using System;
using System.Collections.Generic;
using System.Linq;
using FlowAPI.Application.DTOs.AI;
using FlowAPI.Application.DTOs.Graph;

namespace FlowAPI.Application.Services
{
    public static class AutoLayoutEngine
    {
        private const double StepX = 300.0;
        private const double StepY = 180.0;

        public static FullGraphResponseDto LayoutGraph(QuestSchemaDto schema, Guid userId)
        {
            var graphId = Guid.NewGuid();
            var response = new FullGraphResponseDto
            {
                Id = graphId,
                UserId = userId,
                Title = schema.Title,
                Description = schema.Description,
                CreatedAt = DateTime.UtcNow,
                IsShared = false,
                Permission = "Owner",
                Nodes = new List<NodeDto>(),
                Edges = new List<EdgeDto>()
            };

            if (schema.Nodes == null || !schema.Nodes.Any())
                return response;

            // 1. Map string string-based IDs from LLM into Guids
            var idMap = new Dictionary<string, Guid>();
            foreach (var node in schema.Nodes)
            {
                idMap[node.Id] = Guid.NewGuid();
            }

            // 2. Calculate logical layers (Sugiyama-like ranking)
            var layerMap = new Dictionary<string, int>();
            foreach (var node in schema.Nodes)
            {
                layerMap[node.Id] = 0; // Default layer
            }

            // Transitively propagate layer ranks based on dependencies (max N passes)
            int n = schema.Nodes.Count;
            for (int pass = 0; pass < n; pass++)
            {
                bool changed = false;
                foreach (var node in schema.Nodes)
                {
                    if (!string.IsNullOrEmpty(node.DependsOn) && idMap.ContainsKey(node.DependsOn))
                    {
                        int parentLayer = layerMap[node.DependsOn];
                        int currentLayer = layerMap[node.Id];
                        if (currentLayer < parentLayer + 1)
                        {
                            layerMap[node.Id] = parentLayer + 1;
                            changed = true;
                        }
                    }
                }
                if (!changed) break; // Optimization if stabilized early
            }

            // 3. Group nodes by layers and calculate coordinates
            var layers = new Dictionary<int, List<QuestNodeDto>>();
            foreach (var node in schema.Nodes)
            {
                int layer = layerMap[node.Id];
                if (!layers.ContainsKey(layer))
                {
                    layers[layer] = new List<QuestNodeDto>();
                }
                layers[layer].Add(node);
            }

            // Set coordinates symmetrically per layer
            foreach (var layerKvp in layers)
            {
                int layer = layerKvp.Key;
                var layerNodes = layerKvp.Value;
                int count = layerNodes.Count;

                for (int i = 0; i < count; i++)
                {
                    var node = layerNodes[i];
                    var nodeGuid = idMap[node.Id];

                    // Symmetric distribution horizontally around X = 0, and sequential progression top-to-bottom
                    double posX = (i - (count - 1) / 2.0) * StepX;
                    double posY = layer * StepY;

                    // Determine visual properties
                    string? nodeColor = node.Color;
                    if (string.IsNullOrEmpty(nodeColor) && !string.IsNullOrEmpty(node.Condition))
                    {
                        if (node.Condition.Equals("Fail", StringComparison.OrdinalIgnoreCase))
                        {
                            nodeColor = "pink";
                        }
                        else if (node.Condition.Equals("Success", StringComparison.OrdinalIgnoreCase))
                        {
                            nodeColor = "green";
                        }
                    }

                    // Map Status string to integer State Enum value (Todo = 0, In Progress = 1, Review = 2, Done = 3)
                    int stateVal = 0;
                    if (!string.IsNullOrEmpty(node.Status))
                    {
                        if (node.Status.Equals("Done", StringComparison.OrdinalIgnoreCase)) stateVal = 3;
                        else if (node.Status.Equals("Review", StringComparison.OrdinalIgnoreCase)) stateVal = 2;
                        else if (node.Status.Equals("In Progress", StringComparison.OrdinalIgnoreCase) || node.Status.Equals("Progress", StringComparison.OrdinalIgnoreCase)) stateVal = 1;
                    }

                    // Build rich data object for serialization into Decision column
                    var decisionObj = new Dictionary<string, object?>();
                    decisionObj["decision"] = node.Condition;
                    decisionObj["description"] = node.Description ?? "";
                    decisionObj["progress"] = node.Progress ?? 0;
                    decisionObj["showProgress"] = node.ShowProgress ?? false;
                    decisionObj["color"] = nodeColor ?? "default";
                    decisionObj["isPinned"] = node.IsPinned ?? false;
                    decisionObj["tags"] = node.Tags ?? new List<string>();
                    decisionObj["status"] = node.Status ?? "Todo";
                    decisionObj["assignees"] = node.Assignees ?? new List<QuestAssigneeDto>();

                    if (node.Subgoals != null)
                    {
                        decisionObj["subgoals"] = new { total = node.Subgoals.Total, done = node.Subgoals.Done };
                    }
                    if (node.Options != null)
                    {
                        decisionObj["options"] = node.Options.Select(o => new { id = o.Id, label = o.Label }).ToList();
                    }
                    if (node.SelectedOptions != null)
                    {
                        decisionObj["selectedOptions"] = node.SelectedOptions;
                    }
                    if (node.MultiSelect != null)
                    {
                        decisionObj["multiSelect"] = node.MultiSelect.Value;
                    }
                    if (node.ResetRule != null)
                    {
                        decisionObj["resetRule"] = node.ResetRule;
                    }
                    if (!string.IsNullOrEmpty(node.Url))
                    {
                        decisionObj["url"] = node.Url;
                    }

                    // For image/path/text nodes, save payload inside Data if needed
                    string? nodeData = null;
                    if (node.Type == "image" && !string.IsNullOrEmpty(node.Url))
                    {
                        nodeData = node.Url;
                    }

                    string decisionJson = System.Text.Json.JsonSerializer.Serialize(decisionObj);

                    response.Nodes.Add(new NodeDto
                    {
                        Id = nodeGuid,
                        Label = node.Label,
                        PosX = posX,
                        PosY = posY,
                        Type = node.Type ?? "sketch",
                        State = stateVal,
                        Decision = decisionJson, // JSON string matches frontend expected parsing!
                        Description = node.Description,
                        Color = nodeColor,
                        IsPinned = node.IsPinned ?? false,
                        Width = node.Width ?? 220,
                        Height = node.Height ?? 116,
                        Data = nodeData
                    });

                    // 4. Create Edges
                    if (!string.IsNullOrEmpty(node.DependsOn) && idMap.ContainsKey(node.DependsOn))
                    {
                        response.Edges.Add(new EdgeDto
                        {
                            Id = Guid.NewGuid(),
                            FromNodeId = idMap[node.DependsOn],
                            ToNodeId = nodeGuid,
                            Condition = node.Condition ?? "True"
                        });
                    }
                }
            }

            return response;
        }
    }
}