// This example reads a .ppm file and displays the image on screen. It shows how to work
// with images.

use x11rb::connection::Connection;
use x11rb::errors::ReplyOrIdError;
use x11rb::image::{ColorComponent, Image, PixelLayout};
use x11rb::protocol::xproto::{
    AtomEnum, ConnectionExt, CreateGCAux, CreateWindowAux, PropMode, Screen, VisualClass, Visualid,
    Window, WindowClass,
};
use x11rb::protocol::Event;
use x11rb::wrapper::ConnectionExt as _;

x11rb::atom_manager! {
    Atoms: AtomsCookie {
        WM_PROTOCOLS,
        WM_DELETE_WINDOW,
    }
}

/// Create a window with the given image as background.
fn create_window(
    conn: &impl Connection,
    screen: &Screen,
    atoms: &Atoms,
    image: &Image,
) -> Result<Window, ReplyOrIdError> {
    let win_id = conn.generate_id()?;
    let pixmap_id = conn.generate_id()?;
    let gc_id = conn.generate_id()?;

    conn.create_gc(
        gc_id,
        screen.root,
        &CreateGCAux::default().graphics_exposures(0),
    )?;
    conn.create_pixmap(
        screen.root_depth,
        pixmap_id,
        screen.root,
        image.width(),
        image.height(),
    )?;
    image.put(conn, pixmap_id, gc_id, 0, 0)?;
    conn.free_gc(gc_id)?;

    conn.create_window(
        screen.root_depth,
        win_id,
        screen.root,
        0,
        0,
        image.width(),
        image.height(),
        0,
        WindowClass::INPUT_OUTPUT,
        0,
        &CreateWindowAux::default().background_pixmap(pixmap_id),
    )?;
    conn.free_pixmap(pixmap_id)?;

    conn.change_property32(
        PropMode::REPLACE,
        win_id,
        atoms.WM_PROTOCOLS,
        AtomEnum::ATOM,
        &[atoms.WM_DELETE_WINDOW],
    )?;

    Ok(win_id)
}

/// Check that the given visual is "as expected" (pixel values are 0xRRGGBB with RR/GG/BB being the
/// colors). Otherwise, this exits the process.
fn check_visual(screen: &Screen, id: Visualid) -> PixelLayout {
    // Find the information about the visual and at the same time check its depth.
    let visual_info = screen
        .allowed_depths
        .iter()
        .filter_map(|depth| {
            let info = depth.visuals.iter().find(|depth| depth.visual_id == id);
            info.map(|info| (depth.depth, info))
        })
        .next();
    let (depth, visual_type) = match visual_info {
        Some(info) => info,
        None => {
            eprintln!("Did not find the root visual's description?!");
            std::process::exit(1);
        }
    };
    // Check that the pixels have red/green/blue components that we can set directly.
    match visual_type.class {
        VisualClass::TRUE_COLOR | VisualClass::DIRECT_COLOR => {}
        _ => {
            eprintln!("The root visual is not true / direct color, but {visual_type:?}");
            std::process::exit(1);
        }
    }
    let result = PixelLayout::from_visual_type(*visual_type)
        .expect("The server sent a malformed visual type");
    assert_eq!(result.depth(), depth);
    result
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Load the image
    let image = match std::env::args_os().nth(1) {
        None => {
            eprintln!(
                "Expected a file name of a PPM as argument, using a built-in default image instead"
            );
            ppm_parser::parse_ppm_bytes(&BUILTIN_IMAGE)?
        }
        Some(arg) => ppm_parser::parse_ppm_file(&arg)?,
    };

    let (conn, screen_num) = connect(None)?;

    // The following is only needed for start_timeout_thread(), which is used for 'tests'
    let conn1 = std::sync::Arc::new(conn);
    let conn = &*conn1;

    let screen = &conn.setup().roots[screen_num];
    let pixel_layout = check_visual(screen, screen.root_visual);

    // Convert the image from the PPM format into the server's native format.
    let ppm_layout = PixelLayout::new(
        ColorComponent::new(8, 16)?,
        ColorComponent::new(8, 8)?,
        ColorComponent::new(8, 0)?,
    );
    let image = image.reencode(ppm_layout, pixel_layout, conn.setup())?;

    let atoms = Atoms::new(conn)?.reply()?;
    let win_id = create_window(conn, screen, &atoms, &image)?;
    conn.map_window(win_id)?;

    util::start_timeout_thread(conn1.clone(), win_id);

    conn.flush()?;

    loop {
        let event = conn.wait_for_event().unwrap();
        match event {
            Event::ClientMessage(event) => {
                let data = event.data.as_data32();
                if event.format == 32 && event.window == win_id && data[0] == atoms.WM_DELETE_WINDOW
                {
                    println!("Window was asked to close");
                    return Ok(());
                }
            }
            Event::Error(err) => println!("Got an unexpected error: {err:?}"),
            ev => println!("Got an unknown event: {ev:?}"),
        }
    }
}

mod ppm_parser {
    use std::ffi::OsStr;
    use std::io::{Error as IOError, ErrorKind, Read, Result as IOResult};

    use x11rb::image::{BitsPerPixel, Image, ImageOrder, ScanlinePad};

    fn make_io_error(text: &'static str) -> IOError {
        IOError::new(ErrorKind::Other, text)
    }

    /// Read until the next b'\n'.
    fn read_to_end_of_line(input: &mut impl Read) -> IOResult<()> {
        let mut byte = [0; 1];
        loop {
            input.read_exact(&mut byte)?;
            if byte[0] == b'\n' {
                return Ok(());
            }
        }
    }

    /// Read a decimal number from the input.
    fn read_decimal(input: &mut impl Read) -> IOResult<u16> {
        let mut byte = [0; 1];

        // Skip leading whitespace and comments
        loop {
            input.read_exact(&mut byte)?;
            match byte[0] {
                b' ' | b'\t' | b'\r' => {}
                // Comment, skip a whole line
                b'#' => read_to_end_of_line(input)?,
                _ => break,
            }
        }

        // Now comes a number
        if !byte[0].is_ascii_digit() {
            return Err(make_io_error("Failed parsing a number"));
        }

        let mut result: u16 = 0;
        while byte[0].is_ascii_digit() {
            let value = u16::from(byte[0] - b'0');
            result = result
                .checked_mul(10)
                .map(|result| result + value)
                .ok_or_else(|| make_io_error("Overflow while parsing number"))?;

            input.read_exact(&mut byte)?;
        }

        // After the number, there should be some whitespace.
        if byte[0].is_ascii_whitespace() {
            Ok(result)
        } else {
            Err(make_io_error("Unexpected character in header"))
        }
    }

    fn parse_ppm(input: &mut impl Read) -> IOResult<Image<'static>> {
        let mut header = [0; 2];
        input.read_exact(&mut header)?;
        if header != *b"P6" {
            return Err(make_io_error("Incorrect file header"));
        }
        read_to_end_of_line(input)?;
        let width = read_decimal(input)?;
        let height = read_decimal(input)?;
        let max = read_decimal(input)?;

        if max != 255 {
            eprintln!("Image declares a max pixel value of {max}, but I expected 255.");
            eprintln!("Something will happen...?");
        }

        let mut image = Image::allocate(
            width,
            height,
            ScanlinePad::Pad8,
            24,
            BitsPerPixel::B24,
            ImageOrder::MsbFirst,
        );
        input.read_exact(image.data_mut())?;

        Ok(image)
    }

    pub fn parse_ppm_bytes(bytes: &[u8]) -> IOResult<Image<'static>> {
        use std::io::Cursor;

        parse_ppm(&mut Cursor::new(bytes))
    }

    pub fn parse_ppm_file(file_name: &OsStr) -> IOResult<Image<'static>> {
        use std::fs::File;
        use std::io::BufReader;

        parse_ppm(&mut BufReader::new(File::open(file_name)?))
    }
}

// Simple builtin PPM that is used if none is provided on the command line
#[rustfmt::skip]
const BUILTIN_IMAGE: [u8; 35] = [
    b'P', b'6', b'\n',
    // width and height
    b'4', b' ', b'2', b'\n',
    b'2', b'5', b'5', b'\n',
    // Black pixel
    0x00, 0x00, 0x00,
    // red pixel
    0xff, 0x00, 0x00,
    // green pixel
    0x00, 0xff, 0x00,
    // blue pixel
    0x00, 0x00, 0xff,
    // white pixel
    0xff, 0xff, 0xff,
    // cyan pixel
    0x00, 0xff, 0xff,
    // magenta pixel
    0xff, 0x00, 0xff,
    // yellow pixel
    0xff, 0xff, 0x00,
];

include!("integration_test_util/connect.rs");
include!("integration_test_util/util.rs");