using System.Linq;
using SQLite;

namespace ParadoxSaveParser.WebAPI.Database;

public class DatabaseConnector
{
    private readonly int _uploadsLifetimeDays;
    private readonly SQLiteAsyncConnection _db;
    private readonly ContextLogger _logger;

    public DatabaseConnector(string databasePath, int uploadsLifetimeDays, ILogger logger)
    {
        _uploadsLifetimeDays = uploadsLifetimeDays;
        _db = new SQLiteAsyncConnection(databasePath);
        _logger = new ContextLogger("Database", logger);
    }

    public async Task InitializeAsync()
    {
        await _db.CreateTableAsync<SaveFileMetadata>();
    }
    
    public async Task<SaveFileMetadata?> GetMetadata(string id)
    {
        return (await _db.QueryAsync<SaveFileMetadata>(
            "select * from SaveFileMetadata where id = ?", id))
            .FirstOrDefault();
    }
    
    public async Task<SaveFileMetadata> CreateMetadata(Game game)
    {
        var meta = new SaveFileMetadata
        {
            id = Guid.NewGuid().ToString(),
            game = game,
            status = SaveFileProcessingStatus.Initialized,
            uploadDateTime = DateTime.Now
        };
        await _db.InsertAsync(meta);
        return meta;
    }

    public async Task UpdateMetadataStatus(SaveFileMetadata meta, SaveFileProcessingStatus status)
    {
        meta.status = status;
        await _db.UpdateAsync(meta);
    }

    public async Task SetMetadataError(SaveFileMetadata meta, string errorMessage)
    {
        meta.errorMessage = errorMessage;
        await UpdateMetadataStatus(meta, SaveFileProcessingStatus.Error);
        DeleteAssociatedFiles(meta);
    }

    public async Task DeleteMetadata(SaveFileMetadata meta)
    {
        _logger.LogDebug($"Deleting save file (id: {meta.id} status: {meta.status} " +
                         $"uploadDate: {meta.uploadDateTime:yyyy/MM/dd})");
        await _db.DeleteAsync(meta);
        DeleteAssociatedFiles(meta);
    }

    /// <summary>
    /// WARNING: Call this method only when no parsing operations are running.
    /// </summary>
    public async Task DeleteInvalidData()
    {
        _logger.LogInfo("Deleting invalid data...");
        
        var expirationDate = DateTime.Now.AddDays(-_uploadsLifetimeDays);
        var metadataTable = _db.Table<SaveFileMetadata>();
        int rowCount = await metadataTable.CountAsync();
        int i = 0;
        int deleteCount = 0;
        while(i < rowCount)
        {
            var meta = await metadataTable.ElementAtAsync(i)!;
            if(meta.status != SaveFileProcessingStatus.Done || 
               meta.uploadDateTime < expirationDate ||
               !meta.AssociatedFilesExist())
            {
                deleteCount++;
                await DeleteMetadata(meta);
            }
            i++;
        }

        _logger.LogInfo($"Deleted {deleteCount} invalid records");
    }

    private void TryDeleteFile(IOPath file)
    {
        if (!File.Exists(file)) return;
        _logger.LogDebug($"Deleting file '{file}'");
        File.Delete(file);
    }

    private void DeleteAssociatedFiles(SaveFileMetadata meta)
    {
        TryDeleteFile(meta.GetSaveFilePath());
        TryDeleteFile(meta.GetParsedDataPath());
    }
}