import 'package:dio/dio.dart';
import 'package:fintracker_api/fintracker_api.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../core/api/api_client.dart';

/// What the События screen asks the ledger for. `instrumentId` has no control of its own —
/// the instrument card already lists an instrument's own events — but it is carried here
/// so navigating in with a preset instrument stays a one-line change.
class EventsFilter {
  const EventsFilter({
    this.q,
    this.from,
    this.to,
    this.accountId,
    this.instrumentId,
    this.kind,
    this.status,
    this.externalFlow,
  });

  final String? q;
  final DateTime? from;
  final DateTime? to;
  final int? accountId;
  final int? instrumentId;
  final EventKind? kind;
  final EventStatus? status;
  final bool? externalFlow;

  EventsFilter copyWith({
    String? Function()? q,
    DateTime? Function()? from,
    DateTime? Function()? to,
    int? Function()? accountId,
    int? Function()? instrumentId,
    EventKind? Function()? kind,
    EventStatus? Function()? status,
    bool? Function()? externalFlow,
  }) {
    return EventsFilter(
      q: q != null ? q() : this.q,
      from: from != null ? from() : this.from,
      to: to != null ? to() : this.to,
      accountId: accountId != null ? accountId() : this.accountId,
      instrumentId: instrumentId != null ? instrumentId() : this.instrumentId,
      kind: kind != null ? kind() : this.kind,
      status: status != null ? status() : this.status,
      externalFlow: externalFlow != null ? externalFlow() : this.externalFlow,
    );
  }
}

class EventsState {
  const EventsState({
    this.items = const [],
    this.page = 1,
    this.pageSize = 50,
    this.total = 0,
    this.loading = false,
    this.loadingMore = false,
    this.error,
  });

  final List<EventOut> items;
  final int page;
  final int pageSize;
  final int total;
  final bool loading;
  final bool loadingMore;
  final Object? error;

  bool get hasMore => items.length < total;

  EventsState copyWith({
    List<EventOut>? items,
    int? page,
    int? pageSize,
    int? total,
    bool? loading,
    bool? loadingMore,
    Object? error,
    bool clearError = false,
  }) {
    return EventsState(
      items: items ?? this.items,
      page: page ?? this.page,
      pageSize: pageSize ?? this.pageSize,
      total: total ?? this.total,
      loading: loading ?? this.loading,
      loadingMore: loadingMore ?? this.loadingMore,
      error: clearError ? null : (error ?? this.error),
    );
  }
}

/// Filters + paginated results for События, the same shape Операции uses: `refresh()`
/// restarts from page 1 (on build and on every filter change), `loadMore()` appends the
/// next page for infinite scroll.
class EventsController extends Notifier<EventsState> {
  EventsFilter filter = const EventsFilter();

  @override
  EventsState build() {
    Future.microtask(refresh);
    return const EventsState(loading: true);
  }

  Future<void> setFilter(EventsFilter Function(EventsFilter) update) {
    filter = update(filter);
    return refresh();
  }

  Future<EventPage> _fetch(int page) async {
    final r = await ref
        .read(apiProvider)
        .getEventsApi()
        .eventsList(
          from: filter.from,
          to: filter.to,
          accountId: filter.accountId,
          instrumentId: filter.instrumentId,
          kind: filter.kind,
          status: filter.status,
          externalFlow: filter.externalFlow,
          q: (filter.q == null || filter.q!.isEmpty) ? null : filter.q,
          page: page,
          pageSize: state.pageSize,
        );
    return r.data!;
  }

  Future<void> refresh() async {
    state = state.copyWith(loading: true, clearError: true);
    try {
      final page = await _fetch(1);
      state = EventsState(
        items: page.items,
        page: page.page,
        pageSize: page.pageSize,
        total: page.total,
      );
    } on DioException catch (e) {
      state = state.copyWith(loading: false, error: e);
    }
  }

  Future<void> loadMore() async {
    if (state.loading || state.loadingMore || !state.hasMore) return;
    state = state.copyWith(loadingMore: true, clearError: true);
    try {
      final page = await _fetch(state.page + 1);
      state = state.copyWith(
        items: [...state.items, ...page.items],
        page: page.page,
        total: page.total,
        loadingMore: false,
      );
    } on DioException catch (e) {
      state = state.copyWith(loadingMore: false, error: e);
    }
  }
}

final eventsControllerProvider =
    NotifierProvider<EventsController, EventsState>(EventsController.new);