#include "acpi.h"
#include "memops.h"
#include "kprintf.h"
#include "asm_inline.h"

#include <stddef.h>

void* getPointerToOtherSDT(ACPISDTHeader* header)
{
    uint8_t* base = (uint8_t*)header;
    return &(base[36]);
}

void* getACPITablesPointer(APICHeader* header)
{
    uint8_t* base = (uint8_t*)header;
    return &(base[44]);
}

#define IS_TABLE(x, header) kmemcmp(x, header->signature, 4*sizeof(uint8_t))

enum ACPI_TABLES getTableType(ACPISDTHeader* header)
{
    if(IS_TABLE("APIC", header)) return APIC;
    if(IS_TABLE("BGRT", header)) return BGRT;
    if(IS_TABLE("BERT", header)) return BERT;
    if(IS_TABLE("CPEP", header)) return CPEP;
    if(IS_TABLE("DSDT", header)) return DSDT;
    if(IS_TABLE("ECDT", header)) return ECDT;
    if(IS_TABLE("EINJ", header)) return EINJ;
    if(IS_TABLE("ERST", header)) return ERST;
    if(IS_TABLE("FACP", header)) return FACP;
    if(IS_TABLE("FACS", header)) return FACS;
    if(IS_TABLE("HEST", header)) return HEST;
    if(IS_TABLE("MSCT", header)) return MSCT;
    if(IS_TABLE("MPST", header)) return MPST;
    if(IS_TABLE("OEMx", header)) return OEMx;
    if(IS_TABLE("PMTT", header)) return PMTT;
    if(IS_TABLE("PSDT", header)) return PSDT;
    if(IS_TABLE("RASF", header)) return RASF;
    if(IS_TABLE("RSDT", header)) return RSDT;
    if(IS_TABLE("SBST", header)) return SBST;
    if(IS_TABLE("SLIT", header)) return SLIT;
    if(IS_TABLE("SRAT", header)) return SRAT;
    if(IS_TABLE("SSDT", header)) return SSDT;
    if(IS_TABLE("XSDT", header)) return XSDT;
    if(IS_TABLE("HPET", header)) return HPET;

    return NONE;
}

void* getTable(void* xsdt, enum ACPI_TABLES table)
{
    ACPISDTHeader* header = (ACPISDTHeader*)xsdt;
    uint64_t* tables = (uint64_t*)getPointerToOtherSDT(xsdt);
    uint64_t entries = (header->length - sizeof(ACPISDTHeader)) / 8;
    
    for(int i = 0; i < entries; i++)
    {
        uint64_t table_ptr = tables[i];

        if(getTableType((ACPISDTHeader*)table_ptr) == table)
        {
            return (ACPISDTHeader*)table_ptr;
        }
    }

    return NULL;
}

void* getAPIC(APICHeader* header, enum APIC_TYPE apic)
{
    header->length;
    uint8_t* apic_tables = (uint8_t*)getACPITablesPointer(header);
    APICEntry* entry = (APICEntry*)apic_tables;
    uint8_t offset = 0;

    while(offset < (header->length - sizeof(APICHeader)))
    {
        APICEntry* entry = (APICEntry*)&(apic_tables[offset]);
        if(entry->type == apic)
        {
            return entry;
        }

        offset += entry->length;
    }

    return NULL;
}

uint64_t numberTables(APICHeader* header)
{
    header->length;
    uint8_t* apic_tables = (uint8_t*)getACPITablesPointer(header);
    APICEntry* entry = (APICEntry*)apic_tables;
    uint8_t offset = 0;
    uint64_t tables = 0;

    while(offset < (header->length - sizeof(APICHeader)))
    {
        /*
        APICEntry* entry = (APICEntry*)&(apic_tables[offset]);
        if(entry->type == apic)
        {
            return entry;
        }
        */

        tables++;
        offset += entry->length;
    }

    return tables;
}

void init_acpi(XSDP* xsdp)
{
    kprintf("=> Initializing ACPI\n");

    uint64_t pic_master = inb(0x21);
    uint64_t pic_slave = inb(0xA1);

    if((pic_master == 0xFF) && (pic_slave == 0xFF))
    {
        kprintf("==> PIC disabled\n");
    }

    if(xsdp != NULL)
    {
        kprintf("==> ACPI 2.0 Found\n");
    }
    else
    {
        kprintf("==X No ACPI 2.0 Found\n");
        return;
    }

    ACPISDTHeader* xsdt = (ACPISDTHeader*)xsdp->xsdtaddress;

    APICHeader* apic_table = (APICHeader*)getTable(xsdt, APIC);
    if(apic_table == NULL)
    {
        kprintf("==X Failed To Find APIC Table\n");
        return;
    }

    kprintf("==> Found APIC Table\n");
    if(apic_table->flags >= 0)
    {
        kprintf("==> Dual 8259 PIC Found\n");
    }

    IOAPICTable* ioapic = getAPIC(apic_table, IOAPIC);
    if(ioapic == NULL)
    {
        kprintf("==X Failed to find a valid IOAPIC\n");
        return;
    }

    uint64_t n_tables = numberTables(apic_table);

    kprintf("Number of Tables: %ld\n", n_tables);

    kprintf("==> IOAPIC Found\n");


    // kprintf("=> ACPI Initialized\n");
}