using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.SelfService.Portal.Core.API.Authorization;
using Microsoft.SelfService.Portal.Core.API.Context;
using Microsoft.SelfService.Portal.Core.API.Dto.Auth;
using Microsoft.SelfService.Portal.Core.API.Models;
using Microsoft.SelfService.Portal.Core.API.Services;
using System.Security.Claims;
using System.Text.Json;

namespace Microsoft.SelfService.Portal.Core.API.Controllers
{
    [Route("api/tokens")]
    [ApiController]
    public class ApiTokenController : Controller
    {
        private readonly DataContext _context;
        private readonly ApiTokenService _tokenService;

        public ApiTokenController(DataContext context, ApiTokenService tokenService)
        {
            _context = context;
            _tokenService = tokenService;
        }

        [HttpGet("my")]
        [Authorize(Policy = ApiPolicies.TokenManage)]
        [ProducesResponseType(200, Type = typeof(IEnumerable<GetManagedTokenDto>))]
        public IActionResult GetMyTokens()
        {
            var subject = GetCurrentSubject();
            var subjectType = GetCurrentSubjectType();

            var tokens = _context.ApiTokens
                .Include(token => token.ApiClient)
                .Where(token => token.Subject == subject && token.SubjectType == subjectType)
                .OrderByDescending(token => token.IssuedAt)
                .ToList();

            return Ok(tokens.Select(ToDto));
        }

        [HttpPost("my")]
        [Authorize(Policy = ApiPolicies.TokenManage)]
        [ProducesResponseType(200, Type = typeof(CreateManagedTokenResponseDto))]
        [ProducesResponseType(400)]
        public IActionResult CreateMyToken([FromBody] CreateManagedTokenRequestDto request)
        {
            if (request == null || string.IsNullOrWhiteSpace(request.Scope))
            {
                return BadRequest(new { message = "Scope is required." });
            }

            IReadOnlyCollection<string> scopes;
            try
            {
                scopes = _tokenService.ResolveRequestedUserScopes(request.Scope);
            }
            catch (InvalidOperationException ex)
            {
                return BadRequest(new { message = ex.Message });
            }

            var subject = GetCurrentSubject();
            var subjectType = GetCurrentSubjectType();
            var name = string.IsNullOrWhiteSpace(request.Name)
                ? $"Token for {subject}"
                : request.Name.Trim();

            var token = _tokenService.CreateAccessToken(
                subject,
                subjectType == "ApiClient" ? subject : null,
                scopes);
            var now = DateTime.UtcNow;
            var expiresAt = request.ExpiresAt.HasValue && request.ExpiresAt.Value < token.ExpiresAt
                ? request.ExpiresAt.Value
                : token.ExpiresAt;

            if (expiresAt <= now)
            {
                return BadRequest(new { message = "ExpiresAt must be in the future." });
            }

            var model = new ApiTokenModel
            {
                Id = Guid.NewGuid(),
                Jti = token.Jti,
                Subject = subject,
                SubjectType = subjectType,
                Name = name,
                ScopesJson = JsonSerializer.Serialize(scopes),
                IssuedAt = token.IssuedAt,
                ExpiresAt = expiresAt,
                Created = now,
                CreatedBy = subject,
                Modified = now,
                ModifiedBy = subject
            };

            _context.ApiTokens.Add(model);
            _context.SaveChanges();

            return Ok(new CreateManagedTokenResponseDto
            {
                Id = model.Id,
                AccessToken = token.AccessToken,
                ExpiresIn = Math.Max(0, Convert.ToInt32((expiresAt - now).TotalSeconds)),
                ExpiresAt = expiresAt,
                Scope = string.Join(' ', scopes)
            });
        }

        [HttpDelete("my/{id}")]
        [Authorize(Policy = ApiPolicies.TokenManage)]
        [ProducesResponseType(200, Type = typeof(GetManagedTokenDto))]
        [ProducesResponseType(404)]
        public IActionResult RevokeMyToken(Guid id)
        {
            var subject = GetCurrentSubject();
            var subjectType = GetCurrentSubjectType();
            var token = _context.ApiTokens.FirstOrDefault(existing =>
                existing.Id == id
                && existing.Subject == subject
                && existing.SubjectType == subjectType);

            if (token == null)
            {
                return NotFound();
            }

            RevokeToken(token, subject);
            _context.SaveChanges();

            return Ok(ToDto(token));
        }

        [HttpGet("admin")]
        [Authorize(Policy = ApiPolicies.TokenAdmin)]
        [ProducesResponseType(200, Type = typeof(IEnumerable<GetManagedTokenDto>))]
        public IActionResult GetAllTokens()
        {
            var tokens = _context.ApiTokens
                .Include(token => token.ApiClient)
                .OrderByDescending(token => token.IssuedAt)
                .ToList();

            return Ok(tokens.Select(ToDto));
        }

        [HttpDelete("admin/{id}")]
        [Authorize(Policy = ApiPolicies.TokenAdmin)]
        [ProducesResponseType(200, Type = typeof(GetManagedTokenDto))]
        [ProducesResponseType(404)]
        public IActionResult RevokeTokenAsAdmin(Guid id)
        {
            var token = _context.ApiTokens.FirstOrDefault(existing => existing.Id == id);
            if (token == null)
            {
                return NotFound();
            }

            RevokeToken(token, GetCurrentSubject());
            _context.SaveChanges();

            return Ok(ToDto(token));
        }

        [HttpGet("scopes")]
        [Authorize(Policy = ApiPolicies.TokenManage)]
        [ProducesResponseType(200, Type = typeof(IEnumerable<string>))]
        public IActionResult GetAllowedScopes()
        {
            return Ok(_tokenService.ReadAllowedTokenScopes());
        }

        private string GetCurrentSubject()
        {
            return User.FindFirstValue("client_id")
                ?? User.FindFirstValue(ClaimTypes.Name)
                ?? User.Identity?.Name
                ?? "Unknown";
        }

        private string GetCurrentSubjectType()
        {
            return User.HasClaim(claim => claim.Type == "client_id") ? "ApiClient" : "User";
        }

        private static void RevokeToken(ApiTokenModel token, string revokedBy)
        {
            if (!token.RevokedAt.HasValue)
            {
                token.RevokedAt = DateTime.UtcNow;
                token.RevokedBy = revokedBy;
                token.Modified = DateTime.UtcNow;
                token.ModifiedBy = revokedBy;
            }
        }

        private static GetManagedTokenDto ToDto(ApiTokenModel token)
        {
            var scopes = JsonSerializer.Deserialize<string[]>(token.ScopesJson) ?? Array.Empty<string>();

            return new GetManagedTokenDto
            {
                Id = token.Id,
                Subject = token.Subject,
                SubjectType = token.SubjectType,
                ClientId = token.ApiClient?.ClientId,
                Name = token.Name,
                Scope = string.Join(' ', scopes),
                IssuedAt = token.IssuedAt,
                ExpiresAt = token.ExpiresAt,
                RevokedAt = token.RevokedAt,
                RevokedBy = token.RevokedBy,
                LastUsedAt = token.LastUsedAt,
                IsActive = !token.RevokedAt.HasValue && token.ExpiresAt > DateTime.UtcNow
            };
        }
    }
}