using System.Collections.Immutable;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace StellaOps.Scanner.EntryTrace.Serialization;

public static class EntryTraceGraphSerializer
{
    private static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web)
    {
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
        WriteIndented = false
    };

    static EntryTraceGraphSerializer()
    {
        SerializerOptions.Converters.Add(new JsonStringEnumConverter());
    }

    public static string Serialize(EntryTraceGraph graph)
    {
        ArgumentNullException.ThrowIfNull(graph);
        var contract = EntryTraceGraphContract.FromGraph(graph);
        return JsonSerializer.Serialize(contract, SerializerOptions);
    }

    public static EntryTraceGraph Deserialize(string json)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(json);
        var contract = JsonSerializer.Deserialize<EntryTraceGraphContract>(json, SerializerOptions)
            ?? throw new InvalidOperationException("Failed to deserialize EntryTrace graph.");
        return contract.ToGraph();
    }

    private sealed class EntryTraceGraphContract
    {
        public EntryTraceOutcome Outcome { get; set; }
        public List<EntryTraceNodeContract> Nodes { get; set; } = new();
        public List<EntryTraceEdgeContract> Edges { get; set; } = new();
        public List<EntryTraceDiagnosticContract> Diagnostics { get; set; } = new();
        public List<EntryTracePlanContract> Plans { get; set; } = new();
        public List<EntryTraceTerminalContract> Terminals { get; set; } = new();

        public static EntryTraceGraphContract FromGraph(EntryTraceGraph graph)
        {
            return new EntryTraceGraphContract
            {
                Outcome = graph.Outcome,
                Nodes = graph.Nodes.Select(EntryTraceNodeContract.FromNode).ToList(),
                Edges = graph.Edges.Select(EntryTraceEdgeContract.FromEdge).ToList(),
                Diagnostics = graph.Diagnostics.Select(EntryTraceDiagnosticContract.FromDiagnostic).ToList(),
                Plans = graph.Plans.Select(EntryTracePlanContract.FromPlan).ToList(),
                Terminals = graph.Terminals.Select(EntryTraceTerminalContract.FromTerminal).ToList()
            };
        }

        public EntryTraceGraph ToGraph()
        {
            return new EntryTraceGraph(
                Outcome,
                Nodes.Select(n => n.ToNode()).ToImmutableArray(),
                Edges.Select(e => e.ToEdge()).ToImmutableArray(),
                Diagnostics.Select(d => d.ToDiagnostic()).ToImmutableArray(),
                Plans.Select(p => p.ToPlan()).ToImmutableArray(),
                Terminals.Select(t => t.ToTerminal()).ToImmutableArray());
        }
    }

    private sealed class EntryTraceNodeContract
    {
        public int Id { get; set; }
        public EntryTraceNodeKind Kind { get; set; }
        public string DisplayName { get; set; } = string.Empty;
        public List<string> Arguments { get; set; } = new();
        public EntryTraceInterpreterKind InterpreterKind { get; set; }
        public EntryTraceEvidenceContract? Evidence { get; set; }
        public EntryTraceSpanContract? Span { get; set; }
        public Dictionary<string, string>? Metadata { get; set; }

        public static EntryTraceNodeContract FromNode(EntryTraceNode node)
        {
            return new EntryTraceNodeContract
            {
                Id = node.Id,
                Kind = node.Kind,
                DisplayName = node.DisplayName,
                Arguments = node.Arguments.ToList(),
                InterpreterKind = node.InterpreterKind,
                Evidence = node.Evidence is null ? null : EntryTraceEvidenceContract.FromEvidence(node.Evidence),
                Span = node.Span is null ? null : EntryTraceSpanContract.FromSpan(node.Span.Value),
                Metadata = node.Metadata?.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal)
            };
        }

        public EntryTraceNode ToNode()
        {
            return new EntryTraceNode(
                Id,
                Kind,
                DisplayName,
                Arguments.ToImmutableArray(),
                InterpreterKind,
                Evidence?.ToEvidence(),
                Span?.ToSpan(),
                Metadata is null ? null : Metadata.ToImmutableDictionary(StringComparer.Ordinal));
        }
    }

    private sealed class EntryTraceEdgeContract
    {
        public int From { get; set; }
        public int To { get; set; }
        public string Relationship { get; set; } = string.Empty;
        public Dictionary<string, string>? Metadata { get; set; }

        public static EntryTraceEdgeContract FromEdge(EntryTraceEdge edge)
        {
            return new EntryTraceEdgeContract
            {
                From = edge.FromNodeId,
                To = edge.ToNodeId,
                Relationship = edge.Relationship,
                Metadata = edge.Metadata?.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal)
            };
        }

        public EntryTraceEdge ToEdge()
        {
            return new EntryTraceEdge(
                From,
                To,
                Relationship,
                Metadata is null ? null : Metadata.ToImmutableDictionary(StringComparer.Ordinal));
        }
    }

    private sealed class EntryTraceDiagnosticContract
    {
        public EntryTraceDiagnosticSeverity Severity { get; set; }
        public EntryTraceUnknownReason Reason { get; set; }
        public string Message { get; set; } = string.Empty;
        public EntryTraceSpanContract? Span { get; set; }
        public string? RelatedPath { get; set; }

        public static EntryTraceDiagnosticContract FromDiagnostic(EntryTraceDiagnostic diagnostic)
        {
            return new EntryTraceDiagnosticContract
            {
                Severity = diagnostic.Severity,
                Reason = diagnostic.Reason,
                Message = diagnostic.Message,
                Span = diagnostic.Span is null ? null : EntryTraceSpanContract.FromSpan(diagnostic.Span.Value),
                RelatedPath = diagnostic.RelatedPath
            };
        }

        public EntryTraceDiagnostic ToDiagnostic()
        {
            return new EntryTraceDiagnostic(
                Severity,
                Reason,
                Message,
                Span?.ToSpan(),
                RelatedPath);
        }
    }

    private sealed class EntryTracePlanContract
    {
        public List<string> Command { get; set; } = new();
        public Dictionary<string, string> Environment { get; set; } = new();
        public string WorkingDirectory { get; set; } = string.Empty;
        public string User { get; set; } = string.Empty;
        public string TerminalPath { get; set; } = string.Empty;
        public EntryTraceTerminalType Type { get; set; }
        public string? Runtime { get; set; }
        public double Confidence { get; set; }
        public Dictionary<string, string> Evidence { get; set; } = new();

        public static EntryTracePlanContract FromPlan(EntryTracePlan plan)
        {
            return new EntryTracePlanContract
            {
                Command = plan.Command.ToList(),
                Environment = plan.Environment.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal),
                WorkingDirectory = plan.WorkingDirectory,
                User = plan.User,
                TerminalPath = plan.TerminalPath,
                Type = plan.Type,
                Runtime = plan.Runtime,
                Confidence = plan.Confidence,
                Evidence = plan.Evidence.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal)
            };
        }

        public EntryTracePlan ToPlan()
        {
            return new EntryTracePlan(
                Command.ToImmutableArray(),
                Environment.ToImmutableDictionary(StringComparer.Ordinal),
                WorkingDirectory,
                User,
                TerminalPath,
                Type,
                Runtime,
                Confidence,
                Evidence.ToImmutableDictionary(StringComparer.Ordinal));
        }
    }

    private sealed class EntryTraceTerminalContract
    {
        public string Path { get; set; } = string.Empty;
        public EntryTraceTerminalType Type { get; set; }
        public string? Runtime { get; set; }
        public double Confidence { get; set; }
        public Dictionary<string, string> Evidence { get; set; } = new();
        public string User { get; set; } = string.Empty;
        public string WorkingDirectory { get; set; } = string.Empty;
        public List<string> Arguments { get; set; } = new();

        public static EntryTraceTerminalContract FromTerminal(EntryTraceTerminal terminal)
        {
            return new EntryTraceTerminalContract
            {
                Path = terminal.Path,
                Type = terminal.Type,
                Runtime = terminal.Runtime,
                Confidence = terminal.Confidence,
                Evidence = terminal.Evidence.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal),
                User = terminal.User,
                WorkingDirectory = terminal.WorkingDirectory,
                Arguments = terminal.Arguments.ToList()
            };
        }

        public EntryTraceTerminal ToTerminal()
        {
            return new EntryTraceTerminal(
                Path,
                Type,
                Runtime,
                Confidence,
                Evidence.ToImmutableDictionary(StringComparer.Ordinal),
                User,
                WorkingDirectory,
                Arguments.ToImmutableArray());
        }
    }

    private sealed class EntryTraceEvidenceContract
    {
        public string Path { get; set; } = string.Empty;
        public string? Layer { get; set; }
        public string? Source { get; set; }
        public Dictionary<string, string>? Metadata { get; set; }

        public static EntryTraceEvidenceContract FromEvidence(EntryTraceEvidence evidence)
        {
            return new EntryTraceEvidenceContract
            {
                Path = evidence.Path,
                Layer = evidence.LayerDigest,
                Source = evidence.Source,
                Metadata = evidence.Metadata?.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal)
            };
        }

        public EntryTraceEvidence ToEvidence()
        {
            return new EntryTraceEvidence(
                Path,
                Layer,
                Source ?? string.Empty,
                Metadata is null ? null : new Dictionary<string, string>(Metadata, StringComparer.Ordinal));
        }
    }

    private sealed class EntryTraceSpanContract
    {
        public string? Path { get; set; }
        public int StartLine { get; set; }
        public int StartColumn { get; set; }
        public int EndLine { get; set; }
        public int EndColumn { get; set; }

        public static EntryTraceSpanContract FromSpan(EntryTraceSpan span)
        {
            return new EntryTraceSpanContract
            {
                Path = span.Path,
                StartLine = span.StartLine,
                StartColumn = span.StartColumn,
                EndLine = span.EndLine,
                EndColumn = span.EndColumn
            };
        }

        public EntryTraceSpan ToSpan()
        {
            return new EntryTraceSpan(
                Path,
                StartLine,
                StartColumn,
                EndLine,
                EndColumn);
        }
    }
}