import type { Canvas } from "./canvas.ts";
import { parseColor } from "./line.ts";

const GLYPH_WIDTH = 5;
const GLYPH_HEIGHT = 7;

/**
 * A tiny 5x7 pixel font, hand-drawn as ASCII art (# = lit, . = off) so each
 * glyph's source reads as the letter it draws. Covers A-Z, a-z, digits,
 * and the punctuation a tile-attribution string, a route title, or a
 * distance/elevation stat is likely to need.
 */
const GLYPHS_ASCII: Record<string, string[]> = {
  " ": [".....", ".....", ".....", ".....", ".....", ".....", "....."],
  ",": [".....", ".....", ".....", ".....", "..#..", "..#..", ".#..."],
  ".": [".....", ".....", ".....", ".....", ".....", "..#..", "....."],
  "©": [".###.", "#...#", "#.#.#", "#.#..", "#.#.#", "#...#", ".###."],
  "+": [".....", "..#..", "..#..", "#####", "..#..", "..#..", "....."],
  "-": [".....", ".....", ".....", "#####", ".....", ".....", "....."],
  "'": ["..#..", "..#..", ".#...", ".....", ".....", ".....", "....."],
  "(": ["...#.", "..#..", ".#...", ".#...", ".#...", "..#..", "...#."],
  ")": [".#...", "..#..", "...#.", "...#.", "...#.", "..#..", ".#..."],
  "!": ["..#..", "..#..", "..#..", "..#..", "..#..", ".....", "..#.."],
  "?": [".###.", "#...#", "....#", "..##.", "..#..", ".....", "..#.."],
  ":": [".....", ".....", "..#..", ".....", "..#..", ".....", "....."],

  "0": [".###.", "#...#", "#..##", "#.#.#", "##..#", "#...#", ".###."],
  "1": ["..#..", ".##..", "..#..", "..#..", "..#..", "..#..", ".###."],
  "2": [".###.", "#...#", "....#", "...#.", "..#..", ".#...", "#####"],
  "3": [".###.", "#...#", "....#", "..##.", "....#", "#...#", ".###."],
  "4": ["...#.", "..##.", ".#.#.", "#..#.", "#####", "...#.", "...#."],
  "5": ["#####", "#....", "#....", "####.", "....#", "#...#", ".###."],
  "6": ["..##.", ".#...", "#....", "####.", "#...#", "#...#", ".###."],
  "7": ["#####", "....#", "...#.", "..#..", ".#...", ".#...", ".#..."],
  "8": [".###.", "#...#", "#...#", ".###.", "#...#", "#...#", ".###."],
  "9": [".###.", "#...#", "#...#", ".####", "....#", "...#.", ".##.."],

  A: [".###.", "#...#", "#...#", "#####", "#...#", "#...#", "#...#"],
  B: ["####.", "#...#", "#...#", "####.", "#...#", "#...#", "####."],
  C: [".####", "#....", "#....", "#....", "#....", "#....", ".####"],
  D: ["###..", "#..#.", "#...#", "#...#", "#...#", "#..#.", "###.."],
  E: ["#####", "#....", "#....", "####.", "#....", "#....", "#####"],
  F: ["#####", "#....", "#....", "####.", "#....", "#....", "#...."],
  G: [".####", "#....", "#....", "#.###", "#...#", "#...#", ".####"],
  H: ["#...#", "#...#", "#...#", "#####", "#...#", "#...#", "#...#"],
  I: ["#####", "..#..", "..#..", "..#..", "..#..", "..#..", "#####"],
  J: ["..###", "...#.", "...#.", "...#.", "...#.", "#..#.", ".##.."],
  K: ["#...#", "#..#.", "#.#..", "##...", "#.#..", "#..#.", "#...#"],
  L: ["#....", "#....", "#....", "#....", "#....", "#....", "#####"],
  M: ["#...#", "##.##", "#.#.#", "#...#", "#...#", "#...#", "#...#"],
  N: ["#...#", "##..#", "#.#.#", "#..##", "#...#", "#...#", "#...#"],
  O: [".###.", "#...#", "#...#", "#...#", "#...#", "#...#", ".###."],
  P: ["####.", "#...#", "#...#", "####.", "#....", "#....", "#...."],
  Q: [".###.", "#...#", "#...#", "#...#", "#.#.#", "#..#.", ".##.#"],
  R: ["####.", "#...#", "#...#", "####.", "#.#..", "#..#.", "#...#"],
  S: [".####", "#....", "#....", ".###.", "....#", "....#", "####."],
  T: ["#####", "..#..", "..#..", "..#..", "..#..", "..#..", "..#.."],
  U: ["#...#", "#...#", "#...#", "#...#", "#...#", "#...#", ".###."],
  V: ["#...#", "#...#", "#...#", "#...#", "#...#", ".#.#.", "..#.."],
  W: ["#...#", "#...#", "#...#", "#.#.#", "#.#.#", "##.##", "#...#"],
  X: ["#...#", ".#.#.", "..#..", "..#..", "..#..", ".#.#.", "#...#"],
  Y: ["#...#", ".#.#.", "..#..", "..#..", "..#..", "..#..", "..#.."],
  Z: ["#####", "....#", "...#.", "..#..", ".#...", "#....", "#####"],

  a: [".....", ".....", ".###.", "....#", ".####", "#...#", ".####"],
  b: ["#....", "#....", "####.", "#...#", "#...#", "#...#", "####."],
  c: [".....", ".....", ".####", "#....", "#....", "#....", ".####"],
  d: ["....#", "....#", ".####", "#...#", "#...#", "#...#", ".####"],
  e: [".....", ".....", ".###.", "#...#", "#####", "#....", ".####"],
  f: ["..##.", ".#..#", ".#...", "###..", ".#...", ".#...", ".#..."],
  g: [".....", ".####", "#...#", "#...#", ".####", "....#", ".###."],
  h: ["#....", "#....", "####.", "#...#", "#...#", "#...#", "#...#"],
  i: ["..#..", ".....", ".##..", "..#..", "..#..", "..#..", ".###."],
  j: ["...#.", ".....", "..##.", "...#.", "...#.", "#..#.", ".##.."],
  k: ["#....", "#....", "#..#.", "#.#..", "##...", "#.#..", "#..#."],
  l: [".##..", "..#..", "..#..", "..#..", "..#..", "..#..", ".###."],
  m: [".....", ".....", "##.#.", "#.#.#", "#.#.#", "#.#.#", "#...#"],
  n: [".....", ".....", "####.", "#...#", "#...#", "#...#", "#...#"],
  o: [".....", ".....", ".###.", "#...#", "#...#", "#...#", ".###."],
  p: [".....", ".....", "####.", "#...#", "#...#", "####.", "#...."],
  q: [".....", ".....", ".####", "#...#", "#...#", ".####", "....#"],
  r: [".....", ".....", "#.##.", "##..#", "#....", "#....", "#...."],
  s: [".....", ".....", ".####", "#....", ".###.", "....#", "####."],
  t: ["..#..", "..#..", "#####", "..#..", "..#..", "..#..", "...##"],
  u: [".....", ".....", "#...#", "#...#", "#...#", "#...#", ".####"],
  v: [".....", ".....", "#...#", "#...#", "#...#", ".#.#.", "..#.."],
  w: [".....", ".....", "#...#", "#...#", "#.#.#", "#.#.#", ".#.#."],
  x: [".....", ".....", "#...#", ".#.#.", "..#..", ".#.#.", "#...#"],
  y: [".....", "#...#", "#...#", "#...#", "#...#", ".####", "....#"],
  z: [".....", ".....", "#####", "...#.", "..#..", ".#...", "#####"],
};

function parseGlyph(rows: readonly string[]): boolean[] {
  const bits: boolean[] = [];
  for (const row of rows) {
    for (const ch of row) bits.push(ch === "#");
  }
  return bits;
}

const GLYPHS = new Map<string, boolean[]>(
  Object.entries(GLYPHS_ASCII).map(([ch, rows]) => [ch, parseGlyph(rows)]),
);

export interface TextStyle {
  color?: string;
  scale?: number;
  opacity?: number;
}

/** The pixel size a string of `text` will occupy when drawn at the given scale. */
export function measureText(text: string, scale = 1): { width: number; height: number } {
  if (text.length === 0) return { width: 0, height: GLYPH_HEIGHT * scale };
  const advance = (GLYPH_WIDTH + 1) * scale;
  return { width: text.length * advance - scale, height: GLYPH_HEIGHT * scale };
}

/**
 * Draws `text` with its top-left corner at (x, y). Throws on any character
 * outside the supported set (see GLYPHS_ASCII above) rather than silently
 * dropping it — attribution text is a policy requirement, not decoration.
 */
export function drawText(
  canvas: Canvas,
  text: string,
  x: number,
  y: number,
  style: TextStyle = {},
): void {
  const scale = style.scale ?? 1;
  const opacity = style.opacity ?? 1;
  const [r, g, b] = parseColor(style.color ?? "#000000");

  let cursorX = x;
  for (const ch of text) {
    const glyph = GLYPHS.get(ch);
    if (!glyph) throw new Error(`unsupported character in text: ${JSON.stringify(ch)}`);

    for (let row = 0; row < GLYPH_HEIGHT; row++) {
      for (let col = 0; col < GLYPH_WIDTH; col++) {
        if (!glyph[row * GLYPH_WIDTH + col]) continue;
        for (let sy = 0; sy < scale; sy++) {
          for (let sx = 0; sx < scale; sx++) {
            canvas.blend(cursorX + col * scale + sx, y + row * scale + sy, r, g, b, opacity);
          }
        }
      }
    }
    cursorX += (GLYPH_WIDTH + 1) * scale;
  }
}