@page "/scripts/new"
@page "/scripts/{ScriptId}"
@* Script CRUD. SourceHash is computed automatically from SourceCode on save so the
   integrity check in v2's deployment pipeline doesn't require operator action. *@
@attribute [Microsoft.AspNetCore.Authorization.Authorize]
@rendermode RenderMode.InteractiveServer
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.EntityFrameworkCore
@using System.ComponentModel.DataAnnotations
@using System.Security.Cryptography
@using System.Text
@using ZB.MOM.WW.OtOpcUa.Configuration
@using ZB.MOM.WW.OtOpcUa.Configuration.Entities
@inject IDbContextFactory<OtOpcUaConfigDbContext> DbFactory
@inject NavigationManager Nav
@inject IJSRuntime JS

<div class="d-flex justify-content-between align-items-center mb-3">
    <h4 class="mb-0">@(IsNew ? "New script" : "Edit script")</h4>
    <a href="/scripts" class="btn btn-outline-secondary btn-sm">Cancel</a>
</div>

@if (!_loaded)
{
    <p>Loading…</p>
}
else if (!IsNew && _existing is null)
{
    <section class="panel notice rise"><span class="mono">@ScriptId</span> not found.</section>
}
else
{
    <EditForm Model="_form" OnValidSubmit="SubmitAsync" FormName="scriptEdit">
        <DataAnnotationsValidator />
        <section class="panel rise">
            <div class="panel-head">Identity</div>
            <div style="padding:1rem">
                <div class="row">
                    <div class="col-md-6 mb-3">
                        <label class="form-label">ScriptId</label>
                        <InputText @bind-Value="_form.ScriptId" disabled="@(!IsNew)" class="form-control form-control-sm mono" />
                    </div>
                    <div class="col-md-4 mb-3">
                        <label class="form-label">Name</label>
                        <InputText @bind-Value="_form.Name" class="form-control form-control-sm" />
                    </div>
                    <div class="col-md-2 mb-3">
                        <label class="form-label">Language</label>
                        <InputSelect @bind-Value="_form.Language" class="form-select form-select-sm">
                            <option value="CSharp">CSharp</option>
                        </InputSelect>
                    </div>
                </div>
            </div>
        </section>

        <section class="panel rise mt-3">
            <div class="panel-head">Source</div>
            <div style="padding:1rem">
                @* The textarea stays in the DOM and remains Blazor's source of truth. Monaco
                   mounts a <div> beside it (textarea hides), and the loader's onDidChangeModelContent
                   handler mirrors edits back into the textarea + fires the input event so @bind
                   picks them up. Falls back to the textarea gracefully if Monaco's CDN is
                   unreachable (air-gapped deployments — see monaco-loader.js). *@
                <InputTextArea id="script-source" @bind-Value="_form.SourceCode"
                               class="form-control form-control-sm mono" rows="20"
                               placeholder="// C# expression body" />
                <div class="form-text">SHA-256 hash is computed automatically on save. Monaco editor attaches over the textarea on render.</div>
            </div>
        </section>

        @if (!string.IsNullOrWhiteSpace(_error)) { <div class="panel notice mt-3" style="border-color:var(--alert)">@_error</div> }

        <div class="mt-3 d-flex gap-2">
            <button type="submit" class="btn btn-primary" disabled="@_busy">@(IsNew ? "Create" : "Save changes")</button>
            <a href="/scripts" class="btn btn-outline-secondary">Cancel</a>
            @if (!IsNew) { <button type="button" class="btn btn-outline-danger ms-auto" @onclick="DeleteAsync" disabled="@_busy">Delete</button> }
        </div>
    </EditForm>
}

@code {
    [Parameter] public string? ScriptId { get; set; }
    private bool IsNew => string.IsNullOrEmpty(ScriptId);

    private FormModel _form = new();
    private Script? _existing;
    private bool _loaded;
    private bool _busy;
    private string? _error;

    protected override async Task OnInitializedAsync()
    {
        if (!IsNew)
        {
            await using var db = await DbFactory.CreateDbContextAsync();
            _existing = await db.Scripts.AsNoTracking().FirstOrDefaultAsync(s => s.ScriptId == ScriptId);
            if (_existing is not null)
            {
                _form = new FormModel
                {
                    ScriptId = _existing.ScriptId,
                    Name = _existing.Name,
                    Language = _existing.Language,
                    SourceCode = _existing.SourceCode,
                    RowVersion = _existing.RowVersion,
                };
            }
        }
        _loaded = true;
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (!firstRender || !_loaded) return;
        // Inject loader once, then attach over the textarea. Failures are silent — the page
        // is fully usable via the underlying textarea if Monaco's CDN is unreachable.
        try
        {
            await JS.InvokeVoidAsync("eval", "if (!document.querySelector('script[data-otopcua=monaco-loader]')) { var s=document.createElement('script'); s.src='/_content/ZB.MOM.WW.OtOpcUa.AdminUI/js/monaco-loader.js'; s.dataset.otopcua='monaco-loader'; document.head.appendChild(s); }");
            // Wait a tick for the loader IIFE to register window.otOpcUaScriptEditor, then attach.
            await Task.Delay(50);
            await JS.InvokeVoidAsync("otOpcUaScriptEditor.attach", "script-source");
        }
        catch
        {
            // Textarea remains the editor — no-op.
        }
    }

    private async Task SubmitAsync()
    {
        _busy = true; _error = null;
        try
        {
            var sourceHash = HashSource(_form.SourceCode);
            await using var db = await DbFactory.CreateDbContextAsync();
            if (IsNew)
            {
                if (await db.Scripts.AnyAsync(s => s.ScriptId == _form.ScriptId))
                { _error = $"Script '{_form.ScriptId}' already exists."; return; }
                db.Scripts.Add(new Script
                {
                    ScriptId = _form.ScriptId,
                    Name = _form.Name,
                    Language = _form.Language,
                    SourceCode = _form.SourceCode,
                    SourceHash = sourceHash,
                });
            }
            else
            {
                var entity = await db.Scripts.FirstOrDefaultAsync(s => s.ScriptId == ScriptId);
                if (entity is null) { _error = "Row no longer exists."; return; }
                db.Entry(entity).Property(e => e.RowVersion).OriginalValue = _form.RowVersion;
                entity.Name = _form.Name;
                entity.Language = _form.Language;
                entity.SourceCode = _form.SourceCode;
                entity.SourceHash = sourceHash;
            }
            await db.SaveChangesAsync();
            Nav.NavigateTo("/scripts");
        }
        catch (DbUpdateConcurrencyException) { _error = "Another user changed this script while you were editing."; }
        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.Scripts.FirstOrDefaultAsync(s => s.ScriptId == ScriptId);
            if (entity is null) { Nav.NavigateTo("/scripts"); return; }
            db.Entry(entity).Property(e => e.RowVersion).OriginalValue = _form.RowVersion;
            db.Scripts.Remove(entity);
            await db.SaveChangesAsync();
            Nav.NavigateTo("/scripts");
        }
        catch (DbUpdateConcurrencyException) { _error = "Another user changed this script while you were viewing it."; }
        catch (Exception ex) { _error = $"Delete failed: {ex.Message}. Likely because virtual tags or scripted alarms still reference this script — remove them first."; }
        finally { _busy = false; }
    }

    private static string HashSource(string source) =>
        Convert.ToHexStringLower(SHA256.HashData(Encoding.UTF8.GetBytes(source)));

    private sealed class FormModel
    {
        [Required, RegularExpression("^[A-Za-z0-9_-]+$")] public string ScriptId { get; set; } = "";
        [Required] public string Name { get; set; } = "";
        [Required] public string Language { get; set; } = "CSharp";
        [Required] public string SourceCode { get; set; } = "";
        public byte[] RowVersion { get; set; } = [];
    }
}
