using System.Text.Json;
using NozCli.Core.Models;
using NozCli.Core.Serialization;

namespace NozCli.Repl;

public static class NotesCache
{
    private static string CachePath => Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile),
        ".cache", "noz", "notes.json");

    public static NotesCacheFile? TryLoad()
    {
        try
        {
            if (!File.Exists(CachePath)) return null;
            var json = File.ReadAllText(CachePath);
            return JsonSerializer.Deserialize(json, NozJsonContext.Default.NotesCacheFile);
        }
        catch { return null; }
    }

    public static async Task SaveAsync(List<NoteInfo> notes)
    {
        try
        {
            var dir = Path.GetDirectoryName(CachePath)!;
            Directory.CreateDirectory(dir);

            var cache = new NotesCacheFile(DateTimeOffset.UtcNow, notes);
            var json  = JsonSerializer.Serialize(cache, NozJsonContext.Default.NotesCacheFile);

            // Atomic write: tmp → rename
            var tmp = CachePath + ".tmp";
            await File.WriteAllTextAsync(tmp, json);
            File.Move(tmp, CachePath, overwrite: true);
        }
        catch { /* cache write failures are non-fatal */ }
    }

    public static string TimeAgo(DateTimeOffset dt)
    {
        var diff = DateTimeOffset.UtcNow - dt;
        return diff.TotalSeconds switch
        {
            < 60    => "gerade eben",
            < 3600  => $"vor {(int)diff.TotalMinutes} Min.",
            < 86400 => $"vor {(int)diff.TotalHours} Std.",
            _       => $"vor {(int)diff.TotalDays} Tagen",
        };
    }
}