using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Dalamud.Plugin;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Pal.Client.Database;
using Pal.Common;

namespace Pal.Client.Configuration.Legacy;

/// <summary>
/// Imports legacy territoryType.json files into the database if it exists, and no markers for that territory exist.
/// </summary>
internal sealed class JsonMigration
{
    private readonly ILogger<JsonMigration> _logger;
    private readonly IServiceScopeFactory _serviceScopeFactory;
    private readonly IDalamudPluginInterface _pluginInterface;

    public JsonMigration(ILogger<JsonMigration> logger, IServiceScopeFactory serviceScopeFactory,
        IDalamudPluginInterface pluginInterface)
    {
        _logger = logger;
        _serviceScopeFactory = serviceScopeFactory;
        _pluginInterface = pluginInterface;
    }

#pragma warning disable CS0612
    public async Task MigrateAsync(CancellationToken cancellationToken)
    {
        List<JsonFloorState> floorsToMigrate = new();
        JsonFloorState.ForEach(floorsToMigrate.Add);

        if (floorsToMigrate.Count == 0)
        {
            _logger.LogInformation("Found no floors to migrate");
            return;
        }

        cancellationToken.ThrowIfCancellationRequested();

        await using var scope = _serviceScopeFactory.CreateAsyncScope();
        await using var dbContext = scope.ServiceProvider.GetRequiredService<PalClientContext>();

        var fileStream = new FileStream(
            Path.Join(_pluginInterface.GetPluginConfigDirectory(),
                $"territory-backup-{DateTime.Now:yyyyMMdd-HHmmss}.zip"),
            FileMode.CreateNew);
        using (var backup = new ZipArchive(fileStream, ZipArchiveMode.Create, false))
        {
            IReadOnlyDictionary<Guid, ImportHistory> imports =
                await dbContext.Imports.ToDictionaryAsync(import => import.Id, cancellationToken);

            foreach (var floorToMigrate in floorsToMigrate)
            {
                backup.CreateEntryFromFile(floorToMigrate.GetSaveLocation(),
                    Path.GetFileName(floorToMigrate.GetSaveLocation()), CompressionLevel.SmallestSize);
                await MigrateFloor(dbContext, floorToMigrate, imports, cancellationToken);
            }

            await dbContext.SaveChangesAsync(cancellationToken);
        }

        _logger.LogInformation("Removing {Count} old json files", floorsToMigrate.Count);
        foreach (var floorToMigrate in floorsToMigrate)
            File.Delete(floorToMigrate.GetSaveLocation());
    }

    /// <returns>Whether to archive this file once complete</returns>
    private async Task MigrateFloor(
        PalClientContext dbContext,
        JsonFloorState floorToMigrate,
        IReadOnlyDictionary<Guid, ImportHistory> imports,
        CancellationToken cancellationToken)
    {
        using var logScope = _logger.BeginScope($"Import {(ETerritoryType)floorToMigrate.TerritoryType}");
        if (floorToMigrate.Markers.Count == 0)
        {
            _logger.LogInformation("Skipping migration, floor has no markers");
        }

        if (await dbContext.Locations.AnyAsync(o => o.TerritoryType == floorToMigrate.TerritoryType,
                cancellationToken))
        {
            _logger.LogInformation("Skipping migration, floor already has locations in the database");
            return;
        }

        _logger.LogInformation("Starting migration of {Count} locations", floorToMigrate.Markers.Count);
        List<ClientLocation> clientLocations = floorToMigrate.Markers
            .Where(o => o.Type == JsonMarker.EType.Trap || o.Type == JsonMarker.EType.Hoard)
            .Select(o =>
            {
                var clientLocation = new ClientLocation
                {
                    TerritoryType = floorToMigrate.TerritoryType,
                    Type = MapJsonType(o.Type),
                    X = o.Position.X,
                    Y = o.Position.Y,
                    Z = o.Position.Z,
                    Seen = o.Seen,

                    // the SelectMany is misleading here, each import has either 0 or 1 associated db entry with that id
                    ImportedBy = o.Imports
                        .Select(importId =>
                            imports.TryGetValue(importId, out ImportHistory? import) ? import : null)
                        .Where(import => import != null)
                        .Cast<ImportHistory>()
                        .Distinct()
                        .ToList(),

                    // if we have a location not encountered locally, which also wasn't imported,
                    // it very likely is a download (but we have no information to track this).
                    Source = o.Seen ? ClientLocation.ESource.SeenLocally :
                        o.Imports.Count > 0 ? ClientLocation.ESource.Import : ClientLocation.ESource.Download,
                    SinceVersion = o.SinceVersion ?? "0.0",
                };

                clientLocation.RemoteEncounters = o.RemoteSeenOn
                    .Select(accountId => new RemoteEncounter(clientLocation, accountId))
                    .ToList();

                return clientLocation;
            }).ToList();
        await dbContext.Locations.AddRangeAsync(clientLocations, cancellationToken);

        _logger.LogInformation("Migrated {Count} locations", clientLocations.Count);
    }

    private ClientLocation.EType MapJsonType(JsonMarker.EType type)
    {
        return type switch
        {
            JsonMarker.EType.Trap => ClientLocation.EType.Trap,
            JsonMarker.EType.Hoard => ClientLocation.EType.Hoard,
            _ => throw new ArgumentOutOfRangeException(nameof(type), type, null)
        };
    }
#pragma warning restore CS0612
}