'use strict';
// Minimal RGB canvas + PNG encoder + 5x7 bitmap font. Only used to generate the demo library.
const zlib = require('zlib');

// prettier-ignore
const FONT = {
  A: '01110 10001 10001 11111 10001 10001 10001', B: '11110 10001 10001 11110 10001 10001 11110',
  C: '01110 10001 10000 10000 10000 10001 01110', D: '11110 10001 10001 10001 10001 10001 11110',
  E: '11111 10000 10000 11110 10000 10000 11111', F: '11111 10000 10000 11110 10000 10000 10000',
  G: '01110 10001 10000 10111 10001 10001 01111', H: '10001 10001 10001 11111 10001 10001 10001',
  I: '01110 00100 00100 00100 00100 00100 01110', J: '00111 00010 00010 00010 00010 10010 01100',
  K: '10001 10010 10100 11000 10100 10010 10001', L: '10000 10000 10000 10000 10000 10000 11111',
  M: '10001 11011 10101 10101 10001 10001 10001', N: '10001 10001 11001 10101 10011 10001 10001',
  O: '01110 10001 10001 10001 10001 10001 01110', P: '11110 10001 10001 11110 10000 10000 10000',
  Q: '01110 10001 10001 10001 10101 10010 01101', R: '11110 10001 10001 11110 10100 10010 10001',
  S: '01111 10000 10000 01110 00001 00001 11110', T: '11111 00100 00100 00100 00100 00100 00100',
  U: '10001 10001 10001 10001 10001 10001 01110', V: '10001 10001 10001 10001 10001 01010 00100',
  W: '10001 10001 10001 10101 10101 10101 01010', X: '10001 10001 01010 00100 01010 10001 10001',
  Y: '10001 10001 01010 00100 00100 00100 00100', Z: '11111 00001 00010 00100 01000 10000 11111',
  0: '01110 10001 10011 10101 11001 10001 01110', 1: '00100 01100 00100 00100 00100 00100 01110',
  2: '01110 10001 00001 00010 00100 01000 11111', 3: '11111 00010 00100 00010 00001 10001 01110',
  4: '00010 00110 01010 10010 11111 00010 00010', 5: '11111 10000 11110 00001 00001 10001 01110',
  6: '00110 01000 10000 11110 10001 10001 01110', 7: '11111 00001 00010 00100 01000 01000 01000',
  8: '01110 10001 10001 01110 10001 10001 01110', 9: '01110 10001 10001 01111 00001 00010 01100',
  '.': '00000 00000 00000 00000 00000 01100 01100', '-': '00000 00000 00000 11111 00000 00000 00000',
  ':': '00000 01100 01100 00000 01100 01100 00000', '/': '00000 00001 00010 00100 01000 10000 00000',
  '#': '01010 01010 11111 01010 11111 01010 01010', '<': '00010 00100 01000 10000 01000 00100 00010',
  '>': '01000 00100 00010 00001 00010 00100 01000', '(': '00010 00100 01000 01000 01000 00100 00010',
  ')': '01000 00100 00010 00010 00010 00100 01000', '!': '00100 00100 00100 00100 00100 00000 00100',
  '?': '01110 10001 00001 00010 00100 00000 00100', ',': '00000 00000 00000 00000 01100 00100 01000',
  "'": '00100 00100 01000 00000 00000 00000 00000', '&': '01100 10010 10100 01000 10101 10010 01101',
  '+': '00000 00100 00100 11111 00100 00100 00000', '=': '00000 00000 11111 00000 11111 00000 00000',
};

const CRC = new Int32Array(256).map((_, n) => {
  for (let k = 0; k < 8; k++) n = n & 1 ? 0xedb88320 ^ (n >>> 1) : n >>> 1;
  return n;
});
function crc32(buf) {
  let c = -1;
  for (let i = 0; i < buf.length; i++) c = CRC[(c ^ buf[i]) & 255] ^ (c >>> 8);
  return (c ^ -1) >>> 0;
}
function chunk(type, data) {
  const head = Buffer.alloc(4), crc = Buffer.alloc(4), body = Buffer.concat([Buffer.from(type, 'ascii'), data]);
  head.writeUInt32BE(data.length);
  crc.writeUInt32BE(crc32(body));
  return Buffer.concat([head, body, crc]);
}

function hsl(h, s, l) {
  h = (((h % 360) + 360) % 360) / 30;
  const a = s * Math.min(l, 1 - l);
  const f = n => { const k = (n + h) % 12; return Math.round(255 * (l - a * Math.max(-1, Math.min(k - 3, 9 - k, 1)))); };
  return [f(0), f(8), f(4)];
}

class Canvas {
  constructor(w, h, bg) {
    this.w = w; this.h = h; this.px = Buffer.alloc(w * h * 3);
    if (bg) this.rect(0, 0, w, h, bg);
  }
  rect(x, y, w, h, color) {
    const x0 = Math.max(0, Math.round(x)), y0 = Math.max(0, Math.round(y));
    const x1 = Math.min(this.w, Math.round(x + w)), y1 = Math.min(this.h, Math.round(y + h));
    if (x1 <= x0 || y1 <= y0) return;
    const pat = Buffer.from(color);
    for (let r = y0; r < y1; r++) this.px.fill(pat, (r * this.w + x0) * 3, (r * this.w + x1) * 3);
  }
  frame(x, y, w, h, t, color) {
    this.rect(x, y, w, t, color); this.rect(x, y + h - t, w, t, color);
    this.rect(x, y, t, h, color); this.rect(x + w - t, y, t, h, color);
  }
  textWidth(s, size) { return String(s).length * 6 * size - size; }
  text(s, x, y, size, color, align) {
    s = String(s).toUpperCase();
    if (align === 'center') x -= this.textWidth(s, size) / 2;
    if (align === 'right') x -= this.textWidth(s, size);
    for (const ch of s) {
      const g = FONT[ch];
      if (g) g.split(' ').forEach((row, ry) => {
        for (let rx = 0; rx < 5; rx++) if (row[rx] === '1') this.rect(x + rx * size, y + ry * size, size, size, color);
      });
      x += 6 * size;
    }
  }
  // Text on a padded box, handy for labels that must stay readable on any background.
  label(s, x, y, size, color, box, align = 'center') {
    const w = this.textWidth(s, size), pad = size * 2;
    const left = align === 'center' ? x - w / 2 : align === 'right' ? x - w : x;
    this.rect(left - pad, y - pad, w + 2 * pad, 7 * size + 2 * pad, box);
    this.text(s, left, y, size, color);
  }
  crop(y, h) {
    const c = new Canvas(this.w, h);
    this.px.copy(c.px, 0, y * this.w * 3, (y + h) * this.w * 3);
    return c;
  }
  // Rotate 90° counter-clockwise (so a viewer must rotate it 90° clockwise to see it upright).
  rotateCCW() {
    const c = new Canvas(this.h, this.w);
    for (let y = 0; y < this.h; y++)
      for (let x = 0; x < this.w; x++) this.px.copy(c.px, ((this.w - 1 - x) * c.w + y) * 3, (y * this.w + x) * 3, (y * this.w + x) * 3 + 3);
    return c;
  }
  png() {
    const ihdr = Buffer.alloc(13), stride = this.w * 3, raw = Buffer.alloc((stride + 1) * this.h);
    ihdr.writeUInt32BE(this.w, 0); ihdr.writeUInt32BE(this.h, 4); ihdr[8] = 8; ihdr[9] = 2; // 8 bit RGB
    for (let y = 0; y < this.h; y++) this.px.copy(raw, y * (stride + 1) + 1, y * stride, (y + 1) * stride);
    return Buffer.concat([Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]), chunk('IHDR', ihdr), chunk('IDAT', zlib.deflateSync(raw)), chunk('IEND', Buffer.alloc(0))]);
  }
}

module.exports = { Canvas, hsl };