@* Per Q1 of the AdminUI rebuild plan — JSON editor only, typed driver editors deferred.
   DriverInstance is the keystone for everything downstream (Equipment, Tag, VirtualTag,
   ScriptedAlarm all reference DriverInstanceId), so this is the second edit page after
   Namespace. *@
@attribute [Microsoft.AspNetCore.Authorization.Authorize]
@rendermode RenderMode.InteractiveServer
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.EntityFrameworkCore
@using System.ComponentModel.DataAnnotations
@using ZB.MOM.WW.OtOpcUa.Configuration
@using ZB.MOM.WW.OtOpcUa.Configuration.Entities
@using ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared.Drivers
@inject IDbContextFactory<OtOpcUaConfigDbContext> DbFactory
@inject NavigationManager Nav

<div class="d-flex justify-content-between align-items-center mb-3">
    <h4 class="mb-0">@(IsNew ? "New driver instance" : "Edit driver instance") &middot; <span class="mono">@ClusterId</span></h4>
    <a href="/clusters/@ClusterId/drivers" class="btn btn-outline-secondary btn-sm">Cancel</a>
</div>

<ClusterNav ClusterId="@ClusterId" ActiveTab="drivers" />

@if (!_loaded)
{
    <p>Loading…</p>
}
else if (!IsNew && _existing is null)
{
    <section class="panel notice rise" style="animation-delay:.02s">
        Driver instance <span class="mono">@DriverInstanceId</span> was not found in cluster <span class="mono">@ClusterId</span>.
    </section>
}
else
{
    <EditForm Model="_form" OnValidSubmit="SubmitAsync" FormName="driverEdit">
        <DataAnnotationsValidator />
        <DriverFormShell IsNew="IsNew" Busy="_busy" Error="_error"
                         CancelHref="@($"/clusters/{ClusterId}/drivers")"
                         OnDelete="@(IsNew ? null : (EventCallback?)EventCallback.Factory.Create(this, DeleteAsync))">
            <DriverIdentitySection Model="_identityModel" Namespaces="_namespaces" IsNew="IsNew" ShowDriverType="true" />

            @* Driver config (JSON) — inlined; will be replaced by typed forms in Phase 4 *@
            <section class="panel rise mt-3" style="animation-delay:.08s">
                <div class="panel-head">Driver config (JSON)</div>
                <div style="padding:1rem">
                    <InputTextArea @bind-Value="_form.DriverConfig" rows="12"
                                   class="form-control form-control-sm mono"
                                   placeholder='{ "endpoint": "10.0.0.42:502", "slaveId": 1 }' />
                    <div class="form-text">Schemaless per driver type — validated server-side at deploy time. JSON is reformatted on save.</div>
                </div>
            </section>

            <DriverResilienceSection @bind-ResilienceConfig="_form.ResilienceConfig" />
        </DriverFormShell>
    </EditForm>
}

@code {
    [Parameter] public string ClusterId { get; set; } = "";
    [Parameter] public string? DriverInstanceId { get; set; }

    private bool IsNew => string.IsNullOrEmpty(DriverInstanceId);

    private DriverIdentitySection.DriverIdentityModel _identityModel = new();
    private FormModel _form = new();
    private DriverInstance? _existing;
    private List<Namespace> _namespaces = new();
    private bool _loaded;
    private bool _busy;
    private string? _error;

    protected override async Task OnInitializedAsync()
    {
        await using var db = await DbFactory.CreateDbContextAsync();
        _namespaces = await db.Namespaces.AsNoTracking()
            .Where(n => n.ClusterId == ClusterId)
            .OrderBy(n => n.NamespaceId)
            .ToListAsync();

        if (IsNew)
        {
            _identityModel = new DriverIdentitySection.DriverIdentityModel
            {
                DriverInstanceId = "",
                Name = "",
                DriverType = "ModbusTcp",
                NamespaceId = _namespaces.FirstOrDefault()?.NamespaceId ?? "",
                Enabled = true,
            };
            _form = new FormModel
            {
                DriverConfig = "{}",
            };
        }
        else
        {
            _existing = await db.DriverInstances.AsNoTracking()
                .FirstOrDefaultAsync(d => d.ClusterId == ClusterId && d.DriverInstanceId == DriverInstanceId);
            if (_existing is not null)
            {
                _identityModel = new DriverIdentitySection.DriverIdentityModel
                {
                    DriverInstanceId = _existing.DriverInstanceId,
                    Name = _existing.Name,
                    DriverType = _existing.DriverType,
                    NamespaceId = _existing.NamespaceId,
                    Enabled = _existing.Enabled,
                };
                _form = new FormModel
                {
                    DriverConfig = _existing.DriverConfig,
                    ResilienceConfig = _existing.ResilienceConfig,
                    RowVersion = _existing.RowVersion,
                };
            }
        }
        _loaded = true;
    }

    private async Task SubmitAsync()
    {
        _busy = true;
        _error = null;
        try
        {
            var normalizedConfig = NormalizeJson(_form.DriverConfig);
            if (normalizedConfig is null)
            {
                _error = "DriverConfig is not valid JSON.";
                return;
            }
            var normalizedResilience = NormalizeOptionalJson(_form.ResilienceConfig);
            if (!string.IsNullOrWhiteSpace(_form.ResilienceConfig) && normalizedResilience is null)
            {
                _error = "ResilienceConfig is not valid JSON. Leave blank to use defaults.";
                return;
            }

            await using var db = await DbFactory.CreateDbContextAsync();
            if (IsNew)
            {
                if (await db.DriverInstances.AnyAsync(d => d.DriverInstanceId == _identityModel.DriverInstanceId))
                {
                    _error = $"Driver instance '{_identityModel.DriverInstanceId}' already exists.";
                    return;
                }
                db.DriverInstances.Add(new DriverInstance
                {
                    DriverInstanceId = _identityModel.DriverInstanceId,
                    ClusterId = ClusterId,
                    NamespaceId = _identityModel.NamespaceId,
                    Name = _identityModel.Name,
                    DriverType = _identityModel.DriverType,
                    Enabled = _identityModel.Enabled,
                    DriverConfig = normalizedConfig,
                    ResilienceConfig = normalizedResilience,
                });
            }
            else
            {
                var entity = await db.DriverInstances.FirstOrDefaultAsync(
                    d => d.ClusterId == ClusterId && d.DriverInstanceId == DriverInstanceId);
                if (entity is null)
                {
                    _error = "Row no longer exists.";
                    return;
                }
                db.Entry(entity).Property(e => e.RowVersion).OriginalValue = _form.RowVersion;
                entity.NamespaceId = _identityModel.NamespaceId;
                entity.Name = _identityModel.Name;
                entity.Enabled = _identityModel.Enabled;
                entity.DriverConfig = normalizedConfig;
                entity.ResilienceConfig = normalizedResilience;
            }
            await db.SaveChangesAsync();
            Nav.NavigateTo($"/clusters/{ClusterId}/drivers");
        }
        catch (DbUpdateConcurrencyException)
        {
            _error = "Another user changed this driver instance while you were editing. Reload to see the latest values, then re-apply your changes.";
        }
        catch (Exception ex)
        {
            _error = ex.Message;
        }
        finally
        {
            _busy = false;
        }
    }

    private async Task DeleteAsync()
    {
        if (IsNew) return;
        _busy = true;
        _error = null;
        try
        {
            await using var db = await DbFactory.CreateDbContextAsync();
            var entity = await db.DriverInstances.FirstOrDefaultAsync(
                d => d.ClusterId == ClusterId && d.DriverInstanceId == DriverInstanceId);
            if (entity is null)
            {
                Nav.NavigateTo($"/clusters/{ClusterId}/drivers");
                return;
            }
            db.Entry(entity).Property(e => e.RowVersion).OriginalValue = _form.RowVersion;
            db.DriverInstances.Remove(entity);
            await db.SaveChangesAsync();
            Nav.NavigateTo($"/clusters/{ClusterId}/drivers");
        }
        catch (DbUpdateConcurrencyException)
        {
            _error = "Another user changed this driver instance while you were viewing it. Reload before deleting.";
        }
        catch (Exception ex)
        {
            _error = $"Delete failed: {ex.Message}. (Likely because equipment/tags still reference this driver — remove them first.)";
        }
        finally
        {
            _busy = false;
        }
    }

    private static string? NormalizeJson(string? input)
    {
        if (string.IsNullOrWhiteSpace(input)) return null;
        try
        {
            using var doc = System.Text.Json.JsonDocument.Parse(input);
            return System.Text.Json.JsonSerializer.Serialize(doc.RootElement);
        }
        catch { return null; }
    }

    private static string? NormalizeOptionalJson(string? input) =>
        string.IsNullOrWhiteSpace(input) ? null : NormalizeJson(input);

    private sealed class FormModel
    {
        [Required]
        public string DriverConfig { get; set; } = "{}";
        public string? ResilienceConfig { get; set; }
        public byte[] RowVersion { get; set; } = [];
    }
}