// MOCK DATA — TEMPORARY. See MockSwitch.dart.

import 'dart:math';

import '../about/external/initial/GroupGoalRequest.dart';
import '../about/external/initial/GroupMessageRequest.dart';
import '../about/external/initial/GroupRequest.dart';
import '../about/external/initial/JoinGroupRequest.dart';
import '../about/external/initial/NudgeRequest.dart';
import '../about/external/initial/ObjectiveProgressRequest.dart';
import '../utils/Colors.dart';
import '../utils/CommonUtils.dart';
import 'MockStore.dart';

/// The fake backend's groups: a couple already joined, one waiting behind an
/// invite code, and members who answer in the chat a moment after you post.
class MockGroups {
  static const String _me = "mock-user";

  static const String _myName = "Alex";

  static bool _seeded = false;

  static final List<Map<String, dynamic>> _groups = <Map<String, dynamic>>[];

  /// Groups that exist but you are not in yet, keyed by invite code.
  static final Map<String, Map<String, dynamic>> _joinable =
      <String, Map<String, dynamic>>{};

  static final Map<String, List<Map<String, dynamic>>> _messages =
      <String, List<Map<String, dynamic>>>{};

  /// Replies that "arrive" once their time has passed.
  static final List<Map<String, dynamic>> _pending = <Map<String, dynamic>>[];

  static final Random _random = Random(7);

  static Map<String, dynamic> _member(String id, String name,
      {String role = "Member",
      double kept = 0.7,
      int streak = 2,
      String standing = "Good",
      int checkedInHoursAgo = 5}) {
    return <String, dynamic>{
      'id': id,
      'name': name,
      'role': role,
      'keptRate': kept,
      'streak': streak,
      'standing': standing,
      'lastCheckIn': DateTime.now()
          .subtract(Duration(hours: checkedInHoursAgo))
          .toIso8601String(),
      'me': id == _me,
    };
  }

  static Map<String, dynamic> _objective(
      String id, String title, String unit, double target, double current,
      double mine) {
    return <String, dynamic>{
      'id': id,
      'title': title,
      'unit': unit,
      'target': target,
      'current': current,
      'mine': mine,
    };
  }

  static Map<String, dynamic> _message(String groupId, String authorId,
      String authorName, String body, int minutesAgo,
      {String kind = "Text"}) {
    return <String, dynamic>{
      'id': MockStore.newId('msg'),
      'groupId': groupId,
      'authorId': authorId,
      'authorName': authorName,
      'body': body,
      'kind': kind,
      'sentAt': DateTime.now()
          .subtract(Duration(minutes: minutesAgo))
          .toIso8601String(),
      'mine': authorId == _me,
    };
  }

  static void _ensureSeeded() {
    if (_seeded) {
      return;
    }
    _seeded = true;

    final DateTime now = DateTime.now();

    _groups.addAll(<Map<String, dynamic>>[
      <String, dynamic>{
        'id': 'group-run',
        'name': 'Morning Crew',
        'description': 'Out the door before 7, five days a week.',
        'colourHex': colorToHex(goalAccents[1]),
        'inviteCode': 'MRN7AM',
        'unread': 3,
        'members': <Map<String, dynamic>>[
          _member('m-sam', 'Sam',
              role: 'Owner', kept: 0.92, streak: 11, checkedInHoursAgo: 2),
          _member(_me, _myName, kept: 0.78, streak: 4, checkedInHoursAgo: 4),
          _member('m-priya', 'Priya', kept: 0.85, streak: 7, checkedInHoursAgo: 3),
          _member('m-jordan', 'Jordan',
              kept: 0.41, streak: 0, standing: 'Warned', checkedInHoursAgo: 52),
        ],
        'goals': <Map<String, dynamic>>[
          <String, dynamic>{
            'id': 'gg-run',
            'title': 'Run 200 km this month',
            'description': 'Every kilometre counts, treadmill included.',
            'targetDate': DateTime(now.year, now.month + 1, 0).toIso8601String(),
            'colourHex': colorToHex(goalAccents[1]),
            'objectives': <Map<String, dynamic>>[
              _objective('ob-km', 'Distance run', 'km', 200, 86, 22),
              _objective('ob-sessions', 'Runs logged', 'runs', 40, 17, 5),
            ],
          },
          <String, dynamic>{
            'id': 'gg-sleep',
            'title': 'In bed before 23:00',
            'description': 'Mornings start the night before.',
            'targetDate': '',
            'colourHex': colorToHex(goalAccents[4]),
            'objectives': <Map<String, dynamic>>[
              _objective('ob-nights', 'Early nights', 'nights', 60, 31, 9),
            ],
          },
        ],
      },
      <String, dynamic>{
        'id': 'group-thesis',
        'name': 'Thesis Sprint',
        'description': 'Drafts in by the 15th. No heroics, just pages.',
        'colourHex': colorToHex(goalAccents[3]),
        'inviteCode': 'THS15D',
        'unread': 0,
        'members': <Map<String, dynamic>>[
          _member(_me, _myName,
              role: 'Owner', kept: 0.78, streak: 4, checkedInHoursAgo: 4),
          _member('m-mei', 'Mei', kept: 0.88, streak: 9, checkedInHoursAgo: 6),
          _member('m-tom', 'Tom', kept: 0.63, streak: 1, checkedInHoursAgo: 20),
        ],
        'goals': <Map<String, dynamic>>[
          <String, dynamic>{
            'id': 'gg-drafts',
            'title': 'Full drafts submitted',
            'description': 'Three theses, one deadline.',
            'targetDate': DateTime(now.year, now.month + 1, 15).toIso8601String(),
            'colourHex': colorToHex(goalAccents[3]),
            'objectives': <Map<String, dynamic>>[
              _objective('ob-words', 'Words written', 'words', 30000, 18400, 7200),
              _objective('ob-chapters', 'Chapters reviewed', 'chapters', 9, 3, 1),
              _objective('ob-hours', 'Deep-work hours', 'hours', 120, 64, 23),
            ],
          },
        ],
      },
    ]);

    _joinable['WLK2GO'] = <String, dynamic>{
      'id': 'group-walk',
      'name': 'Weekend Walkers',
      'description': 'Ten thousand steps, Saturday and Sunday, no excuses.',
      'colourHex': colorToHex(goalAccents[5]),
      'inviteCode': 'WLK2GO',
      'unread': 1,
      'members': <Map<String, dynamic>>[
        _member('m-ade', 'Ade', role: 'Owner', kept: 0.81, streak: 6),
        _member('m-lena', 'Lena', kept: 0.74, streak: 3),
      ],
      'goals': <Map<String, dynamic>>[
        <String, dynamic>{
          'id': 'gg-steps',
          'title': '1 million steps together',
          'description': '',
          'targetDate': '',
          'colourHex': colorToHex(goalAccents[5]),
          'objectives': <Map<String, dynamic>>[
            _objective('ob-steps', 'Steps', 'steps', 1000000, 412000, 0),
          ],
        },
      ],
    };

    _messages['group-run'] = <Map<String, dynamic>>[
      _message('group-run', 'm-sam', 'Sam',
          'Same route tomorrow? Gate at 6:15.', 60 * 20),
      _message('group-run', _me, _myName, "I'm in. Bringing Priya's spare torch.",
          60 * 19 + 40),
      _message('group-run', 'm-priya', 'Priya', 'logged 6 km on Distance run',
          60 * 3, kind: 'CheckIn'),
      _message('group-run', 'm-sam', 'Sam', 'logged 8 km on Distance run',
          60 * 2, kind: 'CheckIn'),
      _message('group-run', 'm-sam', 'Sam',
          'nudged Jordan: two days without a run, we miss you out there',
          95, kind: 'Nudge'),
      _message('group-run', 'm-priya', 'Priya',
          '86 km down. We need about 9 a day to make it, doable.', 40),
    ];
    _messages['group-thesis'] = <Map<String, dynamic>>[
      _message('group-thesis', _me, _myName, 'started the group', 60 * 24 * 6,
          kind: 'System'),
      _message('group-thesis', 'm-mei', 'Mei',
          'Chapter 3 is with my supervisor. Terrified.', 60 * 26),
      _message('group-thesis', _me, _myName, 'logged 1,200 words on Words written',
          60 * 22, kind: 'CheckIn'),
      _message('group-thesis', 'm-tom', 'Tom',
          'Library 9 to 1 tomorrow if anyone wants a co-working block.', 60 * 7),
    ];
    _messages['group-walk'] = <Map<String, dynamic>>[
      _message('group-walk', 'm-ade', 'Ade',
          'Welcome! Saturday loop starts at the bridge, 9:00.', 60 * 30),
    ];
  }

  static Map<String, dynamic>? _find(String id) {
    for (Map<String, dynamic> group in _groups) {
      if (group['id'] == id) {
        return group;
      }
    }
    return null;
  }

  /// Moves any replies whose moment has come into their threads.
  static void _deliver() {
    final DateTime now = DateTime.now();
    final List<Map<String, dynamic>> due = _pending
        .where((item) => DateTime.parse(item['sentAt']).isBefore(now))
        .toList();
    for (Map<String, dynamic> message in due) {
      _pending.remove(message);
      _messages.putIfAbsent(message['groupId'], () => <Map<String, dynamic>>[])
          .add(message);
      final Map<String, dynamic>? group = _find(message['groupId']);
      if (group != null) {
        group['unread'] = (group['unread'] ?? 0) + 1;
      }
    }
  }

  static Map<String, dynamic> _withLast(Map<String, dynamic> group) {
    final List<Map<String, dynamic>> thread =
        _messages[group['id']] ?? <Map<String, dynamic>>[];
    final Map<String, dynamic> copy = Map<String, dynamic>.from(group);
    if (thread.isNotEmpty) {
      final Map<String, dynamic> last = thread.last;
      copy['lastMessage'] = last['body'];
      copy['lastAuthor'] = last['authorName'];
      copy['lastMessageAt'] = last['sentAt'];
    }
    return copy;
  }

  static void _post(String groupId, String body, String kind) {
    _messages.putIfAbsent(groupId, () => <Map<String, dynamic>>[]).add(
        _message(groupId, _me, _myName, body, 0, kind: kind));
  }

  /// Someone answers a few seconds later, so the chat feels inhabited.
  static void _queueReply(String groupId) {
    final Map<String, dynamic>? group = _find(groupId);
    if (group == null) {
      return;
    }
    final List<dynamic> others = (group['members'] as List)
        .where((member) => member['id'] != _me)
        .toList();
    if (others.isEmpty) {
      return;
    }
    const List<String> lines = <String>[
      "Love it. Keep that going.",
      "Same here, just finished mine.",
      "That's the spirit.",
      "Noted. I'll match you tomorrow.",
      "Good — that puts us back on pace.",
      "Who's in for the next one?",
    ];
    final Map<String, dynamic> author = others[_random.nextInt(others.length)];
    final Map<String, dynamic> reply = _message(groupId, author['id'],
        author['name'], lines[_random.nextInt(lines.length)], 0);
    reply['sentAt'] =
        DateTime.now().add(const Duration(seconds: 3)).toIso8601String();
    _pending.add(reply);
  }

  static String _code() {
    const String letters = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789";
    return List<String>.generate(
        6, (index) => letters[_random.nextInt(letters.length)]).join();
  }

  // ── Endpoints ─────────────────────────────────────────────────────────────

  static List<Map<String, dynamic>> mine() {
    _ensureSeeded();
    _deliver();
    return _groups.map(_withLast).toList();
  }

  static Map<String, dynamic> one(String id) {
    _ensureSeeded();
    _deliver();
    return _withLast(_find(id) ?? <String, dynamic>{});
  }

  static Map<String, dynamic> save(GroupRequest request) {
    _ensureSeeded();
    final Map<String, dynamic>? existing =
        request.id == null ? null : _find(request.id!);
    if (existing != null) {
      existing['name'] = request.name;
      existing['description'] = request.description;
      existing['colourHex'] = request.colourHex;
      return _withLast(existing);
    }

    final String id = MockStore.newId('group');
    final Map<String, dynamic> group = <String, dynamic>{
      'id': id,
      'name': request.name,
      'description': request.description,
      'colourHex': request.colourHex,
      'inviteCode': _code(),
      'unread': 0,
      'members': <Map<String, dynamic>>[
        _member(_me, _myName, role: 'Owner', kept: 0.78, streak: 4,
            checkedInHoursAgo: 0),
      ],
      'goals': <Map<String, dynamic>>[],
    };
    _groups.insert(0, group);
    _post(id, 'started the group', 'System');
    return _withLast(group);
  }

  static Map<String, dynamic> join(JoinGroupRequest request) {
    _ensureSeeded();
    final String code = request.inviteCode.trim().toUpperCase();

    for (Map<String, dynamic> group in _groups) {
      if (group['inviteCode'] == code) {
        return _withLast(group);
      }
    }

    // Any well-formed code finds the waiting group, so the preview always
    // has something to join.
    final Map<String, dynamic> group = _joinable.remove(code) ??
        (_joinable.isNotEmpty
            ? _joinable.remove(_joinable.keys.first)!
            : <String, dynamic>{
                'id': MockStore.newId('group'),
                'name': 'Group $code',
                'description': '',
                'colourHex': colorToHex(goalAccents[0]),
                'inviteCode': code,
                'unread': 0,
                'members': <Map<String, dynamic>>[],
                'goals': <Map<String, dynamic>>[],
              });
    (group['members'] as List).add(_member(_me, _myName,
        kept: 0.78, streak: 4, checkedInHoursAgo: 0));
    _groups.insert(0, group);
    _post(group['id'], 'joined the group', 'System');
    _queueReply(group['id']);
    return _withLast(group);
  }

  static Map<String, dynamic> leave(String id) {
    _ensureSeeded();
    _groups.removeWhere((group) => group['id'] == id);
    return <String, dynamic>{'success': true};
  }

  static Map<String, dynamic> saveGoal(GroupGoalRequest request) {
    _ensureSeeded();
    final Map<String, dynamic>? group = _find(request.groupId);
    if (group == null) {
      return <String, dynamic>{};
    }
    final Map<String, dynamic> goal = <String, dynamic>{
      'id': MockStore.newId('gg'),
      'title': request.title,
      'description': request.description,
      'targetDate': request.targetDate,
      'colourHex': request.colourHex,
      'objectives': request.objectives
          .map((draft) => _objective(MockStore.newId('ob'), draft.title,
              draft.unit, draft.target, 0, 0))
          .toList(),
    };
    (group['goals'] as List).add(goal);
    _post(group['id'], 'added a shared goal: ${request.title}', 'System');
    return _withLast(group);
  }

  static Map<String, dynamic> logProgress(ObjectiveProgressRequest request) {
    _ensureSeeded();
    final Map<String, dynamic>? group = _find(request.groupId);
    if (group == null) {
      return <String, dynamic>{};
    }
    for (Map<String, dynamic> goal in (group['goals'] as List)) {
      if (goal['id'] != request.goalId) {
        continue;
      }
      for (Map<String, dynamic> objective in (goal['objectives'] as List)) {
        if (objective['id'] != request.objectiveId) {
          continue;
        }
        objective['current'] = (objective['current'] as num) + request.amount;
        objective['mine'] = (objective['mine'] as num) + request.amount;
        final String amount = formatAmount(request.amount);
        _post(
            group['id'],
            'logged $amount ${objective['unit']} on ${objective['title']}'
            '${request.note.isEmpty ? "" : " — ${request.note}"}',
            'CheckIn');
        _queueReply(group['id']);
      }
    }
    for (Map<String, dynamic> member in (group['members'] as List)) {
      if (member['id'] == _me) {
        member['lastCheckIn'] = DateTime.now().toIso8601String();
      }
    }
    return _withLast(group);
  }

  static List<Map<String, dynamic>> messages(String groupId) {
    _ensureSeeded();
    _deliver();
    final Map<String, dynamic>? group = _find(groupId);
    if (group != null) {
      group['unread'] = 0;
    }
    return List<Map<String, dynamic>>.from(
        _messages[groupId] ?? <Map<String, dynamic>>[]);
  }

  static Map<String, dynamic> send(GroupMessageRequest request) {
    _ensureSeeded();
    _post(request.groupId, request.body, request.kind);
    _queueReply(request.groupId);
    return _messages[request.groupId]!.last;
  }

  static Map<String, dynamic> nudge(NudgeRequest request) {
    _ensureSeeded();
    final Map<String, dynamic>? group = _find(request.groupId);
    if (group == null) {
      return <String, dynamic>{'success': false};
    }
    String who = "everyone";
    for (Map<String, dynamic> member in (group['members'] as List)) {
      if (member['id'] == request.memberId) {
        who = member['name'];
      }
    }
    _post(request.groupId, 'nudged $who: today still counts, go get it',
        'Nudge');
    return <String, dynamic>{'success': true};
  }
}