use std::ffi::{CString, OsStr};
use std::io::Write;
use std::os::unix::prelude::OsStrExt;
use std::path::{Path, PathBuf};
use std::ptr::null_mut;
use std::sync::atomic::AtomicBool;
use std::time::Duration;

use anyhow::{ensure, Context};
use directories::UserDirs;
use git_version::git_version;
use niri_config::Config;
use smithay::output::Output;
use smithay::reexports::rustix::time::{clock_gettime, ClockId};
use smithay::utils::{Logical, Point, Rectangle, Size};

pub mod spawning;
pub mod watcher;

pub static IS_SYSTEMD_SERVICE: AtomicBool = AtomicBool::new(false);

pub fn clone2<T: Clone, U: Clone>(t: (&T, &U)) -> (T, U) {
    (t.0.clone(), t.1.clone())
}

pub fn version() -> String {
    format!(
        "{} ({})",
        env!("CARGO_PKG_VERSION"),
        git_version!(fallback = "unknown commit"),
    )
}

pub fn get_monotonic_time() -> Duration {
    let ts = clock_gettime(ClockId::Monotonic);
    Duration::new(ts.tv_sec as u64, ts.tv_nsec as u32)
}

pub fn center(rect: Rectangle<i32, Logical>) -> Point<i32, Logical> {
    rect.loc + rect.size.downscale(2).to_point()
}

pub fn output_size(output: &Output) -> Size<i32, Logical> {
    let output_scale = output.current_scale().integer_scale();
    let output_transform = output.current_transform();
    let output_mode = output.current_mode().unwrap();

    output_transform
        .transform_size(output_mode.size)
        .to_logical(output_scale)
}

pub fn expand_home(path: &Path) -> anyhow::Result<Option<PathBuf>> {
    if let Ok(rest) = path.strip_prefix("~") {
        let dirs = UserDirs::new().context("error retrieving home directory")?;
        Ok(Some([dirs.home_dir(), rest].iter().collect()))
    } else {
        Ok(None)
    }
}

pub fn make_screenshot_path(config: &Config) -> anyhow::Result<Option<PathBuf>> {
    let Some(path) = &config.screenshot_path else {
        return Ok(None);
    };

    let format = CString::new(path.clone()).context("path must not contain nul bytes")?;

    let mut buf = [0u8; 2048];
    let mut path;
    unsafe {
        let time = libc::time(null_mut());
        ensure!(time != -1, "error in time()");

        let tm = libc::localtime(&time);
        ensure!(!tm.is_null(), "error in localtime()");

        let rv = libc::strftime(buf.as_mut_ptr().cast(), buf.len(), format.as_ptr(), tm);
        ensure!(rv != 0, "error formatting time");

        path = PathBuf::from(OsStr::from_bytes(&buf[..rv]));
    }

    if let Some(expanded) = expand_home(&path).context("error expanding ~")? {
        path = expanded;
    }

    Ok(Some(path))
}

pub fn write_png_rgba8(
    w: impl Write,
    width: u32,
    height: u32,
    pixels: &[u8],
) -> Result<(), png::EncodingError> {
    let mut encoder = png::Encoder::new(w, width, height);
    encoder.set_color(png::ColorType::Rgba);
    encoder.set_depth(png::BitDepth::Eight);

    let mut writer = encoder.write_header()?;
    writer.write_image_data(pixels)
}

#[cfg(feature = "dbus")]
pub fn show_screenshot_notification(image_path: Option<PathBuf>) {
    let mut notification = notify_rust::Notification::new();
    notification
        .summary("Screenshot captured")
        .body("You can paste the image from the clipboard.")
        .urgency(notify_rust::Urgency::Normal)
        .hint(notify_rust::Hint::Transient(true));

    // Try to add the screenshot as an image if possible.
    if let Some(path) = image_path {
        match path.canonicalize() {
            Ok(path) => match url::Url::from_file_path(path) {
                Ok(url) => {
                    notification.image_path(url.as_str());
                }
                Err(err) => {
                    warn!("error converting screenshot path to file url: {err:?}");
                }
            },
            Err(err) => {
                warn!("error canonicalizing screenshot path: {err:?}");
            }
        }
    }

    if let Err(err) = notification.show() {
        warn!("error showing screenshot notification: {err:?}");
    }
}

#[inline(never)]
pub fn cause_panic() {
    let a = Duration::from_secs(1);
    let b = Duration::from_secs(2);
    let _ = a - b;
}