package user

import (
	"context"
	"errors"
	"strings"

	"git.golem15.com/golem15/sm-user-plugin/classes"
	"git.golem15.com/golem15/sm-user-plugin/models"
	"git.golem15.com/golem15/summercms/modules/bouncer"
	"git.golem15.com/golem15/summercms/modules/cabana"
	"git.golem15.com/golem15/summercms/modules/pact"
	"gorm.io/gorm"
)

var _ pact.HasAdminActionExtensions = (*Plugin)(nil)

// AdminActionExtensions adds two record actions to the admin's
// Administrators screen (D-07, D-34), both behind
// golem15.users.manage_backend_links: link_frontend_account asks for the
// email of an active frontend user and links that user to the
// administrator shown (exact, case-insensitive match; no search and no
// list), recording who set it; unlink_frontend_account removes the
// administrator's link. cabana's outranking check runs before either.
func (p *Plugin) AdminActionExtensions() []pact.AdminActionExtension {
	return []pact.AdminActionExtension{{
		Controller: cabana.AdministratorsControllerID,
		RecordActions: []pact.AdminRecordAction{
			{
				Name:        "link_frontend_account",
				Label:       backendLinkLang + "set",
				Confirm:     backendLinkLang + "set_confirm",
				Permissions: []string{classes.PermissionManageBackendLinks},
				Prompt: &pact.AdminActionPrompt{
					Label:     backendLinkLang + "prompt_email",
					Comment:   backendLinkLang + "prompt_comment",
					MaxLength: 254,
				},
				Applies: func(ctx context.Context, record any) (bool, error) {
					link, err := p.adminRecordLink(ctx, record)
					return link == nil, err
				},
				Run: p.setFrontendLink,
			},
			{
				Name:        "unlink_frontend_account",
				Label:       backendLinkLang + "remove",
				Confirm:     backendLinkLang + "remove_confirm",
				Danger:      true,
				Permissions: []string{classes.PermissionManageBackendLinks},
				Applies: func(ctx context.Context, record any) (bool, error) {
					link, err := p.adminRecordLink(ctx, record)
					return link != nil, err
				},
				Run: p.removeFrontendLink,
			},
		},
	}}
}

// adminRecordLink returns the link of the administrator record, or nil.
func (p *Plugin) adminRecordLink(ctx context.Context, record any) (*models.BackendLink, error) {
	admin, ok := record.(*cabana.BackendUser)
	if !ok || admin == nil {
		return nil, errors.New("golem15.user: the record is not an administrator")
	}
	return p.backendLinks().LinkFor(ctx, admin.ID)
}

// payloadError is the 422 on the prompt's input.
func payloadError(key string) error {
	return &cabana.ValidationError{Details: map[string]any{"payload": []string{backendLinkLang + key}}}
}

// setFrontendLink links the active frontend user whose email is the prompt
// value to the administrator record.
func (p *Plugin) setFrontendLink(ctx context.Context, in pact.AdminRecordActionInput) (pact.AdminRecordActionResult, error) {
	admin, ok := in.Record.(*cabana.BackendUser)
	if !ok || admin == nil {
		return pact.AdminRecordActionResult{}, errors.New("golem15.user: the record is not an administrator")
	}
	tx, ok := cabana.TxFromContext(ctx)
	if !ok {
		return pact.AdminRecordActionResult{}, errors.New("golem15.user: linking needs the action's transaction")
	}
	email := strings.TrimSpace(in.Value)
	var ids []uint
	if err := tx.Session(&gorm.Session{NewDB: true}).WithContext(ctx).Model(&models.User{}).
		Where("lower(email) = lower(?) AND is_activated = TRUE", email).Limit(2).Pluck("id", &ids).Error; err != nil {
		return pact.AdminRecordActionResult{}, err
	}
	if email == "" || len(ids) != 1 {
		return pact.AdminRecordActionResult{}, payloadError("unknown_user")
	}
	var by uint
	if caller, ok := bouncer.User(ctx); ok && caller != nil {
		by = caller.ID
	}
	_, err := p.backendLinks().SetLink(ctx, tx, ids[0], admin.ID, by)
	switch {
	case err == nil:
	case errors.Is(err, classes.ErrAlreadyLinked):
		return pact.AdminRecordActionResult{}, payloadError("already_linked")
	case errors.Is(err, classes.ErrFrontendUserUnavailable):
		return pact.AdminRecordActionResult{}, payloadError("unknown_user")
	case errors.Is(err, classes.ErrBackendUserUnavailable):
		return pact.AdminRecordActionResult{}, &cabana.ForbiddenError{}
	default:
		return pact.AdminRecordActionResult{}, err
	}
	return pact.AdminRecordActionResult{Message: backendLinkLang + "set_success"}, nil
}

// removeFrontendLink removes the administrator record's link.
func (p *Plugin) removeFrontendLink(ctx context.Context, in pact.AdminRecordActionInput) (pact.AdminRecordActionResult, error) {
	tx, ok := cabana.TxFromContext(ctx)
	if !ok {
		return pact.AdminRecordActionResult{}, errors.New("golem15.user: unlinking needs the action's transaction")
	}
	link, err := p.adminRecordLink(ctx, in.Record)
	if err != nil {
		return pact.AdminRecordActionResult{}, err
	}
	if err := p.backendLinks().RemoveLink(ctx, tx, link); err != nil {
		return pact.AdminRecordActionResult{}, err
	}
	return pact.AdminRecordActionResult{Message: backendLinkLang + "remove_success"}, nil
}