// Generates src/pdf/decor/scriptWord.generated.ts: the word "invoice" as SVG outline paths (Serenity's
// vertical title) plus a hand-built swash. Run: npm run decor:script-word
//
// The outlines come from Ms Madi Regular (SIL OFL 1.1), read with fontkit at build time. The font file lives in
// scripts/decor/source/ for reproducibility only; it is never copied into public/fonts, never registered with
// react-pdf and never embedded as a font: the PDF carries filled paths, so this is art, not text. the reference design's
// SimpleSerenityScript is not used or traced.
import { readFileSync, writeFileSync } from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";
import ClipperLib from "clipper-lib";
import * as fontkit from "fontkit";

const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "../..");
const FONT = path.join(ROOT, "scripts/decor/source/MsMadi-Regular.ttf");
const OUT = path.join(ROOT, "src/pdf/decor/scriptWord.generated.ts");
const WORD = "invoice";
/** Length of the word's ink along its reading direction, pt (the reference design's word runs from y 780 to y 410). */
const INK_LENGTH = 362;
/**
 * Ms Madi's strokes are heavier than the reference design's hairline script at this size. The glyph contours are merged
 * into one outline and shrunk by this much on every side (pt), which thins the strokes without a
 * paper-coloured stroke trick at render time.
 */
const THIN_BY = 0.95;
/** Clipper works in integers: coordinates are multiplied by this. */
const K = 1000;

const r2 = (v) => Math.round(v * 100) / 100;

/** Flattened outline commands of the laid-out word, in font units (y up, origin on the baseline start). */
function wordCommands(font) {
  const run = font.layout(WORD);
  const cmds = [];
  let x = 0;
  run.glyphs.forEach((g, i) => {
    const pos = run.positions[i];
    for (const c of g.path.commands) {
      const args = [];
      for (let k = 0; k < c.args.length; k += 2) args.push(c.args[k] + x + pos.xOffset, c.args[k + 1] + pos.yOffset);
      cmds.push({ command: c.command, args });
    }
    x += pos.xAdvance;
  });
  return cmds;
}

/**
 * Rotates the word 90 degrees counter-clockwise so it reads bottom to top, scales it to INK_LENGTH and moves
 * its bounding box to the origin (the shrink in `thinned` then re-origins it). In page space (y down) a font point (x, yUp) lands at (-yUp, -x).
 */
function rotate(cmds) {
  const pts = cmds.flatMap((c) => c.args);
  const xs = pts.filter((_, i) => i % 2 === 0);
  const inkLen = Math.max(...xs) - Math.min(...xs);
  const s = INK_LENGTH / inkLen;
  const map = (x, y) => [-y * s, -x * s];
  const mapped = cmds.map((c) => {
    const a = [];
    for (let k = 0; k < c.args.length; k += 2) a.push(...map(c.args[k], c.args[k + 1]));
    return { command: c.command, args: a };
  });
  const mx = mapped.flatMap((c) => c.args.filter((_, i) => i % 2 === 0));
  const my = mapped.flatMap((c) => c.args.filter((_, i) => i % 2 === 1));
  const [x0, y0] = [Math.min(...mx), Math.min(...my)];
  const width = Math.max(...mx) - x0;
  const height = Math.max(...my) - y0;
  const shifted = mapped.map((c) => ({ command: c.command, args: c.args.map((v, i) => (i % 2 === 0 ? v - x0 : v - y0)) }));
  return { cmds: shifted, width, height, scale: s };
}

/** Flattens the outline commands into closed polylines (pt). */
function flatten(cmds) {
  const polys = [];
  let cur = [];
  let last = [0, 0];
  const close = () => {
    if (cur.length > 2) polys.push(cur);
    cur = [];
  };
  for (const c of cmds) {
    if (c.command === "moveTo") {
      close();
      cur = [c.args];
      last = c.args;
    } else if (c.command === "lineTo") {
      cur.push(c.args);
      last = c.args;
    } else if (c.command === "quadraticCurveTo") {
      const [cx, cy, x, y] = c.args;
      for (let i = 1; i <= 10; i++) {
        const t = i / 10;
        const u = 1 - t;
        cur.push([u * u * last[0] + 2 * u * t * cx + t * t * x, u * u * last[1] + 2 * u * t * cy + t * t * y]);
      }
      last = [x, y];
    } else if (c.command === "bezierCurveTo") {
      const [c1x, c1y, c2x, c2y, x, y] = c.args;
      for (let i = 1; i <= 14; i++) {
        const t = i / 14;
        const u = 1 - t;
        cur.push([
          u * u * u * last[0] + 3 * u * u * t * c1x + 3 * u * t * t * c2x + t * t * t * x,
          u * u * u * last[1] + 3 * u * u * t * c1y + 3 * u * t * t * c2y + t * t * t * y,
        ]);
      }
      last = [x, y];
    } else if (c.command === "closePath") close();
  }
  close();
  return polys;
}

/** Union of all contours, shrunk by THIN_BY, as one path. Returns { d, width, height, shiftX } with the box moved to the origin. */
function thinned(cmds) {
  const subj = flatten(cmds).map((poly) => poly.map(([x, y]) => ({ X: Math.round(x * K), Y: Math.round(y * K) })));
  const clipper = new ClipperLib.Clipper();
  clipper.AddPaths(subj, ClipperLib.PolyType.ptSubject, true);
  const merged = new ClipperLib.Paths();
  clipper.Execute(ClipperLib.ClipType.ctUnion, merged, ClipperLib.PolyFillType.pftNonZero, ClipperLib.PolyFillType.pftNonZero);
  const offset = new ClipperLib.ClipperOffset(2, 0.05 * K);
  offset.AddPaths(merged, ClipperLib.JoinType.jtRound, ClipperLib.EndType.etClosedPolygon);
  const eroded = new ClipperLib.Paths();
  offset.Execute(eroded, -THIN_BY * K);
  const clean = ClipperLib.Clipper.CleanPolygons(eroded, 0.04 * K);
  const pts = clean.flat();
  const x0 = Math.min(...pts.map((p) => p.X)) / K;
  const y0 = Math.min(...pts.map((p) => p.Y)) / K;
  const x1 = Math.max(...pts.map((p) => p.X)) / K;
  const y1 = Math.max(...pts.map((p) => p.Y)) / K;
  const d = clean
    .filter((poly) => poly.length > 2)
    .map((poly) => `M${poly.map((p) => `${r2(p.X / K - x0)} ${r2(p.Y / K - y0)}`).join("L")}Z`)
    .join("");
  // Where the word ends (its topmost point): the swash continues from here.
  const top = pts.reduce((a, p) => (p.Y < a.Y ? p : a), pts[0]);
  return { d, width: x1 - x0, height: y1 - y0, anchorX: top.X / K - x0 };
}

/** The swash spine is drawn this much wider than first designed, to match the 25 pt width of the reference design's swash. */
const SWASH_X_SCALE = 1.4;

const bez = (p0, p1, p2, p3, t) => {
  const u = 1 - t;
  return [0, 1].map((k) => u * u * u * p0[k] + 3 * u * u * t * p1[k] + 3 * u * t * t * p2[k] + t * t * t * p3[k]);
};

/**
 * A tapered swash: a spine of cubic segments, thickened by a sine envelope into one filled outline.
 * Own drawing, in a 28 x 270 pt box; it continues upward from the end of the word like the reference design's does.
 */
function swash() {
  const segs = [
    [[19, 270], [-2, 222], [30, 176], [13, 130]],
    [[13, 130], [-4, 86], [26, 52], [15, 14]],
    [[15, 14], [11, 2], [22, -1], [24, 7]],
  ];
  const spine = [];
  segs.forEach((s, si) => {
    for (let i = si === 0 ? 0 : 1; i <= 40; i++) { const q = bez(s[0], s[1], s[2], s[3], i / 40); spine.push([q[0] * SWASH_X_SCALE, q[1]]); }
  });
  const n = spine.length;
  const left = [];
  const right = [];
  spine.forEach((p, i) => {
    const a = spine[Math.max(0, i - 1)];
    const b = spine[Math.min(n - 1, i + 1)];
    const len = Math.hypot(b[0] - a[0], b[1] - a[1]) || 1;
    const nx = -(b[1] - a[1]) / len;
    const ny = (b[0] - a[0]) / len;
    const u = i / (n - 1);
    const half = 0.25 + 1.25 * Math.pow(Math.sin(Math.PI * Math.min(1, u * 1.15)), 0.9);
    left.push([p[0] + nx * half, p[1] + ny * half]);
    right.push([p[0] - nx * half, p[1] - ny * half]);
  });
  const all = [...left, ...right.reverse()];
  const minY = Math.min(...all.map((p) => p[1]));
  const minX = Math.min(...all.map((p) => p[0]));
  const maxX = Math.max(...all.map((p) => p[0]));
  const maxY = Math.max(...all.map((p) => p[1]));
  const pts = all.map(([x, y]) => [x - minX, y - minY]);
  // The spine starts at the bottom of the box: that point meets the end of the word.
  const anchorX = spine[0][0] - minX;
  const d = `M${pts.map((p) => p.map(r2).join(" ")).join("L")}Z`;
  return { d, width: r2(maxX - minX), height: r2(maxY - minY), anchorX: r2(anchorX) };
}

const font = fontkit.create(readFileSync(FONT));
const rotated = rotate(wordCommands(font));
const thin = thinned(rotated.cmds);
const word = { d: thin.d, width: thin.width, height: thin.height, anchorX: thin.anchorX };
const sw = swash();
const ts = `// Generated by \`npm run decor:script-word\` (scripts/decor/script-word.mjs). Do not edit by hand.
//
// Outline paths of the word "${WORD}" traced from Ms Madi Regular, rotated 90 degrees counter-clockwise (reads
// bottom to top), plus a hand-drawn swash. Ms Madi is Copyright 2018 The Ms Madi Project Authors
// (https://github.com/googlefonts/ms-madi), licensed under the SIL Open Font License 1.1 (scripts/decor/source/OFL-MsMadi.txt).
// The font itself is not bundled or registered: only these vector outlines are drawn, as art.

export interface ScriptArt {
  /** SVG path data in a box of \`width\` x \`height\` pt starting at the origin (page space, y down). */
  d: string;
  width: number;
  height: number;
  /** x inside the box where the word ends (word) or the swash starts (swash): they are joined here. */
  anchorX: number;
}

export const SCRIPT_WORD: ScriptArt = {
  d: ${JSON.stringify(word.d)},
  width: ${r2(word.width)},
  height: ${r2(word.height)},
  anchorX: ${r2(word.anchorX)},
};

export const SCRIPT_SWASH: ScriptArt = {
  d: ${JSON.stringify(sw.d)},
  width: ${sw.width},
  height: ${sw.height},
  anchorX: ${sw.anchorX},
};
`;
writeFileSync(OUT, ts);
console.log(`scriptWord.generated.ts: word ${r2(word.width)} x ${r2(word.height)} pt swash ${sw.width} x ${sw.height} pt`);