using axXez.Utils;
using System;
using System.Linq;
using System.Reflection;

namespace axXez.TS3.Bot
{
    /// <summary>A registered chat command, bound to a module method and ready to execute.</summary>
    public class Command
    {
        private readonly CommandAttribute _attr;
        private readonly Func<CommandContext, CommandResponse> _callback;

        /// <summary>The command keyword without the leading <c>!</c>, e.g. <c>"bot status"</c>.</summary>
        public string Keyword => _attr.Keyword;
        /// <summary>Short description of what the command does, shown in <c>!help</c> output.</summary>
        public string Description => _attr.Description;
        /// <summary>Minimum role required to invoke this command.</summary>
        public CommandRole Role { get; set; }
        /// <summary>Chat scopes this command responds to.</summary>
        public CommandScope Scope { get; set; }

        /// <summary>Parameter signature string, e.g. <c>&lt;name&gt; [seconds]</c>. Null if the command takes no parameters.</summary>
        public string Parameters { get; private set; }
        /// <summary>Full usage string, e.g. <c>!keyword &lt;name&gt; [seconds]</c>.</summary>
        public string Usage { get; private set; }
        /// <summary>BBCode-formatted help line shown in <c>!help</c> output, e.g. <c>[B]!keyword[/B] — description</c>.</summary>
        public string Help { get; private set; }

        /// <summary>The module instance that owns this command.</summary>
        public Module Module { get; private set; }
        internal MethodInfo Method { get; private set; }

        internal Command(CommandAttribute attr, MethodInfo method, Module module, Func<CommandContext, CommandResponse> callback, CommandLineParser parser = null)
        {
            _attr = attr;
            Method = method;
            Module = module;
            _callback = callback;
            Role = attr.Role;
            Scope = attr.Scope;

            if (!string.IsNullOrWhiteSpace(attr.Parameters))
                Parameters = attr.Parameters;
            else if (parser != null && parser.Parameters.Count > 0)
                Parameters = string.Join(" ", parser.Parameters.Select(p => p.IsRequired ? $"<{p.Name}>" : $"[{p.Name}]"));

            Usage = string.IsNullOrWhiteSpace(Parameters) ? $"!{Keyword}" : $"!{Keyword} {Parameters}";
            Help = string.IsNullOrWhiteSpace(Description) ? $"[B]{Usage}[/B]" : $"[B]{Usage}[/B] — {Description}";
        }

        internal CommandResponse Execute(CommandContext context)
            => _callback(context);

        /// <inheritdoc/>
        public override string ToString() => Keyword;
        /// <inheritdoc/>
        public override int GetHashCode() => Keyword.GetHashCode();
        /// <inheritdoc/>
        public override bool Equals(object obj)
            => typeof(Command).IsAssignableFrom(obj.GetType()) && (obj as Command).Keyword.Equals(Keyword) && (obj as Command).Module.Equals(Module);
    }
}