/**
 * @factory/editor — slash command registry + fuzzy search (TASK-0054).
 *
 * The single, data-driven source for the `/` menu, the block `+` menu and
 * the command palette (PRODUCT-SPEC §6, ux-requirements §12: every command
 * is reachable from the menus too — never palette-only). Icons are NOT
 * part of the registry (this package has no React/DOM dependency);
 * apps/web attaches its own icon per command id.
 *
 * `blockType` values are the wire format (`@factory/shared` snake_case
 * BlockType); `special` marks commands that are not a plain block insert
 * (database creation flow, synced block, template).
 */

import type { BlockType } from "@factory/shared/dto";

/** One slash command (a row of the `/` menu). */
export interface SlashCommandDef {
  /** Stable id (menu icon key, E2E anchor). */
  readonly id: string;
  /** Display label (exactly what the user sees). */
  readonly label: string;
  /** Space-separated extra match terms for fuzzy search. */
  readonly keywords: string;
  /** The block type inserted when picked (plain-block commands). */
  readonly blockType?: BlockType;
  /** Non-insert commands. */
  readonly special?: "database" | "synced" | "template";
  /** Menu group header. */
  readonly group: string;
  /** Keyboard hint shown in the menu (`kbd`). */
  readonly shortcut?: string;
}

/** All slash commands, in menu order (grouped by `group`). */
export const SLASH_COMMANDS: readonly SlashCommandDef[] = [
  // --- Basic writing -------------------------------------------------------
  { id: "paragraph", label: "Text", keywords: "text plain paragraph default", blockType: "paragraph", group: "Basic writing" },
  { id: "heading_1", label: "Heading 1", keywords: "h1 title big large", blockType: "heading_1", group: "Basic writing" },
  { id: "heading_2", label: "Heading 2", keywords: "h2 subtitle medium", blockType: "heading_2", group: "Basic writing" },
  { id: "heading_3", label: "Heading 3", keywords: "h3 subheading small", blockType: "heading_3", group: "Basic writing" },
  { id: "quote", label: "Quote", keywords: "quotation blockquote cite", blockType: "quote", group: "Basic writing" },
  { id: "callout", label: "Callout", keywords: "note hint info banner", blockType: "callout", group: "Basic writing" },
  // --- Lists ----------------------------------------------------------------
  { id: "bulleted_list", label: "Bulleted list", keywords: "bullet unordered list items", blockType: "bulleted_list", group: "Lists" },
  { id: "numbered_list", label: "Numbered list", keywords: "ordered list steps numbers", blockType: "numbered_list", group: "Lists" },
  { id: "todo", label: "To-do", keywords: "todo task checkbox check", blockType: "todo", group: "Lists" },
  { id: "toggle", label: "Toggle", keywords: "collapse collapsible expand fold", blockType: "toggle", group: "Lists" },
  // --- Media ----------------------------------------------------------------
  { id: "image", label: "Image", keywords: "picture photo upload media", blockType: "image", group: "Media" },
  { id: "video", label: "Video", keywords: "movie film clip media", blockType: "video", group: "Media" },
  { id: "audio", label: "Audio", keywords: "sound music voice media", blockType: "audio", group: "Media" },
  { id: "file", label: "File", keywords: "document attachment upload pdf", blockType: "file", group: "Media" },
  { id: "bookmark", label: "Bookmark", keywords: "link url web page", blockType: "bookmark", group: "Media" },
  { id: "embed", label: "Embed", keywords: "loom figma twitter youtube link url", blockType: "embed", group: "Media" },
  // --- Code & math ----------------------------------------------------------
  { id: "code", label: "Code", keywords: "snippet programming codeblock", blockType: "code", group: "Code & math" },
  { id: "equation", label: "Equation", keywords: "formula math latex", blockType: "equation", group: "Code & math" },
  // --- Layout ---------------------------------------------------------------
  { id: "divider", label: "Divider", keywords: "separator hr line rule", blockType: "divider", group: "Layout" },
  { id: "toc", label: "Table of contents", keywords: "toc contents headings outline navigation", blockType: "toc", group: "Layout" },
  { id: "spacer", label: "Spacer", keywords: "space padding blank gap", blockType: "spacer", group: "Layout" },
  { id: "column_list", label: "Columns", keywords: "grid layout two three", blockType: "column_list", group: "Layout" },
  // --- Data -----------------------------------------------------------------
  { id: "table", label: "Table", keywords: "rows columns grid static", blockType: "table", group: "Data" },
  { id: "database", label: "Database", keywords: "db records tracker table", special: "database", group: "Data" },
  { id: "linked_database", label: "Linked view", keywords: "linked database view embed", blockType: "linked_database", group: "Data" },
  { id: "chart", label: "Chart", keywords: "bar line pie donut number graph", blockType: "chart", group: "Data" },
  { id: "form", label: "Form", keywords: "survey input questionnaire", blockType: "form", group: "Data" },
  // --- Advanced -------------------------------------------------------------
  { id: "child_page", label: "Sub-page", keywords: "page nested subpage child", blockType: "child_page", group: "Advanced" },
  { id: "child_database", label: "Linked database block", keywords: "child database embed", blockType: "child_database", group: "Advanced" },
  { id: "synced_block", label: "Synced block", keywords: "sync duplicate mirror", special: "synced", group: "Advanced" },
];

/** A command with its fuzzy rank (lower = better). */
export interface SlashCommandHit {
  readonly command: SlashCommandDef;
  readonly score: number;
}

/**
 * Subsequence fuzzy match: does `query` occur in `text` in order (case
 * insensitive)? Returns the rank (0 = best; each gap/case-penalty raises it)
 * or `null` when the query is not a subsequence. Deterministic.
 */
export function fuzzyScore(query: string, text: string): number | null {
  if (query.length === 0) return 0;
  const q = query.toLowerCase();
  const t = text.toLowerCase();
  let qi = 0;
  let score = 0;
  let lastMatch = -2;
  for (let ti = 0; ti < t.length && qi < q.length; ti += 1) {
    if (t[ti] === q[qi]) {
      // gap penalty (distance from previous match) + non-consecutive bonus
      if (lastMatch >= 0 && ti !== lastMatch + 1) score += 4;
      score += 1;
      lastMatch = ti;
      qi += 1;
    }
  }
  if (qi < q.length) return null;
  // exact prefix beats subsequence
  if (t.startsWith(q)) score = 1;
  return score;
}

/**
 * Search the registry for a query. An empty query returns every command in
 * menu order. Otherwise commands are ranked by (score, menu index) so the
 * result order is stable and deterministic.
 */
export function searchSlashCommands(query: string): readonly SlashCommandHit[] {
  const trimmed = query.trim().toLowerCase();
  if (trimmed.length === 0) {
    return SLASH_COMMANDS.map((command) => ({ command, score: 0 }));
  }
  const hits: SlashCommandHit[] = [];
  SLASH_COMMANDS.forEach((command, index) => {
    const haystack = `${command.label} ${command.keywords}`;
    const exact = fuzzyScore(trimmed, command.label);
    const loose = exact !== null ? exact + 10 : fuzzyScore(trimmed, haystack);
    if (loose !== null) {
      hits.push({ command, score: loose * 1000 + index });
    }
  });
  hits.sort((a, b) => a.score - b.score);
  return hits;
}