package gameserver

import (
	"fmt"
	"sort"

	"google.golang.org/protobuf/proto"

	"gac-hkrpg-go/internal/common"
	goproto "gac-hkrpg-go/protocol/proto"
)

// Challenge flows use the generated request and response layouts. Command
// numbers are resolved through the current protocol table at registration/send.

type decodedChallengeStart struct {
	challengeID   uint32
	stageIndex    uint32
	isSingleStage bool
	firstAvatars  []uint32
	secondAvatars []uint32
	thirdAvatars  []uint32
	stageInfoList [][]uint32
	buffID        uint32
}

// ---------------------------------------------------------------------------
// protobuf wire helpers (mirroring the Rust prost decoding loops)
// ---------------------------------------------------------------------------

func skipWireField(wireType uint32, buf *[]byte) {
	b := *buf
	switch wireType {
	case 0:
		_, n := readUvarint(b)
		if n == 0 {
			*buf = nil
		} else {
			*buf = b[n:]
		}
	case 1:
		if len(b) >= 8 {
			*buf = b[8:]
		} else {
			*buf = nil
		}
	case 2:
		l, n := readUvarint(b)
		if n == 0 || int(l) > len(b[n:]) {
			*buf = nil
		} else {
			*buf = b[n+int(l):]
		}
	case 5:
		if len(b) >= 4 {
			*buf = b[4:]
		} else {
			*buf = nil
		}
	default:
		*buf = nil
	}
}

func mapChallengeStageID(id uint32) uint32 {
	cd := getChallengeData()
	if _, ok := cd.Challenges[id]; ok {
		return id
	}
	if _, ok := cd.Tierce[id]; ok {
		return id
	}
	switch {
	case id >= 5400 && id <= 5700: // MoC 1035/1036 -> 5301..5312
		rem := id % 100
		if rem < 1 {
			rem = 1
		}
		if rem > 12 {
			rem = 12
		}
		return 5300 + rem
	case id >= 20200 && id <= 20300: // Pure Fiction -> 20251..20254
		rem := id % 10
		if rem < 1 {
			rem = 1
		}
		if rem > 4 {
			rem = 4
		}
		return 20250 + rem
	case id >= 30200 && id <= 30300: // Apocalyptic Shadow -> 30201..30204
		rem := id % 10
		if rem < 1 {
			rem = 1
		}
		if rem > 4 {
			rem = 4
		}
		return 30200 + rem
	case id > 1:
		if _, ok := cd.Challenges[id]; !ok {
			return id - 1
		}
		return id
	}
	return id
}

func decodeStartChallengeReq(payload []byte) decodedChallengeStart {
	var pbReq goproto.StartChallengeCsReq
	if err := proto.Unmarshal(payload, &pbReq); err != nil {
		return decodedChallengeStart{}
	}
	req := decodedChallengeStart{challengeID: pbReq.ChallengeId,
		firstAvatars: pbReq.FirstLineup, secondAvatars: pbReq.SecondLineup}
	if len(req.firstAvatars) == 0 {
		for _, avatar := range pbReq.AvatarLineupFirst {
			if avatar.Id != 0 {
				req.firstAvatars = append(req.firstAvatars, avatar.Id)
			}
		}
	}
	if len(req.secondAvatars) == 0 {
		for _, avatar := range pbReq.AvatarLineupSecond {
			if avatar.Id != 0 {
				req.secondAvatars = append(req.secondAvatars, avatar.Id)
			}
		}
	}
	if pbReq.StageInfo != nil {
		if info := pbReq.StageInfo.BossInfo; info != nil {
			req.buffID = info.BuffOne
		}
		if info := pbReq.StageInfo.StoryInfo; info != nil && req.buffID == 0 {
			req.buffID = info.BuffOne
		}
	}
	return req
}

func decodeStartChallengeTierceReq(payload []byte) decodedChallengeStart {
	var pbReq goproto.StartChallengeTierceCsReq
	if err := proto.Unmarshal(payload, &pbReq); err != nil {
		return decodedChallengeStart{}
	}
	req := decodedChallengeStart{challengeID: pbReq.ChallengeId,
		stageIndex: pbReq.FINOCEGDBDI, isSingleStage: pbReq.MPKMIKBFEHG}
	for index, stage := range pbReq.LineupTierceList {
		var avatars []uint32
		for _, avatar := range stage.TierceAvatarIdList {
			if avatar.Id != 0 {
				avatars = append(avatars, avatar.Id)
			}
		}
		req.stageInfoList = append(req.stageInfoList, avatars)
		if uint32(index) == req.stageIndex {
			req.buffID = stage.BuffId
		}
	}
	if len(req.stageInfoList) > 0 {
		req.firstAvatars = req.stageInfoList[0]
	}
	if len(req.stageInfoList) > 1 {
		req.secondAvatars = req.stageInfoList[1]
	}
	if len(req.stageInfoList) > 2 {
		req.thirdAvatars = req.stageInfoList[2]
	}
	return req
}

func decodeSetChallengeTierceLineupReq(payload []byte) (uint32, [][]uint32) {
	var req goproto.SetChallengeTierceLineupCsReq
	if err := proto.Unmarshal(payload, &req); err != nil {
		return 0, nil
	}
	var stages [][]uint32
	for _, stage := range req.StageInfoList {
		var avatars []uint32
		for _, avatar := range stage.TierceAvatarIdList {
			if avatar.Id != 0 {
				avatars = append(avatars, avatar.Id)
			}
		}
		stages = append(stages, avatars)
	}
	return req.ChallengeId, stages
}

// ---------------------------------------------------------------------------
// config setup shared by start handlers
// ---------------------------------------------------------------------------

func setChallengeBattleConfig(player *common.FreesrData, avatars []uint32, challengeID uint32, eventID uint32, buff uint32) {
	customLineup := map[uint32]uint32{}
	for i, aid := range avatars {
		customLineup[uint32(i)] = aid
	}
	player.BattleConfig.CustomBattleLineup = customLineup
	player.BattleConfig.StageID = eventID

	isPF := challengeID >= 20000 && challengeID < 30000
	isAS := challengeID >= 30000
	if isPF {
		player.BattleConfig.CycleCount = 4
		player.BattleConfig.BattleType = common.BattleTypePF
	} else if isAS {
		player.BattleConfig.CycleCount = 30
		player.BattleConfig.BattleType = common.BattleTypeAS
	} else {
		player.BattleConfig.CycleCount = 30
		player.BattleConfig.BattleType = common.BattleTypeDefault
	}

	if sb, ok := getChallengeData().Stages[eventID]; ok {
		var waves [][]common.Monster
		for _, wave := range sb.Monsters {
			var ms []common.Monster
			for _, mid := range wave {
				ms = append(ms, common.Monster{Level: sb.Level, MonsterID: mid})
			}
			waves = append(waves, ms)
		}
		player.BattleConfig.Monsters = waves
	}

	if buff != 0 {
		player.BattleConfig.Blessings = []common.BattleBuffJson{{
			ID:    buff,
			Level: 1,
		}}
	}

	player.SavePersistent()
}

func lineupInfoFromAvatars(avatars []uint32, planeID uint32, extraType goproto.ExtraLineupType, index uint32) *goproto.LineupInfo {
	custom := map[uint32]uint32{}
	for i, aid := range avatars {
		custom[uint32(i)] = aid
	}
	lineup := common.ToLineupInfo(custom)
	lineup.PlaneId = planeID
	lineup.ExtraLineupType = extraType
	lineup.Index = index
	return lineup
}

func challengeAvatarsFallback(s *Session) []uint32 {
	if player := s.JSON(); player != nil {
		var out []uint32
		for _, slot := range player.SortedLineupKeys() {
			if v := player.Lineups[slot]; v != 0 {
				out = append(out, v)
			}
		}
		return out
	}
	return []uint32{1304, 1313, 1406, 1004}
}

func dedupeTruncate4(in []uint32) []uint32 {
	seen := map[uint32]bool{}
	var out []uint32
	for _, v := range in {
		if !seen[v] {
			seen[v] = true
			out = append(out, v)
		}
		if len(out) == 4 {
			break
		}
	}
	return out
}

// handleStartChallenge ports handle_start_challenge: respond cmd 1787 with
// retcode(3) + cur_challenge(5) + lineup_list(6) + scene(10) + stage_info(13).
func handleStartChallenge(s *Session, payload []byte) error {
	req := decodeStartChallengeReq(payload)
	if req.challengeID == 0 {
		return s.Send(&goproto.StartChallengeScRsp{Retcode: uint32(goproto.Retcode_RET_CHALLENGE_NOT_EXIST)})
	}
	Log("handle_start_challenge: challenge_id=" + itoa(int(req.challengeID)))

	chosenAvatars := req.firstAvatars
	if len(chosenAvatars) == 0 {
		chosenAvatars = challengeAvatarsFallback(s)
	}
	// cap team at 4 (client TeamManager IndexOutOfRange otherwise)
	chosenAvatars = dedupeTruncate4(chosenAvatars)

	baseID := mapChallengeStageID(req.challengeID)
	cd := getChallengeData()
	entrance, group, monster, event, buff := uint32(3000101), uint32(5), uint32(4033010), uint32(30124011), uint32(0)
	if c, ok := cd.Challenges[baseID]; ok {
		entrance, group, monster, event = c.Entrance, c.Group1, c.Monster1, c.Event1
		if req.buffID != 0 {
			buff = req.buffID
		} else {
			buff = c.Buff
		}
	} else if t, ok := cd.Tierce[baseID]; ok {
		entrance, group, monster, event = t.Entrance, t.Group, t.Monster, t.Event
		buff = req.buffID
	}

	if res, err := common.GameRes(); err == nil && !mapHasEntry(res, entrance) {
		Log("[CHALLENGE] Arena entrance missing in res.json, fallback to 3000101")
		entrance = 3000101
	}

	Log("[CHALLENGE] Start: challenge_id=" + itoa(int(req.challengeID)) + " (mapped " + itoa(int(baseID)) + ")")
	Log("[CHALLENGE] Arena: entrance=" + itoa(int(entrance)) + " group=" + itoa(int(group)) + " monster=" + itoa(int(monster)) + " event=" + itoa(int(event)))

	if player := s.JSON(); player != nil {
		setChallengeBattleConfig(player, chosenAvatars, req.challengeID, event, buff)
	}

	sceneInfo, _, err := loadChallengeScene(s, entrance, group, monster, event, chosenAvatars)
	if err != nil {
		return err
	}

	var lineups []*goproto.LineupInfo
	lineups = append(lineups, lineupInfoFromAvatars(chosenAvatars, sceneInfo.PlaneId, goproto.ExtraLineupType(1), 0))

	secondAvatars := req.secondAvatars
	if len(secondAvatars) == 0 {
		secondAvatars = chosenAvatars
	}
	secondAvatars = dedupeTruncate4(secondAvatars)
	lineups = append(lineups, lineupInfoFromAvatars(secondAvatars, sceneInfo.PlaneId, goproto.ExtraLineupType(1), 1))

	curChallenge := &goproto.CurChallenge{
		ChallengeId:     req.challengeID,
		Status:          goproto.ChallengeStatus_CHALLENGE_DOING,
		RoundCount:      0,
		ScoreId:         scoreIDFor(req.challengeID),
		ScoreTwo:        0,
		ExtraLineupType: goproto.ExtraLineupType(1),
	}

	rsp := &goproto.StartChallengeScRsp{
		Retcode:      0,
		CurChallenge: curChallenge,
		LineupList:   lineups,
		Scene:        sceneInfo,
	}
	return s.Send(rsp)
}

func scoreIDFor(challengeID uint32) uint32 {
	if challengeID >= 20000 && challengeID < 30000 {
		return 40000
	}
	return 0
}

// handleStartChallengeTierce uses the current Tierce request schema.
func handleStartChallengeTierce(s *Session, payload []byte) error {
	req := decodeStartChallengeTierceReq(payload)
	if req.challengeID == 0 {
		return s.Send(&goproto.StartChallengeTierceScRsp{Retcode: uint32(goproto.Retcode_RET_CHALLENGE_NOT_EXIST)})
	}
	baseID := mapChallengeStageID(req.challengeID)
	Log("handle_start_challenge_tierce: challenge_id=" + itoa(int(req.challengeID)) + " (mapped " + itoa(int(baseID)) + ")")

	tierceLineupsMu.Lock()
	if len(req.stageInfoList) > 0 {
		tierceLineups[req.challengeID] = req.stageInfoList
	}
	tierceLineupsMu.Unlock()

	var chosenAvatars []uint32
	switch req.stageIndex {
	case 0:
		chosenAvatars = req.firstAvatars
	case 1:
		if len(req.secondAvatars) > 0 {
			chosenAvatars = req.secondAvatars
		} else {
			chosenAvatars = req.firstAvatars
		}
	case 2:
		if len(req.thirdAvatars) > 0 {
			chosenAvatars = req.thirdAvatars
		} else {
			chosenAvatars = req.firstAvatars
		}
	}

	if len(chosenAvatars) == 0 {
		tierceLineupsMu.Lock()
		if list, ok := tierceLineups[req.challengeID]; ok && int(req.stageIndex) < len(list) {
			chosenAvatars = list[req.stageIndex]
		}
		tierceLineupsMu.Unlock()
	}
	if len(chosenAvatars) == 0 {
		chosenAvatars = challengeAvatarsFallback(s)
	}

	cd := getChallengeData()
	entrance, group, monster, event, buff := uint32(3000101), uint32(5), uint32(4033010), uint32(30124011), uint32(0)

	if req.stageIndex == 0 {
		if t, ok := cd.Tierce[baseID]; ok {
			entrance, group, monster, event, buff = t.Entrance, t.Group, t.Monster, t.Event, req.buffID
		} else if c, ok2 := cd.Challenges[baseID]; ok2 {
			entrance, group, monster, event = c.Entrance, c.Group1, c.Monster1, c.Event1
			if req.buffID != 0 {
				buff = req.buffID
			} else {
				buff = c.Buff
			}
		}
	} else if req.stageIndex == 1 {
		// Stage 2 (Node 2)
		if c, ok := cd.Challenges[baseID-1]; ok && c.Entrance2 != 0 {
			entrance, group, monster, event = c.Entrance2, c.Group2, c.Monster2, c.Event2
			if req.buffID != 0 {
				buff = req.buffID
			} else {
				buff = c.Buff
			}
		} else if c, ok2 := cd.Challenges[baseID]; ok2 && c.Entrance2 != 0 {
			entrance, group, monster, event = c.Entrance2, c.Group2, c.Monster2, c.Event2
			if req.buffID != 0 {
				buff = req.buffID
			} else {
				buff = c.Buff
			}
		} else if t, ok3 := cd.Tierce[baseID]; ok3 {
			entrance, group, monster, event, buff = t.Entrance, t.Group, t.Monster, t.Event, req.buffID
		}
	} else {
		if t, ok := cd.Tierce[baseID]; ok {
			entrance, group, monster, event, buff = t.Entrance, t.Group, t.Monster, t.Event, req.buffID
		}
	}

	if res, err := common.GameRes(); err == nil && !mapHasEntry(res, entrance) {
		Log("[CHALLENGE] Tierce arena entrance missing in res.json, fallback to 3000101")
		entrance = 3000101
	}

	if player := s.JSON(); player != nil {
		setChallengeBattleConfig(player, chosenAvatars, req.challengeID, event, buff)
	}

	sceneInfo, _, err := loadChallengeScene(s, entrance, group, monster, event, chosenAvatars)
	if err != nil {
		return err
	}

	// build all lineups for tierce_info
	var allLineups [][]uint32
	firstLineup := req.firstAvatars
	if len(firstLineup) == 0 && len(req.stageInfoList) > 0 {
		firstLineup = req.stageInfoList[0]
	}
	if len(firstLineup) == 0 {
		tierceLineupsMu.Lock()
		if list, ok := tierceLineups[req.challengeID]; ok && len(list) > 0 {
			firstLineup = list[0]
		}
		tierceLineupsMu.Unlock()
	}
	if len(firstLineup) == 0 {
		firstLineup = chosenAvatars
	}
	allLineups = append(allLineups, firstLineup)

	if !req.isSingleStage {
		secondLineup := req.secondAvatars
		if len(secondLineup) == 0 && len(req.stageInfoList) > 1 {
			secondLineup = req.stageInfoList[1]
		}
		if len(secondLineup) == 0 {
			tierceLineupsMu.Lock()
			if list, ok := tierceLineups[req.challengeID]; ok && len(list) > 1 {
				secondLineup = list[1]
			}
			tierceLineupsMu.Unlock()
		}
		if len(secondLineup) == 0 {
			secondLineup = firstLineup
		}
		allLineups = append(allLineups, secondLineup)

		thirdLineup := req.thirdAvatars
		if len(thirdLineup) == 0 && len(req.stageInfoList) > 2 {
			thirdLineup = req.stageInfoList[2]
		}
		if len(thirdLineup) == 0 {
			tierceLineupsMu.Lock()
			if list, ok := tierceLineups[req.challengeID]; ok && len(list) > 2 {
				thirdLineup = list[2]
			}
			tierceLineupsMu.Unlock()
		}
		if len(thirdLineup) > 0 || req.stageIndex == 2 {
			if len(thirdLineup) == 0 {
				thirdLineup = firstLineup
			}
			allLineups = append(allLineups, thirdLineup)
		}
	}

	var tierceLineupList []*goproto.LineupInfo
	for stIdx, stageAvatars := range allLineups {
		tierceLineupList = append(tierceLineupList, lineupInfoFromAvatars(stageAvatars, sceneInfo.PlaneId, goproto.ExtraLineupType(1), uint32(stIdx)))
	}

	// Generated response resolves its command ID through Session.Send.
	rsp := &goproto.StartChallengeTierceScRsp{
		Retcode: 0,
		Scene:   sceneInfo,
		CurTierceChallenge: &goproto.CurTierceChallenge{
			LineupList:  tierceLineupList,
			ChallengeId: req.challengeID,
			FINOCEGDBDI: req.stageIndex,
			MPKMIKBFEHG: req.isSingleStage,
		},
	}
	return s.Send(rsp)
}

func handleSetChallengeTierceLineup(s *Session, payload []byte) error {
	challengeID, stages := decodeSetChallengeTierceLineupReq(payload)
	if challengeID == 0 {
		return s.Send(&goproto.SetChallengeTierceLineupScRsp{Retcode: uint32(goproto.Retcode_RET_CHALLENGE_NOT_EXIST)})
	}
	if len(stages) > 0 {
		tierceLineupsMu.Lock()
		tierceLineups[challengeID] = stages
		tierceLineupsMu.Unlock()
	}
	return s.Send(&goproto.SetChallengeTierceLineupScRsp{})
}

func handleLeaveChallenge(s *Session, _ []byte) error {
	return leaveChallengeScene(s, &goproto.LeaveChallengeScRsp{})
}

func handleLeaveChallengeTierce(s *Session, _ []byte) error {
	return leaveChallengeScene(s, &goproto.LeaveChallengeTierceScRsp{})
}

func leaveChallengeScene(s *Session, response proto.Message) error {
	player := s.JSON()
	if player == nil || player.Scene.EntryID == 0 {
		return fmt.Errorf("challenge return scene is unavailable")
	}
	// loadChallengeScene preserves the player's saved overworld scene.
	entryID := player.Scene.EntryID
	player.BattleConfig.CustomBattleLineup = nil
	CURRENT_BATTLE.Delete(s.Token)
	if err := s.Send(&goproto.QuitBattleScNotify{}); err != nil {
		return err
	}
	if _, err := loadScene(s, entryID, true, true, nil, nil); err != nil {
		return err
	}
	if err := refreshLineup(s); err != nil {
		return err
	}
	return s.Send(response)
}

func handleTakeChallengeReward(s *Session, payload []byte) error {
	var req goproto.TakeChallengeRewardCsReq
	if err := proto.Unmarshal(payload, &req); err != nil {
		return err
	}
	return s.Send(&goproto.TakeChallengeRewardScRsp{GroupId: req.GroupId})
}

// buildGetChallengeTierceDataScRspReal builds the generated current response.
func buildGetChallengeTierceDataScRspReal() *goproto.GetChallengeTierceDataScRsp {
	cd := getChallengeData()

	type tierceEntry struct {
		id      uint32
		targets []uint32
		score   uint32
	}
	var tierceStages []tierceEntry
	for id, data := range cd.Tierce {
		var targets []uint32
		switch {
		case len(data.Targets) > 0:
			targets = data.Targets
		case id >= 30000:
			targets = []uint32{5001, 5002, 5003, 5000}
		case id >= 20000:
			targets = []uint32{4001, 4002, 4003, 4000}
		default:
			targets = []uint32{601, 602, 603, 600}
		}
		score := data.Score
		if score == 0 {
			if id >= 20000 && id < 30000 {
				score = 40000
			} else {
				score = 4000
			}
		}
		tierceStages = append(tierceStages, tierceEntry{id, targets, score})
	}
	sort.Slice(tierceStages, func(i, j int) bool { return tierceStages[i].id < tierceStages[j].id })

	var groups []*goproto.ChallengeTierceGroup
	for _, e := range tierceStages {
		groups = append(groups, &goproto.ChallengeTierceGroup{
			ChallengeId:        e.id,
			IsWin:              true,
			FinishedTargetList: e.targets,
		})
	}

	return &goproto.GetChallengeTierceDataScRsp{
		ChallengeTierceGroups: groups,
		Retcode:               0,
	}
}