using System.Text;

namespace SQLLinter.Infrastructure.Diagram;

public static class MermaidRenderer
{
    public static string ToMermaidContent(BpmnDiagram diagram)
    {
        var sb = new StringBuilder();
        sb.AppendLine("flowchart TB");

        // -----------------------------------------
        // Рендер каждого процесса как subgraph
        // -----------------------------------------
        foreach (var proc in diagram.Processes)
        {
            var procId = SanitizeId(proc.Id);
            sb.AppendLine($"  subgraph {procId} [\"{Escape(proc.Name)}\"]");
            sb.AppendLine("    direction TB");

            foreach (var node in proc.Nodes)
            {
                var nid = SanitizeId(node.Id);
                var label = Escape(node.Label);

                label = node.Type switch
                {
                    BpmnNodeType.Start => $@"((""{label}""))",
                    BpmnNodeType.Task => $@"[""{label}""]",
                    BpmnNodeType.Subprocess => $@"[[""{label}""]]",
                    BpmnNodeType.Gateway => $@"{{""{label}""}}",
                    BpmnNodeType.Hexagon => $@"{{{{""{label}""}}}}",
                    BpmnNodeType.End => $@"((""{label}""))",
                    _ => $@">""{label}""]"
                };

                sb.AppendLine($"    {nid}{label}");
            }

            // Edges внутри процесса
            foreach (var e in proc.Edges)
            {
                var from = SanitizeId(e.From);
                var to = SanitizeId(e.To);
                var arrow = e.ArrowType switch
                {
                    BpmnArrowType.Dashed => "-.->",
                    _ => "-->",
                };
                var lbl = string.IsNullOrWhiteSpace(e.Label) ? string.Empty : $" |{Escape(e.Label)}|";

                sb.AppendLine($"    {from} {arrow}{lbl} {to}");
            }

            sb.AppendLine("  end");
            sb.AppendLine();
        }

        // -----------------------------------------
        // Рендер глобальных связей между процессами
        // -----------------------------------------
        foreach (var e in diagram.GlobalEdges)
        {
            var from = SanitizeId(e.From);
            var to = SanitizeId(e.To);
            var arrow = e.ArrowType switch
            {
                BpmnArrowType.Dashed => "-.->",
                _ => "-->",
            };
            var lbl = string.IsNullOrWhiteSpace(e.Label) ? string.Empty : $" |{Escape(e.Label)}|";
            sb.AppendLine($"  {from} {arrow}{lbl} {to}");
        }

        return sb.ToString();
    }

    private static string Escape(string s)
    {
        if (s == null) return string.Empty;
        return s.Replace("\"", "\\\"").Replace("\n", " ").Replace("\r", " ");
    }

    private static string SanitizeId(string s)
    {
        if (string.IsNullOrEmpty(s)) return "id";
        var sb = new StringBuilder();
        foreach (var ch in s)
        {
            if (char.IsLetterOrDigit(ch)) sb.Append(ch);
            else sb.Append('_');
        }
        return sb.ToString();
    }
}