package classes

import (
	"context"
	"crypto/md5"
	"errors"
	"fmt"
	"strconv"
	"strings"

	"git.golem15.com/golem15/sm-user-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/lagoon/attach"
	"gocloud.dev/blob"
	"gorm.io/gorm"
)

// AvatarURL returns the display picture URL of user at size pixels, the
// rule the user API payload follows: the thumbnail (size by size, mode
// auto) of the user's avatar attachment when there is one and a file
// bucket is published, the attachment's file path when the thumbnail
// fails (logged), and otherwise the gravatar URL
// //www.gravatar.com/avatar/{md5 of the email}?s={size}&d=mm. The URL may
// be protocol-relative or relative; a caller that needs an absolute URL
// resolves it. Only a failing database lookup is an error.
func AvatarURL(ctx context.Context, app *backpack.App, user *models.User, size int) (string, error) {
	if user == nil {
		return "", errors.New("golem15.user: avatar needs a user")
	}
	fallback := gravatar(user.Email, size)
	if app == nil || user.ID == 0 {
		return fallback, nil
	}
	gdb, ok := app.Lookup[*gorm.DB]()
	if !ok || gdb == nil {
		return fallback, nil
	}
	var f attach.File
	err := gdb.WithContext(ctx).
		Where("attachment_type = ? AND attachment_id = ? AND field = ?", user.MorphName(), strconv.FormatUint(uint64(user.ID), 10), models.AvatarField).
		Take(&f).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return fallback, nil
	}
	if err != nil {
		return "", err
	}
	bucket, ok := app.Lookup[*blob.Bucket]()
	if !ok || bucket == nil {
		return fallback, nil
	}
	url, err := f.Thumb(ctx, bucket, size, size, "auto")
	if err != nil {
		pluginLog.Error("golem15.user: avatar thumb", "err", err)
		return "/" + attach.BlobKey(f.DiskName), nil
	}
	return url, nil
}

// gravatar is the gravatar URL of an email at size pixels.
func gravatar(email string, size int) string {
	sum := md5.Sum([]byte(strings.ToLower(strings.TrimSpace(email))))
	return fmt.Sprintf("//www.gravatar.com/avatar/%x?s=%d&d=mm", sum, size)
}