using System;
using System.IO;
using Microsoft.AspNetCore.Mvc;
using Umbraco.Cms.Core.IO;
using Umbraco.Cms.Core.Media;
using Umbraco.Cms.Core.Models;
using Umbraco.Cms.Web.Common.Attributes;
using Umbraco.Extensions;
using Constants = Umbraco.Cms.Core.Constants;

namespace Umbraco.Cms.Web.BackOffice.Controllers
{
    /// <summary>
    /// A controller used to return images for media
    /// </summary>
    [PluginController(Constants.Web.Mvc.BackOfficeApiArea)]
    public class ImagesController : UmbracoAuthorizedApiController
    {
        private readonly MediaFileManager _mediaFileManager;
        private readonly IImageUrlGenerator _imageUrlGenerator;

        public ImagesController(
            MediaFileManager mediaFileManager,
            IImageUrlGenerator imageUrlGenerator)
        {
            _mediaFileManager = mediaFileManager;
            _imageUrlGenerator = imageUrlGenerator;
        }

        /// <summary>
        /// Gets the big thumbnail image for the original image path
        /// </summary>
        /// <param name="originalImagePath"></param>
        /// <returns></returns>
        /// <remarks>
        /// If there is no original image is found then this will return not found.
        /// </remarks>
        public IActionResult GetBigThumbnail(string originalImagePath)
        {
            return string.IsNullOrWhiteSpace(originalImagePath)
                ? Ok()
                : GetResized(originalImagePath, 500);
        }

        /// <summary>
        /// Gets a resized image for the image at the given path
        /// </summary>
        /// <param name="imagePath"></param>
        /// <param name="width"></param>
        /// <returns></returns>
        /// <remarks>
        /// If there is no media, image property or image file is found then this will return not found.
        /// </remarks>
        public IActionResult GetResized(string imagePath, int width)
        {
            var ext = Path.GetExtension(imagePath);
            
            // check if imagePath is local to prevent open redirect
            if (!Uri.IsWellFormedUriString(imagePath, UriKind.Relative))
            {
                return Unauthorized();
            }
            
            // we need to check if it is an image by extension
            if (_imageUrlGenerator.IsSupportedImageFormat(ext) == false)
            {
                return NotFound();
            }
            
            // redirect to ImageProcessor thumbnail with rnd generated from last modified time of original media file
            DateTimeOffset? imageLastModified = null;
            try
            {
                imageLastModified = _mediaFileManager.FileSystem.GetLastModified(imagePath);
            }
            catch (Exception)
            {
                // if we get an exception here it's probably because the image path being requested is an image that doesn't exist
                // in the local media file system. This can happen if someone is storing an absolute path to an image online, which
                // is perfectly legal but in that case the media file system isn't going to resolve it.
                // so ignore and we won't set a last modified date.
            }

            var rnd = imageLastModified.HasValue ? $"&rnd={imageLastModified:yyyyMMddHHmmss}" : null;
            var imageUrl = _imageUrlGenerator.GetImageUrl(new ImageUrlGenerationOptions(imagePath)
            {
                Width = width,
                ImageCropMode = ImageCropMode.Max,
                CacheBusterValue = rnd
            });
            if (Url.IsLocalUrl(imageUrl))
            {
                return new LocalRedirectResult(imageUrl, false);
            }
            else
            {
                return Unauthorized();
            }
        }

        /// <summary>
        /// Gets a processed image for the image at the given path
        /// </summary>
        /// <param name="imagePath"></param>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <param name="focalPointLeft"></param>
        /// <param name="focalPointTop"></param>
        /// <param name="mode"></param>
        /// <returns></returns>
        /// <remarks>
        /// If there is no media, image property or image file is found then this will return not found.
        /// </remarks>
        public string GetProcessedImageUrl(string imagePath,
            int? width = null,
            int? height = null,
            decimal? focalPointLeft = null,
            decimal? focalPointTop = null,
            ImageCropMode mode = ImageCropMode.Max,
            string cacheBusterValue = "",
            decimal? cropX1 = null,
            decimal? cropX2 = null,
            decimal? cropY1 = null,
            decimal? cropY2 = null
            )
        {
            var options = new ImageUrlGenerationOptions(imagePath)
            {
                Width = width,
                Height = height,
                ImageCropMode = mode,
                CacheBusterValue = cacheBusterValue
            };

            if (focalPointLeft.HasValue && focalPointTop.HasValue)
            {
                options.FocalPoint = new ImageUrlGenerationOptions.FocalPointPosition(focalPointLeft.Value, focalPointTop.Value);
            }
            else if (cropX1.HasValue && cropX2.HasValue && cropY1.HasValue && cropY2.HasValue)
            {
                options.Crop = new ImageUrlGenerationOptions.CropCoordinates(cropX1.Value, cropY1.Value, cropX2.Value, cropY2.Value);
            }

            return _imageUrlGenerator.GetImageUrl(options);
        }
    }
}