// tslint:disable:no-invalid-this
import memoizeOne from "memoize-one";
import { EditorState, Plugin, Transaction, PluginSpec } from "prosemirror-state";
import { Schema } from "prosemirror-model";

declare module "prosemirror-state" {
  // tslint:disable-next-line:no-any
  interface PluginSpec<S extends Schema = any> {
    replaceTransaction?:
      | ((tr: Transaction, oldState: EditorState, newState: EditorState) => undefined | null | false | Transaction)
      | null;
  }
}

/**
 * Installs a monkey patch for `replaceTransaction`. This avoids forking
 * prosemirror-state (which would be tricky for distribution), and serves as
 * reference implementation for https://github.com/ProseMirror/rfcs/pull/10.
 */
export const installReplaceTransactionMonkeyPatch = memoizeOne(() => {
  // tslint:disable-next-line:no-any
  interface PluginWithReplaceTransaction<S extends Schema = any> extends Plugin<S> {
    spec: Pick<PluginSpec<S>, "replaceTransaction">;
  }

  interface EditorStateWithPrivate extends EditorState {
    filterTransaction(tr: Transaction, ignore?: number): boolean;
    applyInner(tr: Transaction): EditorState;
    config: {
      plugins: PluginWithReplaceTransaction[];
    };
  }

  function replaceTransaction(
    state: EditorState,
    tr: Transaction,
    ignorePlugin = -1
  ): false | { tr: Transaction; state: EditorState } {
    if (!(state as EditorStateWithPrivate).filterTransaction(tr, ignorePlugin)) {
      return false;
    }

    let newState = (state as EditorStateWithPrivate).applyInner(tr);
    const { plugins } = (state as EditorStateWithPrivate).config;

    for (let i = 0; i < plugins.length; i++) {
      if (i !== ignorePlugin) {
        const plugin = plugins[i];
        if (plugin.spec.replaceTransaction != null) {
          const replaceResult = plugin.spec.replaceTransaction.call(plugin, tr, state, newState);
          if (replaceResult === false) {
            // Equivalent effect of `filterTransaction`
            return false;
          } else if (replaceResult != null) {
            tr = replaceResult;
            newState = (state as EditorStateWithPrivate).applyInner(tr);
          }
        }
      }
    }

    return { tr, state: newState };
  }

  EditorState.prototype.applyTransaction = function(tr) {
    const replaceResult = replaceTransaction(this, tr);
    if (replaceResult === false) {
      return { state: this, transactions: [] };
    }

    // tslint:disable-next-line:no-any
    const { plugins } = (this as any).config;

    const trs = [replaceResult.tr];
    let newState = replaceResult.state;
    let seen = null;
    // This loop repeatedly gives plugins a chance to respond to
    // transactions as new transactions are added, making sure to only
    // pass the transactions the plugin did not see before.
    for (;;) {
      let haveNew = false;
      for (let i = 0; i < plugins.length; i++) {
        const plugin = plugins[i];
        if (plugin.spec.appendTransaction) {
          const n = seen !== null ? seen[i].n : 0;
          const oldState = seen !== null ? seen[i].state : this;
          const trAppended =
            n < trs.length && plugin.spec.appendTransaction.call(plugin, n > 0 ? trs.slice(n) : trs, oldState, newState);
          if (trAppended) {
            const replaceResult = replaceTransaction(newState, trAppended, i);
            if (replaceResult !== false) {
              replaceResult.tr.setMeta("appendedTransaction", tr);
              if (seen === null) {
                seen = [];
                for (let j = 0; j < plugins.length; j++) {
                  seen.push(j < i ? { state: newState, n: trs.length } : { state: this, n: 0 });
                }
              }
              trs.push(replaceResult.tr);
              newState = replaceResult.state;
              haveNew = true;
            }
          }
          if (seen !== null) seen[i] = { state: newState, n: trs.length };
        }
      }
      if (!haveNew) return { state: newState, transactions: trs };
    }
  };
});