package web

import (
	"context"
	"time"
)

// UserInfo represents user information with tracking details
type UserInfo struct {
	UserID    string    `json:"user_id"`
	UserName  string    `json:"user_name"`
	Trace     string    `json:"trace"`
	VisitTime time.Time `json:"visit_time"`
	FromIP    string    `json:"from_ip"`
}

// contextKey is the type for context keys to prevent collisions
type contextKey string

const (
	// Context keys for each field
	UserIDKey    contextKey = "userID"
	UserNameKey  contextKey = "userName"
	TraceKey     contextKey = "trace"
	VisitTimeKey contextKey = "visitTime"
	FromIPKey    contextKey = "fromIP"
)

// GetUserID returns user ID from context
func GetUserID(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if val, ok := ctx.Value(UserIDKey).(string); ok {
		return val
	}
	return ""
}

// SetUserID sets user ID in context and returns new context
func SetUserID(ctx context.Context, userID string) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, UserIDKey, userID)
}

// GetUserName returns user name from context
func GetUserName(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if val, ok := ctx.Value(UserNameKey).(string); ok {
		return val
	}
	return ""
}

// SetUserName sets user name in context and returns new context
func SetUserName(ctx context.Context, userName string) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, UserNameKey, userName)
}

// GetTrace returns trace ID from context
func GetTrace(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if val, ok := ctx.Value(TraceKey).(string); ok {
		return val
	}
	return ""
}

// SetTrace sets trace ID in context and returns new context
func SetTrace(ctx context.Context, trace string) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, TraceKey, trace)
}

// GetVisitTime returns visit time from context
func GetVisitTime(ctx context.Context) time.Time {
	if ctx == nil {
		return time.Time{}
	}
	if val, ok := ctx.Value(VisitTimeKey).(time.Time); ok {
		return val
	}
	return time.Time{}
}

// SetVisitTime sets visit time in context and returns new context
func SetVisitTime(ctx context.Context, visitTime time.Time) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, VisitTimeKey, visitTime)
}

// GetFromIP returns from IP from context
func GetFromIP(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if val, ok := ctx.Value(FromIPKey).(string); ok {
		return val
	}
	return ""
}

// SetFromIP sets from IP in context and returns new context
func SetFromIP(ctx context.Context, fromIP string) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, FromIPKey, fromIP)
}

// FromContext builds UserInfo from individual context fields
// Returns nil if no fields are found
func FromContext(ctx context.Context) *UserInfo {
	if ctx == nil {
		return nil
	}
	info := &UserInfo{}
	hasData := false

	if userID := GetUserID(ctx); userID != "" {
		info.UserID = userID
		hasData = true
	}
	if userName := GetUserName(ctx); userName != "" {
		info.UserName = userName
		hasData = true
	}
	if trace := GetTrace(ctx); trace != "" {
		info.Trace = trace
		hasData = true
	}
	if visitTime := GetVisitTime(ctx); !visitTime.IsZero() {
		info.VisitTime = visitTime
		hasData = true
	}
	if fromIP := GetFromIP(ctx); fromIP != "" {
		info.FromIP = fromIP
		hasData = true
	}

	if !hasData {
		return nil
	}
	return info
}

// ToContext sets all UserInfo fields to context and returns new context
func ToContext(ctx context.Context, userInfo *UserInfo) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	if userInfo == nil {
		return ctx
	}

	ctx = SetUserID(ctx, userInfo.UserID)
	ctx = SetUserName(ctx, userInfo.UserName)
	ctx = SetTrace(ctx, userInfo.Trace)
	ctx = SetVisitTime(ctx, userInfo.VisitTime)
	ctx = SetFromIP(ctx, userInfo.FromIP)

	return ctx
}

// NewUserInfo creates a new UserInfo instance
func NewUserInfo() *UserInfo {
	return &UserInfo{
		VisitTime: time.Now(),
	}
}

// WithUserID sets the user ID
func (u *UserInfo) WithUserID(userID string) *UserInfo {
	u.UserID = userID
	return u
}

// WithUserName sets the user name
func (u *UserInfo) WithUserName(userName string) *UserInfo {
	u.UserName = userName
	return u
}

// WithTrace sets the trace ID
func (u *UserInfo) WithTrace(trace string) *UserInfo {
	u.Trace = trace
	return u
}

// WithFromIP sets the from IP address
func (u *UserInfo) WithFromIP(ip string) *UserInfo {
	u.FromIP = ip
	return u
}

// WithVisitTime sets the visit time
func (u *UserInfo) WithVisitTime(visitTime time.Time) *UserInfo {
	u.VisitTime = visitTime
	return u
}