// Package modules 实现 Nakama RPC handler 桩。
// 所有 handler 仅完成参数解析、鉴权调用与 TODO 注释，业务逻辑待后续填充。
package modules

import (
	"context"
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"encoding/json"

	"github.com/heroiclabs/nakama-common/runtime"
)

// newTraceID 生成简易追踪 ID。
func newTraceID() string {
	b := make([]byte, 16)
	_, _ = rand.Read(b)
	return hex.EncodeToString(b)
}

// userIDFromCtx 从 Nakama runtime context 读取用户 ID。
func userIDFromCtx(ctx context.Context) string {
	if v := ctx.Value(runtime.RUNTIME_CTX_USER_ID); v != nil {
		if s, ok := v.(string); ok {
			return s
		}
	}
	return ""
}

// writeJSON 将响应对象序列化为 JSON 字符串。
func writeJSON(v interface{}) (string, error) {
	data, err := json.Marshal(v)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

// commonResp 构造统一响应外层。
type commonResp struct {
	Code    int         `json:"code"`
	Message string      `json:"message"`
	Data    interface{} `json:"data"`
	TraceID string      `json:"trace_id"`
}

func okResp(data interface{}, traceID string) (string, error) {
	return writeJSON(commonResp{Code: 0, Message: "success", Data: data, TraceID: traceID})
}

func errResp(code int, message string, traceID string) (string, error) {
	return writeJSON(commonResp{Code: code, Message: message, Data: nil, TraceID: traceID})
}

// -----------------------------------------------------------------------------
// Auth
// -----------------------------------------------------------------------------

// RegisterAuth 向 Nakama 注册账号相关 RPC。
func RegisterAuth(initializer runtime.Initializer) error {
	if err := initializer.RegisterRpc("AuthService/Register", authRegister); err != nil {
		return err
	}
	if err := initializer.RegisterRpc("AuthService/Login", authLogin); err != nil {
		return err
	}
	return nil
}

type registerReq struct {
	DeviceID   string `json:"device_id"`
	Platform   string `json:"platform"`
	InviteCode string `json:"invite_code"`
}

type loginReq struct {
	DeviceID     string `json:"device_id"`
	Platform     string `json:"platform"`
	RefreshToken string `json:"refresh_token"`
}

type authData struct {
	PlayerID    string `json:"player_id"`
	NakamaToken string `json:"nakama_token"`
	ExpiresAt   string `json:"expires_at"`
	IsNew       bool   `json:"is_new"`
}

func authRegister(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, payload string) (string, error) {
	traceID := newTraceID()
	var req registerReq
	if err := json.Unmarshal([]byte(payload), &req); err != nil {
		return errResp(1001, "invalid payload", traceID)
	}

	// 校验参数
	if req.DeviceID == "" {
		return errResp(1003, "device_id required", traceID)
	}
	if req.Platform == "" {
		return errResp(1004, "platform required", traceID)
	}

	// 检查设备是否已注册
	var existingPlayerID string
	err := db.QueryRowContext(ctx, `
		SELECT id FROM players WHERE device_id_hash = $1
	`, req.DeviceID).Scan(&existingPlayerID)
	if err == nil {
		// 设备已注册，返回已有账号
		return okResp(authData{
			PlayerID:  existingPlayerID,
			IsNew:     false,
		}, traceID)
	}

	// 创建新玩家
	var playerID string
	err = db.QueryRowContext(ctx, `
		INSERT INTO players (nakama_user_id, platform, device_id_hash, status)
		VALUES (gen_random_uuid(), $1, $2, 'active')
		RETURNING id::text
	`, req.Platform, req.DeviceID).Scan(&playerID)
	if err != nil {
		logger.Error("auth register failed: %v", err)
		return errResp(9002, "internal error", traceID)
	}

	logger.Info("AuthService/Register success: player_id=%s", playerID)
	return okResp(authData{
		PlayerID: playerID,
		IsNew:    true,
	}, traceID)
}

func authLogin(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, payload string) (string, error) {
	traceID := newTraceID()
	var req loginReq
	if err := json.Unmarshal([]byte(payload), &req); err != nil {
		return errResp(1002, "invalid payload", traceID)
	}

	// 校验参数
	if req.DeviceID == "" {
		return errResp(1003, "device_id required", traceID)
	}

	// 查询玩家
	var playerID string
	var status string
	err := db.QueryRowContext(ctx, `
		SELECT id, status FROM players WHERE device_id_hash = $1
	`, req.DeviceID).Scan(&playerID, &status)
	if err != nil {
		return errResp(1005, "player not found", traceID)
	}

	if status != "active" {
		return errResp(1006, "account not active", traceID)
	}

	// 更新最后在线时间
	_, err = db.ExecContext(ctx, `
		UPDATE players SET last_online_at = NOW() WHERE id = $1
	`, playerID)
	if err != nil {
		logger.Error("auth login update failed: %v", err)
	}

	logger.Info("AuthService/Login success: player_id=%s", playerID)
	return okResp(authData{
		PlayerID: playerID,
		IsNew:    false,
	}, traceID)
}