using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using RebootKit.Engine.Foundation;
using UnityEngine;
using Logger = RebootKit.Engine.Foundation.Logger;

namespace RebootKit.Engine.Services.Console {
    public interface IConsoleCommand {
        string Name { get; }
        string Description { get; }
        void Execute(string[] args);
    }

    public class HelpCommand : IConsoleCommand {
        public string Name { get; } = "help";
        public string Description { get; } = "Prints available commands/cvars and their descriptions.";

        public void Execute(string[] args) {
            RR.Console.PrintHelp();
        }
    }

    public class PrintCVarsCommand : IConsoleCommand {
        public string Name { get; } = "print_cvars";
        public string Description { get; } = "Prints all cvars and their values.";

        public void Execute(string[] args) {
            RR.Console.PrintCVars();
        }
    }

    public class ConsoleService : IService {
        static readonly Logger s_logger = new(nameof(ConsoleService));

        readonly List<IConsoleCommand> m_ConsoleCommands = new();

        FileStream m_LogFileStream;
        TextWriter m_LogFileWriter;

        bool m_IsLoading;

        public ConsoleService() {
            ConfigVar.StateChanged += OnCVarStateChanged;
            
            m_LogFileStream = new FileStream(Application.persistentDataPath + "/rr_logs.txt", FileMode.Append, FileAccess.Write);
            m_LogFileWriter = new StreamWriter(m_LogFileStream);
            
            m_LogFileWriter.WriteLine("============================");
            m_LogFileWriter.WriteLine("Starting new log");
            m_LogFileWriter.WriteLine($" > Game: {Application.productName}");
            m_LogFileWriter.WriteLine($" > Version: {Application.version}");
            m_LogFileWriter.WriteLine($" > Date: {DateTime.Now}");
            m_LogFileWriter.WriteLine("============================");
            m_LogFileWriter.Flush();

            s_logger.Info("Waking up");
            
            Load();

            RegisterCommand(new PrintCVarsCommand());
            RegisterCommand(new HelpCommand());
        }

        public void Dispose() {
            s_logger.Info("Shutting down");

            ConfigVar.StateChanged -= OnCVarStateChanged;

            m_LogFileWriter.Dispose();
            m_LogFileStream.Dispose();

            m_LogFileStream = null;
            m_LogFileWriter = null;
        }

        void OnCVarStateChanged(ConfigVar cvar) {
            if (m_IsLoading) {
                return;
            }

            if (!cvar.flags.HasFlag(CVarFlags.ReadOnly)) {
                Save();
            }
        }

        public event Action<string> OnOutputMessage = _ => { };

        public void WriteToOutput(string message) {
            if (m_LogFileWriter != null) {
                m_LogFileWriter.WriteLine(message);
                m_LogFileWriter.Flush();
            }

            OnOutputMessage?.Invoke(message);
        }

        string[] ParseCommandInputArguments(string text) {
            if (text.Length == 0) {
                return Array.Empty<string>();
            }

            return new[] {text};
        }

        public void Execute(string input) {
            if (input.Length == 0) {
                return;
            }

            string commandName = input;
            if (input.IndexOf(' ') != -1) {
                commandName = input.Substring(0, input.IndexOf(' '));
            }

            string[] arguments = ParseCommandInputArguments(input.Substring(commandName.Length));

            foreach (IConsoleCommand command in m_ConsoleCommands) {
                if (command.Name.Equals(commandName)) {
                    command.Execute(arguments);
                    return;
                }
            }

            foreach (ConfigVar cvar in ConfigVarsContainer.All()) {
                if (cvar.name.Equals(commandName)) {
                    if (arguments.Length == 1) {
                        cvar.ParseFromString(arguments[0]);
                    }

                    WriteToOutput($"<b>{cvar.name}</b> - {cvar}\n");
                    return;
                }
            }

            WriteToOutput($"ERROR: Command/CVar `{commandName}` not found.");
        }

        public void RegisterCommand(IConsoleCommand command) {
            if (m_ConsoleCommands.Any(t => t.Name.Equals(command.Name))) {
                s_logger.Error($"`{command.Name}` command is already registered");
                return;
            }

            m_ConsoleCommands.Add(command);
            s_logger.Info($"Registered command: {command.Name}");
        }

        public void PrintHelp() {
            StringBuilder message = new();

            message.AppendLine("Available commands:");
            foreach (IConsoleCommand command in m_ConsoleCommands) {
                message.Append("    ");
                message.Append(command.Name);
                message.Append(" - ");
                message.Append(command.Description);
                message.AppendLine();
            }

            message.AppendLine("Available cvars:");
            foreach (ConfigVar cvar in ConfigVarsContainer.All()) {
                message.Append("    ");
                message.Append(cvar.name);
                message.Append(" - ");
                message.Append(cvar.description);
                message.AppendLine();
            }

            WriteToOutput(message.ToString());
        }
        
        public void PrintCVars() {
            StringBuilder message = new();

            foreach (ConfigVar cvar in ConfigVarsContainer.All()) {
                message.AppendLine($"{cvar.name} - {cvar}");
            }

            WriteToOutput(message.ToString());
        }

        void Save() {
            string path = Application.persistentDataPath + "/" + RConsts.k_CVarsFilename;
            
            s_logger.Info("Saving cvars to file: " + path);

            StringBuilder sb = new();

            foreach (ConfigVar cvar in ConfigVarsContainer.All()) {
                if (!cvar.flags.HasFlag(CVarFlags.ReadOnly)) {
                    sb.AppendFormat("{0} {1}\n", cvar.name, cvar);
                }
            }

            File.WriteAllText(path, sb.ToString());
        }

        void Load() {
            string path = Application.persistentDataPath + "/" + RConsts.k_CVarsFilename;
            if (!File.Exists(path)) {
                s_logger.Info("CVar file not found, skipping load");
                return;
            }

            m_IsLoading = true;
            ExecuteFile(path);
            m_IsLoading = false;
        }

        bool ExecuteFile(string path) {
            if (!File.Exists(path)) {
                s_logger.Error($"Cannot load file '{path}', file not found");
                return false;
            }

            s_logger.Info($"Executing file '{path}'");

            string[] lines = File.ReadAllLines(path);
            foreach (string line in lines) {
                WriteToOutput(path + " > " + line);
                Execute(line);
            }

            return true;
        }
    }
}