using System;
using System.Collections.Generic;
using System.IO;
using Newtonsoft.Json;
using StardewModdingAPI.Enums;
using StardewModdingAPI.Toolkit.Serialization;
using StardewModdingAPI.Toolkit.Utilities;
using StardewValley;

namespace StardewModdingAPI.Framework.ModHelpers
{
    /// <summary>Provides an API for reading and storing local mod data.</summary>
    internal class DataHelper : BaseHelper, IDataHelper
    {
        /*********
        ** Fields
        *********/
        /// <summary>Encapsulates SMAPI's JSON file parsing.</summary>
        private readonly JsonHelper JsonHelper;

        /// <summary>The absolute path to the mod folder.</summary>
        private readonly string ModFolderPath;


        /*********
        ** Public methods
        *********/
        /// <summary>Construct an instance.</summary>
        /// <param name="modID">The unique ID of the relevant mod.</param>
        /// <param name="modFolderPath">The absolute path to the mod folder.</param>
        /// <param name="jsonHelper">The absolute path to the mod folder.</param>
        public DataHelper(string modID, string modFolderPath, JsonHelper jsonHelper)
            : base(modID)
        {
            this.ModFolderPath = modFolderPath;
            this.JsonHelper = jsonHelper;
        }

        /****
        ** JSON file
        ****/
        /// <inheritdoc />
        public TModel? ReadJsonFile<TModel>(string path)
            where TModel : class
        {
            if (!PathUtilities.IsSafeRelativePath(path))
                throw new InvalidOperationException($"You must call {nameof(IModHelper.Data)}.{nameof(this.ReadJsonFile)} with a relative path.");

            path = Path.Combine(this.ModFolderPath, PathUtilities.NormalizePath(path));
            return this.JsonHelper.ReadJsonFileIfExists(path, out TModel? data)
                ? data
                : null;
        }

        /// <inheritdoc />
        public void WriteJsonFile<TModel>(string path, TModel? data)
            where TModel : class
        {
            if (!PathUtilities.IsSafeRelativePath(path))
                throw new InvalidOperationException($"You must call {nameof(IMod.Helper)}.{nameof(IModHelper.Data)}.{nameof(this.WriteJsonFile)} with a relative path (without directory climbing).");

            path = Path.Combine(this.ModFolderPath, PathUtilities.NormalizePath(path));

            if (data != null)
                this.JsonHelper.WriteJsonFile(path, data);
            else
                File.Delete(path);
        }

        /****
        ** Save file
        ****/
        /// <inheritdoc />
        public TModel? ReadSaveData<TModel>(string key)
            where TModel : class
        {
            if (Context.LoadStage == LoadStage.None)
                throw new InvalidOperationException($"Can't use {nameof(IMod.Helper)}.{nameof(IModHelper.Data)}.{nameof(this.ReadSaveData)} when a save file isn't loaded.");
            if (!Context.IsOnHostComputer)
                throw new InvalidOperationException($"Can't use {nameof(IMod.Helper)}.{nameof(IModHelper.Data)}.{nameof(this.ReadSaveData)} when connected to a remote host. (Save files are stored on the main player's computer.)");


            string internalKey = this.GetSaveFileKey(key);
            foreach (IDictionary<string, string> dataField in this.GetDataFields(Context.LoadStage))
            {
                if (dataField.TryGetValue(internalKey, out string? value))
                    return this.JsonHelper.Deserialize<TModel>(value);
            }
            return null;
        }

        /// <inheritdoc />
        public void WriteSaveData<TModel>(string key, TModel? model)
            where TModel : class
        {
            if (Context.LoadStage == LoadStage.None)
                throw new InvalidOperationException($"Can't use {nameof(IMod.Helper)}.{nameof(IModHelper.Data)}.{nameof(this.WriteSaveData)} when a save file isn't loaded.");
            if (!Context.IsOnHostComputer)
                throw new InvalidOperationException($"Can't use {nameof(IMod.Helper)}.{nameof(IModHelper.Data)}.{nameof(this.WriteSaveData)} when connected to a remote host. (Save files are stored on the main player's computer.)");

            string internalKey = this.GetSaveFileKey(key);
            string? data = model != null
                ? this.JsonHelper.Serialize(model, Formatting.None)
                : null;

            foreach (IDictionary<string, string> dataField in this.GetDataFields(Context.LoadStage))
            {
                if (data != null)
                    dataField[internalKey] = data;
                else
                    dataField.Remove(internalKey);
            }
        }

        /****
        ** Global app data
        ****/
        /// <inheritdoc />
        public TModel? ReadGlobalData<TModel>(string key)
            where TModel : class
        {
            string path = this.GetGlobalDataPath(key);
            return this.JsonHelper.ReadJsonFileIfExists(path, out TModel? data)
                ? data
                : null;
        }

        /// <inheritdoc />
        public void WriteGlobalData<TModel>(string key, TModel? data)
            where TModel : class
        {
            string path = this.GetGlobalDataPath(key);
            if (data != null)
                this.JsonHelper.WriteJsonFile(path, data);
            else
                File.Delete(path);
        }


        /*********
        ** Public methods
        *********/
        /// <summary>Get the unique key for a save file data entry.</summary>
        /// <param name="key">The unique key identifying the data.</param>
        private string GetSaveFileKey(string key)
        {
            this.AssertSlug(key, nameof(key));
            return $"smapi/mod-data/{this.ModID}/{key}".ToLower();
        }

        /// <summary>Get the data fields to read/write for save data.</summary>
        /// <param name="stage">The current load stage.</param>
        private IEnumerable<IDictionary<string, string>> GetDataFields(LoadStage stage)
        {
            if (stage == LoadStage.None)
                yield break;

            yield return Game1.CustomData;
            if (SaveGame.loaded != null)
                yield return SaveGame.loaded.CustomData;
        }

        /// <summary>Get the absolute path for a global data file.</summary>
        /// <param name="key">The unique key identifying the data.</param>
        private string GetGlobalDataPath(string key)
        {
            this.AssertSlug(key, nameof(key));
            return Path.Combine(Constants.DataPath, ".smapi", "mod-data", this.ModID.ToLower(), $"{key}.json".ToLower());
        }

        /// <summary>Assert that a key contains only characters that are safe in all contexts.</summary>
        /// <param name="key">The key to check.</param>
        /// <param name="paramName">The argument name for any assertion error.</param>
        private void AssertSlug(string key, string paramName)
        {
            if (!PathUtilities.IsSlug(key))
                throw new ArgumentException("The data key is invalid (keys must only contain letters, numbers, underscores, periods, or hyphens).", paramName);
        }
    }
}