use anyhow::{Result, anyhow};
use lesavka_common::{
    hid::append_char_reports,
    lesavka::KeyboardReport,
};
use std::time::Duration;

#[cfg(not(coverage))]
use {
    crate::paste,
    async_stream::stream,
    lesavka_common::lesavka::relay_client::RelayClient,
    std::process::Command,
    tokio::runtime::Builder as RuntimeBuilder,
    tonic::{Request, transport::Channel},
};

#[cfg(not(coverage))]
/// Deliver the local clipboard to the remote side, preferring the encrypted
/// paste RPC and falling back to direct HID keyboard reports when the shared
/// key is unavailable.
pub fn send_clipboard_to_remote(server_addr: &str) -> Result<String> {
    let text = read_clipboard_text().ok_or_else(|| anyhow!("clipboard is empty or unavailable"))?;
    match send_clipboard_via_rpc(server_addr, &text) {
        Ok(()) => Ok("Clipboard delivered to remote".to_string()),
        Err(rpc_err) => match send_clipboard_via_hid(server_addr, &text) {
            Ok(()) => Ok(format!("Clipboard delivered via HID fallback ({rpc_err})")),
            Err(hid_err) => Err(anyhow!("rpc failed: {rpc_err}; hid fallback failed: {hid_err}")),
        },
    }
}

#[cfg(not(coverage))]
/// Use the shared-key paste RPC when both the launcher and relay host are
/// configured for encrypted clipboard delivery.
fn send_clipboard_via_rpc(server_addr: &str, text: &str) -> Result<()> {
    let req = paste::build_paste_request(text)?;
    let rt = RuntimeBuilder::new_current_thread().enable_all().build()?;
    rt.block_on(async {
        let channel = Channel::from_shared(server_addr.to_string())?
            .connect()
            .await?;
        let mut cli = RelayClient::new(channel);
        let reply = cli.paste_text(Request::new(req)).await?;
        if reply.get_ref().ok {
            Ok(())
        } else {
            Err(anyhow!("server rejected paste: {}", reply.get_ref().error))
        }
    })
}

#[cfg(not(coverage))]
/// Fall back to keyboard HID reports so launcher-driven paste still works
/// against relay hosts that have not been given `LESAVKA_PASTE_KEY`.
fn send_clipboard_via_hid(server_addr: &str, text: &str) -> Result<()> {
    let reports = build_hid_paste_reports(text)?;
    let delay = clipboard_hid_delay();
    let report_count = reports.len();
    let rt = RuntimeBuilder::new_current_thread().enable_all().build()?;
    rt.block_on(async {
        let channel = Channel::from_shared(server_addr.to_string())?
            .connect()
            .await?;
        let mut cli = RelayClient::new(channel);
        let outbound = stream! {
            for report in reports {
                yield report;
                if !delay.is_zero() {
                    tokio::time::sleep(delay).await;
                }
            }
        };
        let mut resp = cli.stream_keyboard(Request::new(outbound)).await?;
        let mut echoed = 0usize;
        while let Some(item) = resp.get_mut().message().await.transpose() {
            item?;
            echoed += 1;
            if echoed >= report_count {
                break;
            }
        }
        Ok(())
    })
}

/// Convert clipboard text into press/release HID reports that match the
/// server-side keyboard gadget mapping.
fn build_hid_paste_reports(text: &str) -> Result<Vec<KeyboardReport>> {
    let mut raw_reports = Vec::with_capacity(text.len() * 4);
    let mut unsupported = 0usize;
    for ch in text.chars() {
        if !append_char_reports(&mut raw_reports, ch) {
            unsupported += 1;
        }
    }
    if unsupported > 0 {
        return Err(anyhow!(
            "clipboard contains {unsupported} unsupported character(s) for HID fallback"
        ));
    }
    Ok(raw_reports
        .into_iter()
        .map(|data| KeyboardReport { data: data.to_vec() })
        .collect())
}

/// Keep launcher-driven HID paste slightly slower than live typing so login
/// prompts have more time to digest each character.
fn clipboard_hid_delay() -> Duration {
    let delay_ms = std::env::var("LESAVKA_CLIPBOARD_DELAY_MS")
        .ok()
        .and_then(|value| value.parse::<u64>().ok())
        .unwrap_or(18);
    Duration::from_millis(delay_ms)
}

/// Read the local clipboard and drop trailing file-copy newlines so password
/// pastes do not accidentally submit an extra Enter.
#[cfg(not(coverage))]
fn read_clipboard_text() -> Option<String> {
    if let Ok(out) = Command::new("sh")
        .arg("-lc")
        .arg(std::env::var("LESAVKA_CLIPBOARD_CMD").unwrap_or_else(
            |_| "wl-paste --no-newline --type text/plain || xclip -selection clipboard -o || xsel -b -o".to_string(),
        ))
        .output()
        && out.status.success()
    {
        let text = trim_clipboard_text(String::from_utf8_lossy(&out.stdout).to_string());
        if !text.is_empty() {
            return Some(text);
        }
    }
    None
}

/// Trim trailing clipboard newlines so pasted passwords do not gain a
/// synthetic submit keystroke.
fn trim_clipboard_text(text: String) -> String {
    text.trim_end_matches(['\r', '\n']).to_string()
}

#[cfg(test)]
mod tests {
    use super::{build_hid_paste_reports, clipboard_hid_delay, trim_clipboard_text};
    use std::time::Duration;

    #[test]
    fn trim_clipboard_text_strips_trailing_newlines() {
        assert_eq!(trim_clipboard_text("secret\n".to_string()), "secret");
        assert_eq!(trim_clipboard_text("secret\r\n".to_string()), "secret");
        assert_eq!(trim_clipboard_text("secret".to_string()), "secret");
    }

    #[test]
    fn build_hid_paste_reports_emits_press_and_release_pairs() {
        let reports = build_hid_paste_reports("Az").expect("hid reports");
        assert_eq!(reports.len(), 6);
        assert_eq!(reports[0].data.len(), 8);
        assert_eq!(reports[0].data, vec![0x02, 0, 0, 0, 0, 0, 0, 0]);
        assert_eq!(reports[3].data, vec![0; 8]);
        assert_eq!(reports[5].data, vec![0; 8]);
    }

    #[test]
    fn build_hid_paste_reports_rejects_unsupported_chars() {
        let err = build_hid_paste_reports("snowman \u{2603}").expect_err("unsupported");
        assert!(format!("{err:#}").contains("unsupported character"));
    }

    #[test]
    fn clipboard_hid_delay_has_stable_default() {
        assert_eq!(clipboard_hid_delay(), Duration::from_millis(18));
    }
}