/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */

// @flow

import {
  buildScopeList,
  parseSourceScopes,
  type SourceScope,
  type ParsedScope,
  type BindingData,
  type BindingDeclarationLocation,
  type BindingLocation,
  type BindingLocationType,
  type BindingMetaValue,
  type BindingType
} from "./visitor";

export type {
  SourceScope,
  BindingData,
  BindingDeclarationLocation,
  BindingLocation,
  BindingLocationType,
  BindingMetaValue,
  BindingType
};

import type { SourceLocation } from "../../../types";

let parsedScopesCache = new Map();

export default function getScopes(location: SourceLocation): SourceScope[] {
  const { sourceId } = location;
  let parsedScopes = parsedScopesCache.get(sourceId);
  if (!parsedScopes) {
    parsedScopes = parseSourceScopes(sourceId);
    parsedScopesCache.set(sourceId, parsedScopes);
  }
  return parsedScopes ? findScopes(parsedScopes, location) : [];
}

export function clearScopes() {
  parsedScopesCache = new Map();
}

export { buildScopeList };

/**
 * Searches all scopes and their bindings at the specific location.
 */
function findScopes(
  scopes: ParsedScope[],
  location: SourceLocation
): SourceScope[] {
  // Find inner most in the tree structure.
  let searchInScopes: ?(ParsedScope[]) = scopes;
  const found = [];
  while (searchInScopes) {
    const foundOne = searchInScopes.some(s => {
      if (
        compareLocations(s.start, location) <= 0 &&
        compareLocations(location, s.end) < 0
      ) {
        // Found the next scope, trying to search recusevly in its children.
        found.unshift(s);
        searchInScopes = s.children;
        return true;
      }
      return false;
    });
    if (!foundOne) {
      break;
    }
  }
  return found.map(i => {
    return {
      type: i.type,
      displayName: i.displayName,
      start: i.start,
      end: i.end,
      bindings: i.bindings
    };
  });
}

function compareLocations(a: SourceLocation, b: SourceLocation): number {
  // According to type of Location.column can be undefined, if will not be the
  // case here, ignoring flow error.
  // $FlowIgnore
  return a.line == b.line ? a.column - b.column : a.line - b.line;
}