using DataModel.Database;
using DataModel.Database.Common;
using DataModel.MigrationScripts;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace DataModel;

public static class Setup
{
    private const string ENV_EF_TOOLING_DATABASE = "ENV_EF_TOOLING_DATABASE";
    private const string DB_READ_WRITE_MODE = "ReadWrite";
    private const string DB_READ_WRITE_CREATE_MODE = "ReadWriteCreate";

    private static string USED_DATA_FILE = string.Empty;
    private static SetupMaintenance SETUP_MAINTENANCE = new();

    public static string DataFile => Setup.USED_DATA_FILE;

    public static SetupMaintenance Maintenance => Setup.SETUP_MAINTENANCE;

    /// <summary>
    /// Tries to migrate the database.
    /// </summary>
    public static async Task PerformDataMigration(DataContext dbContext)
    {
        var pendingMigrations = (await dbContext.Database.GetPendingMigrationsAsync()).ToList();
        foreach (var pendingMigration in pendingMigrations)
        {
            Console.WriteLine($"The migration '{pendingMigration}' is pending.");
        }

        await dbContext.Database.MigrateAsync();
        
        //
        // Post migration actions:
        //
        if (pendingMigrations.Contains("20221106193544_202211AddUniqueIds"))
            await Script202211AddUniqueIds.PostMigrationAsync(dbContext);
    }

    /// <summary>
    /// Imports a JSON file into a new database.
    /// </summary>
    public static async Task ImportDataAndAddDatabase(this IServiceCollection serviceCollection, string path2JSONFile)
    {
        var tempPath = Path.GetTempFileName();

        Setup.USED_DATA_FILE = tempPath;
        Setup.SETUP_MAINTENANCE = new(path2JSONFile, true);
        serviceCollection.AddDbContext<DataContext>(options => options.UseSqlite($"Filename={tempPath};Mode={DB_READ_WRITE_CREATE_MODE};"), ServiceLifetime.Transient);
        
        // Get the database service:
        await using var serviceProvider = serviceCollection.BuildServiceProvider();
        var dbContext = serviceProvider.GetRequiredService<DataContext>();
        
        // Next, we import the data from the provided JSON file:
        await dbContext.ImportAsync(path2JSONFile);

        //
        // Next, we enable the auto-export feature to keep the source file up to date.
        // The auto-export feature might exist, but we enforce it, when we work with a
        // temporary database source by a JSON file.
        //
        
        // Enable the auto-export feature:
        var autoExportEnabled = await dbContext.Settings.FirstAsync(n => n.Code == SettingNames.AUTO_EXPORT_ENABLED);
        autoExportEnabled.BoolValue = true;
        
        // Set the auto-export path and file:
        var autoExportPath = await dbContext.Settings.FirstAsync(n => n.Code == SettingNames.AUTO_EXPORT_DESTINATION_PATH);
        autoExportPath.TextValue = Path.GetDirectoryName(path2JSONFile) ?? string.Empty;
        
        var autoExportFile = await dbContext.Settings.FirstAsync(n => n.Code == SettingNames.AUTO_EXPORT_FILENAME);
        autoExportFile.TextValue = Path.GetFileName(path2JSONFile);
        
        // Save the changes:
        await dbContext.SaveChangesAsync();
    }
    
    /// <summary>
    /// Creates and adds the database instance to the DI system (extension method).
    /// </summary>
    public static void AddDatabase(this IServiceCollection serviceCollection, string path2DataFile, bool createWhenNecessary = true)
    {
        Setup.USED_DATA_FILE = path2DataFile;
        Setup.SETUP_MAINTENANCE = new(path2DataFile, false);
        serviceCollection.AddDbContext<DataContext>(options => options.UseSqlite($"Filename={path2DataFile};Mode={(createWhenNecessary ? DB_READ_WRITE_CREATE_MODE : DB_READ_WRITE_MODE)};"), ServiceLifetime.Transient);
    }

    /// <summary>
    /// Sets up the DI & db context ready for the EF tooling.
    /// </summary>
    public static IHostBuilder Setup4EFTooling(string[] args)
    {
        var dataFile = Environment.GetEnvironmentVariable(ENV_EF_TOOLING_DATABASE);
        if (string.IsNullOrWhiteSpace(dataFile))
        {
            Console.WriteLine("In order to use EF tooling, point the environment variable ENV_EF_TOOLING_DATABASE to the data file, which should be used for the EF tooling.");
            Environment.Exit(100);
        }
        
        var builder = Host.CreateDefaultBuilder(args);
        builder.ConfigureServices((hostContext, serviceCollection) =>
        {
            serviceCollection.AddDbContext<DataContext>(options => options.UseSqlite($"Filename={dataFile};Mode=ReadWriteCreate"));
        });

        return builder;
    }

    public readonly record struct SetupMaintenance(string PathToDataFile = "", bool RemoveTempDatabaseAfterwards = false) : IDisposable
    {
        public void Dispose()
        {
            if (!this.RemoveTempDatabaseAfterwards)
                return;
            
            try
            {
                File.Delete(this.PathToDataFile);
            }
            catch(Exception e)
            {
                Console.WriteLine($"Failed to remove the temporary database file: {e.Message} // {e.InnerException?.Message}");
            }
        }
    }
}