package entranceserver

import (
	"encoding/binary"
	"encoding/hex"
	"erupe-ce/common/stringsupport"
	cfg "erupe-ce/config"
	"net"

	"erupe-ce/common/byteframe"
	"erupe-ce/common/gametime"
	"go.uber.org/zap"
)

func encodeServerInfo(config *cfg.Config, s *Server, local bool) []byte {
	serverInfos := config.Entrance.Entries
	bf := byteframe.NewByteFrame()

	for serverIdx, si := range serverInfos {
		// Prevent MezFes Worlds displaying on Z1
		if config.RealClientMode <= cfg.Z1 {
			if si.Type == 6 {
				continue
			}
		}
		if config.RealClientMode <= cfg.G6 {
			if si.Type == 5 {
				continue
			}
		}

		if si.IP == "" {
			si.IP = config.Host
		}
		if local {
			bf.WriteUint32(0x0100007F) // 127.0.0.1
		} else {
			bf.WriteUint32(binary.LittleEndian.Uint32(net.ParseIP(si.IP).To4()))
		}
		bf.WriteUint16(uint16(serverIdx | 16))
		bf.WriteUint16(0)
		bf.WriteUint16(uint16(len(si.Channels)))
		bf.WriteUint8(si.Type)
		bf.WriteUint8(uint8(((gametime.Adjusted().Unix() / 86400) + int64(serverIdx)) % 3))
		if s.erupeConfig.RealClientMode >= cfg.G1 {
			bf.WriteUint8(si.Recommended)
		}

		fullName := append(append(stringsupport.UTF8ToSJIS(si.Name), []byte{0x00}...), stringsupport.UTF8ToSJIS(si.Description)...)
		if s.erupeConfig.RealClientMode >= cfg.G1 && s.erupeConfig.RealClientMode <= cfg.G5 {
			bf.WriteUint8(uint8(len(fullName)))
			bf.WriteBytes(fullName)
		} else {
			if s.erupeConfig.RealClientMode >= cfg.G51 {
				bf.WriteUint8(0) // Ignored
			}
			bf.WriteBytes(stringsupport.PaddedString(string(fullName), 65, false))
		}

		if s.erupeConfig.RealClientMode >= cfg.GG {
			bf.WriteUint32(si.AllowedClientFlags)
		}

		for channelIdx, ci := range si.Channels {
			sid := (serverIdx<<8 | 4096) + (channelIdx | 16)
			if config.DebugOptions.ProxyPort != 0 {
				bf.WriteUint16(config.DebugOptions.ProxyPort)
			} else {
				bf.WriteUint16(ci.Port)
			}
			bf.WriteUint16(uint16(channelIdx | 16))
			bf.WriteUint16(ci.MaxPlayers)
			var currentPlayers uint16
			if s.serverRepo != nil {
				currentPlayers, _ = s.serverRepo.GetCurrentPlayers(sid)
			}
			bf.WriteUint16(currentPlayers)
			bf.WriteUint16(0)
			bf.WriteUint16(0)
			bf.WriteUint16(0)
			bf.WriteUint16(0)
			bf.WriteUint16(0)
			bf.WriteUint16(0)
			bf.WriteUint16(319)                  // Unk
			bf.WriteUint16(254 - currentPlayers) // Unk
			bf.WriteUint16(255 - currentPlayers) // Unk
			bf.WriteUint16(12345)
		}
	}
	bf.WriteUint32(uint32(gametime.Adjusted().Unix()))

	// ClanMemberLimits requires at least 1 element with 2 columns to avoid index out of range panics
	// Use default value (60) if array is empty or last row is too small
	var maxClanMembers uint8 = 60
	if len(s.erupeConfig.GameplayOptions.ClanMemberLimits) > 0 {
		lastRow := s.erupeConfig.GameplayOptions.ClanMemberLimits[len(s.erupeConfig.GameplayOptions.ClanMemberLimits)-1]
		if len(lastRow) > 1 {
			maxClanMembers = lastRow[1]
		}
	}
	bf.WriteUint32(uint32(maxClanMembers))

	return bf.Data()
}

func makeHeader(data []byte, respType string, entryCount uint16, key byte) []byte {
	bf := byteframe.NewByteFrame()
	bf.WriteBytes([]byte(respType))
	bf.WriteUint16(entryCount)
	bf.WriteUint16(uint16(len(data)))
	if len(data) > 0 {
		bf.WriteUint32(CalcSum32(data))
		bf.WriteBytes(data)
	}

	dataToEncrypt := bf.Data()

	bf = byteframe.NewByteFrame()
	bf.WriteUint8(key)
	bf.WriteBytes(EncryptBin8(dataToEncrypt, key))
	return bf.Data()
}

func makeSv2Resp(config *cfg.Config, s *Server, local bool) []byte {
	serverInfos := config.Entrance.Entries
	// Decrease by the number of MezFes Worlds
	var mf int
	if config.RealClientMode <= cfg.Z1 {
		for _, si := range serverInfos {
			if si.Type == 6 {
				mf++
			}
		}
	}
	// and Return Worlds
	var ret int
	if config.RealClientMode <= cfg.G6 {
		for _, si := range serverInfos {
			if si.Type == 5 {
				ret++
			}
		}
	}
	rawServerData := encodeServerInfo(config, s, local)

	if s.erupeConfig.DebugOptions.LogOutboundMessages {
		s.logger.Debug("Outbound SV2 response", zap.Int("bytes", len(rawServerData)), zap.String("data", hex.Dump(rawServerData)))
	}

	respType := "SV2"
	if config.RealClientMode <= cfg.G32 {
		respType = "SVR"
	}

	bf := byteframe.NewByteFrame()
	bf.WriteBytes(makeHeader(rawServerData, respType, uint16(len(serverInfos)-(mf+ret)), 0x00))
	return bf.Data()
}

func makeUsrResp(pkt []byte, s *Server) []byte {
	bf := byteframe.NewByteFrameFromBytes(pkt)
	_ = bf.ReadUint32() // ALL+
	_ = bf.ReadUint8()  // 0x00
	userEntries := bf.ReadUint16()
	resp := byteframe.NewByteFrame()
	for i := 0; i < int(userEntries); i++ {
		cid := bf.ReadUint32()
		var sid uint16
		if s.sessionRepo != nil {
			sid, _ = s.sessionRepo.GetServerIDForCharacter(cid)
		}
		resp.WriteUint16(sid)
		resp.WriteUint16(0)
	}

	if s.erupeConfig.DebugOptions.LogOutboundMessages {
		s.logger.Debug("Outbound USR response", zap.Int("bytes", len(resp.Data())), zap.String("data", hex.Dump(resp.Data())))
	}

	return makeHeader(resp.Data(), "USR", userEntries, 0x00)
}
