//! x86-64 architecture implementation
use core::{
    mem::size_of,
    ops::{Deref, DerefMut},
    ptr::null_mut,
    sync::atomic::Ordering,
};

use ::acpi::{mcfg::Mcfg, AcpiTables, InterruptModel};
use abi::error::Error;
use alloc::boxed::Box;
use device_api::{interrupt::Irq, Device};
use git_version::git_version;
use kernel_arch_x86::{
    cpuid::{self, CpuFeatures, EcxFeatures, EdxFeatures},
    gdt,
};
use kernel_arch_x86_64::{
    mem::{
        init_fixed_tables,
        table::{PageAttributes, PageEntry, PageTable, L1, L2, L3},
        EarlyMapping, MEMORY_LIMIT, RAM_MAPPING_L1,
    },
    PerCpuData,
};
use kernel_fs::devfs::{self, BlockDeviceType};
use libk::{
    arch::Cpu,
    device::{
        display::{
            register_display_device, set_display_registration_callback, DisplayDeviceWrapper,
            DriverFlags, PixelFormat,
        },
        register_external_interrupt_controller,
    },
};
use libk_device::register_monotonic_timestamp_provider;
use libk_mm::{
    address::{PhysicalAddress, Virtualize},
    phys::{self, reserved::reserve_region, PhysicalMemoryRegion},
    table::{EntryLevel, EntryLevelExt},
};
use libk_util::{sync::SpinFence, OneTimeInit};
use yboot_proto::{
    v1::{self, AvailableMemoryRegion},
    LoadProtocolV1,
};
use ygg_driver_pci::PciBusManager;

mod acpi;
mod apic;
mod boot;
mod exception;
mod smp;
mod syscall;

use crate::{
    arch::x86::peripherals::{i8253::I8253, i8259::I8259, ps2::PS2, rtc::RTC, serial::ComPort},
    debug::{self, LogLevel},
    device::{
        self,
        display::{fb_console::FramebufferConsole, linear_fb::LinearFramebuffer},
    },
    fs::{Initrd, INITRD_DATA},
};

use self::{
    acpi::{AcpiAllocator, AcpiHandlerImpl},
    apic::{ioapic::IoApic, local::LocalApic},
    boot::BootData,
};

use super::{x86::intrinsics, Platform};

/// Offset where legacy ISA IRQs are remapped
pub const ISA_IRQ_OFFSET: u32 = apic::ioapic::ISA_IRQ_OFFSET;

/// x86-64 architecture implementation
pub struct X86_64 {
    boot_data: OneTimeInit<BootData>,
    acpi: OneTimeInit<AcpiTables<AcpiHandlerImpl>>,

    // Display
    gop_framebuffer: OneTimeInit<LinearFramebuffer>,
    fbconsole: OneTimeInit<FramebufferConsole>,
}

static SHUTDOWN_FENCE: SpinFence = SpinFence::new();

/// Global x86-64 architecture value
pub static PLATFORM: X86_64 = X86_64 {
    boot_data: OneTimeInit::new(),
    acpi: OneTimeInit::new(),

    gop_framebuffer: OneTimeInit::new(),
    fbconsole: OneTimeInit::new(),
};

impl Platform for X86_64 {
    const KERNEL_VIRT_OFFSET: usize = 0xFFFFFF8000000000;
    type L3 = kernel_arch_x86_64::mem::table::L3;

    unsafe fn start_application_processors(&self) {
        if let Some(acpi) = self.acpi.try_get() {
            let Some(pinfo) = acpi
                .platform_info_in(AcpiAllocator)
                .ok()
                .and_then(|p| p.processor_info)
            else {
                return;
            };

            smp::start_ap_cores(&pinfo);
        }
    }
}

impl X86_64 {
    fn set_boot_data(&self, data: BootData) {
        match data {
            BootData::YBoot(data) => {
                // Reserve the memory map
                reserve_region(
                    "mmap",
                    PhysicalMemoryRegion {
                        base: PhysicalAddress::from_u64(data.memory_map.address),
                        size: data.memory_map.len as usize * size_of::<AvailableMemoryRegion>(),
                    },
                );

                // Reserve initrd, if not NULL
                if data.initrd_address != 0 && data.initrd_size != 0 {
                    let aligned_start = data.initrd_address & !0xFFF;
                    let aligned_end = (data.initrd_address + data.initrd_size + 0xFFF) & !0xFFF;

                    reserve_region(
                        "initrd",
                        PhysicalMemoryRegion {
                            base: PhysicalAddress::from_u64(aligned_start),
                            size: (aligned_end - aligned_start) as usize,
                        },
                    );
                }
            }
        }

        self.boot_data.init(data);
    }

    fn map_physical_memory<I: Iterator<Item = PhysicalMemoryRegion> + Clone>(
        it: I,
        _memory_start: PhysicalAddress,
        memory_end: PhysicalAddress,
    ) -> Result<(), Error> {
        let end_l1i = memory_end
            .into_usize()
            .page_align_up::<L1>()
            .page_index::<L1>();

        if end_l1i > 512 {
            panic!(
                "Cannot handle {}GiB of RAM",
                end_l1i * L1::SIZE / (1024 * 1024 * 1024)
            );
        }

        MEMORY_LIMIT.store(memory_end.into_usize(), Ordering::Release);

        // Check if 1GiB pages are supported
        // TODO
        // if PROCESSOR_FEATURES
        //     .get()
        //     .contains(ProcessorFeatures::PDPE1GB)
        // {
        //     // Just map gigabytes of RAM
        //     for l1i in 0..end_l1i {
        //         // TODO NX
        //         unsafe {
        //             RAM_MAPPING_L1[l1i] = PageEntry::<L1>::block(
        //                 PhysicalAddress::from_usize(l1i * L1::SIZE),
        //                 PageAttributes::WRITABLE,
        //             );
        //         }
        //     }
        // } else {
        // Allocate the intermediate tables first
        let l2_tables_start = phys::find_contiguous_region(it, end_l1i)
            .expect("Could not allocate the memory for RAM mapping L2 tables");

        reserve_region(
            "ram-l2-tables",
            PhysicalMemoryRegion {
                base: l2_tables_start,
                size: end_l1i * L3::SIZE,
            },
        );

        // Fill in the tables
        for l1i in 0..end_l1i {
            let l2_phys_addr = l2_tables_start.add(l1i * L3::SIZE);

            // Safety: ok, the mapping is done to the memory obtained from
            // find_contiguous_region()
            let mut l2_data = unsafe { EarlyMapping::<[PageEntry<L2>; 512]>::map(l2_phys_addr)? };
            // Safety: ok, the slice comes from EarlyMapping of a page-aligned region
            let l2 = unsafe { PageTable::from_raw_slice_mut(l2_data.deref_mut()) };

            for l2i in 0..512 {
                // TODO NX
                l2[l2i] = PageEntry::<L2>::block(
                    PhysicalAddress::from_usize((l1i * L1::SIZE) | (l2i * L2::SIZE)),
                    PageAttributes::WRITABLE,
                );
            }

            // Point the L1 entry to the L2 table
            unsafe {
                RAM_MAPPING_L1[l1i] = PageEntry::<L1>::table(l2_phys_addr, PageAttributes::WRITABLE)
            };

            intrinsics::flush_cpu_cache();
            // The EarlyMapping is then dropped
        }
        // }

        Ok(())
    }

    unsafe fn init_physical_memory_from_yboot(data: &LoadProtocolV1) -> Result<(), Error> {
        let mmap = EarlyMapping::<AvailableMemoryRegion>::map_slice(
            PhysicalAddress::from_u64(data.memory_map.address),
            data.memory_map.len as usize,
        )?;

        phys::init_from_iter(
            mmap.as_ref().iter().map(|reg| PhysicalMemoryRegion {
                base: PhysicalAddress::from_u64(reg.start_address),
                size: reg.page_count as usize * L3::SIZE,
            }),
            Self::map_physical_memory,
        )
    }

    unsafe fn init_memory_management(&self) -> Result<(), Error> {
        init_fixed_tables();

        // Reserve lower 4MiB just in case
        reserve_region(
            "lowmem",
            PhysicalMemoryRegion {
                base: PhysicalAddress::ZERO,
                size: 4 * 1024 * 1024,
            },
        );

        match self.boot_data.get() {
            &BootData::YBoot(data) => Self::init_physical_memory_from_yboot(data)?,
        }

        Ok(())
    }

    unsafe fn init_platform(&'static self, cpu_id: usize) -> Result<(), Error> {
        let local_apic = Box::leak(Box::new(LocalApic::new()));
        let tss_address = gdt::init();

        let (have_features, will_features) = cpuid::setup_features(
            CpuFeatures {
                ecx: EcxFeatures::SSE3
                    | EcxFeatures::SSE4_1
                    | EcxFeatures::SSE4_2
                    | EcxFeatures::AVX,
                edx: EdxFeatures::empty(),
            },
            CpuFeatures {
                ecx: EcxFeatures::XSAVE,
                edx: EdxFeatures::FXSR
                    | EdxFeatures::SSE
                    | EdxFeatures::PGE
                    | EdxFeatures::PSE
                    | EdxFeatures::FPU,
            },
        );
        let will_features = will_features.expect("Could not initialize CPU features");

        let cpu_data = PerCpuData {
            this: null_mut(),
            tss_address,
            tmp_address: 0,
            local_apic,
            available_features: have_features,
            enabled_features: will_features,
        };

        Cpu::init_local(Some(cpu_id as _), cpu_data);
        syscall::init_syscall();

        if cpu_id == 0 {
            // Register the PCI drivers
            //  TODO make this implicit init
            ygg_driver_pci::register_class_driver(
                "NVMe Host Controller",
                0x01,
                Some(0x08),
                Some(0x02),
                ygg_driver_nvme::probe,
            );
            ygg_driver_pci::register_class_driver(
                "AHCI SATA Controller",
                0x01,
                Some(0x06),
                Some(0x01),
                ygg_driver_ahci::probe,
            );
            ygg_driver_pci::register_class_driver(
                "USB xHCI",
                0x0C,
                Some(0x03),
                Some(0x30),
                ygg_driver_usb_xhci::probe,
            );
            ygg_driver_pci::register_vendor_driver(
                "Virtio PCI GPU Device",
                0x1AF4,
                0x1050,
                ygg_driver_virtio_gpu::probe,
            );
            ygg_driver_pci::register_vendor_driver(
                "Virtio PCI Network Device",
                0x1AF4,
                0x1000,
                ygg_driver_virtio_net::probe,
            );

            match self.boot_data.get() {
                &BootData::YBoot(data) => {
                    let start = PhysicalAddress::from_u64(data.initrd_address);
                    Self::init_initrd(start, start.add(data.initrd_size as usize));
                }
            }

            self.init_acpi_from_boot_data()?;

            I8259.disable();

            let com1_3 = Box::leak(Box::new(ComPort::new(
                0x3F8,
                0x3E8,
                Irq::External(ISA_IRQ_OFFSET + 4),
            )));
            debug::add_sink(com1_3.port_a(), LogLevel::Debug);

            set_display_registration_callback(|device| {
                log::info!("Display registered: {:?}", device.display_name());
                let node = devfs::add_block_device(device, BlockDeviceType::Framebuffer);

                if device
                    .driver_flags()
                    .contains(DriverFlags::REPLACES_BOOT_FRAMEBUFFER)
                {
                    // Switch fbconsole to the new framebuffer
                    if let Some(fbconsole) = PLATFORM.fbconsole.try_get()
                        && fbconsole.uses_boot_framebuffer()
                    {
                        if let Err(error) = fbconsole.set_display(device.deref()) {
                            log::error!("Couldn't set fb console display: {error:?}");
                        }
                    }

                    // Switch /dev/fb0 to the new node
                    if let Ok(node) = node {
                        devfs::set_node("fb0", node).ok();
                    }
                }
            });
            self.init_framebuffer()?;

            debug::init();

            log::info!(
                "Yggdrasil v{} ({})",
                env!("CARGO_PKG_VERSION"),
                git_version!()
            );

            RTC.init()?;
            PS2.init()?;

            if let Some(acpi) = self.acpi.try_get() {
                self.init_platform_from_acpi(acpi)?;
            }

            register_monotonic_timestamp_provider(&I8253);
            I8253.init_irq()?;

            RTC.init_irq()?;
            // ps2.connect(self.tty.get());
            PS2.init_irq()?;

            device::register_device(&PS2);

            PciBusManager::setup_bus_devices()?;
        }

        Ok(())
    }

    unsafe fn init_acpi_from_boot_data(&self) -> Result<(), Error> {
        match self.boot_data.get() {
            &BootData::YBoot(data) => self.init_acpi_from_rsdp(data.rsdp_address as usize),
        }
    }

    unsafe fn init_acpi_from_rsdp(&self, rsdp: usize) -> Result<(), Error> {
        let acpi_tables = AcpiTables::from_rsdp(AcpiHandlerImpl, rsdp).map_err(|err| {
            log::error!("Could not initialize ACPI tables: {:?}", err);
            Error::InvalidArgument
        })?;
        self.acpi.init(acpi_tables);
        Ok(())
    }

    unsafe fn init_platform_from_acpi(
        &self,
        acpi: &'static AcpiTables<AcpiHandlerImpl>,
    ) -> Result<(), Error> {
        let platform_info = acpi.platform_info_in(AcpiAllocator).map_err(|err| {
            log::error!("Could not get ACPI platform info: {:?}", err);
            Error::InvalidArgument
        })?;

        let InterruptModel::Apic(apic_info) = platform_info.interrupt_model else {
            panic!("The processor does not support APIC");
        };

        let ioapic = IoApic::from_acpi(&apic_info)?;
        let ioapic = Box::leak(Box::new(ioapic));
        register_external_interrupt_controller(ioapic);

        // acpi::init_acpi(acpi).unwrap();
        if let Ok(mcfg) = acpi.find_table::<Mcfg>() {
            for entry in mcfg.entries() {
                PciBusManager::add_segment_from_mcfg(entry)?;
            }
        }

        Ok(())
    }

    unsafe fn init_framebuffer(&'static self) -> Result<(), Error> {
        let display = match self.boot_data.get() {
            &BootData::YBoot(data) => {
                let info = &data.opt_framebuffer;
                let format = match info.res_format {
                    v1::PIXEL_B8G8R8A8 => PixelFormat::B8G8R8A8,
                    v1::PIXEL_R8G8B8A8 => PixelFormat::R8G8B8A8,
                    // Fallback
                    _ => PixelFormat::R8G8B8A8,
                };

                let framebuffer = LinearFramebuffer::from_physical_bits(
                    PhysicalAddress::from_u64(info.res_address),
                    info.res_size as usize,
                    info.res_stride as usize,
                    info.res_width,
                    info.res_height,
                    format,
                )?;
                let framebuffer = self.gop_framebuffer.init(framebuffer);

                Some(framebuffer)
            }
        };

        let Some(display) = display else {
            return Ok(());
        };

        // Register boot display
        let display = Box::leak(Box::new(DisplayDeviceWrapper::new(display)));
        register_display_device(display);

        let fbconsole = self.fbconsole.init(FramebufferConsole::from_framebuffer(
            (*display).deref(),
            None,
            true,
        )?);

        debug::add_sink(fbconsole, LogLevel::Info);

        Ok(())
    }

    fn init_initrd(initrd_start: PhysicalAddress, initrd_end: PhysicalAddress) {
        if initrd_start.is_zero() || initrd_end <= initrd_start {
            log::info!("No initrd loaded");
            return;
        }

        let start_aligned = initrd_start.page_align_down::<L3>();
        let end_aligned = initrd_start.page_align_up::<L3>();

        let data = unsafe {
            core::slice::from_raw_parts(
                start_aligned.virtualize() as *const u8,
                initrd_end - initrd_start,
            )
        };

        let initrd = Initrd {
            phys_page_start: start_aligned,
            phys_page_len: end_aligned - start_aligned,
            data,
        };

        INITRD_DATA.init(initrd);
    }
}