using System.Collections.Generic;
using System.IO;

namespace pkNX.Structures;

/// <summary>
/// Rewards given by <see cref="GameVersion.GG"/> after capturing a Pokémon.
/// </summary>
/// <remarks>They do this because the Pickup Ability no longer exists, and to ease the grind of marts.</remarks>
public class CaptureRewardTable
{
    public List<CaptureRewardGroup> Table = [];

    public CaptureRewardTable(byte[] data)
    {
        using var ms = new MemoryStream(data);
        using var br = new BinaryReader(ms);
        ReadHeader(br);
        ReadEntries(br);
    }

    private void ReadEntries(BinaryReader br)
    {
        foreach (var g in Table)
            ReadTable(br, g);
    }

    private static void ReadTable(BinaryReader br, CaptureRewardGroup g)
    {
        for (int i = 0; i < g.EntryCount; i++)
            g.Entries.Add(ReadEntry(br));
    }

    private static CaptureRewardEntry ReadEntry(BinaryReader br) => new()
    {
        Item = br.ReadInt32(),
        Count = br.ReadInt32(),
        Rate = br.ReadInt32(),
    };

    private void ReadHeader(BinaryReader br)
    {
        while (true)
        {
            var count = br.ReadInt32();
            if (Table.Count != 0 && Table[^1].CaptureCount > count)
            {
                br.BaseStream.Position -= 4;
                break;
            }
            var entries = br.ReadInt32();
            var group = new CaptureRewardGroup(count, entries);
            Table.Add(group);
        }
    }

    public byte[] Write()
    {
        using var ms = new MemoryStream();
        using var bw = new BinaryWriter(ms);
        foreach (var g in Table)
        {
            bw.Write(g.CaptureCount);
            bw.Write(g.Entries.Count); // instead of using the read value, use the list count (allow modification)
        }
        foreach (var g in Table)
        {
            foreach (var e in g.Entries)
            {
                bw.Write(e.Item);
                bw.Write(e.Count);
                bw.Write(e.Rate);
            }
        }
        return ms.ToArray();
    }

    public IEnumerable<string> Dump(string[] itemNames)
    {
        foreach (var g in Table)
        {
            yield return "========";
            yield return $"Count: {g.CaptureCount}";
            yield return "========";
            foreach (var item in g.Entries)
                yield return $"{item.Rate:00}%\tx{item.Count}\t{itemNames[item.Item]}";
            yield return "";
        }
    }
}

public class CaptureRewardGroup(int count, int entries)
{
    public int CaptureCount = count;
    public int EntryCount = entries;

    public List<CaptureRewardEntry> Entries = new(entries);
}

public class CaptureRewardEntry
{
    public int Item;
    public int Count;
    public int Rate;
}