import 'package:miler/Models/summary/riderweeklykms.dart';
import 'package:miler/data/miler_api.dart';

/// ─────────────────────────────────────────────────────────────────────────
/// THE WEEK'S KILOMETRES
///
/// ── Why the chart was empty ──
///
/// This read `data.breakdown` off `GET /miler/earnings?period=weekly` and
/// mapped it into the seven bars. That field is not on the contract: the
/// earnings response carries `completed_stops`, `cancelled_stops`,
/// `total_stops`, `total_kms`, `total_earnings` and `total_bonus` — six
/// **totals for the period asked for**, and no per-day series at all.
///
/// So `breakdown` was always null, the list was always empty, and the chart
/// drew seven bars of nothing while the rider had ridden all week. It failed
/// silently because an absent key and an empty week look identical downstream.
///
/// ── What it does instead ──
///
/// The endpoint answers for *a* period, and it takes a `date`. A week is seven
/// days, so the week is seven daily calls — asked concurrently, so the page
/// waits for the slowest one rather than the sum of seven.
///
/// That is more requests than one, and it is the honest cost of a contract that
/// has no series on it. It is bounded (seven, on a screen opened occasionally
/// rather than polled), and it is built from the same figure the totals row
/// prints, so the bars and the total cannot disagree.
///
/// **The fast path stays.** If `breakdown` ever ships, it is used and the seven
/// calls are skipped — that check is two lines and it is what makes this
/// removable later without touching the page.
/// ─────────────────────────────────────────────────────────────────────────
class RiderWeeklyKmController {
  /// `Mon` … `Sun`. Written out rather than taken from `intl` because these
  /// strings are matched against the server's own day names elsewhere, and a
  /// locale-aware formatter would introduce a mismatch that comparison cannot
  /// survive.
  static const List<String> _days = [
    'Mon',
    'Tue',
    'Wed',
    'Thu',
    'Fri',
    'Sat',
    'Sun',
  ];

  static String _iso(DateTime d) =>
      '${d.year}-${d.month.toString().padLeft(2, '0')}-'
      '${d.day.toString().padLeft(2, '0')}';

  static double _num(dynamic v) {
    if (v is num) return v.toDouble();
    return double.tryParse('${v ?? ''}') ?? 0;
  }

  /// Reads a weekly `breakdown` into the chart's series, or returns null when
  /// there is nothing usable in it.
  ///
  /// ── Null is the whole contract here ──
  ///
  /// Anything short of a series the chart can draw has to fall through to the
  /// seven daily calls, because the alternative is what this page shipped for
  /// months: an empty list drawn as seven empty bars, indistinguishable from a
  /// week with no riding in it. Absent, null, not a list, empty, entries that
  /// are not maps, entries with no day or no parseable distance — all of them
  /// are "no series", and none of them is a chart.
  ///
  /// ── The day label is normalised ──
  ///
  /// The chart labels its bars with the first three characters of `day`, which
  /// works for `Mon` and produces `202` for `2026-08-19`. The backend's example
  /// uses the ISO form, so an ISO date is converted to the weekday it names and
  /// anything else is passed through — a server that sends `Monday`, `Mon` or
  /// `mon` already works, and one that sends something unrecognisable is
  /// unusable rather than silently mislabelled.
  static List<RiderWeeklyKms>? _readBreakdown(dynamic raw) {
    if (raw is! List || raw.isEmpty) return null;

    final rows = <RiderWeeklyKms>[];
    for (final entry in raw) {
      if (entry is! Map) return null;
      final day = _dayLabel(entry['day']);
      if (day.isEmpty) return null;
      final kms = entry['kms'];
      if (kms != null && kms is! num && double.tryParse('$kms') == null) {
        return null;
      }
      rows.add(RiderWeeklyKms(day: day, kms: _num(kms)));
    }
    return rows.isEmpty ? null : rows;
  }

  /// `2026-08-19` → `Tue`. Any other non-empty string is returned as it came.
  static String _dayLabel(dynamic raw) {
    final s = raw?.toString().trim() ?? '';
    if (s.isEmpty) return '';
    final parsed = DateTime.tryParse(s);
    if (parsed != null) return _days[parsed.weekday - 1];
    return s;
  }

  /// The last seven days, oldest first, plus the week's total.
  ///
  /// [userId] is unused: the token identifies the rider, and asking for someone
  /// else's kilometres is not a thing the endpoint offers. Kept on the
  /// signature because the call sites read better for naming whose distance
  /// they mean.
  Future<Map<String, dynamic>> getRiderWeeklyKms(int userId) async {
    final weekly = await MilerApi.earnings(period: 'weekly');
    if (!weekly.ok) {
      throw Exception('Failed to fetch (code: ${weekly.status})');
    }

    final weekTotal = _num(weekly.map['total_kms']);

    // ── The fast path ──
    //
    // If the server returns a per-day series, take it and spend no further
    // requests. Nothing below runs.
    final fast = _readBreakdown(weekly.map['breakdown']);
    if (fast != null) {
      return {'details': fast, 'total_kms': weekTotal};
    }

    // Seven days ending today, asked at once.
    final today = DateTime.now();
    final dates = <DateTime>[
      for (var back = 6; back >= 0; back--)
        DateTime(today.year, today.month, today.day - back),
    ];

    final results = await Future.wait(
      dates.map((d) => MilerApi.earnings(period: 'daily', date: _iso(d))),
    );

    final details = <RiderWeeklyKms>[];
    var summed = 0.0;
    for (final (i, res) in results.indexed) {
      // A day that failed is a day with no figure, not a zero worth charting
      // against the others — but the bar still has to exist or the week is six
      // days long and the labels slide. Zero, and the total below is what
      // corrects for it.
      final km = res.ok ? _num(res.map['total_kms']) : 0.0;
      summed += km;
      details.add(RiderWeeklyKms(day: _days[dates[i].weekday - 1], kms: km));
    }

    return {
      'details': details,
      // The weekly total is the server's own where it has one — the seven daily
      // figures are a reconstruction, and a reconstruction should not overrule
      // the number the backend computed. It stands in only when the weekly call
      // reported nothing.
      'total_kms': weekTotal > 0 ? weekTotal : summed,
    };
  }
}