using System.Collections.Generic;
using System.Linq;
using System.Text.Json.Nodes;
using Chessistics.Engine.Model;

namespace Chessistics.Scripts.Automation;

/// <summary>
/// Serializes BoardSnapshot into plain JSON so the agent can reason about game state.
/// </summary>
internal static class SnapshotSerializer
{
    public static JsonObject Serialize(BoardSnapshot snap)
    {
        var root = new JsonObject
        {
            ["phase"] = snap.Phase.ToString(),
            ["turn"] = snap.TurnNumber,
            ["width"] = snap.Width,
            ["height"] = snap.Height,
            ["grid"] = SerializeGrid(snap.Grid, snap.Width, snap.Height),
            ["productions"] = new JsonArray(snap.Productions.Select(SerializeProd).ToArray<JsonNode?>()),
            ["demands"] = new JsonArray(snap.Demands.Select(SerializeDemand).ToArray<JsonNode?>()),
            ["transformers"] = new JsonArray(snap.Transformers.Select(SerializeTransformer).ToArray<JsonNode?>()),
            ["pieces"] = new JsonArray(snap.Pieces.Select(SerializePiece).ToArray<JsonNode?>()),
            ["remainingStock"] = SerializeStock(snap.RemainingStock),
        };

        if (snap.Campaign != null)
        {
            root["campaign"] = new JsonObject
            {
                ["name"] = snap.Campaign.Name,
                ["currentMissionIndex"] = snap.Campaign.CurrentMissionIndex,
                ["completedMissions"] = new JsonArray(snap.Campaign.CompletedMissions.Select(i => (JsonNode?)JsonValue.Create(i)).ToArray()),
                ["availablePieceKinds"] = new JsonArray(snap.Campaign.AvailablePieceKinds.Select(k => (JsonNode?)JsonValue.Create(k.ToString())).ToArray()),
                ["availableLevels"] = new JsonArray(snap.Campaign.AvailableLevels
                    .Select(u => (JsonNode?)new JsonObject { ["kind"] = u.Kind.ToString(), ["level"] = u.Level })
                    .ToArray()),
            };
        }
        else
        {
            root["campaign"] = null;
        }

        return root;
    }

    private static JsonArray SerializeGrid(CellType[,] grid, int w, int h)
    {
        var rows = new JsonArray();
        for (int r = 0; r < h; r++)
        {
            var row = new JsonArray();
            for (int c = 0; c < w; c++)
                row.Add(grid[c, r].ToString());
            rows.Add(row);
        }
        return rows;
    }

    private static JsonObject SerializeProd(ProductionSnapshot p) => new()
    {
        ["pos"] = CoordsJson(p.Position),
        ["name"] = p.Name,
        ["cargo"] = p.Cargo.ToString(),
        ["amount"] = p.Amount,
        ["buffer"] = p.BufferCount,
    };

    private static JsonObject SerializeDemand(DemandSnapshot d) => new()
    {
        ["pos"] = CoordsJson(d.Position),
        ["name"] = d.Name,
        ["cargo"] = d.Cargo.ToString(),
        ["required"] = d.Required,
        ["deadline"] = d.Deadline,
        ["received"] = d.ReceivedCount,
        ["satisfied"] = d.IsSatisfied,
        ["missionIndex"] = d.MissionIndex,
    };

    private static JsonObject SerializeTransformer(TransformerSnapshot t) => new()
    {
        ["pos"] = CoordsJson(t.Position),
        ["name"] = t.Name,
        ["inputCargo"] = t.InputCargo.ToString(),
        ["inputRequired"] = t.InputRequired,
        ["outputCargo"] = t.OutputCargo.ToString(),
        ["outputAmount"] = t.OutputAmount,
        ["inputBuffer"] = t.InputBufferCount,
        ["outputBuffer"] = t.OutputBufferCount,
    };

    private static JsonObject SerializePiece(PieceSnapshot p) => new()
    {
        ["id"] = p.Id,
        ["kind"] = p.Kind.ToString(),
        ["level"] = p.Level,
        ["start"] = CoordsJson(p.StartCell),
        ["end"] = CoordsJson(p.EndCell),
        ["current"] = CoordsJson(p.CurrentCell),
        ["cargo"] = p.Cargo?.ToString(),
        ["cargoFilter"] = p.CargoFilter?.ToString(),
        ["socialStatus"] = p.SocialStatus,
    };

    private static JsonObject SerializeStock(IReadOnlyDictionary<PieceKind, int> stock)
    {
        var obj = new JsonObject();
        foreach (var (k, v) in stock) obj[k.ToString()] = v;
        return obj;
    }

    private static JsonArray CoordsJson(Coords c)
    {
        var arr = new JsonArray();
        arr.Add(c.Col);
        arr.Add(c.Row);
        return arr;
    }
}