/* 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/>. */

import { positionCmp } from "./positionCmp";
import { filterSortedArray } from "./filtering";
import { mappingContains } from "./mappingContains";
import { getGeneratedLocation } from "../../source-maps";

export async function originalRangeStartsInside({ start, end }, thunkArgs) {
  const endPosition = await getGeneratedLocation(end, thunkArgs);
  const startPosition = await getGeneratedLocation(start, thunkArgs);

  // 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,
  source,
  { start, end },
  bindingType,
  locationType,
  thunkArgs
) {
  const { sourceMapLoader } = thunkArgs;
  const ranges = await sourceMapLoader.getGeneratedRanges(start);

  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 getGeneratedLocation(end, thunkArgs);
    const startPosition = await getGeneratedLocation(start, thunkArgs);

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

  return filterApplicableBindings(generatedAstBindings, resultRanges);
}

function filterApplicableBindings(bindings, ranges) {
  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;
}