using Discord;
using System;
using System.Collections.Generic;
using System.Text;

namespace BirthdayBot.UserInterface
{
    internal class CommandDocumentation
    {
        public string[] Commands { get; }
        public string Usage { get; }
        public string Examples { get; }

        public CommandDocumentation(IEnumerable<string> commands, string usage, string examples)
        {
            var cmds = new List<string>();
            foreach (var item in commands) cmds.Add(CommandsCommon.CommandPrefix + item);
            if (cmds.Count == 0) throw new ArgumentException(null, nameof(commands));
            Commands = cmds.ToArray();
            Usage = usage ?? throw new ArgumentException(null, nameof(usage));
            Examples = examples;
        }

        /// <summary>
        /// Returns a string that can be inserted into a help or usage message.
        /// </summary>
        public string Export()
        {
            var result = new StringBuilder();
            foreach (var item in Commands) result.Append(", `" + item + "`");
            result.Remove(0, 2);
            result.Insert(0, '●');
            result.AppendLine();
            result.Append("» " + Usage);
            if (Examples != null)
            {
                result.AppendLine();
                result.Append("» Examples: " + Examples);
            }
            return result.ToString();
        }

        /// <summary>
        /// Creates an embeddable message containing the command documentation.
        /// </summary>
        public Embed UsageEmbed => new EmbedBuilder()
        {
            Author = new EmbedAuthorBuilder() { Name = "Usage" },
            Description = Export()
        }.Build();
    }
}