// SPDX-License-Identifier: GPL-3.0-only
/*
 * Copyright (c) 2024, Richard Acayan. All rights reserved.
 */

use core::Keyboard;
use core::Layout;
use core::Part;
use core::xkeysym::Keysym;
use std::collections::HashMap;
use std::fs::File;
use std::fs::OpenOptions;
use std::io::Seek;
use std::io::Write;
use std::os::fd::AsFd;
use std::process;
use wayland::wayland_client::Dispatch;
use wayland::wayland_client::QueueHandle;
use wayland::wayland_client::protocol::wl_seat::WlSeat;
use wayland::wayland_client::protocol::wl_keyboard::KeymapFormat;
use wayland::virtual_keyboard_unstable_v1::zwp_virtual_keyboard_manager_v1::ZwpVirtualKeyboardManagerV1;
use wayland::virtual_keyboard_unstable_v1::zwp_virtual_keyboard_v1::ZwpVirtualKeyboardV1;

pub struct VirtualKeyboard {
    vk: ZwpVirtualKeyboardV1,
    keymap: File,
    keymap_id: u8,

    keycodes: HashMap<Keysym, u8>,
    mod_state: u32,
}

impl VirtualKeyboard {
    pub fn new<T: Dispatch<ZwpVirtualKeyboardV1, ()>
                + 'static>(queue: &QueueHandle<T>,
                               vk_man: &ZwpVirtualKeyboardManagerV1,
                               seat: &WlSeat)
                            -> VirtualKeyboard
    {
        let vk = vk_man.create_virtual_keyboard(seat, queue, ());

        let path = format!("/tmp/ufkbd-keymap-pid{}-1", process::id());
        let keymap = File::create(path).unwrap();

        VirtualKeyboard {
            vk,
            keymap,
            keymap_id: 1,

            keycodes: HashMap::new(),
            mod_state: 0,
        }
    }

    fn write_key(&mut self, part: &Part, keycode: u8)
    {
        let sym = part.sym();
        let lower = &sym.name().unwrap()[3..];
        let upper = &Part::modify_shift(sym).name().unwrap()[3..];

        write!(self.keymap, "    key <I{:03}> {{ [ {}, {} ] }};\n",
               keycode, lower, upper).unwrap();

        if sym == Keysym::Shift_L {
            write!(self.keymap,
                   "    modifier_map Shift {{ <I{:03}> }};\n",
                   keycode).unwrap();
        } else if sym == Keysym::Control_L {
            write!(self.keymap,
                   "    modifier_map Control {{ <I{:03}> }};\n",
                   keycode).unwrap();
        } else if sym == Keysym::Alt_L {
            write!(self.keymap,
                   "    modifier_map Mod1 {{ <I{:03}> }};\n",
                   keycode).unwrap();
        }
    }
}

impl Keyboard for VirtualKeyboard {
    fn press(&mut self, sym: Keysym)
    {
        if sym == Keysym::NoSymbol || sym == Keysym::XF86_Fn {
            return;
        }

        match sym {
            Keysym::Shift_L => {
                self.mod_state |= 0x1;
                self.vk.modifiers(self.mod_state, 0, 0, 0);
            },
            Keysym::Control_L => {
                self.mod_state |= 0x4;
                self.vk.modifiers(self.mod_state, 0, 0, 0);
            },
            Keysym::Alt_L => {
                self.mod_state |= 0x8;
                self.vk.modifiers(self.mod_state, 0, 0, 0);
            },
            _ => (),
        }

        let keycode = *self.keycodes.get(&sym).unwrap();
        self.vk.key(0, keycode as u32, 1);
    }

    fn release(&mut self, sym: Keysym)
    {
        if sym == Keysym::NoSymbol || sym == Keysym::XF86_Fn {
            return;
        }

        match sym {
            Keysym::Shift_L => {
                self.mod_state &= !0x1;
                self.vk.modifiers(self.mod_state, 0, 0, 0);
            },
            Keysym::Control_L => {
                self.mod_state &= !0x4;
                self.vk.modifiers(self.mod_state, 0, 0, 0);
            },
            Keysym::Alt_L => {
                self.mod_state &= !0x8;
                self.vk.modifiers(self.mod_state, 0, 0, 0);
            },
            _ => (),
        }

        let keycode = *self.keycodes.get(&sym).unwrap();
        self.vk.key(0, keycode as u32, 0);
    }

    fn change_layout(&mut self, layout: &Layout)
    {
        let mut keycode = 8;

        self.keymap_id = match self.keymap_id {
            0 => 1,
            1 => 0,
            _ => panic!("There should only be up to two keymaps"),
        };

        let path = format!("/tmp/ufkbd-keymap-pid{}-{}",
                           process::id(), self.keymap_id);
        self.keymap = OpenOptions::new()
                       .read(true)
                       .write(true)
                       .create(true)
                       .truncate(true)
                       .open(path)
                       .unwrap();

        self.keymap.write(b"xkb_keymap {\n").unwrap();
        self.keymap.write(b"  xkb_symbols \"ufkbd\" {\n").unwrap();

        for row in layout.rows() {
            for key in row {
                for part in &key.parts {
                    if part.sym() == Keysym::NoSymbol || part.sym() == Keysym::XF86_Fn {
                        continue;
                    }

                    self.keycodes.insert(part.sym(), keycode - 8);
                    self.write_key(part, keycode);
                    keycode += 1;
                }
            }
        }

        self.keymap.write(b"  };\n").unwrap();
        self.keymap.write(b"\n").unwrap();
        self.keymap.write(b"  xkb_keycodes \"ufkbd\" {\n").unwrap();
        self.keymap.write(b"    minimum = 8;\n").unwrap();
        self.keymap.write(b"    maximum = 255;\n").unwrap();

        for i in 8..keycode {
            write!(self.keymap, "    <I{:03}> = {};\n", i, i).unwrap();
        }

        self.keymap.write(b"    indicator 1 = \"Caps Lock\";\n").unwrap();
        self.keymap.write(b"  };\n").unwrap();
        self.keymap.write(b"\n").unwrap();
        self.keymap.write(b"  xkb_types \"ufkbd\" {\n").unwrap();
        self.keymap.write(b"    type \"TWO_LEVEL\" {\n").unwrap();
        self.keymap.write(b"        modifiers = Shift;\n").unwrap();
        self.keymap.write(b"        map[Shift] = Level2;\n").unwrap();
        self.keymap.write(b"        level_name[Level1] = \"Base\";\n").unwrap();
        self.keymap.write(b"        level_name[Level2] = \"Shift\";\n").unwrap();
        self.keymap.write(b"    };\n").unwrap();
        self.keymap.write(b"  };\n").unwrap();
        self.keymap.write(b"\n").unwrap();
        self.keymap.write(b"  xkb_compatibility \"ufkbd\" {\n").unwrap();
        self.keymap.write(b"  };\n").unwrap();
        self.keymap.write(b"};\n").unwrap();

        let len = self.keymap.stream_position().unwrap() as u32;
        self.vk.keymap(KeymapFormat::XkbV1 as u32, self.keymap.as_fd(), len);
    }
}