#pragma once
#include <stdint.h>
#include "memory.c"
#include "vga.c"

struct rsdp_t {
    char signature[8];
    uint8_t checksum;
    char oem_id[6];
    uint8_t revision;
    uint32_t rsdt_address;
} __attribute__ ((packed));

struct xsdp_t {
    char signature[8];
    uint8_t checksum;
    char oem_id[6];
    uint8_t revision;
    uint32_t unused;
    uint32_t length;
    uint32_t xsdt_addr_hi;
    uint32_t xsdt_addr_lo;
    uint8_t checksum_ext;
    uint8_t unused_[3]
} __attribute__ ((packed));

struct acpi_header_t {
    char signature[4];
    uint32_t length;
    uint8_t revision;
    uint8_t checksum;
    char oem_id[6];
    char oem_table_id[8];
    uint32_t oem_revision;
    uint32_t creator_id;
    uint32_t creator_division;
} __attribute__ ((packed));

struct GenericAddressStructure
{
  uint8_t AddressSpace;
  uint8_t BitWidth;
  uint8_t BitOffset;
  uint8_t AccessSize;
  uint64_t Address;
};

struct fadt_t 
{
    struct   acpi_header_t header;
    uint32_t firmware_ctl;
    uint32_t dsdt_ptr;

    uint8_t  reserved;

    uint8_t  PreferredPowerManagementProfile;
    uint16_t SCI_Interrupt;
    uint32_t SMI_CommandPort;
    uint8_t  AcpiEnable;
    uint8_t  AcpiDisable;
    uint8_t  S4BIOS_REQ;
    uint8_t  PSTATE_Control;
    uint32_t PM1aEventBlock;
    uint32_t PM1bEventBlock;
    uint32_t PM1aControlBlock;
    uint32_t PM1bControlBlock;
    uint32_t PM2ControlBlock;
    uint32_t PMTimerBlock;
    uint32_t GPE0Block;
    uint32_t GPE1Block;
    uint8_t  PM1EventLength;
    uint8_t  PM1ControlLength;
    uint8_t  PM2ControlLength;
    uint8_t  PMTimerLength;
    uint8_t  GPE0Length;
    uint8_t  GPE1Length;
    uint8_t  GPE1Base;
    uint8_t  CStateControl;
    uint16_t WorstC2Latency;
    uint16_t WorstC3Latency;
    uint16_t FlushSize;
    uint16_t FlushStride;
    uint8_t  DutyOffset;
    uint8_t  DutyWidth;
    uint8_t  DayAlarm;
    uint8_t  MonthAlarm;
    uint8_t  Century;

    // reserved in ACPI 1.0; used since ACPI 2.0+
    uint16_t BootArchitectureFlags;

    uint8_t  Reserved2;
    uint32_t Flags;

    // 12 byte structure; see below for details
    struct GenericAddressStructure ResetReg;

    uint8_t  ResetValue;
    uint8_t  Reserved3[3];
  
    // 64bit pointers - Available on ACPI 2.0+
    uint64_t                X_FirmwareControl;
    uint64_t                X_Dsdt;

    struct GenericAddressStructure X_PM1aEventBlock;
    struct GenericAddressStructure X_PM1bEventBlock;
    struct GenericAddressStructure X_PM1aControlBlock;
    struct GenericAddressStructure X_PM1bControlBlock;
    struct GenericAddressStructure X_PM2ControlBlock;
    struct GenericAddressStructure X_PMTimerBlock;
    struct GenericAddressStructure X_GPE0Block;
    struct GenericAddressStructure X_GPE1Block;
};

struct rsdt_t {
    struct acpi_header_t header;
    uint32_t pointer[64];
};




uint8_t validate(struct rsdp_t *ptr) {
    char sig[] = "RSD PTR ";
    if (!memseq(ptr->signature, sig, 8)) return 0;

    uint8_t *rsdp_bytes = (uint8_t *) ptr;
    uint8_t sum = 0;
    for(uint8_t i = 0; i < 20; i++) {
        sum += rsdp_bytes[i];
    }

    if (sum == 0 && ptr->revision == 2) {
        printf_nolock("ACPI v2+ not yet supported :(\n");
        for(;;){}
        // TODO: test with ACPI 2 System
        struct xsdp_t *r2_ptr = (struct xsdp_t*) ptr;

        uint8_t *xsdp_bytes = ((uint8_t *) r2_ptr) + 8;
        uint8_t x_sum = 0;
        for(uint8_t i = 0; i < 16; i++) {
            sum += xsdp_bytes[i];
        }
    }

    return sum == 0;
}

char* find_table(struct rsdt_t* table, char* sig) {
    uint32_t entries = (table->header.length - sizeof table->header) / 4;
    for (uint32_t i = 0; i < entries; i++) {
        struct acpi_header_t* entry = (struct acpi_header_t*) table->pointer[i];
        if (memseq(entry->signature, sig, 4)) {
            printf_nolock("Found %s /  %s\n", entry->oem_id, entry->signature);
            printf_nolock("Signature: %s\n", entry->signature);
            printf_nolock("Length   : %d\n", entry->length);
            printf_nolock("Oem ID   : %s\n", entry->oem_id);
            printf_nolock("Checksum : %d\n", entry->checksum);
            return (void*)entry;
        }
    }

    printf_nolock("Not Found");
    return 0;
}

void find_rsdp() {
    struct rsdp_t *ptr;

    volatile uint8_t found = 0;
    for (uint32_t addr = 0x00000000; addr <= 0x000FFFFF; addr++) {
        ptr = (struct rsdp_t *) addr;

        if (validate(ptr)) {
            found = 1;
            break;
        }
    }

    if (!found) {
        uint8_t* ebda = (uint8_t*)(*((uint16_t*)0x40e) << 4);
        for (uint32_t i = 0; i <= 1024; i += 16) {
            ptr = (struct rsdp_t*) ebda;
            if (validate(ptr)) {
                found = 1;
                break;
            }
        }
    }
        
    printf_nolock("RSDP Found %s /  %s / %d\n", ptr->oem_id, ptr->signature);

    struct fadt_t* fadt = (struct fadt_t*) find_table((struct rsdt_t*) ptr->rsdt_address, "FACP");

    facp.
}