package entity

import (
	"encoding/json"
	"fmt"
	"net"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/jinzhu/gorm"

	"github.com/photoprism/photoprism/internal/event"
	"github.com/photoprism/photoprism/internal/i18n"
	"github.com/photoprism/photoprism/pkg/clean"
	"github.com/photoprism/photoprism/pkg/rnd"
	"github.com/photoprism/photoprism/pkg/txt"
)

// SessionPrefix for RefID.
const (
	SessionPrefix = "sess"
	UnknownIP     = "0.0.0.0"
)

// Sessions represents a list of sessions.
type Sessions []Session

// Session represents a User session.
type Session struct {
	ID            string          `gorm:"type:VARBINARY(2048);primary_key;auto_increment:false;" json:"ID" yaml:"ID"`
	ClientIP      string          `gorm:"size:64;column:client_ip;index" json:"-" yaml:"ClientIP,omitempty"`
	UserUID       string          `gorm:"type:VARBINARY(42);index;default:'';" json:"UserUID,omitempty" yaml:"UserUID,omitempty"`
	UserName      string          `gorm:"size:64;index;" json:"UserName,omitempty" yaml:"UserName,omitempty"`
	user          *User           `gorm:"-"`
	AuthProvider  string          `gorm:"type:VARBINARY(128);default:'';" json:"-" yaml:"AuthProvider,omitempty"`
	AuthMethod    string          `gorm:"type:VARBINARY(128);default:'';" json:"-" yaml:"AuthMethod,omitempty"`
	AuthDomain    string          `gorm:"type:VARBINARY(255);default:'';" json:"-" yaml:"AuthDomain,omitempty"`
	AuthID        string          `gorm:"type:VARBINARY(128);index;default:'';" json:"-" yaml:"AuthID,omitempty"`
	AuthScope     string          `gorm:"size:1024;default:'';" json:"-" yaml:"AuthScope,omitempty"`
	LastActive    int64           `json:"LastActive,omitempty" yaml:"LastActive,omitempty"`
	SessExpires   int64           `gorm:"index" json:"Expires,omitempty" yaml:"Expires,omitempty"`
	SessTimeout   int64           `json:"Timeout,omitempty" yaml:"Timeout,omitempty"`
	PreviewToken  string          `gorm:"type:VARBINARY(64);column:preview_token;default:'';" json:"-" yaml:"-"`
	DownloadToken string          `gorm:"type:VARBINARY(64);column:download_token;default:'';" json:"-" yaml:"-"`
	AccessToken   string          `gorm:"type:VARBINARY(4096);column:access_token;default:'';" json:"-" yaml:"-"`
	RefreshToken  string          `gorm:"type:VARBINARY(512);column:refresh_token;default:'';" json:"-" yaml:"-"`
	IdToken       string          `gorm:"type:VARBINARY(1024);column:id_token;default:'';" json:"IdToken,omitempty" yaml:"IdToken,omitempty"`
	UserAgent     string          `gorm:"size:512;" json:"-" yaml:"UserAgent,omitempty"`
	DataJSON      json.RawMessage `gorm:"type:VARBINARY(4096);" json:"Data,omitempty" yaml:"Data,omitempty"`
	data          *SessionData    `gorm:"-"`
	RefID         string          `gorm:"type:VARBINARY(16);default:'';" json:"-" yaml:"-"`
	LoginIP       string          `gorm:"size:64;column:login_ip" json:"-" yaml:"-"`
	LoginAt       time.Time       `json:"-" yaml:"-"`
	CreatedAt     time.Time       `json:"CreatedAt" yaml:"CreatedAt"`
	UpdatedAt     time.Time       `json:"UpdatedAt" yaml:"UpdatedAt"`
	Status        int             `gorm:"-" json:"Status,omitempty" yaml:"-"`
}

// TableName returns the entity table name.
func (Session) TableName() string {
	return "auth_sessions"
}

// NewSession creates a new session using the maxAge and timeout in seconds.
func NewSession(maxAge, timeout int64) (m *Session) {
	created := TimeStamp()

	m = &Session{
		ID:        rnd.SessionID(),
		RefID:     rnd.RefID(SessionPrefix),
		CreatedAt: created,
		UpdatedAt: created,
	}

	if maxAge > 0 {
		m.SessExpires = created.Unix() + maxAge
	}

	if timeout > 0 {
		m.SessTimeout = timeout
	}

	return m
}

// Expires sets an explicit expiration time.
func (m *Session) Expires(t time.Time) *Session {
	if t.IsZero() {
		return m
	}

	m.SessExpires = t.Unix()
	return m
}

// DeleteExpiredSessions deletes expired sessions.
func DeleteExpiredSessions() (deleted int) {
	expired := Sessions{}

	if err := Db().Where("sess_expires > 0 AND sess_expires < ?", UnixTime()).Find(&expired).Error; err != nil {
		event.AuditErr([]string{"failed to fetch sessions sessions", "%s"}, err)
		return deleted
	}

	for _, s := range expired {
		if err := s.Delete(); err != nil {
			event.AuditErr([]string{s.IP(), "session %s", "failed to delete", "%s"}, s.RefID, err)
		} else {
			deleted++
		}
	}

	return deleted
}

// SessionStatusUnauthorized returns a session with status unauthorized (401).
func SessionStatusUnauthorized() *Session {
	return &Session{Status: http.StatusUnauthorized}
}

// SessionStatusForbidden returns a session with status forbidden (403).
func SessionStatusForbidden() *Session {
	return &Session{Status: http.StatusForbidden}
}

// RegenerateID regenerated the random session ID.
func (m *Session) RegenerateID() *Session {
	if m.ID == "" {
		// Do not delete the old session if no ID is set yet.
	} else if err := m.Delete(); err != nil {
		event.AuditErr([]string{m.IP(), "session %s", "failed to delete", "%s"}, m.RefID, err)
	} else {
		event.AuditErr([]string{m.IP(), "session %s", "deleted"}, m.RefID)
	}

	generated := TimeStamp()

	m.ID = rnd.SessionID()
	m.RefID = rnd.RefID(SessionPrefix)
	m.CreatedAt = generated
	m.UpdatedAt = generated

	return m
}

// CacheDuration updates the session entity cache.
func (m *Session) CacheDuration(d time.Duration) {
	if !rnd.IsSessionID(m.ID) {
		return
	}

	CacheSession(m, d)
}

// Cache caches the session with the default expiration duration.
func (m *Session) Cache() {
	m.CacheDuration(sessionCacheExpiration)
}

// ClearCache deletes the session from the cache.
func (m *Session) ClearCache() {
	DeleteFromSessionCache(m.ID)
}

// Create new entity in the database.
func (m *Session) Create() (err error) {
	if err = Db().Create(m).Error; err == nil && rnd.IsSessionID(m.ID) {
		m.Cache()
	}

	return err
}

// Save updates the record in the database or inserts a new record if it does not already exist.
func (m *Session) Save() error {
	if err := Db().Save(m).Error; err != nil {
		return err
	} else if rnd.IsSessionID(m.ID) {
		m.Cache()
	}

	return nil
}

// Delete permanently deletes a session.
func (m *Session) Delete() error {
	return DeleteSession(m)
}

// Updates multiple properties in the database.
func (m *Session) Updates(values interface{}) error {
	return UnscopedDb().Model(m).Updates(values).Error
}

// BeforeCreate creates a random UID if needed before inserting a new row to the database.
func (m *Session) BeforeCreate(scope *gorm.Scope) error {
	if rnd.InvalidRefID(m.RefID) {
		m.RefID = rnd.RefID(SessionPrefix)
		Log("session", "set ref id", scope.SetColumn("RefID", m.RefID))
	}

	if rnd.IsSessionID(m.ID) {
		return nil
	}

	m.ID = rnd.SessionID()

	return scope.SetColumn("ID", m.ID)
}

// User returns the session's user.
func (m *Session) User() *User {
	if m.user != nil {
		return m.user
	}

	if u := FindUserByUID(m.UserUID); u != nil {
		m.SetUser(u)
		return m.user
	}

	return &User{}
}

// RefreshUser updates the cached user data.
func (m *Session) RefreshUser() *Session {
	// Remove user if uid is nil.
	if m.UserUID == "" {
		m.user = nil
		return m
	}

	// Fetch matching record.
	if u := FindUserByUID(m.UserUID); u != nil {
		m.SetUser(u)
	}

	return m
}

// SetUser updates the session's user.
func (m *Session) SetUser(u *User) *Session {
	if u == nil {
		return m
	}

	// Update user.
	m.user = u
	m.UserUID = u.UserUID
	m.UserName = u.UserName

	// Update tokens.
	m.SetPreviewToken(u.PreviewToken)
	m.SetDownloadToken(u.DownloadToken)

	return m
}

// ChangePassword changes the password of the current user.
func (m *Session) ChangePassword(newPw string) (err error) {
	u := m.User()

	if u == nil {
		return fmt.Errorf("unknown user")
	}

	// Change password.
	err = u.SetPassword(newPw)

	m.SetPreviewToken(u.PreviewToken)
	m.SetDownloadToken(u.DownloadToken)

	return nil
}

// SetPreviewToken updates the preview token if not empty.
func (m *Session) SetPreviewToken(token string) *Session {
	if m.ID == "" {
		return m
	}

	if token != "" {
		m.PreviewToken = token
		PreviewToken.Set(token, m.ID)
	} else if m.PreviewToken == "" {
		m.PreviewToken = GenerateToken()
		PreviewToken.Set(token, m.ID)
	}

	return m
}

// SetDownloadToken updates the download token if not empty.
func (m *Session) SetDownloadToken(token string) *Session {
	if m.ID == "" {
		return m
	}

	if token != "" {
		m.DownloadToken = token
		DownloadToken.Set(token, m.ID)
	} else if m.DownloadToken == "" {
		m.DownloadToken = GenerateToken()
		DownloadToken.Set(token, m.ID)
	}

	return m
}

// Data returns the session's data.
func (m *Session) Data() (data *SessionData) {
	if m.data != nil {
		data = m.data
	}

	data = NewSessionData()

	if len(m.DataJSON) == 0 {
		return data
	} else if err := json.Unmarshal(m.DataJSON, data); err != nil {
		log.Errorf("failed parsing session json: %s", err)
	} else {
		data.RefreshShares()
		m.data = data
	}

	return data
}

// SetData updates the session's data.
func (m *Session) SetData(data *SessionData) *Session {
	if data == nil {
		log.Debugf("auth: empty data passed to session %s", m.RefID)
		return m
	}

	// Refresh session data.
	data.RefreshShares()

	if j, err := json.Marshal(data); err != nil {
		log.Debugf("auth:  %s", err)
	} else {
		m.DataJSON = j
	}

	m.data = data

	return m
}

// SetContext updates the session's request context.
func (m *Session) SetContext(c *gin.Context) *Session {
	if c == nil || m == nil {
		return m
	}

	// Set client ip address.
	if ip := c.ClientIP(); ip != "" {
		m.SetClientIP(ip)
	} else if m.ClientIP == "" {
		// Unit tests often do not set a client IP.
		m.SetClientIP(UnknownIP)
	}

	// Set client user agent.
	if ua := c.GetHeader("User-Agent"); ua != "" {
		m.SetUserAgent(ua)
	}

	return m
}

// IsVisitor checks if the session belongs to a sharing link visitor.
func (m *Session) IsVisitor() bool {
	return m.User().IsVisitor()
}

// IsRegistered checks if the session belongs to a registered user account.
func (m *Session) IsRegistered() bool {
	if m == nil || m.user == nil || rnd.InvalidUID(m.UserUID, UserUID) {
		return false
	}

	return m.User().IsRegistered()
}

// NotRegistered checks if the user is not registered with an own account.
func (m *Session) NotRegistered() bool {
	return !m.IsRegistered()
}

// NoShares checks if the session has no shares yet.
func (m *Session) NoShares() bool {
	return !m.HasShares()
}

// HasShares checks if the session has any shares.
func (m *Session) HasShares() bool {
	if user := m.User(); user.IsRegistered() {
		return user.HasShares()
	} else if data := m.Data(); data == nil {
		return false
	} else {
		return data.HasShares()
	}
}

// HasShare if the session includes the specified share
func (m *Session) HasShare(uid string) bool {
	if user := m.User(); user.IsRegistered() {
		return user.HasShare(uid)
	} else if data := m.Data(); data == nil {
		return false
	} else {
		return data.HasShare(uid)
	}
}

// SharedUIDs returns shared entity UIDs.
func (m *Session) SharedUIDs() UIDs {
	if user := m.User(); user.IsRegistered() {
		return user.SharedUIDs()
	} else if data := m.Data(); data == nil {
		return UIDs{}
	} else {
		return data.SharedUIDs()
	}
}

// RedeemToken updates shared entity UIDs using the specified token.
func (m *Session) RedeemToken(token string) (n int) {
	if user := m.User(); user.IsRegistered() {
		return user.RedeemToken(token)
	} else if data := m.Data(); data == nil {
		return 0
	} else {
		return data.RedeemToken(token)
	}
}

// ExpiresAt returns the time when the session expires.
func (m *Session) ExpiresAt() time.Time {
	if m.SessExpires <= 0 {
		return time.Time{}
	}

	return time.Unix(m.SessExpires, 0)
}

// TimeoutAt returns the time at which the session will expire due to inactivity.
func (m *Session) TimeoutAt() time.Time {
	if m.SessTimeout <= 0 || m.LastActive <= 0 {
		return m.ExpiresAt()
	} else if t := m.LastActive + m.SessTimeout; t <= m.SessExpires || m.SessExpires <= 0 {
		return time.Unix(m.LastActive+m.SessTimeout, 0)
	} else {
		return m.ExpiresAt()
	}
}

// TimedOut checks if the session has expired due to inactivity..
func (m *Session) TimedOut() bool {
	if at := m.TimeoutAt(); at.IsZero() {
		return false
	} else {
		return at.Before(UTC())
	}
}

// Expired checks if the session has expired.
func (m *Session) Expired() bool {
	if m.SessExpires <= 0 {
		return m.TimedOut()
	} else if at := m.ExpiresAt(); at.IsZero() {
		return false
	} else {
		return at.Before(UTC())
	}
}

// UpdateLastActive sets the last activity of the session to now.
func (m *Session) UpdateLastActive() *Session {
	if m.Invalid() {
		return m
	}

	m.LastActive = UnixTime()

	if err := Db().Model(m).UpdateColumn("LastActive", m.LastActive).Error; err != nil {
		event.AuditWarn([]string{m.IP(), "session %s", "failed to update last active time", "%s"}, m.RefID, err)
	}

	return m
}

// Invalid checks if the session does not belong to a registered user or a visitor with shares.
func (m *Session) Invalid() bool {
	return !m.Valid()
}

// Valid checks whether the session belongs to a registered user or a visitor with shares.
func (m *Session) Valid() bool {
	return m.User().IsRegistered() || m.IsVisitor() && m.HasShares()
}

// Abort aborts the request with the appropriate error code if access to the requested resource is denied.
func (m *Session) Abort(c *gin.Context) bool {
	if m.Valid() {
		return false
	}

	// Abort the request with the appropriate HTTP error code and message.
	switch m.Status {
	case http.StatusUnauthorized:
		c.AbortWithStatusJSON(m.Status, i18n.NewResponse(m.Status, i18n.ErrUnauthorized))
	default:
		c.AbortWithStatusJSON(http.StatusForbidden, i18n.NewResponse(http.StatusForbidden, i18n.ErrForbidden))
	}

	return true
}

// SetUserAgent sets the client user agent.
func (m *Session) SetUserAgent(ua string) {
	if m == nil || ua == "" {
		return
	} else if ua = txt.Clip(ua, 512); ua == "" {
		return
	} else if m.UserAgent != "" && m.UserAgent != ua {
		event.AuditWarn([]string{m.IP(), "session %s", "user agent has changed from %s to %s"}, m.RefID, clean.LogQuote(m.UserAgent), clean.LogQuote(ua))
	}

	m.UserAgent = ua

	return
}

// SetClientIP sets the client IP address.
func (m *Session) SetClientIP(ip string) {
	if m == nil || ip == "" {
		return
	} else if parsed := net.ParseIP(ip); parsed == nil {
		return
	} else if ip = parsed.String(); ip == "" {
		return
	} else if m.ClientIP != "" && m.ClientIP != ip {
		event.AuditWarn([]string{ip, "session %s", "client address has changed from %s to %s"}, m.RefID, clean.LogQuote(m.ClientIP), clean.LogQuote(ip))
	}

	m.ClientIP = ip

	if m.LoginIP == "" {
		m.LoginIP = ip
		m.LoginAt = TimeStamp()
	}

	return
}

// IP returns the client IP address, or "unknown" if it is unknown.
func (m *Session) IP() string {
	if m.ClientIP != "" {
		return m.ClientIP
	} else {
		return "0.0.0.0"
	}
}

// HttpStatus returns the session status as HTTP code for the client.
func (m *Session) HttpStatus() int {
	if m.Status > 0 {
		return m.Status
	} else if m.Valid() {
		return http.StatusOK
	}

	return http.StatusUnauthorized
}