@using System.Text.Json
@using MudBlazor
@using Microsoft.AspNetCore.Components.Forms

<MudDialog>

    <!-- ================= TITLE ================= -->
    <TitleContent>
        <MudStack Row AlignItems="AlignItems.Center" Spacing="2">
            <MudIcon Icon="@Icons.Material.Filled.UploadFile"
                     Color="Color.Primary" />
            <MudText Typo="Typo.h6">
                Import Order JSON
            </MudText>
        </MudStack>
    </TitleContent>

    <!-- ================= CONTENT ================= -->
    <DialogContent>

        @if (ShowWarning)
        {
            <MudAlert Severity="Severity.Warning"
                      Variant="Variant.Outlined"
                      Class="mb-4">
                Only valid <b>VDA 5050 Order JSON</b> is accepted.<br />
                Invalid structure will be rejected.
            </MudAlert>
        }

        <!-- ===== FILE INPUT (PURE BLAZOR) ===== -->
        <div class="mb-4">
            <label class="mud-button-root mud-button mud-button-outlined mud-button-outlined-primary"
                   style="cursor:pointer;">
                <MudIcon Icon="@Icons.Material.Filled.AttachFile" Class="mr-2" />
                Choose JSON file
                <InputFile OnChange="OnFileSelected"
                           accept=".json"
                           style="display:none" />
            </label>
        </div>

        <MudDivider Class="my-3" />

        <!-- ===== PASTE JSON ===== -->
        <MudTextField @bind-Value="JsonText"
                      Label="Paste Order JSON"
                      Lines="20"
                      Variant="Variant.Filled"
                      Immediate
                      Style="font-family: monospace" />

        @if (!string.IsNullOrEmpty(ErrorMessage))
        {
            <MudAlert Severity="Severity.Error" Class="mt-3">
                @ErrorMessage
            </MudAlert>
        }

    </DialogContent>

    <!-- ================= ACTIONS ================= -->
    <DialogActions>
        <MudButton OnClick="Cancel">
            Cancel
        </MudButton>

        <MudButton Variant="Variant.Filled"
                   Color="Color.Primary"
                   OnClick="ValidateAndImport">
            Import
        </MudButton>
    </DialogActions>

</MudDialog>

@code {
    [CascadingParameter]
    public IMudDialogInstance MudDialog { get; set; } = default!;

    public string JsonText { get; set; } = "";
    public string? ErrorMessage;
    public bool ShowWarning { get; set; }

    private void Cancel() => MudDialog.Cancel();

    // ================= FILE HANDLER =================
    private async Task OnFileSelected(InputFileChangeEventArgs e)
    {
        ErrorMessage = null;
        ShowWarning = false;

        var file = e.File;
        if (file == null)
            return;

        if (!file.Name.EndsWith(".json", StringComparison.OrdinalIgnoreCase) &&
            !file.Name.EndsWith(".txt", StringComparison.OrdinalIgnoreCase))
        {
            ShowWarning = true;
            ErrorMessage = "Only .json or .txt files are supported.";
            return;
        }

        try
        {
            using var stream = file.OpenReadStream(maxAllowedSize: 1_048_576);
            using var reader = new StreamReader(stream);

            JsonText = await reader.ReadToEndAsync();
            StateHasChanged();
        }
        catch (Exception ex)
        {
            ShowWarning = true;
            ErrorMessage = $"Failed to read file: {ex.Message}";
        }
    }

    // ================= VALIDATE & IMPORT =================
    private void ValidateAndImport()
    {
        ErrorMessage = null;
        ShowWarning = false;

        if (string.IsNullOrWhiteSpace(JsonText))
        {
            ShowWarning = true;
            ErrorMessage = "JSON content is empty.";
            return;
        }

        try
        {
            using var doc = JsonDocument.Parse(JsonText);
            var root = doc.RootElement;

            // ===== BASIC STRUCTURE CHECK =====
            if (!root.TryGetProperty("nodes", out _) ||
                !root.TryGetProperty("edges", out _))
            {
                throw new Exception("Missing 'nodes' or 'edges' field.");
            }

            var order = OrderMessage.FromSchemaObject(root);
            ValidateOrder(order);

            MudDialog.Close(DialogResult.Ok(order));
        }
        catch (JsonException)
        {
            ShowWarning = true;
            ErrorMessage = "Invalid JSON format.";
        }
        catch (Exception ex)
        {
            ShowWarning = true;
            ErrorMessage = ex.Message;
        }
    }

    // ================= DOMAIN VALIDATION =================
    private void ValidateOrder(OrderMessage order)
    {
        if (order.Nodes.Count == 0)
            throw new Exception("Order must contain at least one node.");

        if (order.Nodes.Count != order.Edges.Count + 1)
            throw new Exception(
                $"Invalid path structure: Nodes count ({order.Nodes.Count}) " +
                $"must equal Edges count + 1 ({order.Edges.Count + 1})."
            );

        var nodeIds = order.Nodes
            .Select(n => n.NodeId)
            .ToHashSet(StringComparer.Ordinal);

        foreach (var e in order.Edges)
        {
            if (string.IsNullOrWhiteSpace(e.StartNodeId) ||
                string.IsNullOrWhiteSpace(e.EndNodeId))
            {
                throw new Exception(
                    $"Edge '{e.EdgeId}' must define both StartNodeId and EndNodeId."
                );
            }

            if (!nodeIds.Contains(e.StartNodeId))
                throw new Exception(
                    $"Edge '{e.EdgeId}' references unknown StartNodeId '{e.StartNodeId}'."
                );

            if (!nodeIds.Contains(e.EndNodeId))
                throw new Exception(
                    $"Edge '{e.EdgeId}' references unknown EndNodeId '{e.EndNodeId}'."
                );
        }
    }
}