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

#include <libc/libc.h>
#include <libk/libk.h>
#include <libc/kprintf.h>
#include <mem/malloc.h>
#include <tasks/task.h>
#include <tasks/locking.h>
#include <attributes.h>
#include "blockdev.h"

#define MAX_BLOCK_DEVS 64

int last_block_dev = 0;
block_device block_devices[MAX_BLOCK_DEVS] = {0};

extern struct block_dev_driver __start_block_dev_driver[];
extern struct block_dev_driver __stop_block_dev_driver[];
#define NUM_DRIVERS ((size_t)(__stop_block_dev_driver - __start_block_dev_driver))
#define DRIVER(i) ((__start_block_dev_driver) + (i))

semaphore_t *block_semaphore;
bool blockdev_task_running = false;

uint8_t block_dev_register(block_device *device) {
    if (last_block_dev >= MAX_BLOCK_DEVS - 1) {
        return BLOCK_DEV_REGISTER_FULL;
    }

    memcpy((uint8_t *) &block_devices[last_block_dev++], (const uint8_t *) device, sizeof(block_device));

    if (blockdev_task_running) {
        semaphore_signal(block_semaphore);
    }
    return BLOCK_DEV_REGISTER_OK;
}

void block_dev_free(block_device *device) {
    //todo
    k_panics("block dev free not supported");
}

int block_dev_num_not_scanned() {
    int not_scanned = 0;
    for (int i = 0; i < last_block_dev; ++i) {
        if (block_devices[i].flags.present && !block_devices[i].flags.scanned) not_scanned++;
    }
    return not_scanned;
}

void block_dev_scan() {
    int c_last_block_dev = last_block_dev;
    for (int i = 0; i < c_last_block_dev; ++i) {
        if (block_devices[i].flags.scanned || !block_devices[i].flags.present) continue;
        uint8_t *lba0 = malloc(block_devices[i].block_size);
        uint8_t read_result = block_devices[i].access(&block_devices[i], BLOCK_DEV_DIRECTION_READ, 0, 1, lba0);
        if (read_result != BLOCK_DEV_ACCESS_OK) {
            block_devices[i].flags.unreadable = 1;
            goto _block_dev_scan_free;
        }
        for (size_t j = 0; j < NUM_DRIVERS; ++j) {
            // validate if driver is appropriate at all
            // don't use a root device driver (i.e. mbr) for a non-root device
            if (DRIVER(j)->flags.root_only && !block_devices[i].flags.root_device) continue;

            // let the driver test the disk
            uint8_t driver_result = DRIVER(j)->check_device(&block_devices[i], lba0);
            if (driver_result == BLOCK_DEV_DRIVER_CHECK_OK) {
                block_devices[i].driver = DRIVER(j);
                block_devices[i].flags.driver_installed = 1;
                break;
            }
        }
        _block_dev_scan_free:
        free(lba0);
        block_devices[i].flags.scanned = 1;
    }
}

void noreturn block_dev_task(void *data) {
    while (true) {
        semaphore_wait(block_semaphore);
        block_dev_scan();
    }
}

void block_dev_start_task() {
    block_semaphore = semaphore_create(1);
    blockdev_task_running = true;
    task_spawn(block_dev_task, NULL);
}

void block_dev_print_info() {
    printf("Block devices:\n");
    for (int i = 0; i < last_block_dev; ++i) {
        printf("-%s driver: %s\n",
               block_devices[i].identifier,
               block_devices[i].flags.driver_installed ? block_devices[i].driver->name : "n/a");
    }
}