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

namespace Foodsoft.Alpm
{
    internal static class Detail
    {
        internal static unsafe IntPtr ListNext(IntPtr list) => ((alpm_list_t*) list)->next;
        internal static unsafe IntPtr ListData(IntPtr list) => ((alpm_list_t*) list)->data;

        internal static TResult UseHandle<TResult>(this SafeHandle handle, IntPtr ptr, Func<IntPtr, TResult> op)
        {
            var release = false;

            RuntimeHelpers.PrepareConstrainedRegions();
            try
            {
                handle.DangerousAddRef(ref release);
                if (!release) throw new ObjectDisposedException(handle.GetType().FullName);
                return op(ptr);
            }
            finally
            {
                if (release)
                    handle.DangerousRelease();
            }
        }

        internal static TResult UseHandle<TResult>(this SafeHandle handle, Func<IntPtr, TResult> op) =>
            handle.UseHandle(handle.DangerousGetHandle(), op);

        internal static void SetStringCollection(IEnumerable<string> value, SafeAlpmHandle safeAlpmHandle, Func<string, int> op)
        {
            // ReSharper disable once LoopCanBeConvertedToQuery
            foreach (var s in value)
            {
                if (op(s) < 0)
                    throw new AlpmException(safeAlpmHandle);
            }
        }

        internal static void WrapError(SafeAlpmHandle alpmHandle, Func<int> f)
        {
            var err = f();
            if (err != 0)
                throw new AlpmException(alpmHandle);
        }

        internal delegate int OutFunc<T, in THandle>(THandle handle, out T result);

        internal static T WrapError<T, THandle>(SafeAlpmHandle alpmHandle, THandle handle, OutFunc<T, THandle> f)
        {
            var err = f(handle, out var result);
            if (err != 0)
                throw new AlpmException(alpmHandle);
            return result;
        }

        internal static bool WrapErrorBool(SafeAlpmHandle h, Func<int> f)
        {
            var err = f();
            if (err < 0)
            {
                throw new AlpmException(h);
            }
            return err == 0;
        }
    }
}