using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace Foodsoft.Alpm
{
    public sealed class Handle : IDisposable
    {
        private readonly SafeAlpmHandle _handle;

        public Handle(string root, string dbpath)
        {
            _handle = alpm.alpm_initialize(root, dbpath, out var err);
            if (_handle.IsInvalid)
            {
                throw new AlpmException(err);
            }
        }

        public void Dispose()
        {
            _handle.Dispose();
        }

        private Database ToDatabase(IntPtr ptr)
        {
            // It's ok that the database pointer is kept outside atomic section, because the resource is actually
            // managed by the alpm handle.
            if (ptr == IntPtr.Zero)
            {
                throw new AlpmException(_handle);
            }

            return new Database(new SafeDatabaseHandle(ptr, _handle));
        }

        public Database LocalDB => ToDatabase(alpm.alpm_get_localdb(_handle));

        public Database RegisterSyncDB(string treename, SigLevel sigLevel = 0) =>
            ToDatabase(alpm.alpm_register_syncdb(_handle, treename, sigLevel));
        
        public void AddCacheDir(string dir) => API.WrapError(_handle, () => alpm.alpm_option_add_cachedir(_handle, dir));
        public bool RemoveCacheDir(string dir) => API.WrapErrorBool(_handle, () => alpm.alpm_option_add_cachedir(_handle, dir));

        private readonly struct CacheDirsImpl : ICollectionImpl<string>
        {
            private readonly SafeAlpmHandle _handle;
            internal CacheDirsImpl(SafeAlpmHandle handle) => _handle = handle;
            public SafeHandle Handle => _handle;
            public IntPtr GetItems() => alpm.alpm_option_get_cachedirs(_handle);
            public string PtrToItem(IntPtr p) => Marshal.PtrToStringUTF8(p)!;
        }
        
        public ICollection<string> CacheDirs
        {
            get =>
                EnumerableWrapperEx<string>.Create(_handle, alpm.alpm_option_get_cachedirs, Marshal.PtrToStringUTF8!);
            set => Wrapper.SetStringCollection(value, _handle, (s) => alpm.alpm_option_add_cachedir(_handle, s));
        }

        public bool ShouldIgnorePackage(Package pkg) => alpm.alpm_pkg_should_ignore(_handle, pkg.Handle) == 0;
    }
}