using System.Text.Json;
using WebApp.Models;

namespace WebApp.Services;

/// <summary>
/// Persists chapter settings to <c>Data/appsettings.json</c>.
/// </summary>
public class ChapterSettingsWriter : IChapterSettingsWriter
{
    private readonly IWebHostEnvironment _environment;
    private readonly IConfiguration _configuration;
    private readonly ILogger<ChapterSettingsWriter> _logger;

    public ChapterSettingsWriter(
        IWebHostEnvironment environment,
        IConfiguration configuration,
        ILogger<ChapterSettingsWriter> logger)
    {
        _environment = environment;
        _configuration = configuration;
        _logger = logger;
    }

    public async Task WriteAsync(ChapterSettings settings, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(settings);

        var appSettingsPath = GetAppSettingsPath();
        var dataDir = Path.GetDirectoryName(appSettingsPath);
        if (dataDir != null && !Directory.Exists(dataDir))
        {
            Directory.CreateDirectory(dataDir);
        }

        Dictionary<string, object?> root;
        if (File.Exists(appSettingsPath))
        {
            var existingJson = await File.ReadAllTextAsync(appSettingsPath, cancellationToken);
            root = JsonSerializer.Deserialize<Dictionary<string, object?>>(existingJson)
                   ?? [];
        }
        else
        {
            root = [];
        }

        root["ChapterSettings"] = settings;

        var options = new JsonSerializerOptions { WriteIndented = true };
        var json = JsonSerializer.Serialize(root, options);
        await File.WriteAllTextAsync(appSettingsPath, json, cancellationToken);

        _logger.LogInformation("Chapter settings written to {Path}", appSettingsPath);
    }

    public async Task UpdateCompetitionYearAsync(string competitionYear, CancellationToken cancellationToken = default)
    {
        var settings = _configuration.GetSection("ChapterSettings").Get<ChapterSettings>()
                       ?? new ChapterSettings();
        settings.CompetitionYear = competitionYear;
        await WriteAsync(settings, cancellationToken);
    }

    private string GetAppSettingsPath() =>
        Path.Combine(_environment.ContentRootPath, "Data", "appsettings.json");
}