package entities

import (
	"database/sql/driver"
	"encoding/json"
	"errors"
	"time"

	"github.com/google/uuid"
	"gorm.io/gorm"
)

type NotificationPriority string
type NotificationDeliveryStatus string
type NotificationChannel string
type NotificationProvider string

const (
	NotificationPriorityLow    NotificationPriority = "low"
	NotificationPriorityNormal NotificationPriority = "normal"
	NotificationPriorityHigh   NotificationPriority = "high"

	NotificationDeliveryStatusPending   NotificationDeliveryStatus = "pending"
	NotificationDeliveryStatusSent      NotificationDeliveryStatus = "sent"
	NotificationDeliveryStatusDelivered NotificationDeliveryStatus = "delivered"
	NotificationDeliveryStatusFailed    NotificationDeliveryStatus = "failed"

	NotificationChannelPush      NotificationChannel = "push"
	NotificationChannelWebsocket NotificationChannel = "websocket"
	NotificationChannelEmail     NotificationChannel = "email"

	NotificationProviderFirebase NotificationProvider = "firebase"
)

// NotificationData is a JSON-serializable map for extra notification payload.
type NotificationData map[string]interface{}

func (d NotificationData) Value() (driver.Value, error) {
	if d == nil {
		return nil, nil
	}
	return json.Marshal(d)
}

func (d *NotificationData) Scan(value interface{}) error {
	if value == nil {
		*d = nil
		return nil
	}
	bytes, ok := value.([]byte)
	if !ok {
		return errors.New("type assertion to []byte failed")
	}
	return json.Unmarshal(bytes, d)
}

// Notification is the master notification record.
type Notification struct {
	ID             uuid.UUID            `gorm:"type:uuid;primary_key;default:gen_random_uuid()" json:"id"`
	Title          string               `gorm:"not null;size:255" json:"title"`
	Body           string               `gorm:"type:text" json:"body"`
	Type           string               `gorm:"size:100" json:"type"`
	Category       string               `gorm:"size:100" json:"category"`
	Priority       NotificationPriority `gorm:"size:50;default:'normal'" json:"priority"`
	ImageURL       string               `gorm:"size:512" json:"image_url"`
	ActionURL      string               `gorm:"size:512" json:"action_url"`
	NotifiableType string               `gorm:"size:100" json:"notifiable_type"`
	NotifiableID   *uuid.UUID           `gorm:"type:uuid" json:"notifiable_id"`
	Data           NotificationData     `gorm:"type:jsonb" json:"data"`
	ScheduledAt    *time.Time           `gorm:"type:timestamptz" json:"scheduled_at"`
	SentAt         *time.Time           `gorm:"type:timestamptz" json:"sent_at"`
	ExpiredAt      *time.Time           `gorm:"type:timestamptz" json:"expired_at"`
	CreatedBy      *uuid.UUID           `gorm:"type:uuid" json:"created_by"`
	CreatedAt      time.Time            `gorm:"autoCreateTime" json:"created_at"`
	UpdatedAt      time.Time            `gorm:"autoUpdateTime" json:"updated_at"`

	Creator   *User                   `gorm:"foreignKey:CreatedBy" json:"creator,omitempty"`
	Receivers []*NotificationReceiver `gorm:"foreignKey:NotificationID" json:"receivers,omitempty"`
}

func (n *Notification) BeforeCreate(tx *gorm.DB) error {
	if n.ID == uuid.Nil {
		n.ID = uuid.New()
	}
	return nil
}

func (Notification) TableName() string {
	return "notifications"
}

// NotificationReceiver links a notification to a specific user.
type NotificationReceiver struct {
	ID             uuid.UUID  `gorm:"type:uuid;primary_key;default:gen_random_uuid()" json:"id"`
	NotificationID uuid.UUID  `gorm:"type:uuid;not null;index" json:"notification_id"`
	UserID         uuid.UUID  `gorm:"type:uuid;not null;index" json:"user_id"`
	IsRead         bool       `gorm:"default:false" json:"is_read"`
	ReadAt         *time.Time `gorm:"type:timestamptz" json:"read_at"`
	IsDeleted      bool       `gorm:"default:false" json:"is_deleted"`
	DeletedAt      *time.Time `gorm:"type:timestamptz" json:"deleted_at"`
	CreatedAt      time.Time  `gorm:"autoCreateTime" json:"created_at"`
	UpdatedAt      time.Time  `gorm:"autoUpdateTime" json:"updated_at"`

	Notification *Notification           `gorm:"foreignKey:NotificationID" json:"notification,omitempty"`
	User         *User                   `gorm:"foreignKey:UserID" json:"user,omitempty"`
	Deliveries   []*NotificationDelivery `gorm:"foreignKey:NotificationReceiverID" json:"deliveries,omitempty"`
}

func (n *NotificationReceiver) BeforeCreate(tx *gorm.DB) error {
	if n.ID == uuid.Nil {
		n.ID = uuid.New()
	}
	return nil
}

func (NotificationReceiver) TableName() string {
	return "notification_receivers"
}

// NotificationDelivery tracks per-device delivery attempts.
type NotificationDelivery struct {
	ID                     uuid.UUID                  `gorm:"type:uuid;primary_key;default:gen_random_uuid()" json:"id"`
	NotificationReceiverID uuid.UUID                  `gorm:"type:uuid;not null;index" json:"notification_receiver_id"`
	UserDeviceID           uuid.UUID                  `gorm:"type:uuid;not null;index" json:"user_device_id"`
	Channel                NotificationChannel        `gorm:"size:50;default:'push'" json:"channel"`
	DeliveryStatus         NotificationDeliveryStatus `gorm:"size:50;default:'pending'" json:"delivery_status"`
	Provider               NotificationProvider       `gorm:"size:50" json:"provider"`
	ProviderMessageID      string                     `gorm:"size:255" json:"provider_message_id"`
	SentAt                 *time.Time                 `gorm:"type:timestamptz" json:"sent_at"`
	DeliveredAt            *time.Time                 `gorm:"type:timestamptz" json:"delivered_at"`
	FailedAt               *time.Time                 `gorm:"type:timestamptz" json:"failed_at"`
	FailureReason          string                     `gorm:"type:text" json:"failure_reason"`
	RetryCount             int                        `gorm:"default:0" json:"retry_count"`
	CreatedAt              time.Time                  `gorm:"autoCreateTime" json:"created_at"`
	UpdatedAt              time.Time                  `gorm:"autoUpdateTime" json:"updated_at"`

	NotificationReceiver *NotificationReceiver `gorm:"foreignKey:NotificationReceiverID" json:"notification_receiver,omitempty"`
	UserDevice           *UserDevice           `gorm:"foreignKey:UserDeviceID" json:"user_device,omitempty"`
}

func (n *NotificationDelivery) BeforeCreate(tx *gorm.DB) error {
	if n.ID == uuid.Nil {
		n.ID = uuid.New()
	}
	return nil
}

func (NotificationDelivery) TableName() string {
	return "notification_deliveries"
}