using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using MCPForUnity.Editor.Helpers;
using Newtonsoft.Json.Linq;

namespace MCPForUnity.Editor.Tools
{
    /// <summary>
    /// Executes multiple MCP commands within a single Unity-side handler. Commands are executed sequentially
    /// on the main thread to preserve determinism and Unity API safety.
    /// </summary>
    [McpForUnityTool("batch_execute", AutoRegister = false)]
    public static class BatchExecute
    {
        private const int MaxCommandsPerBatch = 25;

        public static async Task<object> HandleCommand(JObject @params)
        {
            if (@params == null)
            {
                return new ErrorResponse("'commands' payload is required.");
            }

            var commandsToken = @params["commands"] as JArray;
            if (commandsToken == null || commandsToken.Count == 0)
            {
                return new ErrorResponse("Provide at least one command entry in 'commands'.");
            }

            if (commandsToken.Count > MaxCommandsPerBatch)
            {
                return new ErrorResponse($"A maximum of {MaxCommandsPerBatch} commands are allowed per batch.");
            }

            bool failFast = @params.Value<bool?>("failFast") ?? false;
            bool parallelRequested = @params.Value<bool?>("parallel") ?? false;
            int? maxParallel = @params.Value<int?>("maxParallelism");

            if (parallelRequested)
            {
                McpLog.Warn("batch_execute parallel mode requested, but commands will run sequentially on the main thread for safety.");
            }

            var commandResults = new List<object>(commandsToken.Count);
            int invocationSuccessCount = 0;
            int invocationFailureCount = 0;
            bool anyCommandFailed = false;

            foreach (var token in commandsToken)
            {
                if (token is not JObject commandObj)
                {
                    invocationFailureCount++;
                    anyCommandFailed = true;
                    commandResults.Add(new
                    {
                        tool = (string)null,
                        callSucceeded = false,
                        error = "Command entries must be JSON objects."
                    });
                    if (failFast)
                    {
                        break;
                    }
                    continue;
                }

                string toolName = commandObj["tool"]?.ToString();
                var rawParams = commandObj["params"] as JObject ?? new JObject();
                var commandParams = NormalizeParameterKeys(rawParams);

                if (string.IsNullOrWhiteSpace(toolName))
                {
                    invocationFailureCount++;
                    anyCommandFailed = true;
                    commandResults.Add(new
                    {
                        tool = toolName,
                        callSucceeded = false,
                        error = "Each command must include a non-empty 'tool' field."
                    });
                    if (failFast)
                    {
                        break;
                    }
                    continue;
                }

                try
                {
                    var result = await CommandRegistry.InvokeCommandAsync(toolName, commandParams).ConfigureAwait(true);
                    bool callSucceeded = DetermineCallSucceeded(result);
                    if (callSucceeded)
                    {
                        invocationSuccessCount++;
                    }
                    else
                    {
                        invocationFailureCount++;
                        anyCommandFailed = true;
                    }

                    commandResults.Add(new
                    {
                        tool = toolName,
                        callSucceeded,
                        result
                    });

                    if (!callSucceeded && failFast)
                    {
                        break;
                    }
                }
                catch (Exception ex)
                {
                    invocationFailureCount++;
                    anyCommandFailed = true;
                    commandResults.Add(new
                    {
                        tool = toolName,
                        callSucceeded = false,
                        error = ex.Message
                    });

                    if (failFast)
                    {
                        break;
                    }
                }
            }

            bool overallSuccess = !anyCommandFailed;
            var data = new
            {
                results = commandResults,
                callSuccessCount = invocationSuccessCount,
                callFailureCount = invocationFailureCount,
                parallelRequested,
                parallelApplied = false,
                maxParallelism = maxParallel
            };

            return overallSuccess
                ? new SuccessResponse("Batch execution completed.", data)
                : new ErrorResponse("One or more commands failed.", data);
        }

        private static bool DetermineCallSucceeded(object result)
        {
            if (result == null)
            {
                return true;
            }

            if (result is IMcpResponse response)
            {
                return response.Success;
            }

            if (result is JObject obj)
            {
                var successToken = obj["success"];
                if (successToken != null && successToken.Type == JTokenType.Boolean)
                {
                    return successToken.Value<bool>();
                }
            }

            if (result is JToken token)
            {
                var successToken = token["success"];
                if (successToken != null && successToken.Type == JTokenType.Boolean)
                {
                    return successToken.Value<bool>();
                }
            }

            return true;
        }

        private static JObject NormalizeParameterKeys(JObject source)
        {
            if (source == null)
            {
                return new JObject();
            }

            var normalized = new JObject();
            foreach (var property in source.Properties())
            {
                string normalizedName = ToCamelCase(property.Name);
                normalized[normalizedName] = NormalizeToken(property.Value);
            }
            return normalized;
        }

        private static JArray NormalizeArray(JArray source)
        {
            var normalized = new JArray();
            foreach (var token in source)
            {
                normalized.Add(NormalizeToken(token));
            }
            return normalized;
        }

        private static JToken NormalizeToken(JToken token)
        {
            return token switch
            {
                JObject obj => NormalizeParameterKeys(obj),
                JArray arr => NormalizeArray(arr),
                _ => token.DeepClone()
            };
        }

        private static string ToCamelCase(string key)
        {
            if (string.IsNullOrEmpty(key) || key.IndexOf('_') < 0)
            {
                return key;
            }

            var parts = key.Split(new[] { '_' }, StringSplitOptions.RemoveEmptyEntries);
            if (parts.Length == 0)
            {
                return key;
            }

            var builder = new StringBuilder(parts[0]);
            for (int i = 1; i < parts.Length; i++)
            {
                var part = parts[i];
                if (string.IsNullOrEmpty(part))
                {
                    continue;
                }

                builder.Append(char.ToUpperInvariant(part[0]));
                if (part.Length > 1)
                {
                    builder.Append(part.AsSpan(1));
                }
            }

            return builder.ToString();
        }
    }
}