using System.Collections.Generic;
using System.IO;
using System.CommandLine;
using System.Text.Json;
using System.Threading.Tasks;
using System.Resources.NetStandard;

namespace DotNetResxUtils.Commands
{
    internal class GenerationCommand  : Command
    {
        const string NAME = "generate";
        const string DESC = "Generate a .resx file.";

        public GenerationCommand() : base(NAME, DESC)
        {

            Option<FileInfo?> fromOpt = new Option<FileInfo?>("--from", "Generates a .resx file from the given file.");

            Argument<FileInfo> destArg = new Argument<FileInfo>("destination", "The destination path to store this file. If no extension is given, .resx will automatically be concatenated.");

            this.AddOption(fromOpt);
            this.AddArgument(destArg);

            this.SetHandler<FileInfo, FileInfo?>(CommandHandler, destArg, fromOpt);
        }
        private async void CommandHandler(FileInfo to, FileInfo? from)
        {
            IDictionary<string, string> flattened = new Dictionary<string, string>();
            if (from != null)
            {
                flattened = await FlattenJson(from);
            }
            using (ResXResourceWriter resxWriter = new ResXResourceWriter(to.FullName))
            {
                foreach (KeyValuePair<string, string> keyVal in flattened)
                {
                    resxWriter.AddResource(keyVal.Key, keyVal.Value);
                }
            }
        }

        private async Task<IDictionary<string, string>> FlattenJson(FileInfo jsonFile)
        {
            JsonElement jsonObj;
            using (FileStream readStream = jsonFile.OpenRead())
            {
                jsonObj = await JsonSerializer.DeserializeAsync<JsonElement>(readStream);
            }
            Dictionary<string, string> result = new Dictionary<string, string>();
            FlattenJsonElement(result, jsonObj, "");
            return result;
        }

        private void FlattenJsonElement(IDictionary<string, string> flattened, JsonElement jsonElement, string namepath)
        {
            if (jsonElement.ValueKind == JsonValueKind.Array)
            {
                int itemIndex = 0;
                foreach (JsonElement item in jsonElement.EnumerateArray())
                {
                    FlattenJsonElement(flattened, item, namepath + $"[{itemIndex}]");
                }
            }
            else if (jsonElement.ValueKind == JsonValueKind.Object)
            {
                foreach (JsonProperty item in jsonElement.EnumerateObject())
                {
                    FlattenJsonElement(flattened, item.Value, namepath + $".{item.Name}");
                }
            }
            else
            {
                string? stored = jsonElement.GetString();
                if (stored != null)
                {
                    flattened[namepath] = stored;
                }
            }
        }
    }


}