const STYLE_VALUE_KEYS = [
  "backgroundColor", "textColor", "fontFamily", "fontSize", "fontWeight", "fontStyle",
  "synopsisTextColor", "synopsisFontFamily", "synopsisFontSize", "synopsisFontWeight",
  "synopsisFontStyle", "submapBackgroundColor", "submapBorderColor"
];

/** Return a detached value at the model boundary. */
function copy(value) {
  return JSON.parse(JSON.stringify(value));
}

/** Return a six-digit HTML colour or the supplied fallback. */
function cmapColorValue(value, fallback = "#f3f6f8") {
  return /^#[0-9a-f]{6}$/i.test(value || "") ? value.toLowerCase() : fallback;
}

/** Convert a stored CSS font size to typographic points. */
function cmapFontSizeInPoints(value, baseSize = 11) {
  const size = Number.parseFloat(value);
  if (!Number.isFinite(size)) return baseSize;
  if (/px$/i.test(value || "")) return size * 0.75;
  if (/em$/i.test(value || "")) return size * baseSize;
  if (/%$/i.test(value || "")) return (size / 100) * baseSize;
  return size;
}

/** Normalize an editable font size to the range accepted by the backend. */
function normalizedCmapFontSize(value, fallback) {
  const size = Number(value);
  const usableSize = Number.isFinite(size) ? size : fallback;
  return Math.max(6, Math.min(54, Math.round(usableSize * 2) / 2));
}

/** Format a typographic point value for a form input. */
function displayCmapFontSize(value) {
  return String(Math.round(value * 2) / 2);
}

/**
 * Own the wiki-wide CMap styles and colour palette.
 * The backend supplies the default style; this model validates UI changes
 * against that style and exposes detached values to its consumers.
 */
export class CmapAppearance {
  constructor(data) {
    this.replace(data);
  }

  get styles() {
    return copy(this._styles);
  }

  get palette() {
    return [...this._palette];
  }

  get defaultValues() {
    return copy(this._styles.find((style) => style.id === "default").values);
  }

  /** Replace the aggregate with a complete backend representation. */
  replace(data) {
    const styles = Array.isArray(data?.styles) ? data.styles : [];
    const defaultStyle = styles.find((style) => style?.id === "default");
    const palette = Array.isArray(data?.palette) ? data.palette : [];
    const completeDefault = defaultStyle?.values &&
      STYLE_VALUE_KEYS.every((key) => Object.hasOwn(defaultStyle.values, key));
    if (!completeDefault || palette.length === 0) {
      throw new TypeError("CMap appearance requires a default style and colour palette");
    }
    const seenIds = new Set();
    this._styles = styles.map((style) => {
      const id = typeof style?.id === "string" ? style.id.trim() : "";
      const hasName = typeof style?.name === "string" && style.name.trim();
      const hasNameKey = typeof style?.nameKey === "string" && style.nameKey.trim();
      if (!/^[A-Za-z0-9_-]+$/.test(id) || seenIds.has(id) ||
          (!hasName && !hasNameKey) || !style.values) {
        throw new TypeError("CMap appearance contains an invalid style");
      }
      seenIds.add(id);
      return {
        id,
        ...(hasNameKey ? { nameKey: style.nameKey.trim() } : { name: style.name.trim() }),
        protected: id === "default",
        values: this.normalizeValues(style.values, defaultStyle.values)
      };
    });
    this._palette = palette.map((color) => {
      if (!/^#[0-9a-f]{6}$/i.test(color || "")) {
        throw new TypeError("CMap appearance contains an invalid palette colour");
      }
      return color.toLowerCase();
    });
    return this;
  }

  /** Return the complete detached representation for backend storage. */
  toData() {
    return { styles: this.styles, palette: this.palette };
  }

  /** Normalize editable values using the backend-provided default style. */
  normalizeValues(values, fallbackValues = null) {
    if (!values || typeof values !== "object") return null;
    const fallback = fallbackValues || this.defaultValues;
    const fontSize = normalizedCmapFontSize(values.fontSize, fallback.fontSize);
    return {
      backgroundColor: cmapColorValue(values.backgroundColor, fallback.backgroundColor),
      textColor: cmapColorValue(values.textColor, fallback.textColor),
      fontFamily: typeof values.fontFamily === "string" && values.fontFamily.trim() ?
        values.fontFamily.trim() : fallback.fontFamily,
      fontSize,
      fontWeight: String(values.fontWeight) === "400" ? "400" : "700",
      fontStyle: values.fontStyle === "italic" ? "italic" : "normal",
      synopsisTextColor: cmapColorValue(values.synopsisTextColor, fallback.synopsisTextColor),
      synopsisFontFamily: typeof values.synopsisFontFamily === "string" && values.synopsisFontFamily.trim() ?
        values.synopsisFontFamily.trim() : fallback.synopsisFontFamily,
      synopsisFontSize: normalizedCmapFontSize(
        values.synopsisFontSize, Math.max(6, fontSize - 2)),
      synopsisFontWeight: String(values.synopsisFontWeight) === "700" ? "700" : "400",
      synopsisFontStyle: values.synopsisFontStyle === "italic" ? "italic" : "normal",
      submapBackgroundColor: cmapColorValue(
        values.submapBackgroundColor, fallback.submapBackgroundColor),
      submapBorderColor: cmapColorValue(values.submapBorderColor, fallback.submapBorderColor)
    };
  }

  style(id) {
    const style = this._styles.find((candidate) => candidate.id === id);
    return style ? copy(style) : null;
  }

  matchingStyleId(values) {
    const normalized = this.normalizeValues(values);
    if (!normalized) return "";
    const style = this._styles.find((candidate) =>
      STYLE_VALUE_KEYS.every((key) => candidate.values[key] === normalized[key]));
    return style?.id || "";
  }

  /** Insert or replace one non-default named style. */
  putStyle(style) {
    const name = typeof style?.name === "string" ? style.name.trim() : "";
    const id = typeof style?.id === "string" ? style.id.trim() : "";
    if (!/^[A-Za-z0-9_-]+$/.test(id) || id === "default" || !name) {
      throw new TypeError("A custom CMap style requires an id and name");
    }
    const normalized = {
      id,
      name,
      protected: false,
      values: this.normalizeValues(style.values)
    };
    const existingIndex = this._styles.findIndex((candidate) => candidate.id === normalized.id);
    if (existingIndex < 0) this._styles.push(normalized);
    else this._styles.splice(existingIndex, 1, normalized);
    return copy(normalized);
  }

  /** Delete a custom style and refuse deletion of protected styles. */
  deleteStyle(id) {
    const style = this._styles.find((candidate) => candidate.id === id);
    if (!style || style.protected) return false;
    this._styles = this._styles.filter((candidate) => candidate.id !== id);
    return true;
  }

  setPaletteColor(index, color) {
    if (!Number.isInteger(index) || index < 0 || index >= this._palette.length ||
        !/^#[0-9a-f]{6}$/i.test(color || "")) return false;
    this._palette[index] = color.toLowerCase();
    return true;
  }
}

export {
  cmapColorValue,
  cmapFontSizeInPoints,
  displayCmapFontSize,
  normalizedCmapFontSize
};