using Foxnouns.Backend.Database.Models;
using Microsoft.EntityFrameworkCore;

namespace Foxnouns.Backend.Database;

public static class FlagQueryExtensions
{
    private static async Task<List<PrideFlag>> GetFlagsAsync(this DatabaseContext db, Snowflake userId) =>
        await db.PrideFlags.Where(f => f.UserId == userId).OrderBy(f => f.Id).ToListAsync();

    /// <summary>
    /// Sets the user's profile flags to the given IDs. Returns a validation error if any of the flag IDs are unknown
    /// or if too many IDs are given. Duplicates are allowed.
    /// </summary>
    public static async Task<ValidationError?> SetUserFlagsAsync(this DatabaseContext db, Snowflake userId,
        Snowflake[] flagIds)
    {
        var currentFlags = await db.UserFlags.Where(f => f.UserId == userId).ToListAsync();
        foreach (var flag in currentFlags)
            db.UserFlags.Remove(flag);

        // If there's no new flags to set, we're done
        if (flagIds.Length == 0) return null;
        if (flagIds.Length > 100) return ValidationError.LengthError("Too many profile flags", 0, 100, flagIds.Length);

        var flags = await db.GetFlagsAsync(userId);
        var unknownFlagIds = flagIds.Where(id => flags.All(f => f.Id != id)).ToArray();
        if (unknownFlagIds.Length != 0)
            return ValidationError.GenericValidationError("Unknown flag IDs", unknownFlagIds);

        var userFlags = flagIds.Select(id => new UserFlag { PrideFlagId = id, UserId = userId });
        db.UserFlags.AddRange(userFlags);

        return null;
    }
}