#include <luna/CString.h>
#include <luna/Check.h>
#include <luna/Types.h>

struct IDTEntry
{
    u16 offset0;
    u16 selector;
    u8 ist;
    u8 type_attr;
    u16 offset1;
    u32 offset2;
    u32 ignore;
    void set_offset(u64 offset);
    u64 get_offset() const;
};

static_assert(sizeof(IDTEntry) == 16UL);

void IDTEntry::set_offset(u64 offset)
{
    offset0 = (u16)(offset & 0x000000000000ffff);
    offset1 = (u16)((offset & 0x00000000ffff0000) >> 16);
    offset2 = (u32)((offset & 0xffffffff00000000) >> 32);
}

u64 IDTEntry::get_offset() const
{
    u64 offset = 0;
    offset |= (u64)offset0;
    offset |= (u64)offset1 << 16;
    offset |= (u64)offset2 << 32;
    return offset;
}

static IDTEntry idt[256];

#define IDT_TA_InterruptGate 0b10001110
#define IDT_TA_UserCallableInterruptGate 0b11101110
#define IDT_TA_TrapGate 0b10001111

struct [[gnu::packed]] IDTR
{
    u16 limit;
    u64 offset;
};

static_assert(sizeof(IDTR) == 10UL);

static void idt_add_handler(short num, void* handler, u8 type_attr)
{
    check(handler != nullptr);
    expect(num < 256, "IDT can only hold up to 256 entries");
    IDTEntry* const entry_for_handler = &idt[num];
    entry_for_handler->selector = 0x08;
    entry_for_handler->type_attr = type_attr;
    entry_for_handler->set_offset((u64)handler);
}

#define INT(x) extern "C" void _isr##x()
#define TRAP(x) idt_add_handler(x, (void*)_isr##x, IDT_TA_TrapGate)
#define IRQ(x) idt_add_handler(x, (void*)_isr##x, IDT_TA_InterruptGate)
#define SYS(x) idt_add_handler(x, (void*)_isr##x, IDT_TA_UserCallableInterruptGate)

INT(0);
INT(1);
INT(2);
INT(3);
INT(4);
INT(5);
INT(6);
INT(7);
INT(8);
INT(10);
INT(11);
INT(12);
INT(13);
INT(14);
INT(16);
INT(17);
INT(18);
INT(19);
INT(20);
INT(21);
INT(32);
INT(33);
INT(34);
INT(35);
INT(36);
INT(37);
INT(38);
INT(39);
INT(40);
INT(41);
INT(42);
INT(43);
INT(44);
INT(45);
INT(46);
INT(47);
INT(66);

void setup_idt()
{
    memset(idt, 0, sizeof(idt));

    TRAP(0);
    TRAP(1);
    TRAP(2);
    TRAP(3);
    TRAP(4);
    TRAP(5);
    TRAP(6);
    TRAP(7);
    TRAP(8);
    TRAP(10);
    TRAP(11);
    TRAP(12);
    TRAP(13);
    TRAP(14);
    TRAP(16);
    TRAP(17);
    TRAP(18);
    TRAP(19);
    TRAP(20);
    TRAP(21);
    IRQ(32);
    IRQ(33);
    IRQ(34);
    IRQ(35);
    IRQ(36);
    IRQ(37);
    IRQ(38);
    IRQ(39);
    IRQ(40);
    IRQ(41);
    IRQ(42);
    IRQ(43);
    IRQ(44);
    IRQ(45);
    IRQ(46);
    IRQ(47);
    SYS(66);

    static IDTR idtr;
    idtr.limit = 0x0FFF;
    idtr.offset = (u64)idt;
    asm volatile("lidt %0" : : "m"(idtr));
}