using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using MediaBrowser.Common.Configuration;

namespace Jellyfin.Plugin.MediaBarEnhanced.Api
{
    /// <summary>
    /// Controller for handling custom overlay image uploads and retrieval.
    /// </summary>
    [ApiController]
    [Route("MediaBarEnhanced")]
    public class OverlayImageController : ControllerBase
    {
        private readonly IApplicationPaths _applicationPaths;
        private readonly string _imageDirectory;

        public OverlayImageController(IApplicationPaths applicationPaths)
        {
            _applicationPaths = applicationPaths;
            
            // We use the plugin's data folder to store the image
            _imageDirectory = MediaBarEnhancedPlugin.Instance?.DataFolderPath ?? Path.Combine(applicationPaths.DataPath, "plugins", "MediaBarEnhanced");
            
            // We no longer define the exact path here, just the directory
            // The filename is determined per request
        }

        /// <summary>
        /// Uploads a new custom overlay image.
        /// </summary>
        [HttpPost("OverlayImage")]
        [Consumes("multipart/form-data")]
        public async Task<IActionResult> UploadImage([FromForm] IFormFile file, [FromQuery] string? filename = null)
        {
            if (file == null || file.Length == 0)
            {
                return BadRequest("No file uploaded.");
            }

            string targetFileName = string.IsNullOrWhiteSpace(filename) 
                ? "custom_overlay_image.dat" 
                : $"custom_overlay_image_{filename}.dat";
            string targetPath = Path.Combine(_imageDirectory, targetFileName);

            try
            {
                if (!Directory.Exists(_imageDirectory))
                {
                    Directory.CreateDirectory(_imageDirectory);
                }

                // Delete is not strictly necessary and can cause locking issues if someone is currently reading it.
                // FileMode.Create will truncate the file if it exists, effectively overwriting it.
                // We use FileShare.None to ensure we have exclusive write access, but handle potential IOExceptions gracefully.
                using (var stream = new FileStream(targetPath, FileMode.Create, FileAccess.Write, FileShare.None))
                {
                    await file.CopyToAsync(stream).ConfigureAwait(false);
                }

                // Return the GET URL that the frontend can use
                var qs = string.IsNullOrWhiteSpace(filename) ? "" : $"?filename={Uri.EscapeDataString(filename)}&";
                var getUrl = $"/MediaBarEnhanced/OverlayImage{qs}{(qs == "" ? "?" : "")}t={DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}";
                return Ok(new { url = getUrl });
            }
            catch (Exception ex)
            {
                return StatusCode(500, $"Internal server error: {ex.Message}");
            }
        }

        /// <summary>
        /// Retrieves the custom overlay image.
        /// </summary>
        [HttpGet("OverlayImage")]
        public IActionResult GetImage([FromQuery] string? filename = null)
        {
            string targetFileName = string.IsNullOrWhiteSpace(filename) 
                ? "custom_overlay_image.dat" 
                : $"custom_overlay_image_{filename}.dat";
            string targetPath = Path.Combine(_imageDirectory, targetFileName);

            if (!System.IO.File.Exists(targetPath))
            {
                return NotFound();
            }

            // Read the file and return as a generic octet stream. 
            // We use FileShare.ReadWrite so that if someone is currently overwriting the file (uploading), we don't block them,
            // and we also don't get blocked by other readers.
            var stream = new FileStream(targetPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            
            // "image/*" works reliably as browsers will sniff the exact image mime type (jpeg, png, webp).
            return File(stream, "image/*");
        }

        /// <summary>
        /// Deletes a custom overlay image.
        /// </summary>
        [HttpDelete("OverlayImage")]
        public IActionResult DeleteImage([FromQuery] string? filename = null)
        {
            string targetFileName = string.IsNullOrWhiteSpace(filename) 
                ? "custom_overlay_image.dat" 
                : $"custom_overlay_image_{filename}.dat";
            string targetPath = Path.Combine(_imageDirectory, targetFileName);

            if (System.IO.File.Exists(targetPath))
            {
                try
                {
                    System.IO.File.Delete(targetPath);
                    return Ok();
                }
                catch (Exception ex)
                {
                    return StatusCode(500, $"Error deleting file: {ex.Message}");
                }
            }

            return NotFound();
        }

        /// <summary>
        /// Renames a custom overlay image (used when a seasonal section is renamed).
        /// </summary>
        [HttpPut("OverlayImage/Rename")]
        public IActionResult RenameImage([FromQuery] string oldName, [FromQuery] string newName)
        {
            if (string.IsNullOrWhiteSpace(oldName) || string.IsNullOrWhiteSpace(newName))
            {
                return BadRequest("Both oldName and newName must be provided.");
            }

            string oldPath = Path.Combine(_imageDirectory, $"custom_overlay_image_{oldName}.dat");
            string newPath = Path.Combine(_imageDirectory, $"custom_overlay_image_{newName}.dat");

            if (!System.IO.File.Exists(oldPath))
            {
                // If it doesn't exist, there is nothing to rename, but we still consider it a success 
                // since the end state (file with oldName is gone, file with newName doesn't exist yet) is acceptable.
                return Ok(); 
            }

            try
            {
                // If a file with the new name already exists, delete it first to avoid conflicts
                if (System.IO.File.Exists(newPath))
                {
                    System.IO.File.Delete(newPath);
                }
                
                System.IO.File.Move(oldPath, newPath);
                
                var qs = $"?filename={Uri.EscapeDataString(newName)}&";
                var getUrl = $"/MediaBarEnhanced/OverlayImage{qs}t={DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}";
                return Ok(new { url = getUrl });
            }
            catch (Exception ex)
            {
                return StatusCode(500, $"Error renaming file: {ex.Message}");
            }
        }
    }
}