/* 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 type { BindingLocationType, BindingType } from "../../../workers/parser";
import { positionCmp } from "./positionCmp";
import { filterSortedArray } from "./filtering";
import { mappingContains } from "./mappingContains";

import type { Source, Location, Position } from "../../../types";

import type { GeneratedBindingLocation } from "./buildGeneratedBindingList";

export type ApplicableBinding = {
  binding: GeneratedBindingLocation,
  range: GeneratedRange,
  firstInRange: boolean,
  firstOnLine: boolean
};

type GeneratedRange = {
  start: Position,
  end: Position
};

export async function originalRangeStartsInside(
  source: Source,
  {
    start,
    end
  }: {
    start: Location,
    end: Location
  },
  sourceMaps: any
) {
  const endPosition = await sourceMaps.getGeneratedLocation(end, source);
  const startPosition = await sourceMaps.getGeneratedLocation(start, source);

  // If the start and end positions collapse into eachother, it means that
  // the range in the original content didn't _start_ at the start position.
  // Since this likely means that the range doesn't logically apply to this
  // binding location, we skip it.
  return positionCmp(startPosition, endPosition) !== 0;
}

export async function getApplicableBindingsForOriginalPosition(
  generatedAstBindings: Array<GeneratedBindingLocation>,
  source: Source,
  {
    start,
    end
  }: {
    start: Location,
    end: Location
  },
  bindingType: BindingType,
  locationType: BindingLocationType,
  sourceMaps: any
): Promise<Array<ApplicableBinding>> {
  const ranges = await sourceMaps.getGeneratedRanges(start, source);

  const resultRanges = ranges.map(mapRange => ({
    start: {
      line: mapRange.line,
      column: mapRange.columnStart
    },
    end: {
      line: mapRange.line,
      // SourceMapConsumer's 'lastColumn' is inclusive, so we add 1 to make
      // it exclusive like all other locations.
      column: mapRange.columnEnd + 1
    }
  }));

  // When searching for imports, we expand the range to up to the next available
  // mapping to allow for import declarations that are composed of multiple
  // variable statements, where the later ones are entirely unmapped.
  // Babel 6 produces imports in this style, e.g.
  //
  // var _mod = require("mod"); // mapped from import statement
  // var _mod2 = interop(_mod); // entirely unmapped
  if (bindingType === "import" && locationType !== "ref") {
    const endPosition = await sourceMaps.getGeneratedLocation(end, source);
    const startPosition = await sourceMaps.getGeneratedLocation(start, source);

    for (const range of resultRanges) {
      if (
        mappingContains(range, { start: startPosition, end: startPosition }) &&
        positionCmp(range.end, endPosition) < 0
      ) {
        range.end.line = endPosition.line;
        range.end.column = endPosition.column;
        break;
      }
    }
  }

  return filterApplicableBindings(generatedAstBindings, resultRanges);
}

function filterApplicableBindings(
  bindings: Array<GeneratedBindingLocation>,
  ranges: Array<GeneratedRange>
): Array<ApplicableBinding> {
  const result = [];
  for (const range of ranges) {
    // Any binding overlapping a part of the mapping range.
    const filteredBindings = filterSortedArray(bindings, binding => {
      if (positionCmp(binding.loc.end, range.start) <= 0) {
        return -1;
      }
      if (positionCmp(binding.loc.start, range.end) >= 0) {
        return 1;
      }

      return 0;
    });

    let firstInRange = true;
    let firstOnLine = true;
    let line = -1;

    for (const binding of filteredBindings) {
      if (binding.loc.start.line === line) {
        firstOnLine = false;
      } else {
        line = binding.loc.start.line;
        firstOnLine = true;
      }

      result.push({
        binding,
        range,
        firstOnLine,
        firstInRange
      });

      firstInRange = false;
    }
  }

  return result;
}