using System.Text.Json.Serialization;
using ZstdSharp;

namespace ParadoxSaveParser.WebAPI;

public class Config
{
    [JsonIgnore]
    public const int ActualVersion = 1;
    public int Version { get; set; } = ActualVersion;
    public string BaseUrl { get; set; } = "http://127.0.0.1:5226/";
    public int UploadLifetimeDays { get; set; } = 30;
    public string DbPath { get; set; } = "database.sqlite";
    public SaveUploadConfig SaveUpload { get; set; } = new();
    /// level used to compress parsed save data
    public int ZstdCompressionLevel { get; set; } = 10;

    public class SaveUploadConfig
    {
        /// max size of game data entry after decompression, in MiB
        public int MaxSizePlainTextMegabytes { get; set; } = 200;
        /// max size of uploaded .tar.zst, in MiB
        public int MaxSizeCompressedMegabytes { get; set; } = 60;

        // long, because int overflows at 2048 MiB
        [JsonIgnore]
        public long MaxSizePlainTextBytes => MaxSizePlainTextMegabytes * 1024L * 1024L;
        [JsonIgnore]
        public long MaxSizeCompressedBytes => MaxSizeCompressedMegabytes * 1024L * 1024L;
    }

    public static JsonSerializerOptions JsonOptions = new()
    {
        WriteIndented = false,
        MaxDepth = 1024,
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
    };

    public static Config Load(IOPath configPath)
    {
        var cfg = JsonSerializer.Deserialize<Config>(File.ReadAllText(configPath))
            ?? throw new Exception("Could not parse config file");
        if (cfg.Version < ActualVersion)
            throw new Exception($"config is obsolete (config v{cfg.Version} < program v{ActualVersion})");
        if (cfg.Version > ActualVersion)
            throw new Exception($"program is obsolete (config v{cfg.Version} > program v{ActualVersion})");
        // fail on start instead of on first parsed save
        if (cfg.ZstdCompressionLevel < Compressor.MinCompressionLevel
            || cfg.ZstdCompressionLevel > Compressor.MaxCompressionLevel)
            throw new Exception($"{nameof(ZstdCompressionLevel)} must be in range "
                + $"[{Compressor.MinCompressionLevel}, {Compressor.MaxCompressionLevel}]");
        return cfg;
    }

    public override string ToString() => JsonSerializer.Serialize(this, JsonOptions);

    public void Save(IOPath configPath)
    {
        File.WriteAllText(configPath, ToString());
    }
}