#include "kernel_main.h"

#include <asm/boot.h>
#include <asm/port_io.h>
#include <asm/sys.h>
#include <kernel/event/event.h>
#include <kernel/hw/keyboard.h>
#include <kernel/hw/serial.h>
#include <kernel/hw/timer.h>
#include <kernel/interrupt.h>
#include <kernel/mem.h>
#include <kernel/process.hpp>
#include <kernel/stdio.h>
#include <kernel/task.h>
#include <kernel/tty.h>
#include <kernel/vfs.h>
#include <kernel/vga.h>
#include <types/bitmap.h>

#define KERNEL_MAIN_BUF_SIZE (128)

struct tty* console = NULL;
#define printkf(x...)                       \
    snprintf(buf, KERNEL_MAIN_BUF_SIZE, x); \
    tty_print(console, buf)

#define EVE_START(x) printkf(x "... ")
#define INIT_START(x) EVE_START("initializing " x)
#define INIT_OK() printkf("ok\n")
#define INIT_FAILED() printkf("failed\n")

static inline void check_a20_status(void)
{
    uint32_t result;
    result = check_a20_on();

    if (result) {
        tty_print(console, "a20 is on");
    } else {
        tty_print(console, "a20 is NOT on");
    }
}

static inline void halt_on_init_error(void)
{
    MAKE_BREAK_POINT();
    asm_cli();
    while (1)
        asm_hlt();
}

typedef void (*constructor)(void);
extern constructor start_ctors;
extern constructor end_ctors;
void call_constructors_for_cpp(void)
{
    for (constructor* ctor = &start_ctors; ctor != &end_ctors; ++ctor) {
        (*ctor)();
    }
}

uint8_t e820_mem_map[1024];
uint32_t e820_mem_map_count;
uint32_t e820_mem_map_entry_size;
size_t kernel_size;
struct mem_size_info mem_size_info;

static inline void save_loader_data(void)
{
    memcpy(e820_mem_map, asm_e820_mem_map, sizeof(e820_mem_map));
    e820_mem_map_count = asm_e820_mem_map_count;
    e820_mem_map_entry_size = asm_e820_mem_map_entry_size;
    kernel_size = asm_kernel_size;
    memcpy(&mem_size_info, &asm_mem_size_info, sizeof(struct mem_size_info));
}

static inline void show_mem_info(char* buf)
{
    uint32_t mem_size = 0;
    mem_size += 1024 * mem_size_info.n_1k_blks;
    mem_size += 64 * 1024 * mem_size_info.n_64k_blks;

    printkf(
        "Memory size: %d bytes (%d MB), 16k blocks: %d, 64k blocks: %d\n",
        mem_size,
        mem_size / 1024 / 1024,
        (int32_t)mem_size_info.n_1k_blks,
        (int32_t)mem_size_info.n_64k_blks);

    printkf(
        "mem_map_entry_count: %d , mem_map_entry_size: %d \n",
        e820_mem_map_count,
        e820_mem_map_entry_size);

    if (e820_mem_map_entry_size == 20) {
        struct e820_mem_map_entry_20* entry = (struct e820_mem_map_entry_20*)e820_mem_map;
        for (uint32_t i = 0; i < e820_mem_map_count; ++i, ++entry) {
            printkf(
                "[mem] entry %d: %llx ~ %llx, type: %d\n",
                i,
                entry->base,
                entry->base + entry->len,
                entry->type);
        }
    } else {
        struct e820_mem_map_entry_24* entry = (struct e820_mem_map_entry_24*)e820_mem_map;
        for (uint32_t i = 0; i < e820_mem_map_count; ++i, ++entry) {
            printkf(
                "[mem] entry %d: %lld ~ %lld, type: %d, acpi_attr: %d\n",
                i,
                entry->in.base,
                entry->in.base + entry->in.len,
                entry->in.type,
                entry->acpi_extension_attr);
        }
    }
    printkf("kernel size: %x\n", kernel_size);
}

static segment_descriptor new_gdt[6];
struct tss32_t tss;

void load_new_gdt(void)
{
    create_segment_descriptor(new_gdt + 0, 0, 0, 0, 0);
    create_segment_descriptor(new_gdt + 1, 0, ~0, 0b1100, SD_TYPE_CODE_SYSTEM);
    create_segment_descriptor(new_gdt + 2, 0, ~0, 0b1100, SD_TYPE_DATA_SYSTEM);
    create_segment_descriptor(new_gdt + 3, 0, ~0, 0b1100, SD_TYPE_CODE_USER);
    create_segment_descriptor(new_gdt + 4, 0, ~0, 0b1100, SD_TYPE_DATA_USER);
    create_segment_descriptor(new_gdt + 5, (uint32_t)&tss, sizeof(tss), 0b0000, SD_TYPE_TSS);

    asm_load_gdt((6 * 8 - 1) << 16, (phys_ptr_t)new_gdt);
    asm_load_tr((6 - 1) * 8);

    asm_cli();
}

void init_bss_section(void)
{
    void* bss_addr = (void*)bss_section_start_addr;
    size_t bss_size = bss_section_end_addr - bss_section_start_addr;
    memset(bss_addr, 0x00, bss_size);
}

static struct tty early_console;

void NORETURN kernel_main(void)
{
    // MAKE_BREAK_POINT();
    asm_enable_sse();

    init_bss_section();

    save_loader_data();

    load_new_gdt();

    char buf[KERNEL_MAIN_BUF_SIZE];

    init_serial_port(PORT_SERIAL0);

    if (make_serial_tty(&early_console, PORT_SERIAL0) != GB_OK) {
        halt_on_init_error();
    }
    console = &early_console;

    show_mem_info(buf);

    INIT_START("exception handlers");
    init_idt();
    INIT_OK();

    // NOTE:
    // the initializer of c++ global objects MUST NOT contain
    // all kinds of memory allocations
    INIT_START("C++ global objects");
    call_constructors_for_cpp();
    INIT_OK();

    INIT_START("memory allocation");
    init_mem();
    INIT_OK();

    INIT_START("programmable interrupt controller and timer");
    init_pic();
    init_pit();
    INIT_OK();

    printkf("Testing k_malloc...\n");
    char* k_malloc_buf = (char*)k_malloc(sizeof(char) * 4097);
    snprintf(k_malloc_buf, 4097, "This text is printed on the heap!\n");
    tty_print(console, k_malloc_buf);
    k_free(k_malloc_buf);

    k_malloc_buf[4096] = '\x89';

    init_vfs();

    struct inode* init = vfs_open("/init");
    vfs_read(init, buf, 128, 1, 10);

    printkf("switching execution to the scheduler...\n");
    init_scheduler(&tss);
}