#include "disk.h"
#include "common/io.h"
#include "common/strutil.h"

#include <sys/mntent.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/mount.h>
#include <sys/mnttab.h>

static bool isPhysicalDevice(const struct mnttab* device) {
    // Always show the root path
    if (ffStrEquals(device->mnt_mountp, "/")) {
        return true;
    }

    if (ffStrEquals(device->mnt_special, "none")) {
        return false;
    }

    // ZFS pool
    if (ffStrEquals(device->mnt_fstype, "zfs")) {
        return true;
    }

    // Pseudo filesystems don't have a device in /dev
    if (!ffStrStartsWith(device->mnt_special, "/dev/")) {
        return false;
    }

    struct stat deviceStat;
    if (stat(device->mnt_special, &deviceStat) != 0) {
        return false;
    }

    // Ignore all devices that are not block devices
    if (!S_ISBLK(deviceStat.st_mode)) {
        return false;
    }

    return true;
}

static bool isSubvolume(const FFlist* disks, FFDisk* currentDisk) {
    if (ffStrbufEqualS(&currentDisk->filesystem, "zfs")) {
        // ZFS subvolumes
        uint32_t index = ffStrbufFirstIndexC(&currentDisk->mountFrom, '/');
        if (index == currentDisk->mountFrom.length) {
            return false;
        }

        FF_STRBUF_AUTO_DESTROY zpoolName = ffStrbufCreateNS(index, currentDisk->mountFrom.chars);
        for (uint32_t i = 0; i < disks->length - 1; i++) {
            const FFDisk* otherDevice = FF_LIST_GET(FFDisk, *disks, i);
            if (ffStrbufEqualS(&otherDevice->filesystem, "zfs") && ffStrbufStartsWith(&otherDevice->mountFrom, &zpoolName)) {
                return true;
            }
        }

        return false;
    } else {
        // Filter all disks which device was already found. This catches BTRFS subvolumes.
        for (uint32_t i = 0; i < disks->length - 1; i++) {
            const FFDisk* otherDevice = FF_LIST_GET(FFDisk, *disks, i);

            if (ffStrbufEqual(&currentDisk->mountFrom, &otherDevice->mountFrom)) {
                return true;
            }
        }
    }

    return false;
}

static void detectType(const FFlist* disks, FFDisk* currentDisk, struct mnttab* device) {
    if (hasmntopt(device, MNTOPT_NOBROWSE)) {
        currentDisk->type = FF_DISK_VOLUME_TYPE_HIDDEN_BIT;
    } else if (isSubvolume(disks, currentDisk)) {
        currentDisk->type = FF_DISK_VOLUME_TYPE_SUBVOLUME_BIT;
    } else {
        currentDisk->type = FF_DISK_VOLUME_TYPE_REGULAR_BIT;
    }
    if (hasmntopt(device, MNTOPT_RO)) {
        currentDisk->type |= FF_DISK_VOLUME_TYPE_READONLY_BIT;
    }
}

static void detectStats(FFDisk* disk) {
    struct statvfs fs;
    if (statvfs(disk->mountpoint.chars, &fs) != 0) {
        memset(&fs, 0, sizeof(fs));
    }

    disk->bytesTotal = fs.f_blocks * fs.f_frsize;
    disk->bytesFree = fs.f_bfree * fs.f_frsize;
    disk->bytesAvailable = fs.f_bavail * fs.f_frsize;
    disk->bytesUsed = 0; // To be filled in ./disk.c

    disk->filesTotal = (uint32_t) fs.f_files;
    disk->filesUsed = (uint32_t) (disk->filesTotal - fs.f_ffree);

    ffStrbufSetS(&disk->name, fs.f_fstr);
    ffStrbufTrimRightSpace(&disk->name);

    disk->createTime = 0;
}

const char* ffDetectDisksImpl(FFDiskOptions* options, FFlist* disks) {
    FF_AUTO_CLOSE_FILE FILE* mountsFile = fopen(MNTTAB, "r");
    if (mountsFile == NULL) {
        return "fopen(\"" MNTTAB "\", \"r\") == NULL";
    }

    struct mnttab device;

    while (getmntent(mountsFile, &device) == 0) {
        if (__builtin_expect(options->folders.length, 0)) {
            if (!ffStrbufSeparatedContainS(&options->folders, device.mnt_mountp, FF_DISK_FOLDER_SEPARATOR)) {
                continue;
            }
        } else if (!isPhysicalDevice(&device)) {
            continue;
        }

        if (options->hideFolders.length && ffDiskMatchesFolderPatterns(&options->hideFolders, device.mnt_mountp, FF_DISK_FOLDER_SEPARATOR)) {
            continue;
        }

        if (options->hideFS.length && ffStrbufSeparatedContainS(&options->hideFS, device.mnt_fstype, ':')) {
            continue;
        }

        // We have a valid device, add it to the list
        FFDisk* disk = FF_LIST_ADD(FFDisk, *disks);
        disk->type = FF_DISK_VOLUME_TYPE_NONE;
        ffStrbufInitS(&disk->mountFrom, device.mnt_special);
        ffStrbufInitS(&disk->mountpoint, device.mnt_mountp);
        ffStrbufInitS(&disk->filesystem, device.mnt_fstype);
        ffStrbufInit(&disk->name);
        detectType(disks, disk, &device);
        detectStats(disk);
    }

    return NULL;
}