/// 服务端上传历史页（P3 计划 Task 6，A19 语义）。
///
/// GET /uploads（operationId listUploads）游标分页展示**当前账号跨设备**
/// 的上传会话记录：会话状态 / photo.processingState / sourceDeviceId /
/// 创建时间。顶部横幅明确标注「本机待传队列不在此列」——本机队列是
/// drift 任务库（TaskStore），两者数据源与生命周期不同（A19 标注要求）。
///
/// 记录不含 filename（契约 UploadSessionRecord 无该字段），行首展示
/// clientTaskId 前 8 位作识别；sourceDeviceId 与本机 [DeviceId] 一致时
/// 标记「本设备」。
library;

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../core/api_client.dart';
import '../core/app_exception.dart';
import '../core/device_id.dart';
import '../core/error_codes.dart';
import '../core/error_l10n.dart';
import '../features/photos/models.dart';
import '../features/uploads/models.dart';
import '../l10n/app_localizations.dart';

/// 服务端上传历史（从队列页占位入口进入）。
class ServerHistoryPage extends ConsumerStatefulWidget {
  const ServerHistoryPage({super.key});

  @override
  ConsumerState<ServerHistoryPage> createState() => _ServerHistoryPageState();
}

class _ServerHistoryPageState extends ConsumerState<ServerHistoryPage> {
  static const int _pageSize = 20;

  List<UploadSessionRecord> _items = const <UploadSessionRecord>[];
  String? _nextCursor;
  bool _hasMore = false;
  bool _loading = true;
  bool _loadingMore = false;
  String? _errorCode;

  /// 本机设备标识（「本设备」标记比对，A19）。
  String? _ownDeviceId;

  @override
  void initState() {
    super.initState();
    _reload();
    unawaited(
      ref.read(deviceIdProvider).value().then((id) {
        if (mounted) setState(() => _ownDeviceId = id);
      }),
    );
  }

  Future<void> _reload() async {
    setState(() {
      _loading = true;
      _errorCode = null;
    });
    try {
      final page = await ref
          .read(apiClientProvider)
          .listUploads(limit: _pageSize);
      if (mounted) {
        setState(() {
          _items = page.items;
          _nextCursor = page.nextCursor;
          _hasMore = page.hasMore;
          _loading = false;
        });
      }
    } on AppException catch (e) {
      if (mounted) {
        setState(() {
          _errorCode = e.code;
          _loading = false;
        });
      }
    } on Object {
      if (mounted) {
        setState(() {
          _errorCode = ErrorCodes.internalError;
          _loading = false;
        });
      }
    }
  }

  Future<void> _loadMore() async {
    if (_loading || _loadingMore || !_hasMore) return;
    setState(() => _loadingMore = true);
    try {
      final page = await ref.read(apiClientProvider).listUploads(
            cursor: _nextCursor,
            limit: _pageSize,
          );
      if (mounted) {
        setState(() {
          _items = <UploadSessionRecord>[..._items, ...page.items];
          _nextCursor = page.nextCursor;
          _hasMore = page.hasMore;
          _loadingMore = false;
        });
      }
    } on AppException {
      if (mounted) {
        setState(() => _loadingMore = false);
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(
              AppLocalizations.of(context)
                  .messageForErrorCode(ErrorCodes.networkError),
            ),
          ),
        );
      }
    } on Object {
      if (mounted) {
        setState(() => _loadingMore = false);
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(AppLocalizations.of(context).errorGeneric),
          ),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(title: Text(l10n.serverHistoryTitle)),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          // A19 标注横幅：与「队列」页（本机任务库）的数据源区分。
          Card(
            margin: const EdgeInsets.fromLTRB(12, 12, 12, 0),
            child: Padding(
              padding: const EdgeInsets.all(12),
              child: Row(
                children: [
                  Icon(
                    Icons.devices_outlined,
                    size: 18,
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                  const SizedBox(width: 8),
                  Expanded(
                    child: Text(
                      l10n.serverHistoryBanner,
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
          Expanded(
            child: _loading
                ? const Center(child: CircularProgressIndicator())
                : _items.isEmpty && _errorCode != null
                    ? Center(
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            const Icon(Icons.cloud_off, size: 48),
                            const SizedBox(height: 12),
                            Text(l10n.messageForErrorCode(_errorCode!)),
                            const SizedBox(height: 12),
                            FilledButton.icon(
                              onPressed: _reload,
                              icon: const Icon(Icons.refresh),
                              label: Text(l10n.retry),
                            ),
                          ],
                        ),
                      )
                    : ListView.builder(
                        itemCount: _items.length +
                            (_items.isEmpty || _hasMore || _loadingMore ? 1 : 0),
                        itemBuilder: (context, index) {
                          if (_items.isEmpty) {
                            return Padding(
                              padding: const EdgeInsets.all(32),
                              child: Text(
                                l10n.serverHistoryEmpty,
                                textAlign: TextAlign.center,
                                style: theme.textTheme.bodySmall,
                              ),
                            );
                          }
                          if (index >= _items.length) {
                            return const Padding(
                              padding: EdgeInsets.symmetric(vertical: 16),
                              child: Center(
                                child: SizedBox(
                                  height: 24,
                                  width: 24,
                                  child: CircularProgressIndicator(
                                    strokeWidth: 2,
                                  ),
                                ),
                              ),
                            );
                          }
                          if (index >= _items.length - 3 &&
                              _hasMore &&
                              !_loadingMore) {
                            WidgetsBinding.instance.addPostFrameCallback(
                              (_) => _loadMore(),
                            );
                          }
                          return _sessionTile(l10n, theme, _items[index]);
                        },
                      ),
          ),
        ],
      ),
    );
  }

  Widget _sessionTile(
    AppLocalizations l10n,
    ThemeData theme,
    UploadSessionRecord record,
  ) {
    // createdAt 以本机时区展示（记录跨相册，无单一相册时区可依）。
    final local = record.createdAt.toLocal();
    final time = '${local.year}/${local.month}/${local.day} '
        '${local.hour.toString().padLeft(2, '0')}:'
        '${local.minute.toString().padLeft(2, '0')}';
    final deviceShort = record.sourceDeviceId?.substring(0, 8);
    final ownDevice =
        _ownDeviceId != null && record.sourceDeviceId == _ownDeviceId;
    return ListTile(
      leading: const Icon(Icons.cloud_done_outlined),
      title: Text(
        '${record.clientTaskId.substring(0, 8)} · '
        '${(record.expectedBytes / 1024).round()} KB',
        style: theme.textTheme.bodyMedium?.copyWith(
          fontFeatures: const [FontFeature.tabularFigures()],
        ),
      ),
      subtitle: Text(
        deviceShort == null
            ? time
            : '$time · $deviceShort${ownDevice ? '（${l10n.thisDevice}）' : ''}',
      ),
      trailing: Wrap(
        spacing: 6,
        runSpacing: 4,
        crossAxisAlignment: WrapCrossAlignment.center,
        children: [
          _HistoryTag(
            label: _sessionStateLabel(l10n, record.state),
            highlight: record.state == UploadSessionState.confirmed,
          ),
          _HistoryTag(
            label: _processingLabel(l10n, record.photo.processingState),
            highlight: record.photo.processingState ==
                PhotoProcessingState.ready,
          ),
        ],
      ),
    );
  }

  static String _sessionStateLabel(
    AppLocalizations l10n,
    UploadSessionState state,
  ) {
    switch (state) {
      case UploadSessionState.pending:
        return l10n.uploadStatePending;
      case UploadSessionState.confirmed:
        return l10n.uploadStateConfirmed;
      case UploadSessionState.cancelled:
        return l10n.uploadStateCancelled;
      case UploadSessionState.expired:
        return l10n.uploadStateExpired;
    }
  }

  static String _processingLabel(
    AppLocalizations l10n,
    PhotoProcessingState s,
  ) {
    switch (s) {
      case PhotoProcessingState.pendingUpload:
        return l10n.procPendingUpload;
      case PhotoProcessingState.uploaded:
        return l10n.procUploaded;
      case PhotoProcessingState.processing:
        return l10n.procProcessing;
      case PhotoProcessingState.ready:
        return l10n.procReady;
      case PhotoProcessingState.processingFailed:
        return l10n.procProcessingFailed;
    }
  }
}

/// 会话记录标签（会话状态/处理状态）。
class _HistoryTag extends StatelessWidget {
  const _HistoryTag({required this.label, required this.highlight});

  final String label;
  final bool highlight;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 2),
      decoration: BoxDecoration(
        color: highlight
            ? theme.colorScheme.secondaryContainer
            : theme.colorScheme.surfaceContainerHighest,
        borderRadius: BorderRadius.circular(999),
      ),
      child: Text(
        label,
        style: theme.textTheme.labelSmall?.copyWith(
          color: highlight
              ? theme.colorScheme.onSecondaryContainer
              : theme.colorScheme.onSurfaceVariant,
        ),
      ),
    );
  }
}