using System.Security.Cryptography;
using Data.SeaHavenIndustries;
using Microsoft.EntityFrameworkCore;

namespace Api.SeaHavenIndustries.Helper
{
    public class VendorPortalTokenService
    {
        private readonly ApplicationDbContext _db;
        private readonly int _lifetimeDays;

        public VendorPortalTokenService(ApplicationDbContext db, IConfiguration config)
        {
            _db = db;
            _lifetimeDays = config.GetValue<int?>("VendorPortal:TokenLifetimeDays") ?? 365;
        }

        public async Task<VendorAccessToken> GetOrCreateActiveTokenAsync(int vendorId)
        {
            var now = DateTime.UtcNow;
            var existing = await _db.VendorAccessTokens
                .Where(t => t.VendorId == vendorId
                    && t.RevokedAt == null
                    && t.ExpiresAt > now
                    && (t.IsDeleted == null || t.IsDeleted == false))
                .OrderByDescending(t => t.IssuedAt)
                .FirstOrDefaultAsync();

            if (existing != null) return existing;

            var token = new VendorAccessToken
            {
                VendorId = vendorId,
                Token = GenerateToken(),
                IssuedAt = now,
                ExpiresAt = now.AddDays(_lifetimeDays),
                CreatedDate = now
            };
            _db.VendorAccessTokens.Add(token);
            await _db.SaveChangesAsync();
            return token;
        }

        public async Task<Vendor?> ResolveVendorAsync(string? token)
        {
            if (string.IsNullOrWhiteSpace(token)) return null;
            var now = DateTime.UtcNow;
            var record = await _db.VendorAccessTokens
                .Include(t => t.Vendor)
                .FirstOrDefaultAsync(t => t.Token == token
                    && t.RevokedAt == null
                    && t.ExpiresAt > now
                    && (t.IsDeleted == null || t.IsDeleted == false));

            if (record?.Vendor == null) return null;

            record.LastUsedAt = now;
            await _db.SaveChangesAsync();
            return record.Vendor;
        }

        public async Task<VendorAccessToken> RotateAsync(int vendorId)
        {
            var now = DateTime.UtcNow;
            var active = await _db.VendorAccessTokens
                .Where(t => t.VendorId == vendorId && t.RevokedAt == null)
                .ToListAsync();
            foreach (var t in active) t.RevokedAt = now;
            await _db.SaveChangesAsync();
            return await GetOrCreateActiveTokenAsync(vendorId);
        }

        public async Task RevokeAllAsync(int vendorId)
        {
            var now = DateTime.UtcNow;
            var active = await _db.VendorAccessTokens
                .Where(t => t.VendorId == vendorId && t.RevokedAt == null)
                .ToListAsync();
            foreach (var t in active) t.RevokedAt = now;
            await _db.SaveChangesAsync();
        }

        private static string GenerateToken()
        {
            var bytes = RandomNumberGenerator.GetBytes(32);
            return Convert.ToBase64String(bytes)
                .Replace("+", "-")
                .Replace("/", "_")
                .TrimEnd('=');
        }
    }
}