {
    /// Send a raw JSON line (without delimiters) to KeePassXC.
    fn send_line(&mut self, line: &str) -> io::Result<()>;
    /// Read a single response frame from KeePassXC.
    fn read_line(&mut self) -> io::Result<String>;
}

trait ReadWrite: Read + Write + Send {}

impl<T> ReadWrite for T where T: Read + Write + Send + 'static {}

/// Native KeePassXC transport (Unix domain socket on Unix, named pipe on Windows).
pub struct NativeTransport {
    stream: Box<dyn ReadWrite>,
}

impl NativeTransport {
    /// Wrap an arbitrary read/write stream as a native KeePassXC transport.
    pub fn from_stream<T>(stream: T) -> Self
    where
        T: Read + Write + Send + 'static,
    {
        Self {
            stream: Box::new(stream),
        }
    }

    #[cfg(unix)]
    #[instrument(level = "debug", skip_all, err)]
    /// Connect to the KeePassXC Unix domain socket at a specific path.
    pub fn connect_path(path: impl AsRef<Path>) -> io::Result<Self> {
        let path_buf = path.as_ref().to_path_buf();
        let stream = UnixStream::connect(&path_buf)?;
        stream.set_nonblocking(false)?;
        info!(path = %path_buf.display(), "connected to KeePassXC socket");
        Ok(Self::from_stream(stream))
    }

    #[cfg(unix)]
    #[instrument(level = "debug", skip_all, err)]
    /// Attempt to connect to the first reachable KeePassXC Unix domain socket.
    pub fn connect_default() -> io::Result<Self> {
        let mut last_err = None;
        for candidate in socket_candidates() {
            trace!(path = %candidate.display(), "trying KeePassXC socket candidate");
            match UnixStream::connect(&candidate) {
                Ok(stream) => {
                    stream.set_nonblocking(false)?;
                    info!(path = %candidate.display(), "connected to KeePassXC socket");
                    return Ok(Self::from_stream(stream));
                }
                Err(err) => last_err = Some(err),
            }
        }
        Err(last_err.unwrap_or_else(|| {
            io::Error::new(
                io::ErrorKind::NotFound,
                "Unable to locate KeePassXC browser socket",
            )
        }))
    }

    #[cfg(windows)]
    #[instrument(level = "debug", skip_all, err)]
    /// Connect to the KeePassXC named pipe using an explicit pipe name.
    pub fn connect_pipe(name: impl Into<OsString>) -> io::Result<Self> {
        let os_name: OsString = name.into();
        let client = PipeClient::connect(&os_name)?;
        info!(pipe = %os_name.to_string_lossy(), "connected to KeePassXC pipe");
        Ok(Self::from_stream(client))
    }

    #[cfg(windows)]
    #[instrument(level = "debug", skip_all, err)]
    /// Connect to the KeePassXC named pipe using the default well-known name.
    pub fn connect_default() -> io::Result<Self> {
        let name = std::env::var("KEEPASSXC_PIPE")
            .unwrap_or_else(|_| String::from(r"\\.\pipe\keepassxc-browser"));
        Self::connect_pipe(name)
    }

    #[cfg(not(any(unix, windows)))]
    /// Return an error on unsupported platforms.
    pub fn connect_default() -> io::Result<Self> {
        Err(io::Error::new(
            io::ErrorKind::Unsupported,
            "KeePassXC native transport not supported on this platform",
        ))
    }
}

impl Transport for NativeTransport {
    fn send_line(&mut self, line: &str) -> io::Result<()> {
        // KeePassXC expects raw JSON without newlines
        self.stream.write_all(line.as_bytes())?;
        self.stream.flush()
    }

    fn read_line(&mut self) -> io::Result<String> {
        // KeePassXC sends complete JSON messages in chunks
        // Read until we have a complete JSON object
        const BUFFER_SIZE: usize = 1024 * 1024; // 1 MB as per native messaging spec
        let mut buf = vec![0u8; BUFFER_SIZE];

        let bytes_read = self.stream.read(&mut buf)?;
        if bytes_read == 0 {
            return Err(io::Error::new(
                io::ErrorKind::UnexpectedEof,
                "KeePassXC connection closed",
            ));
        }

        // Trim the buffer to the actual bytes read
        buf.truncate(bytes_read);

        String::from_utf8(buf).map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))
    }
}

#[cfg(unix)]
fn socket_candidates() -> Vec<PathBuf> {
    let mut result = Vec::new();

    if let Ok(path) = std::env::var("KEEPASSXC_SOCKET") {
        result.push(normalize_path(path.into()));
    }

    if let Some(home) = home_dir() {
        result.push(home.join(".cache/keepassxc/keepassxc-browser.socket"));
        result.push(home.join(".config/keepassxc/keepassxc-browser.socket"));
    }

    if let Ok(runtime_dir) = std::env::var("XDG_RUNTIME_DIR") {
        let runtime_path = PathBuf::from(&runtime_dir);
        result.push(runtime_path.join("keepassxc/keepassxc-browser.socket"));
        result.push(
            runtime_path.join("app/org.keepassxc.KeePassXC/org.keepassxc.KeePassXC.BrowserServer"),
        );
    }

    #[cfg(target_os = "macos")]
    if let Some(home) = home_dir() {
        result.push(home.join("Library/Application Support/KeepassXC/keepassxc-browser.socket"));
        result.push(home.join("Library/Caches/keepassxc/keepassxc-browser.socket"));
    }

    result
}

#[cfg(unix)]
fn home_dir() -> Option<PathBuf> {
    std::env::var_os("HOME").map(PathBuf::from)
}

#[cfg(unix)]
fn normalize_path(path: PathBuf) -> PathBuf {
    if let Some(str_path) = path.to_str() {
        if str_path.starts_with('~') {
            if let Some(home) = home_dir() {
                let without_tilde = &str_path[1..];
                return if without_tilde.starts_with('/') {
                    home.join(&without_tilde[1..])
                } else {
                    home.join(without_tilde)
                };
            }
        }
    }
    path
}

#[cfg(test)]
pub(crate) mod tests {
    use super::*;
    use std::collections::VecDeque;
    use std::sync::{Arc, Mutex};

    #[derive(Clone, Default)]
    pub struct MockTransport {
        pub sent: Arc<Mutex<Vec<String>>>,
        pub incoming: Arc<Mutex<VecDeque<String>>>,
    }

    impl MockTransport {
        pub fn with_responses(responses: Vec<String>) -> Self {
            Self {
                sent: Arc::new(Mutex::new(Vec::new())),
                incoming: Arc::new(Mutex::new(responses.into())),
            }
        }

        pub fn push_response(&self, response: String) {
            self.incoming.lock().unwrap().push_back(response);
        }
    }

    impl Transport for MockTransport {
        fn send_line(&mut self, line: &str) -> io::Result<()> {
            self.sent.lock().unwrap().push(line.to_string());
            Ok(())
        }

        fn read_line(&mut self) -> io::Result<String> {
            self.incoming
                .lock()
                .unwrap()
                .pop_front()
                .ok_or_else(|| io::Error::new(io::ErrorKind::UnexpectedEof, "no response queued"))
        }
    }
}