import 'package:ac_web/Api/AcApi.dart';
import 'package:ac_web/Api/Dtos/AgentDto.dart';
import 'package:ac_web/Api/Dtos/AgentTaskDto.dart';
import 'package:ac_web/Widgets/AgentStatusIndicator.dart';
import 'package:ac_web/Widgets/AgentTaskCard.dart';
import 'package:ac_web/Widgets/AgentTypeIcons.dart';
import 'package:flutter/material.dart';

/// Page that shows every detail of a single agent, including all of its tasks
/// together with the status updates the agent reported for them.
class AgentDetails extends StatefulWidget {
  const AgentDetails({super.key, required this.agent});

  /// The agent as it was known when the page got opened.
  final AgentDto agent;

  @override
  State<AgentDetails> createState() => _AgentDetailsState();
}

class _AgentDetailsState extends State<AgentDetails> {

  late AgentDto mAgent;

  bool mIsReloading = false;

  @override
  void initState() {
    super.initState();
    mAgent = widget.agent;
  }

  /// The api only offers the whole list of agents, so the agent this page
  /// shows is looked up by its name again.
  Future<void> ReloadAgent() async {

    if (mIsReloading) {
      return;
    }

    setState(() {
      mIsReloading = true;
    });

    try {
      final List<AgentDto> agents = await AcApi.instance.agents.getAgents();

      final AgentDto? updated = agents
          .where((agent) => agent.name == mAgent.name)
          .firstOrNull;

      if (!mounted) {
        return;
      }

      setState(() {
        mIsReloading = false;
        if (updated != null) {
          mAgent = updated;
        }
      });

      if (updated == null) {
        _showMessage("This agent is no longer reported by the api.");
      }
    } catch (error) {

      if (!mounted) {
        return;
      }

      setState(() {
        mIsReloading = false;
      });

      _showMessage("Could not reload the agent: $error");
    }
  }

  void _showMessage(String message) {
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(message)));
  }

  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(
        title: Text(mAgent.name.isEmpty ? "Agent" : mAgent.name),
        actions: [
          IconButton(
            onPressed: mIsReloading ? null : ReloadAgent,
            icon: const Icon(Icons.refresh),
            tooltip: "Reload",
          ),
        ],
      ),
      body: RefreshIndicator(
        onRefresh: ReloadAgent,
        child: ListView(
          padding: EdgeInsetsGeometry.all(16),
          children: [
            _buildHeader(context),
            const SizedBox(height: 12),
            _buildInfoRow(context, "Type", mAgent.type.displayName),
            const SizedBox(height: 8),
            _buildStatusRow(context),
            const SizedBox(height: 8),
            _buildInfoRow(context, "Last seen", _formatTimestamp(mAgent.lastSeen.toLocal())),
            const SizedBox(height: 8),
            _buildInfoRow(context, "Tasks", _taskCountLabel()),
            const Divider(height: 32),
            Text("Tasks", style: Theme.of(context).textTheme.titleLarge),
            const SizedBox(height: 8),
            ..._buildTasks(context),
          ],
        ),
      ),
    );
  }

  Widget _buildHeader(BuildContext context) {
    return Row(
      crossAxisAlignment: CrossAxisAlignment.center,
      spacing: 16,
      children: [
        CircleAvatar(
          backgroundColor: Theme.of(context).colorScheme.inversePrimary,
          child: Icon(mAgent.type.icon, color: Theme.of(context).colorScheme.onSurface),
        ),
        Expanded(
          child: Text(
            mAgent.name.isEmpty ? "Unnamed Agent" : mAgent.name,
            style: Theme.of(context).textTheme.headlineSmall,
          ),
        ),
      ],
    );
  }

  /// Same layout as the other info rows, but with the colored status circle.
  Widget _buildStatusRow(BuildContext context) {
    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      spacing: 8,
      children: [
        SizedBox(
          width: 96,
          child: Text("Status", style: Theme.of(context).textTheme.labelLarge),
        ),
        AgentStatusIndicator(status: mAgent.status, size: 14),
        const SizedBox(width: 4),
        Expanded(child: Text(mAgent.status.displayName)),
      ],
    );
  }

  Widget _buildInfoRow(BuildContext context, String label, String value) {
    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      spacing: 8,
      children: [
        SizedBox(
          width: 96,
          child: Text(label, style: Theme.of(context).textTheme.labelLarge),
        ),
        Expanded(child: SelectableText(value)),
      ],
    );
  }

  /// One card per task, newest first, with the newest one already expanded.
  List<Widget> _buildTasks(BuildContext context) {

    if (!mAgent.hasTasks) {
      return [
        Text(
          "This agent is currently not working on any task.",
          style: Theme.of(context).textTheme.bodyMedium,
        ),
      ];
    }

    final List<AgentTaskDto> tasks = mAgent.tasks.toList()
      ..sort(_byStartTimeDescending);

    return [
      for (int i = 0; i < tasks.length; i++)
        AgentTaskCard(task: tasks[i], initiallyExpanded: i == 0),
    ];
  }

  /// Newest task first. Tasks without a start time are kept at the end.
  int _byStartTimeDescending(AgentTaskDto left, AgentTaskDto right) {

    if (left.startTime == null && right.startTime == null) {
      return 0;
    }
    if (left.startTime == null) {
      return 1;
    }
    if (right.startTime == null) {
      return -1;
    }
    return right.startTime!.compareTo(left.startTime!);
  }

  String _taskCountLabel() {

    final int count = mAgent.tasks.length;

    if (count == 0) {
      return "No running tasks";
    }
    return count == 1 ? "1 running task" : "$count running tasks";
  }

  /// "15. August 2025, 14:32"
  String _formatTimestamp(DateTime timestamp) {

    final String hour = timestamp.hour.toString().padLeft(2, '0');
    final String minute = timestamp.minute.toString().padLeft(2, '0');

    return "${timestamp.day}. ${_monthNames[timestamp.month - 1]} ${timestamp.year}, $hour:$minute";
  }

  static const List<String> _monthNames = <String>[
    "January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December",
  ];
}