using System.Collections.Generic;
using Godot;

namespace IslaApocalypse.Tools
{
	/// <summary>
	/// A 5x7 bitmap font, drawn straight into a <see cref="Image"/>.
	///
	/// ═══ WHY A HAND-ROLLED FONT AND NOT GODOT'S ═══
	///
	/// Godot's <c>Font</c> renders through a CanvasItem, which means a viewport — the SubViewport
	/// capture path the renderer deliberately avoids, because it awaits render frames and is why
	/// `--headless` hangs. A legend is a handful of digits; paying the whole capture path for it
	/// would be a poor trade, and would drag a frame-loop dependency into a tool that currently
	/// needs no display at all.
	///
	/// So: 5x7 glyphs, integer-scaled, drawn per-pixel. Digits, a few punctuation marks and A–Z.
	/// Unknown characters draw as blank rather than throwing — a legend with a missing letter is a
	/// cosmetic problem, not a reason to lose the render.
	/// </summary>
	public static class TinyFont
	{
		public const int GlyphW = 5;
		public const int GlyphH = 7;

		// Each glyph is 7 rows of 5 columns. '#' = ink. Written out rather than hex-packed so a
		// reader can verify a letter by looking at it.
		private static readonly Dictionary<char, string[]> Glyphs = new()
		{
			[' '] = new[] { ".....", ".....", ".....", ".....", ".....", ".....", "....." },
			['.'] = new[] { ".....", ".....", ".....", ".....", ".....", "..##.", "..##." },
			['-'] = new[] { ".....", ".....", ".....", "#####", ".....", ".....", "....." },
			[':'] = new[] { ".....", "..##.", "..##.", ".....", "..##.", "..##.", "....." },
			['/'] = new[] { "....#", "...#.", "...#.", "..#..", ".#...", ".#...", "#...." },
			['('] = new[] { "...#.", "..#..", ".#...", ".#...", ".#...", "..#..", "...#." },
			[')'] = new[] { ".#...", "..#..", "...#.", "...#.", "...#.", "..#..", ".#..." },

			['0'] = new[] { ".###.", "#...#", "#..##", "#.#.#", "##..#", "#...#", ".###." },
			['1'] = new[] { "..#..", ".##..", "..#..", "..#..", "..#..", "..#..", ".###." },
			['2'] = new[] { ".###.", "#...#", "....#", "...#.", "..#..", ".#...", "#####" },
			['3'] = new[] { "#####", "...#.", "..#..", "...#.", "....#", "#...#", ".###." },
			['4'] = new[] { "...#.", "..##.", ".#.#.", "#..#.", "#####", "...#.", "...#." },
			['5'] = new[] { "#####", "#....", "####.", "....#", "....#", "#...#", ".###." },
			['6'] = new[] { "..##.", ".#...", "#....", "####.", "#...#", "#...#", ".###." },
			['7'] = new[] { "#####", "....#", "...#.", "..#..", ".#...", ".#...", ".#..." },
			['8'] = new[] { ".###.", "#...#", "#...#", ".###.", "#...#", "#...#", ".###." },
			['9'] = new[] { ".###.", "#...#", "#...#", ".####", "....#", "...#.", ".##.." },

			['A'] = new[] { ".###.", "#...#", "#...#", "#####", "#...#", "#...#", "#...#" },
			['B'] = new[] { "####.", "#...#", "#...#", "####.", "#...#", "#...#", "####." },
			['C'] = new[] { ".###.", "#...#", "#....", "#....", "#....", "#...#", ".###." },
			['D'] = new[] { "###..", "#..#.", "#...#", "#...#", "#...#", "#..#.", "###.." },
			['E'] = new[] { "#####", "#....", "#....", "####.", "#....", "#....", "#####" },
			['F'] = new[] { "#####", "#....", "#....", "####.", "#....", "#....", "#...." },
			['G'] = new[] { ".###.", "#...#", "#....", "#.###", "#...#", "#...#", ".####" },
			['H'] = new[] { "#...#", "#...#", "#...#", "#####", "#...#", "#...#", "#...#" },
			['I'] = new[] { ".###.", "..#..", "..#..", "..#..", "..#..", "..#..", ".###." },
			['J'] = new[] { "..###", "...#.", "...#.", "...#.", "...#.", "#..#.", ".##.." },
			['K'] = new[] { "#...#", "#..#.", "#.#..", "##...", "#.#..", "#..#.", "#...#" },
			['L'] = new[] { "#....", "#....", "#....", "#....", "#....", "#....", "#####" },
			['M'] = new[] { "#...#", "##.##", "#.#.#", "#.#.#", "#...#", "#...#", "#...#" },
			['N'] = new[] { "#...#", "##..#", "#.#.#", "#..##", "#...#", "#...#", "#...#" },
			['O'] = new[] { ".###.", "#...#", "#...#", "#...#", "#...#", "#...#", ".###." },
			['P'] = new[] { "####.", "#...#", "#...#", "####.", "#....", "#....", "#...." },
			['Q'] = new[] { ".###.", "#...#", "#...#", "#...#", "#.#.#", "#..#.", ".##.#" },
			['R'] = new[] { "####.", "#...#", "#...#", "####.", "#.#..", "#..#.", "#...#" },
			['S'] = new[] { ".####", "#....", "#....", ".###.", "....#", "....#", "####." },
			['T'] = new[] { "#####", "..#..", "..#..", "..#..", "..#..", "..#..", "..#.." },
			['U'] = new[] { "#...#", "#...#", "#...#", "#...#", "#...#", "#...#", ".###." },
			['V'] = new[] { "#...#", "#...#", "#...#", "#...#", "#...#", ".#.#.", "..#.." },
			['W'] = new[] { "#...#", "#...#", "#...#", "#.#.#", "#.#.#", "##.##", "#...#" },
			['X'] = new[] { "#...#", "#...#", ".#.#.", "..#..", ".#.#.", "#...#", "#...#" },
			['Y'] = new[] { "#...#", "#...#", ".#.#.", "..#..", "..#..", "..#..", "..#.." },
			['Z'] = new[] { "#####", "....#", "...#.", "..#..", ".#...", "#....", "#####" },
		};

		/// <summary>Pixel width of <paramref name="text"/> at the given integer scale.</summary>
		public static int Width(string text, int scale) => text.Length * (GlyphW + 1) * scale;

		/// <summary>Pixel height of one line at the given integer scale.</summary>
		public static int Height(int scale) => GlyphH * scale;

		/// <summary>
		/// Draw <paramref name="text"/> with its top-left at (x, y). Uppercases automatically —
		/// the font has no lowercase, and silently dropping letters would be worse than shouting.
		/// </summary>
		public static void Draw(Image img, string text, int x, int y, int scale, Color color)
		{
			int cursor = x;
			foreach (char raw in text.ToUpperInvariant())
			{
				if (Glyphs.TryGetValue(raw, out string[] g))
				{
					for (int row = 0; row < GlyphH; row++)
						for (int col = 0; col < GlyphW; col++)
							if (g[row][col] == '#')
								FillCell(img, cursor + col * scale, y + row * scale, scale, color);
				}
				cursor += (GlyphW + 1) * scale;
			}
		}

		private static void FillCell(Image img, int px, int py, int scale, Color color)
		{
			for (int dy = 0; dy < scale; dy++)
				for (int dx = 0; dx < scale; dx++)
				{
					int tx = px + dx, ty = py + dy;
					if (tx >= 0 && ty >= 0 && tx < img.GetWidth() && ty < img.GetHeight())
						img.SetPixel(tx, ty, color);
				}
		}
	}
}