use crate::gdt;
use crate::print;
use crate::println;
use alloc::string::String;
use alloc::string::ToString;
use alloc::vec::Vec;
use lazy_static::lazy_static;
use pic8259::ChainedPics;
use spin::Mutex;
use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};

lazy_static! {
    static ref IDT: InterruptDescriptorTable = {
        let mut idt = InterruptDescriptorTable::new();
        idt.breakpoint.set_handler_fn(breakpoint_handler);
        unsafe {
            idt.double_fault
                .set_handler_fn(double_fault_handler)
                .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
        }
        idt.page_fault.set_handler_fn(page_fault_handler);
        idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
        idt[InterruptIndex::Keyboard.as_usize()].set_handler_fn(keyboard_interrupt_handler);
        idt.stack_segment_fault
            .set_handler_fn(stack_segment_fault_handler);
        idt.segment_not_present
            .set_handler_fn(segment_not_present_handler);
        idt.general_protection_fault
            .set_handler_fn(general_protection_fault_handler);
        idt
    };
    static ref PREV_COMMANDS: Mutex<Vec<String>> = Mutex::new(Vec::new());
}

pub fn init() {
    IDT.load();
    unsafe { PICS.lock().initialize() };
    x86_64::instructions::interrupts::enable();
}

extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
    println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
}

extern "x86-interrupt" fn double_fault_handler(
    stack_frame: InterruptStackFrame,
    _error_code: u64,
) -> ! {
    println!("{:#?}", x86_64::registers::control::Cr0::read());
    panic!("EXCEPTION : DOUBLE FAULT\n{:#?}", stack_frame);
}

extern "x86-interrupt" fn page_fault_handler(
    stack_frame: InterruptStackFrame,
    error_code: x86_64::structures::idt::PageFaultErrorCode,
) {
    println!("EXCEPTION : PAGE FAULT");
    println!(
        "Accessed Address: {:?}",
        x86_64::registers::control::Cr2::read()
    );
    println!("Error Code: {:?}", error_code);
    println!("{:#?}", stack_frame);
    x86_64::instructions::interrupts::enable_and_hlt();
}

extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: InterruptStackFrame) {
    crate::clock::pit_interrupt_handler();
    unsafe {
        PICS.lock()
            .notify_end_of_interrupt(InterruptIndex::Timer.as_u8());
    }
}

extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: InterruptStackFrame) {
    use pc_keyboard::{layouts, DecodedKey, HandleControl, KeyCode, Keyboard, ScancodeSet1};
    use x86_64::instructions::port::Port;

    lazy_static! {
        static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> = {
            Mutex::new(Keyboard::new(
                layouts::Us104Key,
                ScancodeSet1,
                HandleControl::Ignore,
            ))
        };
    }

    let mut keyboard = KEYBOARD.lock();
    let mut port = Port::new(0x60); // PS/2 Keyboard Address

    let scancode: u8 = unsafe { port.read() };
    if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
        if let Some(key) = keyboard.process_keyevent(key_event) {
            match key {
                DecodedKey::Unicode(character) => {
                    if character == '\u{8}' {
                        crate::vga_buffer::backspace();
                    } else if character == '\u{9}' {
                        print!("    ");
                    } else if character == '\n' {
                        let writer = crate::vga_buffer::WRITER.lock();

                        // Gather all chars in the current row into one ArrayString
                        let mut builder = String::new();
                        for character in &writer.buffer.chars[crate::vga_buffer::BUFFER_HEIGHT - 1]
                        {
                            builder.push(character.read().ascii_character as char);
                        }

                        // We can be sure that we have the writer lock so we can safely call this method
                        unsafe {
                            crate::vga_buffer::WRITER.force_unlock();
                        }
                        crate::shell::evaluate(&builder);

                        PREV_COMMANDS
                            .lock()
                            .push(builder.strip_prefix(">>> ").unwrap().trim().to_string());
                    } else {
                        print!("{}", character)
                    }

                    let writer = crate::vga_buffer::WRITER.lock();
                    let col = writer.column_position;
                    let row = crate::vga_buffer::BUFFER_HEIGHT - 1;

                    crate::vga_buffer::move_cursor(col as u16, row as u16);
                }
                DecodedKey::RawKey(key) => {
                    match key {
                        KeyCode::ArrowUp => {
                            let mut builder = String::new();
                            let writer = crate::vga_buffer::WRITER.lock();

                            for character in
                                &writer.buffer.chars[crate::vga_buffer::BUFFER_HEIGHT - 1]
                            {
                                builder.push(character.read().ascii_character as char);
                            }

                            drop(writer);

                            let command = builder.strip_prefix(">>> ").unwrap();
                            let mut pc = PREV_COMMANDS.lock();
                            if command.trim() == "" {
                                let len = pc.len();
                                if len > 0 {
                                    let prev_command = pc.remove(len - 1);

                                    print!("{}", prev_command);
                                }
                            } else {
                                let pos = pc.iter().position(|s| s.starts_with(command.trim()));

                                if let Some(pos) = pos {
                                    print!("{}", pc[pos].strip_prefix(command.trim()).unwrap());
                                    pc.remove(pos);
                                }
                            }
                            let writer = crate::vga_buffer::WRITER.lock();
                            let col = writer.column_position;
                            let row = crate::vga_buffer::BUFFER_HEIGHT - 1;

                            crate::vga_buffer::move_cursor(col as u16, row as u16);
                        }
                        KeyCode::ArrowLeft => {
                            let mut writer = crate::vga_buffer::WRITER.lock();
                            let col = writer.column_position;
                            let row = crate::vga_buffer::BUFFER_HEIGHT - 1;

                            // Barrier for the prompt
                            if col != 4 {
                                crate::vga_buffer::move_cursor((col as u16) - 1, row as u16);
                                writer.column_position -= 1;
                            }
                        }
                        KeyCode::ArrowRight => {
                            let mut writer = crate::vga_buffer::WRITER.lock();
                            let col = writer.column_position;
                            let row = crate::vga_buffer::BUFFER_HEIGHT - 1;

                            // We don't need a barrier here because if the cursor reaches the end of the line then the VGA buffer stops it automatically
                            crate::vga_buffer::move_cursor((col as u16) + 1, row as u16);
                            writer.column_position += 1;
                        }
                        _ => {} // Ignore all other special keys
                    }
                }
            }
        }
    }

    unsafe {
        PICS.lock()
            .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
    }
}

extern "x86-interrupt" fn general_protection_fault_handler(
    stack_frame: InterruptStackFrame,
    _error_code: u64,
) {
    panic!("EXCEPTION: GENERAL PROTECTION FAULT\n{:#?}", stack_frame);
}

extern "x86-interrupt" fn stack_segment_fault_handler(
    stack_frame: InterruptStackFrame,
    _error_code: u64,
) {
    panic!("EXCEPTION: STACK SEGMENT FAULT\n{:#?}", stack_frame);
}

extern "x86-interrupt" fn segment_not_present_handler(
    stack_frame: InterruptStackFrame,
    _error_code: u64,
) {
    panic!("EXCEPTION: SEGMENT NOT PRESENT\n{:#?}", stack_frame);
}

pub const PIC_1_OFFSET: u8 = 32;
pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;

pub static PICS: Mutex<ChainedPics> =
    Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });

#[derive(Debug, Clone, Copy)]
#[repr(u8)]
pub enum InterruptIndex {
    Timer = PIC_1_OFFSET,
    Keyboard,
}

impl InterruptIndex {
    fn as_u8(self) -> u8 {
        self as u8
    }

    fn as_usize(self) -> usize {
        usize::from(self.as_u8())
    }
}