using Microsoft.EntityFrameworkCore;
using QMax.Api.Data.Entities;

namespace QMax.Api.Data;

public static class QMaxDatabaseCleanup
{
    public static async Task RemoveLegacyWebFileAttachmentEchoesAsync(QMaxDbContext db)
    {
        var connection = db.Database.GetDbConnection();
        if (connection.State != System.Data.ConnectionState.Open)
        {
            await connection.OpenAsync();
        }

        await db.Database.ExecuteSqlRawAsync("DROP TABLE IF EXISTS temp.LegacyWebFileMessageIds;");
        await db.Database.ExecuteSqlRawAsync("""
            CREATE TEMP TABLE LegacyWebFileMessageIds (
                Id TEXT NOT NULL PRIMARY KEY
            );
            """);
        await db.Database.ExecuteSqlRawAsync("""
            INSERT OR IGNORE INTO LegacyWebFileMessageIds (Id)
            SELECT DISTINCT legacy.Id
            FROM Messages AS legacy
            INNER JOIN MessageAttachments AS legacyAttachment ON legacyAttachment.MessageId = legacy.Id
            WHERE legacy.Direction = 'Outgoing'
              AND legacy.ExternalId LIKE 'web-file-%'
              AND legacyAttachment.Sha256 IS NOT NULL
              AND legacyAttachment.Sha256 <> ''
              AND EXISTS (
                  SELECT 1
                  FROM Messages AS confirmed
                  INNER JOIN MessageAttachments AS confirmedAttachment ON confirmedAttachment.MessageId = confirmed.Id
                  WHERE confirmed.ChatId = legacy.ChatId
                    AND confirmed.Id <> legacy.Id
                    AND confirmed.Direction = 'Outgoing'
                    AND confirmed.ExternalId IS NOT NULL
                    AND confirmed.ExternalId NOT LIKE 'web-file-%'
                    AND confirmedAttachment.Sha256 = legacyAttachment.Sha256
              );
            """);
        await db.Database.ExecuteSqlRawAsync("""
            DELETE FROM MessageAttachments
            WHERE MessageId IN (SELECT Id FROM LegacyWebFileMessageIds);
            """);
        await db.Database.ExecuteSqlRawAsync("""
            DELETE FROM Messages
            WHERE Id IN (SELECT Id FROM LegacyWebFileMessageIds);
            """);
        await db.Database.ExecuteSqlRawAsync("DROP TABLE IF EXISTS temp.LegacyWebFileMessageIds;");
    }

    public static async Task ClearUnreadCountsForLatestOutgoingChatsAsync(QMaxDbContext db)
    {
        var unreadChats = await db.Chats
            .Where(chat => chat.UnreadCount > 0)
            .ToListAsync();

        if (unreadChats.Count == 0)
        {
            return;
        }

        var changed = false;
        foreach (var chat in unreadChats)
        {
            var chatMessages = await db.Messages
                .Where(message => message.ChatId == chat.Id && message.DeletedAt == null)
                .Select(message => new { message.Direction, message.SentAt, message.Id })
                .ToListAsync();

            var latestMessage = chatMessages
                .OrderByDescending(message => message.SentAt)
                .ThenByDescending(message => message.Id)
                .FirstOrDefault();

            if (latestMessage?.Direction != MessageDirection.Outgoing)
            {
                continue;
            }

            chat.UnreadCount = 0;
            chat.UpdatedAt = DateTimeOffset.UtcNow;
            changed = true;
        }

        if (changed)
        {
            await db.SaveChangesAsync();
        }
    }
}