//
// Created by rick on 06-02-21.
//

#include "mbr.h"
#include <types.h>
#include <drivers/ide.h>
#include <libc/kprintf.h>
#include <fs/blockdev.h>
#include <libc/libc.h>
#include <mem/malloc.h>
#include <attributes.h>

typedef struct {
    uint8_t bootable;
    uint8_t starting_head;
    uint8_t starting_sector: 6;
    uint16_t starting_cylinder: 10;
    uint8_t system_id;
    uint8_t ending_head;
    uint8_t ending_sector: 6;
    uint16_t ending_cylinder: 10;
    uint32_t start_lba;
    uint32_t num_lbas;
}  packed mbr_partition_table_entry;

typedef struct {
    uint32_t unique_id;
    uint16_t reserved;
    mbr_partition_table_entry entries[4];
    uint8_t signature[2];
} packed mbr_table;

typedef struct {
    const block_device *device;
    uint32_t start_lba;
} mbr_block_driver_info;

uint8_t mbr_block_dev_access(const block_device *device, uint8_t direction, uint32_t lba, uint8_t sectors, void *target) {
    if (!device->flags.present || lba > device->num_lba) {
        return BLOCK_DEV_ACCESS_ERR;
    }
    const mbr_block_driver_info *info = device->device_info;
    const uint32_t actual_lba = info->start_lba + lba;
    if (actual_lba > info->device->num_lba) {
        return BLOCK_DEV_ACCESS_ERR;
    }

    // delegate to backing driver
    return info->device->access(info->device, direction, actual_lba, sectors, target);
}

uint8_t used mbr_check_device(const block_device *device, uint8_t *first_sector) {
    mbr_table table;
    memcpy((uint8_t *) &table, first_sector + (device->block_size - sizeof(mbr_table)), sizeof(mbr_table));
    if (table.signature[0] != 0x55 && table.signature[1] != 0xAA) { // AA 55 but in little endian
        return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
    }

    if (table.reserved != 0x0000 && table.reserved != 0x5A5A) {
        return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
    }

    for (int i = 0; i < 4; ++i) {
        if (table.entries[i].num_lbas > device->num_lba || table.entries[i].start_lba > device->num_lba) {
            return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
        }
    }

    for (int i = 0; i < 4; ++i) {
        if (table.entries[i].system_id == 0) continue;

        mbr_block_driver_info *info = malloc(sizeof(mbr_block_driver_info));
        info->device = device;
        info->start_lba = table.entries[i].start_lba;

        block_device logical_device = {
                .flags.present = 1,

                .num_lba = table.entries[i].num_lbas,
                .block_size = device->block_size,
                .access = mbr_block_dev_access,
                .device_info = info,
        };

        sprintf(logical_device.identifier, "%sp%d", device->identifier, i);

        block_dev_register(&logical_device);

    }

    return BLOCK_DEV_DRIVER_CHECK_OK;
}

void mbr_read_from_ide(uint8_t ide_drive) {
    char *mbr_data = malloc(0x200);
    ide_access(0, ide_drive, 0, 1, mbr_data);
    mbr_partition_table_entry *entry = (mbr_partition_table_entry *) (mbr_data + 0x1BE);
    printf("Start at %d, count: %d\n", entry->start_lba, entry->num_lbas);
    free(mbr_data);
}

BLOCK_DEV_DRIVER(200) = {
        .name = "mbr",
        .flags.root_only = 1,
        .check_device = mbr_check_device,
        .free_device = NULL, // todo
};