/** Shared visual constants: palette, notebook covers, sidebar folders. */

export const COLORS = [
  "#0d1117",
  "#e94560",
  "#0f3460",
  "#533483",
  "#e07c24",
  "#21bf73",
  "#fd5e53",
  "#3282b8",
  "#ff6b6b",
  "#4ecdc4",
  "#f7dc6f",
  "#bb8fce",
  "#85c1e9",
  "#f8c471",
  "#82e0aa",
  "#f1948a",
  "#aeb6bf",
  "#ffffff",
  "#f39c12",
  "#000000",
];

export const COVERS = [
  { bg: "linear-gradient(135deg,#0f0c29,#302b63,#24243e)", spine: "#1a1540", accent: "#6c63ff" },
  { bg: "linear-gradient(135deg,#1a1a2e,#16213e,#0f3460)", spine: "#0a1628", accent: "#4fc3f7" },
  { bg: "linear-gradient(135deg,#134e5e,#71b280)", spine: "#0e3d4a", accent: "#a5d6a7" },
  { bg: "linear-gradient(135deg,#8e2de2,#4a00e0)", spine: "#3a0099", accent: "#ce93d8" },
  { bg: "linear-gradient(135deg,#fc4a1a,#f7b733)", spine: "#c43d15", accent: "#ffe082" },
  { bg: "linear-gradient(135deg,#c94b4b,#4b134f)", spine: "#3d0f40", accent: "#f48fb1" },
  { bg: "linear-gradient(135deg,#11998e,#38ef7d)", spine: "#0d7a71", accent: "#b9f6ca" },
  { bg: "linear-gradient(135deg,#373b44,#4286f4)", spine: "#2a2e35", accent: "#90caf9" },
  { bg: "linear-gradient(135deg,#141e30,#243b55)", spine: "#0e1520", accent: "#78909c" },
  { bg: "linear-gradient(135deg,#f12711,#f5af19)", spine: "#c01f0d", accent: "#fff59d" },
  { bg: "linear-gradient(135deg,#2c3e50,#3498db)", spine: "#1e2b38", accent: "#81d4fa" },
  { bg: "linear-gradient(135deg,#0f2027,#203a43,#2c5364)", spine: "#0a171c", accent: "#80cbc4" },
  { bg: "linear-gradient(135deg,#aa4b6b,#6b6b83,#3b8d99)", spine: "#7a3550", accent: "#f48fb1" },
  { bg: "linear-gradient(135deg,#1f1c2c,#928dab)", spine: "#15131f", accent: "#b39ddb" },
  { bg: "linear-gradient(135deg,#654ea3,#eaafc8)", spine: "#4e3c7e", accent: "#f8bbd0" },

];
/**
 * Colours a chapter's icon can be given.
 *
 * A short, named list rather than the full palette: the point is telling one
 * chapter from another at a glance, and twenty near-identical blues do not help
 * with that. Each is legible on both themes.
 */
export const CHAPTER_COLORS = [
  { label: "Red", value: "#e5534b" },
  { label: "Orange", value: "#e07c24" },
  { label: "Yellow", value: "#d4a017" },
  { label: "Green", value: "#2da44e" },
  { label: "Teal", value: "#1f9c96" },
  { label: "Blue", value: "#4a8ff5" },
  { label: "Purple", value: "#a371f7" },
  { label: "Pink", value: "#db61a2" },
];

/* The icon is a key rather than an emoji: the sidebar draws it from the app's
 * own set, so it matches the stroke weight of everything around it and looks
 * the same on every machine. */
export const DEFAULT_FOLDERS = [
  { id: "all", name: "All Notes", icon: "stack" },
  { id: "starred", name: "Starred", icon: "star" },
  { id: "trash", name: "Trash", icon: "trash" },
];

/**
 * A pattern laid over a cover, chosen separately from its colour.
 *
 * Two decisions rather than one list: a cover is a colour *and* a texture, and
 * offering every combination as its own entry would mean fifteen gradients times
 * a dozen patterns in a grid nobody could take in. Picking each in turn is both
 * shorter and gives every combination, not the handful someone wrote out.
 *
 * `layers` are CSS background layers laid **over** the gradient — no image
 * files, nothing to upload, crisp at any size and offline like the rest of the
 * app. They are deliberately faint: a cover is read at the size of a thumb with
 * a title across it, and anything louder fights the title. One idea each, too —
 * two crossed diagonals meant as a chevron came out as noisy plaid at that size.
 */
export const PATTERNS = [
  { emblem: "ring", id: "plain", label: "Plain", layers: "" },
  {
    id: "ruled",
    emblem: "none",
    label: "Ruled",
    layers: "repeating-linear-gradient(0deg,rgba(255,255,255,.12) 0 1px,transparent 1px 17px)",
  },
  {
    id: "grid",
    emblem: "square",
    label: "Grid",
    layers:
      "repeating-linear-gradient(0deg,rgba(255,255,255,.10) 0 1px,transparent 1px 20px), repeating-linear-gradient(90deg,rgba(255,255,255,.10) 0 1px,transparent 1px 20px)",
  },
  {
    id: "pinstripe",
    emblem: "diamond",
    label: "Pinstripe",
    layers: "repeating-linear-gradient(45deg,rgba(255,255,255,.09) 0 6px,transparent 6px 14px)",
  },
  {
    id: "bands",
    emblem: "none",
    label: "Bands",
    layers: "repeating-linear-gradient(0deg,rgba(0,0,0,.18) 0 13px,transparent 13px 26px)",
  },
  {
    id: "dots",
    emblem: "dot",
    label: "Dots",
    layers: "radial-gradient(rgba(255,255,255,.18) 1.4px,transparent 1.5px) 0 0/13px 13px",
  },
  {
    id: "hatch",
    emblem: "cross",
    label: "Cross-hatch",
    layers:
      "repeating-linear-gradient(45deg,rgba(255,255,255,.08) 0 1px,transparent 1px 11px), repeating-linear-gradient(-45deg,rgba(255,255,255,.08) 0 1px,transparent 1px 11px)",
  },
  {
    id: "linen",
    emblem: "arc",
    label: "Linen",
    layers:
      "repeating-linear-gradient(0deg,rgba(255,255,255,.07) 0 1px,transparent 1px 4px), repeating-linear-gradient(90deg,rgba(0,0,0,.07) 0 1px,transparent 1px 4px)",
  },
  {
    id: "ledger",
    emblem: "bars",
    label: "Ledger",
    layers: "repeating-linear-gradient(90deg,rgba(255,255,255,.09) 0 1px,transparent 1px 26px)",
  },
  {
    id: "glow",
    emblem: "none",
    label: "Corner light",
    layers: "radial-gradient(120% 85% at 18% 0%,rgba(255,255,255,.20),transparent 62%)",
  },
  {
    id: "foot",
    emblem: "square",
    label: "Foot band",
    layers: "linear-gradient(0deg,rgba(0,0,0,.34) 0 22%,transparent 22%)",
  },
];

/**
 * Covers written before patterns were their own choice.
 *
 * Twelve patterned entries were appended to `COVERS` for a day, so a notebook
 * may still hold an index into them. Rather than let those repaint themselves,
 * each is read back as the colour-and-pattern pair it was drawn as.
 */
const LEGACY_COVER = {
  15: [11, 1], 16: [2, 2], 17: [3, 3], 18: [9, 4], 19: [5, 5],
  20: [8, 6], 21: [12, 7], 22: [4, 4], 23: [8, 9], 24: [0, 9],
  25: [2, 10], 26: [8, 8],
};

/** The colour and pattern a notebook is actually drawn with. */
export function coverParts(cover, pattern) {
  const legacy = LEGACY_COVER[cover];
  if (legacy) return { cover: legacy[0], pattern: legacy[1] };
  return { cover: ((cover % COVERS.length) + COVERS.length) % COVERS.length, pattern: pattern || 0 };
}

/** The CSS `background` for a cover: its pattern laid over its colour. */
export function coverBackground(cover, pattern) {
  const parts = coverParts(cover, pattern);
  const base = COVERS[parts.cover];
  const layers = PATTERNS[parts.pattern]?.layers;
  return layers ? `${layers}, ${base.bg}` : base.bg;
}

/**
 * The mark in the middle of a cover.
 *
 * It used to be the same pair of rings on every notebook, whatever cover was
 * chosen — which, with the same title frame and the same three dots, is why a
 * shelf of them all looked alike. It belongs to the design now: some wear a
 * ring, some a diamond, and the ones whose pattern already fills the face wear
 * nothing at all.
 */
export const coverEmblem = (cover, pattern) => PATTERNS[coverParts(cover, pattern).pattern]?.emblem || "none";

/** The rest of a cover's colours — the spine, and the accent used beside it. */
export const coverStyle = (cover, pattern) => COVERS[coverParts(cover, pattern).cover];