// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:convert' show json;
import 'dart:io';

import 'package:coverage/src/resolver.dart';
import 'package:coverage/src/util.dart';

/// Creates a single hitmap from a raw json object. Throws away all entries that
/// are not resolvable.
///
/// `jsonResult` is expected to be a List<Map<String, dynamic>>.
Future<Map<String, Map<int, int>>> createHitmap(
  List<Map<String, dynamic>> jsonResult, {
  bool checkIgnoredLines = false,
  String? packagesPath,
}) async {
  final resolver = Resolver(packagesPath: packagesPath);
  final loader = Loader();

  // Map of source file to map of line to hit count for that line.
  final globalHitMap = <String, Map<int, int>>{};

  void addToMap(Map<int, int> map, int line, int count) {
    final oldCount = map.putIfAbsent(line, () => 0);
    map[line] = count + oldCount;
  }

  for (var e in jsonResult) {
    final source = e['source'] as String?;
    if (source == null) {
      // Couldn't resolve import, so skip this entry.
      continue;
    }

    var ignoredLinesList = <List<int>>[];

    if (checkIgnoredLines) {
      final path = resolver.resolve(source);
      if (path != null) {
        final lines = await loader.load(path);
        ignoredLinesList = getIgnoredLines(lines!);

        // Ignore the whole file.
        if (ignoredLinesList.length == 1 &&
            ignoredLinesList[0][0] == 0 &&
            ignoredLinesList[0][1] == lines.length) {
          continue;
        }
      }
    }

    // Move to the first ignore range.
    final ignoredLines = ignoredLinesList.iterator;
    var hasCurrent = ignoredLines.moveNext();

    bool _shouldIgnoreLine(Iterator<List<int>> ignoredRanges, int line) {
      if (!hasCurrent || ignoredRanges.current.isEmpty) {
        return false;
      }

      if (line < ignoredRanges.current[0]) return false;

      while (hasCurrent &&
          ignoredRanges.current.isNotEmpty &&
          ignoredRanges.current[1] < line) {
        hasCurrent = ignoredRanges.moveNext();
      }

      if (hasCurrent &&
          ignoredRanges.current.isNotEmpty &&
          ignoredRanges.current[0] <= line &&
          line <= ignoredRanges.current[1]) {
        return true;
      }

      return false;
    }

    final sourceHitMap = globalHitMap.putIfAbsent(source, () => <int, int>{});
    final hits = e['hits'] as List;
    // hits is a flat array of the following format:
    // [ <line|linerange>, <hitcount>,...]
    // line: number.
    // linerange: '<line>-<line>'.
    for (var i = 0; i < hits.length; i += 2) {
      final k = hits[i];
      if (k is int) {
        // Single line.
        if (_shouldIgnoreLine(ignoredLines, k)) continue;

        addToMap(sourceHitMap, k, hits[i + 1] as int);
      } else if (k is String) {
        // Linerange. We expand line ranges to actual lines at this point.
        final splitPos = k.indexOf('-');
        final start = int.parse(k.substring(0, splitPos));
        final end = int.parse(k.substring(splitPos + 1));
        for (var j = start; j <= end; j++) {
          if (_shouldIgnoreLine(ignoredLines, j)) continue;

          addToMap(sourceHitMap, j, hits[i + 1] as int);
        }
      } else {
        throw StateError('Expected value of type int or String');
      }
    }
  }
  return globalHitMap;
}

/// Merges [newMap] into [result].
void mergeHitmaps(
    Map<String, Map<int, int>> newMap, Map<String, Map<int, int>> result) {
  newMap.forEach((String file, Map<int, int> v) {
    final fileResult = result[file];
    if (fileResult != null) {
      v.forEach((int line, int cnt) {
        final lineFileResult = fileResult[line];
        if (lineFileResult == null) {
          fileResult[line] = cnt;
        } else {
          fileResult[line] = lineFileResult + cnt;
        }
      });
    } else {
      result[file] = v;
    }
  });
}

/// Generates a merged hitmap from a set of coverage JSON files.
Future<Map<String, Map<int, int>>> parseCoverage(
  Iterable<File> files,
  int _, {
  bool checkIgnoredLines = false,
  String? packagesPath,
}) async {
  final globalHitmap = <String, Map<int, int>>{};
  for (var file in files) {
    final contents = file.readAsStringSync();
    final jsonMap = json.decode(contents) as Map<String, dynamic>;
    if (jsonMap.containsKey('coverage')) {
      final jsonResult = jsonMap['coverage'] as List;
      mergeHitmaps(
        await createHitmap(
          jsonResult.cast<Map<String, dynamic>>(),
          checkIgnoredLines: checkIgnoredLines,
          packagesPath: packagesPath,
        ),
        globalHitmap,
      );
    }
  }
  return globalHitmap;
}