using System.Collections.Generic;
using System.Linq;
using Cysharp.Threading.Tasks;

namespace SLSUtilities.General
{
    /// <summary>命令组的执行模式。</summary>
    public enum ExecutionMode
    {
        /// <summary>子命令逐条顺序执行。</summary>
        Sequential,
        /// <summary>子命令同时并行执行。</summary>
        Parallel
    }

    /// <summary>
    /// 命令组，将多条 <see cref="CommandBase"/> 按 Sequential 或 Parallel 模式执行。
    /// 自身也是 <see cref="CommandBase"/>，可嵌套组合。
    /// </summary>
    public class CommandGroup : CommandBase
    {
        /// <summary>子命令列表。</summary>
        public readonly List<CommandBase> commands = new List<CommandBase>();

        /// <summary>本组的执行模式。</summary>
        public readonly ExecutionMode mode;

        /// <summary>
        /// 组级别上下文，执行过程中会合并每条子命令的 outerContext 与 selfContext。
        /// 可在组执行完成后读取聚合数据（如 DrawnCards）。
        /// </summary>
        public readonly CommandContext groupContext;

        public CommandGroup(ExecutionMode mode = ExecutionMode.Sequential)
        {
            this.mode = mode;
            groupContext = new CommandContext();
        }

        public CommandGroup(ExecutionMode mode, params CommandBase[] commands)
        {
            this.mode = mode;
            groupContext = new CommandContext();
            this.commands.AddRange(commands);
        }

        public CommandGroup(params CommandBase[] commands)
        {
            mode = ExecutionMode.Sequential;
            groupContext = new CommandContext();
            this.commands.AddRange(commands);
        }

        /// <summary>添加一条子命令，返回自身支持链式调用。</summary>
        public CommandGroup AddCommand(CommandBase command)
        {
            commands.Add(command);
            return this;
        }

        /// <summary>
        /// 获取所有子命令。设 <paramref name="alsoIncludeGroups"/> 为 true 时，
        /// 返回结果中也包含 <see cref="CommandGroup"/> 自身节点。
        /// </summary>
        public List<CommandBase> GetAllCommands(bool alsoIncludeGroups = false)
        {
            //CommandBase可能也是CommandGroup,需要递归获取
            var allCommands = new List<CommandBase>();
            
            if (alsoIncludeGroups)
            {
                allCommands.Add(this);
            }
            
            foreach (CommandBase cmd in commands)
            {
                if (cmd is CommandGroup group)
                {
                    if (alsoIncludeGroups)
                    {
                        allCommands.Add(group);
                    }
                    
                    allCommands.AddRange(group.GetAllCommands(alsoIncludeGroups));
                }
                else
                {
                    allCommands.Add(cmd);
                }
            }
            
            return allCommands;
        }
        
        /// <summary>获取所有指定类型的子命令（递归，包含组节点）。</summary>
        public List<T> GetAllCommands<T>() where T : CommandBase
        {
            return GetAllCommands(true).OfType<T>().ToList();
        }

        /// <summary>深拷贝整个命令组及其子命令。</summary>
        public override CommandBase Clone()
        {
            var cloned = new CommandGroup(mode);
            foreach (var cmd in commands)
                cloned.AddCommand(cmd.Clone());
            return cloned;
        }

        protected override async UniTask ExecuteAsync(CommandContext outerContext)
        {
            if (mode == ExecutionMode.Sequential)
            {
                foreach (var cmd in commands)
                {
                    await cmd.RunAsync(outerContext);
                    MergeContexts(cmd, outerContext);
                }
            }
            else
            {
                await UniTask.WhenAll(commands.Select(cmd =>
                    ExecuteAndMergeAsync(cmd, outerContext)));
            }
        }

        /// <summary>执行单条子命令并将上下文合并到 groupContext。</summary>
        private async UniTask ExecuteAndMergeAsync(CommandBase cmd, CommandContext outerContext)
        {
            await cmd.RunAsync(outerContext);
            MergeContexts(cmd, outerContext);
        }

        private void MergeContexts(CommandBase cmd, CommandContext outerContext)
        {
            groupContext.Merge(outerContext);
            groupContext.Merge(cmd.selfContext);
        }
    }
}