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

use ::acpi::{mcfg::Mcfg, AcpiTables, HpetInfo, InterruptModel};
use abi::error::Error;
use acpi::{AcpiAllocator, AcpiHandlerImpl};
use alloc::{boxed::Box, sync::Arc};
use apic::{ioapic::IoApic, local::LocalApic};
use device_api::device::Device;
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 libk::{
    arch::Cpu,
    config, debug,
    device::{
        display::{fb_console::FramebufferConsole, DriverFlags, PixelFormat},
        manager::DEVICE_REGISTRY,
        register_external_interrupt_controller,
    },
    fs::devfs,
};
use libk_mm::{
    address::PhysicalAddress,
    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::{self, peripherals::hpet::Hpet},
    device::display::linear_fb::LinearFramebuffer,
};

use self::boot::BootData;

use super::{
    x86::{intrinsics, InitrdSource},
    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>>,

    fbconsole: OneTimeInit<Arc<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(),

    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> {
        if cpu_id == 0 {
            PLATFORM
                .init_memory_management()
                .expect("Could not initialize memory management");
        }

        self.init_local_cpu(cpu_id);

        if cpu_id == 0 {
            x86::register_pci_drivers();

            self.setup_from_boot_data()?;

            // TODO yboot doesn't yet pass any command line options
            let cmdline = self.boot_data.get().cmdline();
            let mut early = x86::init_platform_early(cmdline)?;

            if !config::get().x86.disable_boot_fb {
                if let Err(error) = self.init_framebuffer() {
                    log::error!("Could not initialize boot framebuffer: {error:?}");
                }
            }

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

            if !config::get().x86_64.disable_hpet {
                early.add_preferred_clock_source("hpet", Self::setup_hpet);
            } else {
                log::info!("HPET disabled by config");
            }

            x86::init_platform_devices(early);
        }

        Ok(())
    }

    fn setup_hpet() -> Result<Arc<dyn Device>, Error> {
        let acpi = PLATFORM.acpi.try_get().ok_or(Error::DoesNotExist)?;
        let hpet = HpetInfo::new(acpi).map_err(|_| Error::DoesNotExist)?;
        let hpet = Hpet::setup_from_acpi(&hpet)?;
        let timer = hpet.setup_timer(0, 1000, true)?;
        Ok(timer)
    }

    unsafe fn init_local_cpu(&self, cpu_id: usize) {
        let local_apic = Box::new(LocalApic::new());
        let tss_address = gdt::init();
        exception::init_exceptions(cpu_id);

        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();
    }

    unsafe fn setup_from_boot_data(&self) -> Result<(), Error> {
        match self.boot_data.get() {
            &BootData::YBoot(data) => {
                // Already reserved in set_boot_data()
                x86::set_initrd(data, false);

                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 {
            unreachable!("The processor does not support APIC");
        };

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

        // acpi::init_acpi(acpi).unwrap();

        if let Ok(mcfg) = acpi.find_table::<Mcfg>() {
            for entry in mcfg.entries() {
                if let Err(error) = PciBusManager::add_segment_from_mcfg(entry) {
                    log::error!("Could not add PCI bus segment: {error:?}");
                }
            }
        }

        Ok(())
    }

    unsafe fn init_framebuffer(&'static self) -> Result<(), Error> {
        DEVICE_REGISTRY.display.set_callback(|device, node| {
            log::info!("Display registered: {:?}", device.display_name());

            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.clone()) {
                        log::error!("Couldn't set fb console display: {error:?}");
                    }
                }

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

        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,
                )?;

                Some(Arc::new(framebuffer))
            }
        };

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

        // Register boot display
        DEVICE_REGISTRY.display.register(display.clone(), true)?;

        let fbconsole = self
            .fbconsole
            .init(Arc::new(FramebufferConsole::from_framebuffer(
                display.clone(),
                None,
                true,
            )?));

        debug::add_sink(fbconsole.clone(), config::get().debug.display_level);

        Ok(())
    }
}

impl InitrdSource for LoadProtocolV1 {
    fn start(&self) -> PhysicalAddress {
        PhysicalAddress::from_u64(self.initrd_address)
    }

    fn end(&self) -> PhysicalAddress {
        PhysicalAddress::from_u64(self.initrd_address + self.initrd_size)
    }
}