import 'package:ac_web/Api/AcApi.dart';
import 'package:ac_web/Api/Dtos/AgentDto.dart';
import 'package:ac_web/Pages/AgentDetails.dart';
import 'package:ac_web/Widgets/AgentStatusIndicator.dart';
import 'package:ac_web/Widgets/AgentTypeIcons.dart';
import 'package:ac_web/Widgets/AutoRefreshState.dart';
import 'package:flutter/material.dart';

/// Fetches all agents from the AgentsController and lists them with a colored
/// status indicator in front of their name.
class AgentAvailabilityColumn extends StatefulWidget{
  const AgentAvailabilityColumn({super.key});

  @override
  State<AgentAvailabilityColumn> createState() => _AgentAvailabilityColumnState();
}

class _AgentAvailabilityColumnState extends State<AgentAvailabilityColumn>
    with AutoRefreshState<AgentAvailabilityColumn> {

  late Future<List<AgentDto>> mAgentsFuture;

  @override
  void initState() {
    super.initState();
    mAgentsFuture = AcApi.instance.agents.getAgents();
  }

  /// Reload triggered by the user. Shows the loading indicator again because
  /// the user asked for the request and should see that it is running.
  void ReloadAgents(){
    setState(() {
      mAgentsFuture = AcApi.instance.agents.getAgents();
    });
  }

  /// Automatic reload. The agents that are already on screen stay visible
  /// while the request runs, the future is only replaced once it succeeded.
  @override
  Future<void> RefreshData() async {

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

    if (!mounted) {
      return;
    }

    setState(() {
      mAgentsFuture = Future<List<AgentDto>>.value(agents);
    });
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<List<AgentDto>>(
      future: mAgentsFuture,
      builder: (context, snapshot) {

        // Not `connectionState`: a refresh puts the builder back into the
        // waiting state although the previous agents are still available, and
        // those should stay on screen instead of flashing a spinner.
        if (!snapshot.hasData && !snapshot.hasError) {
          return const Center(child: CircularProgressIndicator());
        }

        if (snapshot.hasError && !snapshot.hasData) {
          return Center(child: Text('Could not load agents: ${snapshot.error}'));
        }

        // The list of agents fetched from the AgentsController.
        final List<AgentDto> agents = snapshot.data ?? <AgentDto>[];

        return _buildList(agents);
      },
    );
  }

  Widget _buildList(List<AgentDto> agents) {

    if (agents.isEmpty) {
      return const Center(child: Text("No agents available"));
    }

    return RefreshIndicator(
      onRefresh: () async => ReloadAgents(),
      child: ListView.builder(
        padding: const EdgeInsets.all(8),
        itemCount: agents.length,
        itemBuilder: (context, index) {

          final AgentDto agent = agents[index];

          return ListTile(
            leading: AgentStatusIndicator(status: agent.status),
            title: Text(agent.name),
            subtitle: Text("${agent.type.displayName} - ${agent.status.displayName}"),
            trailing: Icon(agent.type.icon),
            onTap: () => _openAgent(agent),
          );
        },
      ),
    );
  }

  /// Opens a new page that shows all details of the given agent.
  void _openAgent(AgentDto agent) {
    Navigator.of(context).push(
      MaterialPageRoute<void>(
        builder: (context) => AgentDetails(agent: agent),
      ),
    );
  }
}