using System;
using System.Diagnostics;
using System.Globalization;
using LibGit2Sharp.Core;
using LibGit2Sharp.Core.Handles;

namespace LibGit2Sharp
{
    /// <summary>
    ///   A remote repository whose branches are tracked.
    /// </summary>
    [DebuggerDisplay("{DebuggerDisplay,nq}")]
    public class Remote : IEquatable<Remote>
    {
        private static readonly LambdaEqualityHelper<Remote> equalityHelper =
            new LambdaEqualityHelper<Remote>(x => x.Name, x => x.Url);

        private readonly Repository repository;

        /// <summary>
        ///   Needed for mocking purposes.
        /// </summary>
        protected Remote()
        { }

        private Remote(Repository repository, string name, string url)
        {
            this.repository = repository;
            Name = name;
            Url = url;
        }

        internal static Remote BuildFromPtr(RemoteSafeHandle handle, Repository repo)
        {
            string name = Proxy.git_remote_name(handle);
            string url = Proxy.git_remote_url(handle);

            var remote = new Remote(repo, name, url);

            return remote;
        }

        /// <summary>
        ///   Gets the alias of this remote repository.
        /// </summary>
        public virtual string Name { get; private set; }

        /// <summary>
        ///   Gets the url to use to communicate with this remote repository.
        /// </summary>
        public virtual string Url { get; private set; }

        /// <summary>
        ///   Transform a reference to its source reference using the <see cref = "Remote" />'s default fetchspec.
        /// </summary>
        /// <param name="reference">The reference to transform.</param>
        /// <returns>The transformed reference.</returns>
        internal string FetchSpecTransformToSource(string reference)
        {
            using (RemoteSafeHandle remoteHandle = Proxy.git_remote_load(repository.Handle, Name, true))
            {
                GitRefSpecHandle fetchSpecPtr = Proxy.git_remote_get_refspec(remoteHandle, 0);
                return Proxy.git_refspec_rtransform(fetchSpecPtr, reference);
            }
        }

        /// <summary>
        ///   Determines whether the specified <see cref = "Object" /> is equal to the current <see cref = "Remote" />.
        /// </summary>
        /// <param name = "obj">The <see cref = "Object" /> to compare with the current <see cref = "Remote" />.</param>
        /// <returns>True if the specified <see cref = "Object" /> is equal to the current <see cref = "Remote" />; otherwise, false.</returns>
        public override bool Equals(object obj)
        {
            return Equals(obj as Remote);
        }

        /// <summary>
        ///   Determines whether the specified <see cref = "Remote" /> is equal to the current <see cref = "Remote" />.
        /// </summary>
        /// <param name = "other">The <see cref = "Remote" /> to compare with the current <see cref = "Remote" />.</param>
        /// <returns>True if the specified <see cref = "Remote" /> is equal to the current <see cref = "Remote" />; otherwise, false.</returns>
        public bool Equals(Remote other)
        {
            return equalityHelper.Equals(this, other);
        }

        /// <summary>
        ///   Returns the hash code for this instance.
        /// </summary>
        /// <returns>A 32-bit signed integer hash code.</returns>
        public override int GetHashCode()
        {
            return equalityHelper.GetHashCode(this);
        }

        /// <summary>
        ///   Tests if two <see cref = "Remote" /> are equal.
        /// </summary>
        /// <param name = "left">First <see cref = "Remote" /> to compare.</param>
        /// <param name = "right">Second <see cref = "Remote" /> to compare.</param>
        /// <returns>True if the two objects are equal; false otherwise.</returns>
        public static bool operator ==(Remote left, Remote right)
        {
            return Equals(left, right);
        }

        /// <summary>
        ///   Tests if two <see cref = "Remote" /> are different.
        /// </summary>
        /// <param name = "left">First <see cref = "Remote" /> to compare.</param>
        /// <param name = "right">Second <see cref = "Remote" /> to compare.</param>
        /// <returns>True if the two objects are different; false otherwise.</returns>
        public static bool operator !=(Remote left, Remote right)
        {
            return !Equals(left, right);
        }

        private string DebuggerDisplay
        {
            get
            {
                return string.Format(CultureInfo.InvariantCulture,
                    "{0} => {1}", Name, Url);
            }
        }
    }
}