using System.Text.Json;

namespace ChangeT50.Agent;

public sealed class LocalJournal
{
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
    {
        WriteIndented = true,
        PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
    };

    private readonly string _path;
    private readonly object _sync = new();

    public LocalJournal(string path)
    {
        _path = Path.GetFullPath(path);
    }

    public JournalEntry? Get(string clientOrderNo)
    {
        lock (_sync)
        {
            return ReadAll().GetValueOrDefault(clientOrderNo);
        }
    }

    public void Save(JournalEntry entry)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(entry.ClientOrderNo);
        lock (_sync)
        {
            var entries = ReadAll();
            entry.UpdatedAt = DateTimeOffset.Now;
            entries[entry.ClientOrderNo] = entry;
            WriteAll(entries);
        }
    }

    public int PendingUploadCount()
    {
        lock (_sync)
        {
            return ReadAll().Values.Count(entry => entry.State is "card_debited" or "upload_retrying");
        }
    }

    private Dictionary<string, JournalEntry> ReadAll()
    {
        if (!File.Exists(_path))
        {
            return new Dictionary<string, JournalEntry>(StringComparer.Ordinal);
        }
        var json = File.ReadAllText(_path);
        return JsonSerializer.Deserialize<Dictionary<string, JournalEntry>>(json, JsonOptions)
               ?? new Dictionary<string, JournalEntry>(StringComparer.Ordinal);
    }

    private void WriteAll(Dictionary<string, JournalEntry> entries)
    {
        var directory = Path.GetDirectoryName(_path);
        if (!string.IsNullOrEmpty(directory))
        {
            Directory.CreateDirectory(directory);
        }
        var temporaryPath = _path + ".tmp";
        File.WriteAllText(temporaryPath, JsonSerializer.Serialize(entries, JsonOptions));
        File.Move(temporaryPath, _path, true);
    }
}