package models

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"strings"
	"time"

	"gorm.io/gorm"
)

// Comment status constants.
const (
	CommentPending  = 0 // 待审核
	CommentApproved = 1 // 已通过
	CommentRejected = 2 // 已拒绝（软拒绝；后台仍可查看，但前台不再显示）
)

// Comment represents one reader-submitted comment on an article. Comments may
// be nested via ParentID and authored by either a logged-in user (UserID) or
// an anonymous visitor identified by a long-lived GuestToken cookie.
type Comment struct {
	ID        uint           `gorm:"primarykey" json:"id"`
	CreatedAt time.Time      `json:"created_at"`
	UpdatedAt time.Time      `json:"updated_at"`
	DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`

	ArticleID uint  `gorm:"not null;index" json:"article_id"`
	ParentID  *uint `gorm:"index" json:"parent_id,omitempty"`

	// Authorship: logged-in users get UserID; anonymous visitors get a random
	// GuestToken stored in a cookie so they can see their own pending/private
	// comments on subsequent page loads.
	UserID     *uint  `gorm:"index" json:"user_id,omitempty"`
	GuestToken string `gorm:"size:64;index" json:"-"`

	AuthorName string `gorm:"not null;size:64" json:"author_name"`
	Email      string `gorm:"not null;size:255" json:"-"`
	EmailHash  string `gorm:"size:64;index" json:"email_hash"`
	Website    string `gorm:"size:255" json:"website,omitempty"`

	Content string `gorm:"type:text;not null" json:"content"`

	IsPrivate bool `gorm:"default:false;index" json:"is_private"`
	Status    int  `gorm:"default:0;index" json:"status"`

	IPAddress string `gorm:"size:64" json:"-"`
	UserAgent string `gorm:"size:512" json:"-"`

	Article Article `gorm:"foreignKey:ArticleID" json:"-"`
}

// TableName overrides the default GORM table name.
func (Comment) TableName() string {
	return "comments"
}

// HashEmail returns the md5 hash of a lowercase, trimmed email address. This
// is the form expected by Gravatar.
func HashEmail(email string) string {
	sum := md5.Sum([]byte(strings.ToLower(strings.TrimSpace(email))))
	return hex.EncodeToString(sum[:])
}

// GravatarURL returns a Gravatar avatar URL for this comment's email hash.
// Falls back to the "identicon" default avatar when no Gravatar exists.
func (c *Comment) GravatarURL(size int) string {
	if size <= 0 {
		size = 64
	}
	hash := c.EmailHash
	if hash == "" {
		hash = HashEmail(c.Email)
	}
	return fmt.Sprintf("https://www.gravatar.com/avatar/%s?s=%d&d=identicon", hash, size)
}

// MaskedEmail returns the email with the local part partially obscured, for
// admin-side listings that should hint at identity without exposing the
// full address.
func (c *Comment) MaskedEmail() string {
	email := c.Email
	at := strings.LastIndex(email, "@")
	if at <= 0 {
		return email
	}
	local := email[:at]
	host := email[at:]
	if len(local) <= 2 {
		return string(local[0]) + "***" + host
	}
	return string(local[0]) + "***" + string(local[len(local)-1]) + host
}

// AuthorInitial returns an uppercase first character of AuthorName for use as
// a text-based avatar placeholder when Gravatar is disabled. Returns "?" when
// the name is empty.
func (c *Comment) AuthorInitial() string {
	name := strings.TrimSpace(c.AuthorName)
	if name == "" {
		return "?"
	}
	r := []rune(name)
	return strings.ToUpper(string(r[0]))
}