#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;
use Fcntl ':mode';
use Fuse;
use POSIX qw(ENOENT ENOSYS);

Fuse::main (
    debug       => 1,
    mountpoint  => 'mnt',
    
    getattr     => sub { fuse('getattr',    @_); },
    getdir      => sub { fuse('getdir',     @_); },
    init        => sub { fuse('init',       @_); },
    read        => sub { fuse('read',       @_); },
    truncate    => sub { fuse('truncate',   @_); },
    write       => sub { fuse('write',      @_); },
);

sub fuse {
    my $function = shift;

    my $callback_for = {
        getattr     => \&fuse_getattr,
        getdir      => \&fuse_getdir,
        init        => \&fuse_init,
        read        => \&fuse_read,
        truncate    => \&fuse_truncate,
        write       => \&fuse_write,
    };

    if (exists $callback_for->{$function}) {
        return $callback_for->{$function} -> (@_);
    }
    else {
        return -(ENOSYS);
    }

    die;
}

sub fuse_getattr {
    my $path = shift;

    my $context = Fuse::fuse_get_context();
    print Dumper ($context), "\n";
    my $stat    = undef;

    if ($path eq '/') {
        my $mode = S_IFDIR | S_IRUSR | S_IXUSR;

        $stat = [
            0,                  # dev
            0,                  # inode
            $mode,              # mode
            1,                  # nlink
            $context->{uid},    # uid
            $context->{gid},    # gid
            0,                  # rdev
            0,                  # size
            0,                  # atime
            0,                  # mtime
            0,                  # ctime
            4096,               # blksie
            0,                  # blocks
        ];
    }
    elsif ($path eq '/save') {
        my $mode = S_IFREG | S_IRUSR;

        $stat = [
            0,                  # dev
            0,                  # inode
            $mode,              # mode
            1,                  # nlink
            $context->{uid},    # uid
            $context->{gid},    # gid
            0,                  # rdev
            1_024_000,                  # size
            0,                  # atime
            0,                  # mtime
            0,                  # ctime
            4096,               # blksie
            1,                  # blocks
        ];
    }
    elsif ($path eq '/load') {
        my $mode = S_IFREG | S_IWUSR;

        $stat = [
            0,                  # dev
            0,                  # inode
            $mode,              # mode
            1,                  # nlink
            $context->{uid},    # uid
            $context->{gid},    # gid
            0,                  # rdev
            0,                  # size
            0,                  # atime
            0,                  # mtime
            0,                  # ctime
            4096,               # blksie
            0,                  # blocks
        ];
    }

    if (defined $stat) {
        return @{$stat};
    }
    else {
        return -(ENOENT);
    }

    die;
}

sub fuse_getdir {
    my $path = shift;

    if ($path eq '/') {
        return '.', '..', 'load', 'save', 0;
    }

    return -(ENOENT);
}

sub fuse_init {
    print Dumper [@_], "\n";

    return 'PRIVDAT';
}

sub fuse_read {
    my $path = shift;

    if ($path eq '/save') {
        return 1 x 4096;
    }

    return -(ENOENT);
}

sub fuse_truncate {
    my $path = shift;

    if ($path eq '/load') {
        return 0;
    }
    
    return -(ENOENT);
}

sub fuse_write {
    print Dumper (@_), "\n";

    return length $_[1];

    return -(ENOENT);
}