using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.EntityFrameworkCore;
using ZB.MOM.WW.OtOpcUa.Configuration;
using ZB.MOM.WW.OtOpcUa.Configuration.Entities;

namespace ZB.MOM.WW.OtOpcUa.Admin.Services;

/// <summary>
///     Per-instance detail view for FOCAS driver rows. Loads the latest
///     <see cref="DriverInstance"/> row for the requested <c>DriverInstanceId</c> (most-recent
///     draft wins when multiple rows exist across generations), parses the schemaless
///     <c>DriverConfig</c> JSON into <see cref="FocasDriverConfigView"/>, and joins the
///     per-device <see cref="DriverHostStatus"/> rows so the Admin page can render host
///     state + consecutive-failure counters next to each configured device.
/// </summary>
public sealed class FocasDriverDetailService(OtOpcUaConfigDbContext db)
{
    private static readonly JsonSerializerOptions JsonOpts = new()
    {
        PropertyNameCaseInsensitive = true,
        NumberHandling = JsonNumberHandling.AllowReadingFromString,
    };

    public async Task<FocasDriverDetail?> GetAsync(string driverInstanceId, CancellationToken ct = default)
    {
        if (string.IsNullOrWhiteSpace(driverInstanceId)) return null;

        var instance = await db.DriverInstances.AsNoTracking()
            .Where(d => d.DriverInstanceId == driverInstanceId
                     && d.DriverType.ToLower() == "focas")
            .OrderByDescending(d => d.GenerationId)
            .FirstOrDefaultAsync(ct);
        if (instance is null) return null;

        FocasDriverConfigView? config = null;
        string? parseError = null;
        try { config = JsonSerializer.Deserialize<FocasDriverConfigView>(instance.DriverConfig, JsonOpts); }
        catch (JsonException ex) { parseError = ex.Message; }

        var hostStatuses = await (from s in db.DriverHostStatuses.AsNoTracking()
                                  where s.DriverInstanceId == driverInstanceId
                                  join r in db.DriverInstanceResilienceStatuses.AsNoTracking()
                                      on new { s.DriverInstanceId, s.HostName }
                                      equals new { r.DriverInstanceId, r.HostName } into rj
                                  from r in rj.DefaultIfEmpty()
                                  orderby s.HostName
                                  select new FocasHostStatusRow(
                                      s.NodeId,
                                      s.HostName,
                                      s.State.ToString(),
                                      s.StateChangedUtc,
                                      s.LastSeenUtc,
                                      s.Detail,
                                      r != null ? r.ConsecutiveFailures : 0,
                                      r != null ? r.LastCircuitBreakerOpenUtc : null,
                                      r != null ? r.LastRecycleUtc : null)).ToListAsync(ct);

        return new FocasDriverDetail(instance, config, parseError, hostStatuses);
    }
}

/// <summary>Projected view of a FOCAS driver's parsed config. Unknown fields are ignored.</summary>
public sealed record FocasDriverConfigView
{
    public List<FocasDeviceView>? Devices { get; set; }
    public List<FocasTagView>? Tags { get; set; }
    public FocasProbeView? Probe { get; set; }
    public FocasAlarmProjectionView? AlarmProjection { get; set; }
    public FocasHandleRecycleView? HandleRecycle { get; set; }
}

public sealed record FocasDeviceView
{
    public string? HostAddress { get; set; }
    public string? DeviceName { get; set; }
    public string? Series { get; set; }
}

public sealed record FocasTagView
{
    public string? Name { get; set; }
    public string? DeviceHostAddress { get; set; }
    public string? Address { get; set; }
    public string? DataType { get; set; }
    public bool Writable { get; set; } = true;
}

public sealed record FocasProbeView
{
    public bool Enabled { get; set; } = true;
    public string? Interval { get; set; }
}

public sealed record FocasAlarmProjectionView
{
    public bool Enabled { get; set; }
    public string? PollInterval { get; set; }
}

public sealed record FocasHandleRecycleView
{
    public bool Enabled { get; set; }
    public string? Interval { get; set; }
}

/// <summary>Composite payload returned to the Admin page.</summary>
public sealed record FocasDriverDetail(
    DriverInstance Instance,
    FocasDriverConfigView? Config,
    string? ParseError,
    IReadOnlyList<FocasHostStatusRow> HostStatuses);

public sealed record FocasHostStatusRow(
    string NodeId,
    string HostName,
    string State,
    DateTime StateChangedUtc,
    DateTime LastSeenUtc,
    string? Detail,
    int ConsecutiveFailures,
    DateTime? LastCircuitBreakerOpenUtc,
    DateTime? LastRecycleUtc);