using System;
using System.Collections.Generic;
using System.Drawing;
using System.Text;
using PDFPatcher.Common;
using MuPdfSharp;
using DrawingPoint = System.Drawing.Point;

namespace PDFPatcher.Functions.Editor
{
	public enum ContentDirection
	{
		TopToDown,
		RightToLeft
	}

	public enum MouseMode
	{
		Move, Selection
	}

	public readonly struct PagePoint
	{
		public static readonly PagePoint Empty;

		public readonly int Page;
		public readonly float ImageX, ImageY;
		public PagePoint(int pageNumber, float imageX, float imageY) {
			Page = pageNumber;
			ImageX = imageX;
			ImageY = imageY;
		}
	}

	public readonly struct PagePosition
	{
		public static readonly PagePosition Empty;
		/// <summary>
		/// 所在页码。
		/// </summary>
		public readonly int Page;
		/// <summary>
		/// 在 PDF 页面空间上的位置。
		/// </summary>
		public readonly float PageX, PageY;
		/// <summary>
		/// 在渲染页面上的位置。
		/// </summary>
		public readonly int ImageX, ImageY;
		/// <summary>
		/// 当前点是否在页面上。
		/// </summary>
		public readonly bool IsInPage;
		public MuPdfSharp.Point Location => new MuPdfSharp.Point(PageX, PageY);
		internal PagePosition(int page, PointF position, DrawingPoint imagePosition, bool isInPage)
			: this(page, position.X, position.Y, imagePosition.X, imagePosition.Y, isInPage) { }

		internal PagePosition(int page, float x, float y, int imageX, int imageY, bool isInPage) {
			Page = page;
			PageX = x;
			PageY = y;
			ImageX = imageX;
			ImageY = imageY;
			IsInPage = isInPage;
		}
	}

	public readonly struct PageRegion
	{
		public static readonly PageRegion Empty = new PageRegion();

		public readonly int Page;
		public readonly MuPdfSharp.Rectangle Region;

		internal PageRegion(PagePosition p1, PagePosition p2) {
			if (p1.Page != p2.Page) {
				Page = 0;
				Region = new MuPdfSharp.Rectangle();
			}
			else {
				Page = p1.Page;
				Region = new MuPdfSharp.Rectangle(p1.PageX, p1.PageY, p2.PageX, p2.PageY);
			}
		}
	}

	public readonly struct TextInfo : IMuTextLines, IMuTextSpans, IMuBoundedElement
	{
		public readonly MuPage Page;

		/// <summary>获取文本字符的位置边框。</summary>
		public readonly MuPdfSharp.Rectangle TextBBox;
		/// <summary>获取文本位置以下的文本行。</summary>
		public readonly List<MuTextLine> Lines;
		public readonly List<MuTextSpan> Spans;

		public TextInfo(MuPage page, MuPdfSharp.Rectangle bbox, List<MuTextLine> textLines, List<MuTextSpan> spans) {
			Page = page;
			TextBBox = bbox;
			Lines = textLines;
			Spans = spans;
		}

		IEnumerable<MuTextLine> IMuTextLines.Lines => Lines;

		public MuPdfSharp.Rectangle BBox => TextBBox;

		IEnumerable<MuTextSpan> IMuTextSpans.Spans => Spans;

		public IEnumerable<MuFont> GetFonts() {
			if (Spans.HasContent() == false) {
				yield break;
			}
			HashSet<IntPtr> fonts = new HashSet<IntPtr>();
			foreach (var span in Spans) {
				if (fonts.Add(span.FontID)) {
					yield return Page.GetFont(span);
				}
			}
		}

		public IEnumerable<string> GetFontNames() {
			if (Spans.HasContent() == false) {
				yield break;
			}
			HashSet<string> fonts = new HashSet<string>();
			foreach (var span in Spans) {
				var f = Page.GetFont(span);
				if (fonts.Add(f.Name)) {
					yield return f.Name;
				}
			}
		}

		public override string ToString() {
			if (Lines == null) {
				return null;
			}
			var c = Lines.Count;
			if (c == 1) {
				return Lines[0].Text;
			}
			var sb = new StringBuilder();
			var b = Lines[0].BBox;
			foreach (var line in Lines) {
				if (line.BBox.IsHorizontalNeighbor(b)) {
					sb.Append(line.Text);
					b = b.Union(line.BBox);
				}
				else {
					b = line.BBox;
					sb.AppendLine();
					sb.Append(line.Text);
				}
			}
			return sb.ToString();
		}
	}

	public readonly struct Selection
	{
		readonly RenderResultCache _cache;
		public static readonly Selection Empty;

		/// <summary>
		/// 获取选中区域的页码。
		/// </summary>
		public readonly int Page;
		/// <summary>
		/// 获取选中区域在页面上的矩形区域（屏幕左下角点坐标为0，0）。
		/// </summary>
		public readonly MuPdfSharp.Rectangle PageRegion;
		/// <summary>
		/// 获取选中区域在显示图片上的矩形区域。
		/// </summary>
		public readonly RectangleF ImageRegion;

		public Bitmap GetSelectedBitmap() {
			_cache.LoadPage(Page);
			var p = _cache.GetBitmap(Page);
			var clip = new MuPdfSharp.Rectangle(
					ImageRegion.Left < 0 ? 0 : ImageRegion.Left,
					ImageRegion.Top < 0 ? 0 : ImageRegion.Top,
					ImageRegion.Right > p.Width ? p.Width : ImageRegion.Right,
					ImageRegion.Bottom > p.Height ? p.Height : ImageRegion.Bottom
				);
			return p.Clone(clip, p.PixelFormat);
		}

		public Selection(RenderResultCache cache, int page, MuPdfSharp.Rectangle region, RectangleF imageRegion) {
			Page = page;
			PageRegion = region;
			ImageRegion = imageRegion;
			_cache = cache;
		}
	}
}