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

namespace Foodsoft.Alpm
{
    public sealed class Database : IDisposable
    {
        private readonly SafeDatabaseHandle _handle;

        internal Database(SafeDatabaseHandle handle) => _handle = handle;

        public void Unregister()
        {
            try
            {
                API.WrapError(_handle.SafeAlpmHandle, () => alpm.alpm_db_unregister(_handle));
            }
            finally
            {
                _handle.Close();
            }
        }


        private readonly struct ServersAccessor : IItemsReader<string, SafeDatabaseHandle>
        {
            internal ServersAccessor(SafeDatabaseHandle handle)
            {
                Handle = handle;
            }

            public SafeDatabaseHandle Handle { get; }
            public IntPtr GetItems() => alpm.alpm_db_get_servers(Handle);
            public string PtrToItem(IntPtr p) => Marshal.PtrToStringUTF8(p)!;
        }

        public void AddServer(string url) => API.WrapError(_handle.SafeAlpmHandle, () => alpm.alpm_db_add_server(_handle, url));

        public bool RemoveServer(string url) => API.WrapErrorBool(_handle.SafeAlpmHandle, () => alpm.alpm_db_remove_server(_handle, url));

        public IEnumerable<string> Servers
        {
            get => new EnumerableWrapper<ServersAccessor, string, SafeDatabaseHandle>(new ServersAccessor(_handle));
            set
            {
                foreach (var s in value)
                {
                    API.WrapError(_handle.SafeAlpmHandle, () => alpm.alpm_db_add_server(_handle, s));
                }
            }
        }

        public string Name => alpm.alpm_db_get_name(_handle);

        public SigLevel SigLevel => alpm.alpm_db_get_siglevel(_handle);

        public ErrNo Valid =>
            alpm.alpm_db_get_valid(_handle) != 0 ? alpm.alpm_errno(_handle.SafeAlpmHandle) : ErrNo.ERR_OK;

        public bool Update(bool force = false)
        {
            var err = alpm.alpm_db_update(force ? 1 : 0, _handle);
            if (err < 0)
            {
                throw new Exception(_handle.SafeAlpmHandle);
            }

            return err == 0;
        }

        public Package? GetPackage(string name)
        {
            var pkgPtr = alpm.alpm_pkg_get_pkg(_handle, name);
            if (pkgPtr == IntPtr.Zero)
            {
                var err = alpm.alpm_errno(_handle.SafeAlpmHandle);
                if (err == ErrNo.ERR_PKG_NOT_FOUND)
                    return null;
                throw new Exception(err);
            }

            return new CachePackage(new SafeCachePackageHandle(pkgPtr, _handle), this);
        }

        public PackageList PackageCache
        {
            get
            {
                var listPtr = alpm.alpm_db_get_pkgcache(_handle);
                if (listPtr == IntPtr.Zero)
                    throw new Exception(alpm.alpm_errno(_handle.SafeAlpmHandle));
                return new PackageList(new SafeListHandle<SafeDatabaseHandle>(listPtr, _handle), this);
            }
        }

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