/**
 * Pure, network-free transform primitives for a ProseMirror/TipTap document
 * tree, plus one higher-level orchestration (commentsToFootnotes).
 *
 * A ProseMirror node here is a plain JSON object of the shape produced by
 * Docmost: `{ type, attrs?, content?, text?, marks? }`. Children live in the
 * `content` array; callouts, tables, lists all hold their children in
 * `content`, so a single recursive walk reaches them all.
 *
 * Conventions (matching node-ops.ts):
 *  - functions that produce a new document deep-clone their input and return a
 *    `{ doc, ... }` object; the caller's objects are never mutated.
 *  - functions are defensively null-safe.
 *  - `marks` arrays are preserved verbatim when fragments are split/reordered.
 */

import { blockPlainText } from "./node-ops.js";

/** Deep-clone a JSON-serializable value without mutating the original. */
function clone<T>(value: T): T {
  if (typeof structuredClone === "function") {
    return structuredClone(value);
  }
  // Fallback for environments without structuredClone.
  return JSON.parse(JSON.stringify(value)) as T;
}

/** True if `value` is a non-null object (and not an array). */
function isObject(value: any): value is Record<string, any> {
  return value != null && typeof value === "object" && !Array.isArray(value);
}

/**
 * Plain text of a node (re-export of node-ops' blockPlainText so transform
 * authors have a single import surface). Recurses through nested content.
 */
export function blockText(node: any): string {
  return blockPlainText(node);
}

/**
 * Depth-first visit of every node in the tree, including the root and the
 * nested content of callouts, tables, lists, etc. `fn` is called once per node.
 * Null-safe: a nullish or non-object node is ignored.
 */
export function walk(node: any, fn: (node: any) => void): void {
  if (!isObject(node)) return;
  fn(node);
  if (Array.isArray(node.content)) {
    for (const child of node.content) {
      walk(child, fn);
    }
  }
}

/**
 * Find the FIRST node (depth-first) matching `predicate`, anywhere in the tree.
 * Works even when the node carries no `attrs.id` (it searches the raw tree, not
 * an id index). Returns the live node reference inside `doc` (NOT a clone), or
 * null when nothing matches. Typical use: `getList(doc, n => n.type ===
 * "orderedList")`.
 */
export function getList(
  doc: any,
  predicate: (node: any) => boolean,
): any | null {
  let found: any | null = null;
  walk(doc, (node) => {
    if (found == null && predicate(node)) {
      found = node;
    }
  });
  return found;
}

/** Options for insertMarkerAfter. */
export interface InsertMarkerOptions {
  /**
   * Limit the search to TOP-LEVEL blocks with index < beforeBlock. Used to keep
   * footnote markers in the body and out of the notes section.
   */
  beforeBlock?: number;
}

/**
 * Insert `marker` as a PLAIN (unmarked) text run right after the first
 * occurrence of `anchor`.
 *
 * The text run that contains the END of the anchor is SPLIT at the anchor end,
 * so all existing marks (links, bold, ...) on the surrounding text are
 * preserved, while the inserted marker run carries NO marks. The marker is
 * inserted as a leading-space-padded run (`" " + marker`) so it visually
 * separates from the preceding word.
 *
 * The anchor is matched against the concatenated plain text of each top-level
 * block (so an anchor that spans several text/mark runs still matches). The
 * insertion happens inside the inline content array that holds the anchor's
 * final character.
 *
 * Operates on a clone of `doc`; returns `{ doc, inserted }`. `inserted` is
 * false when the anchor text was not found in any in-scope block.
 */
export function insertMarkerAfter(
  doc: any,
  anchor: string,
  marker: string,
  opts: InsertMarkerOptions = {},
): { doc: any; inserted: boolean } {
  const out = clone(doc);
  if (!isObject(out) || !Array.isArray(out.content) || !anchor) {
    return { doc: out, inserted: false };
  }

  const limit =
    typeof opts.beforeBlock === "number"
      ? Math.min(opts.beforeBlock, out.content.length)
      : out.content.length;

  for (let b = 0; b < limit; b++) {
    const block = out.content[b];
    if (!isObject(block)) continue;
    // Quick reject: skip blocks whose plain text cannot contain the anchor.
    if (!blockPlainText(block).includes(anchor)) continue;

    // Walk the inline content arrays inside this block, tracking a running
    // character offset so we can locate the inline array + text run that holds
    // the END of the anchor's first occurrence.
    let inserted = false;
    let offset = 0; // characters of plain text seen so far in this block
    const anchorEnd = (() => blockPlainText(block).indexOf(anchor) + anchor.length)();

    // Recurse into inline-bearing containers (paragraph, heading, table cell,
    // callout child paragraphs, ...). We only split inside an array of inline
    // nodes (text/inline atoms); the FIRST array whose cumulative range covers
    // anchorEnd receives the split + marker.
    const visit = (container: any): void => {
      if (inserted || !isObject(container) || !Array.isArray(container.content)) {
        return;
      }
      const inline = container.content;
      // Detect whether this array is an inline array (contains text nodes).
      const hasText = inline.some(
        (n: any) => isObject(n) && n.type === "text",
      );
      if (hasText) {
        for (let i = 0; i < inline.length; i++) {
          const n = inline[i];
          const len = isObject(n) ? blockPlainText(n).length : 0;
          const runStart = offset;
          const runEnd = offset + len;
          // The run that contains the anchor end (anchorEnd lands inside this
          // run, i.e. runStart < anchorEnd <= runEnd) is the split point.
          if (
            !inserted &&
            isObject(n) &&
            n.type === "text" &&
            typeof n.text === "string" &&
            anchorEnd > runStart &&
            anchorEnd <= runEnd
          ) {
            const cut = anchorEnd - runStart; // split index within this text run
            const before = n.text.slice(0, cut);
            const after = n.text.slice(cut);
            const marks = Array.isArray(n.marks) ? n.marks : [];
            const parts: any[] = [];
            if (before.length > 0) {
              parts.push({ ...n, text: before, marks: [...marks] });
            }
            // Marker is a PLAIN run: no marks copied. Leading space separates it.
            parts.push({ type: "text", text: " " + marker });
            if (after.length > 0) {
              parts.push({ ...n, text: after, marks: [...marks] });
            }
            inline.splice(i, 1, ...parts);
            inserted = true;
            return;
          }
          offset = runEnd;
        }
      } else {
        // Not an inline array: recurse into children (e.g. callout -> paragraph).
        for (const child of inline) {
          visit(child);
          if (inserted) return;
        }
      }
    };

    visit(block);
    if (inserted) {
      return { doc: out, inserted: true };
    }
    // If the block matched in plain text but we could not split (e.g. anchor
    // lands inside an atom), fall through to the next block rather than failing.
  }

  return { doc: out, inserted: false };
}

/**
 * In the disclaimer callout, replace a `[1]…[K]` range marker with `[1]…[n]`.
 *
 * Docmost translations use a callout that states the footnote range, e.g.
 * "[1]…[5]". When the number of notes changes, this rewrites the trailing
 * number of any `[1]…[K]` (or `[1]...[K]`, ASCII ellipsis) occurrence found in a
 * callout's text nodes to `[1]…[n]`. Operates on a clone; returns
 * `{ doc, changed }` where `changed` is the number of text nodes rewritten.
 */
export function setCalloutRange(
  doc: any,
  n: number,
): { doc: any; changed: number } {
  const out = clone(doc);
  let changed = 0;
  // Match "[1]" + (… or ...) + "[<digits>]"; rewrite the last number to n.
  const rangeRe = /(\[1\]\s*(?:…|\.\.\.)\s*\[)\d+(\])/g;
  walk(out, (node) => {
    if (node.type === "callout") {
      walk(node, (inner) => {
        if (
          inner.type === "text" &&
          typeof inner.text === "string" &&
          rangeRe.test(inner.text)
        ) {
          rangeRe.lastIndex = 0;
          inner.text = inner.text.replace(rangeRe, `$1${n}$2`);
          changed++;
        }
        rangeRe.lastIndex = 0;
      });
    }
  });
  return { doc: out, changed };
}

/**
 * Generate a short random id for a new block's `attrs.id`. Docmost uses nanoid;
 * a base36 random string is sufficient here (uniqueness within one document).
 */
function freshId(): string {
  return (
    Math.random().toString(36).slice(2, 12) +
    Math.random().toString(36).slice(2, 6)
  );
}

/**
 * Wrap inline ProseMirror nodes in a list item:
 *   { type:"listItem", content:[{ type:"paragraph", attrs:{id}, content: inlineNodes }] }
 * with a fresh random block id on the paragraph. The inline nodes are cloned so
 * the result shares no references with the caller's input.
 */
export function noteItem(inlineNodes: any[]): any {
  const content = Array.isArray(inlineNodes) ? clone(inlineNodes) : [];
  return {
    type: "listItem",
    content: [
      {
        type: "paragraph",
        attrs: { id: freshId() },
        content,
      },
    ],
  };
}

/**
 * Convert a comment's markdown (e.g. `**Lead.** body...`) into inline
 * ProseMirror nodes.
 *
 * A leading `комментарий: ` (case-insensitive) or `N. ` numeric prefix is
 * stripped first. Then a minimal bold-split is applied: a leading
 * `**bold lead**` run becomes a text node with a bold mark, and the remainder
 * becomes a plain text node. This keeps the conversion synchronous (the
 * transform sandbox runs synchronously) and dependency-free; the existing
 * async markdownToProseMirror is intentionally NOT used here.
 */
export function mdToInlineNodes(markdown: string): any[] {
  let md = typeof markdown === "string" ? markdown : "";
  // Strip a leading "комментарий: " prefix (case-insensitive) or a "N. " prefix.
  md = md.replace(/^\s*комментарий\s*:\s*/i, "");
  md = md.replace(/^\s*\d+\.\s+/, "");
  md = md.trim();

  if (md === "") return [];

  const nodes: any[] = [];
  // Leading bold lead: **...** at the very start.
  const leadMatch = /^\*\*([^*]+)\*\*\s*/.exec(md);
  if (leadMatch) {
    const leadText = leadMatch[1];
    nodes.push({
      type: "text",
      text: leadText,
      marks: [{ type: "bold" }],
    });
    const rest = md.slice(leadMatch[0].length);
    if (rest.length > 0) {
      // Preserve the separating space that followed the bold lead.
      const sep = /^\*\*[^*]+\*\*(\s*)/.exec(md);
      const spacing = sep ? sep[1] : "";
      nodes.push({ type: "text", text: spacing + rest });
    }
    return nodes;
  }

  // No bold lead: emit the whole thing as a single plain text node, with any
  // remaining **bold** spans split out inline.
  return splitInlineBold(md);
}

/**
 * Split a string with inline `**bold**` spans into text nodes, bolding the
 * spans. Used as the no-lead fallback in mdToInlineNodes.
 */
function splitInlineBold(text: string): any[] {
  const nodes: any[] = [];
  const re = /\*\*([^*]+)\*\*/g;
  let last = 0;
  let m: RegExpExecArray | null;
  while ((m = re.exec(text)) !== null) {
    if (m.index > last) {
      nodes.push({ type: "text", text: text.slice(last, m.index) });
    }
    nodes.push({ type: "text", text: m[1], marks: [{ type: "bold" }] });
    last = m.index + m[0].length;
  }
  if (last < text.length) {
    nodes.push({ type: "text", text: text.slice(last) });
  }
  return nodes.length > 0 ? nodes : [{ type: "text", text }];
}

/** Options for commentsToFootnotes. */
export interface CommentsToFootnotesOptions {
  /** Heading text under which the notes orderedList lives. */
  notesHeading?: string;
}

/** A comment shape as returned by DocmostClient.listComments. */
export interface FootnoteComment {
  id: string;
  content: string;
  selection?: string | null;
  [k: string]: any;
}

/**
 * Turn inline comments into numbered footnotes.
 *
 * For each inline comment that carries a `selection`:
 *   1. insert a placeholder marker (a NUL-delimited "\u0000FN<i>\u0000"
 *      sentinel) right after the selection text in the BODY (before the
 *      notes heading);
 *   2. build a note list item from the comment's markdown content.
 *
 * Then RENUMBER every footnote marker in the body by reading order: existing
 * `[N]` markers and the new "\u0000FN<i>\u0000" placeholders are both replaced by a
 * sequential `[seq]`, and the notes orderedList is reordered so each note lines
 * up with its marker's reading-order position. Finally the disclaimer callout
 * range is synced to the new note count.
 *
 * Returns `{ doc, consumed }` where `consumed` lists the ids of comments that
 * were successfully anchored (their selection was found and a placeholder
 * inserted). Operates on a clone of `doc`.
 */
export function commentsToFootnotes(
  doc: any,
  comments: FootnoteComment[],
  opts: CommentsToFootnotesOptions = {},
): { doc: any; consumed: string[] } {
  let working = clone(doc);
  const notesHeading = opts.notesHeading ?? "Примечания переводчика";

  const top: any[] = Array.isArray(working.content) ? working.content : [];
  const notesIdx = top.findIndex(
    (n) => isObject(n) && n.type === "heading" && blockText(n).trim() === notesHeading,
  );
  if (notesIdx < 0) {
    throw new Error(`heading "${notesHeading}" not found`);
  }
  // The notes orderedList lives at or after the heading.
  const notesList = top
    .slice(notesIdx)
    .find((n) => isObject(n) && n.type === "orderedList");
  if (!notesList) {
    throw new Error("notes orderedList not found");
  }

  const consumed: string[] = [];
  const noteByPh = new Map<string, any>();

  (Array.isArray(comments) ? comments : []).forEach((c, i) => {
    if (!c || !c.selection) return;
    // Collision-proof sentinel delimited by NUL control chars, which never occur
    // in real Docmost prose — so the renumber regex below cannot mistake any body
    // text (e.g. "Press F1 for help", model "FN2") for a placeholder. The NUL is
    // transient: the placeholder round-trips within this function (insertMarkerAfter
    // inserts it, the renumber pass replaces it with "[N]"), so it never persists
    // in a returned/pushed document.
    const ph = `\u0000FN${i}\u0000`;
    // insertMarkerAfter returns a NEW cloned doc; reassign `working` and refresh
    // the `top` / `notesList` references that point into it.
    const r = insertMarkerAfter(working, c.selection.trimEnd(), ph, {
      beforeBlock: notesIdx,
    });
    if (!r.inserted) return;
    working = r.doc;
    noteByPh.set(ph, noteItem(mdToInlineNodes(c.content)));
    consumed.push(c.id);
  });

  // Re-resolve references into the (possibly re-cloned) working doc.
  const top2: any[] = Array.isArray(working.content) ? working.content : [];
  const notesList2 = top2
    .slice(notesIdx)
    .find((n) => isObject(n) && n.type === "orderedList");
  if (!notesList2) {
    throw new Error("notes orderedList not found");
  }

  const oldNotes: any[] = Array.isArray(notesList2.content)
    ? notesList2.content
    : [];
  const newNotes: any[] = [];
  let seq = 0;
  // Match either an existing "[N]" marker or a NUL-delimited "\u0000FN<i>\u0000"
  // placeholder, in reading order across the body (blocks before the notes heading).
  const re = /\[(\d+)\]|\u0000FN(\d+)\u0000/g;
  // Same range regex setCalloutRange uses to detect the disclaimer callout's
  // "[1]…[K]" range; used here to decide whether a top-level callout is the
  // disclaimer (skip) or an ordinary callout (renumber normally).
  const disclaimerRangeRe = /(\[1\]\s*(?:…|\.\.\.)\s*\[)\d+(\])/;
  for (let i = 0; i < notesIdx; i++) {
    // Skip ONLY the disclaimer callout: its "[1]…[K]" range is NOT a footnote
    // marker and is synced separately by setCalloutRange. Renumbering it here
    // would consume note slots and corrupt the sequence. Other top-level
    // callouts may carry legitimate "[N]" body markers and are renumbered.
    if (
      isObject(top2[i]) &&
      top2[i].type === "callout" &&
      disclaimerRangeRe.test(blockText(top2[i]))
    ) {
      continue;
    }
    walk(top2[i], (node) => {
      if (node.type !== "text" || typeof node.text !== "string") return;
      node.text = node.text.replace(re, (_m: string, oldNum: string, phIdx: string) => {
        if (oldNum != null) {
          const note = oldNotes[Number(oldNum) - 1];
          // Every existing body marker MUST map to a real note. An out-of-range
          // marker means the document is internally inconsistent; fail loudly
          // rather than silently dropping the note and desyncing the callout.
          if (note === undefined) {
            throw new Error(
              `footnote [${oldNum}] has no matching note (notes list has ${oldNotes.length} items); document is inconsistent`,
            );
          }
          newNotes.push(note);
        } else {
          newNotes.push(noteByPh.get(`\u0000FN${phIdx}\u0000`));
        }
        return `[${++seq}]`;
      });
    });
  }

  // Reorder the notes list IN PLACE on `working` first, THEN sync the callout
  // range. setCalloutRange clones `working`, so the reordered notes (mutated
  // before the clone) are carried into its result automatically. No null-filter
  // here: marker count and note count must stay exactly equal (the out-of-range
  // guard above guarantees no undefined entry is ever pushed).
  notesList2.content = newNotes;
  const synced = setCalloutRange(working, notesList2.content.length);

  return { doc: synced.doc, consumed };
}