#include <kernel.h>

/* IDT entry structure */
typedef struct {
    uint16_t base_low;
    uint16_t sel;
    uint8_t  always0;
    uint8_t  flags;
    uint16_t base_high;
} __attribute__((packed)) idt_entry_t;

typedef struct {
    uint16_t limit;
    uint32_t base;
} __attribute__((packed)) idt_ptr_t;

static idt_entry_t idt_entries[256];
static idt_ptr_t   idt_ptr;

/* Set an IDT entry */
void idt_set_gate(uint8_t num, uint32_t base, uint16_t sel, uint8_t flags) {
    idt_entries[num].base_low  = base & 0xFFFF;
    idt_entries[num].base_high = (base >> 16) & 0xFFFF;
    idt_entries[num].sel       = sel;
    idt_entries[num].always0   = 0;
    idt_entries[num].flags     = flags | 0x60; /* Always set ring 0 */
}

/* External ISR entry points from boot.asm */
extern void isr0(void);  extern void isr1(void);  extern void isr2(void);
extern void isr3(void);  extern void isr4(void);  extern void isr5(void);
extern void isr6(void);  extern void isr7(void);  extern void isr8(void);
extern void isr9(void);  extern void isr10(void); extern void isr11(void);
extern void isr12(void); extern void isr13(void); extern void isr14(void);
extern void isr15(void); extern void isr16(void); extern void isr17(void);
extern void isr18(void); extern void isr19(void); extern void isr20(void);
extern void isr21(void); extern void isr22(void); extern void isr23(void);
extern void isr24(void); extern void isr25(void); extern void isr26(void);
extern void isr27(void); extern void isr28(void); extern void isr29(void);
extern void isr30(void); extern void isr31(void);

/* External IRQ entry points from boot.asm */
extern void irq0(void);  extern void irq1(void);  extern void irq2(void);
extern void irq3(void);  extern void irq4(void);  extern void irq5(void);
extern void irq6(void);  extern void irq7(void);  extern void irq8(void);
extern void irq9(void);  extern void irq10(void); extern void irq11(void);
extern void irq12(void); extern void irq13(void); extern void irq14(void);
extern void irq15(void);

void idt_init(void) {
    idt_ptr.limit = sizeof(idt_entries) - 1;
    idt_ptr.base  = (uint32_t)&idt_entries;

    /* Clear IDT */
    for (int i = 0; i < 256; i++) {
        idt_set_gate(i, 0, 0, 0);
    }

    /* Set up ISR handlers */
    idt_set_gate(0,  (uint32_t)isr0,  0x08, 0x8E);
    idt_set_gate(1,  (uint32_t)isr1,  0x08, 0x8E);
    idt_set_gate(2,  (uint32_t)isr2,  0x08, 0x8E);
    idt_set_gate(3,  (uint32_t)isr3,  0x08, 0x8E);
    idt_set_gate(4,  (uint32_t)isr4,  0x08, 0x8E);
    idt_set_gate(5,  (uint32_t)isr5,  0x08, 0x8E);
    idt_set_gate(6,  (uint32_t)isr6,  0x08, 0x8E);
    idt_set_gate(7,  (uint32_t)isr7,  0x08, 0x8E);
    idt_set_gate(8,  (uint32_t)isr8,  0x08, 0x8E);
    idt_set_gate(9,  (uint32_t)isr9,  0x08, 0x8E);
    idt_set_gate(10, (uint32_t)isr10, 0x08, 0x8E);
    idt_set_gate(11, (uint32_t)isr11, 0x08, 0x8E);
    idt_set_gate(12, (uint32_t)isr12, 0x08, 0x8E);
    idt_set_gate(13, (uint32_t)isr13, 0x08, 0x8E);
    idt_set_gate(14, (uint32_t)isr14, 0x08, 0x8E);
    idt_set_gate(15, (uint32_t)isr15, 0x08, 0x8E);
    idt_set_gate(16, (uint32_t)isr16, 0x08, 0x8E);
    idt_set_gate(17, (uint32_t)isr17, 0x08, 0x8E);
    idt_set_gate(18, (uint32_t)isr18, 0x08, 0x8E);
    idt_set_gate(19, (uint32_t)isr19, 0x08, 0x8E);
    idt_set_gate(20, (uint32_t)isr20, 0x08, 0x8E);
    idt_set_gate(21, (uint32_t)isr21, 0x08, 0x8E);
    idt_set_gate(22, (uint32_t)isr22, 0x08, 0x8E);
    idt_set_gate(23, (uint32_t)isr23, 0x08, 0x8E);
    idt_set_gate(24, (uint32_t)isr24, 0x08, 0x8E);
    idt_set_gate(25, (uint32_t)isr25, 0x08, 0x8E);
    idt_set_gate(26, (uint32_t)isr26, 0x08, 0x8E);
    idt_set_gate(27, (uint32_t)isr27, 0x08, 0x8E);
    idt_set_gate(28, (uint32_t)isr28, 0x08, 0x8E);
    idt_set_gate(29, (uint32_t)isr29, 0x08, 0x8E);
    idt_set_gate(30, (uint32_t)isr30, 0x08, 0x8E);
    idt_set_gate(31, (uint32_t)isr31, 0x08, 0x8E);

    /* Set up IRQ handlers (remapped to 32-47) */
    idt_set_gate(32, (uint32_t)irq0,  0x08, 0x8E);
    idt_set_gate(33, (uint32_t)irq1,  0x08, 0x8E);
    idt_set_gate(34, (uint32_t)irq2,  0x08, 0x8E);
    idt_set_gate(35, (uint32_t)irq3,  0x08, 0x8E);
    idt_set_gate(36, (uint32_t)irq4,  0x08, 0x8E);
    idt_set_gate(37, (uint32_t)irq5,  0x08, 0x8E);
    idt_set_gate(38, (uint32_t)irq6,  0x08, 0x8E);
    idt_set_gate(39, (uint32_t)irq7,  0x08, 0x8E);
    idt_set_gate(40, (uint32_t)irq8,  0x08, 0x8E);
    idt_set_gate(41, (uint32_t)irq9,  0x08, 0x8E);
    idt_set_gate(42, (uint32_t)irq10, 0x08, 0x8E);
    idt_set_gate(43, (uint32_t)irq11, 0x08, 0x8E);
    idt_set_gate(44, (uint32_t)irq12, 0x08, 0x8E);
    idt_set_gate(45, (uint32_t)irq13, 0x08, 0x8E);
    idt_set_gate(46, (uint32_t)irq14, 0x08, 0x8E);
    idt_set_gate(47, (uint32_t)irq15, 0x08, 0x8E);

    idt_flush((uint32_t)&idt_ptr);
    screen_writeln("[IDT] Interrupt Descriptor Table initialized");
}