package controllers

import (
	"context"
	"errors"
	"sync/atomic"

	"git.golem15.com/golem15/summercms/modules/cabana"
	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/jakub/sm-bm-plugin/models"
	"gorm.io/gorm"
)

var (
	_ pact.FormAfterCreate = materialsAdmin{}
	_ pact.FormAfterUpdate = materialsAdmin{}
	_ pact.FormAfterDelete = materialsAdmin{}
)

// MaterialIndex keeps the materials search index current once a write
// commits (classes.MaterialIndexer). Its calls never fail the write.
type MaterialIndex interface {
	SyncAfterCommit(ctx context.Context, tx *gorm.DB, id uint)
	RemoveAfterCommit(ctx context.Context, tx *gorm.DB, id uint)
}

type materialIndexHolder struct{ ix MaterialIndex }

var materialIndex atomic.Value

// UseMaterialIndex installs the index the materials admin syncs after a
// save or delete; nil turns the syncs off. Boot installs it, because the
// generated controller value has no field to carry it.
func UseMaterialIndex(ix MaterialIndex) {
	materialIndex.Store(materialIndexHolder{ix: ix})
}

func installedMaterialIndex() MaterialIndex {
	h, _ := materialIndex.Load().(materialIndexHolder)
	return h.ix
}

// FormAfterCreate syncs the new material once the save transaction commits.
func (materialsAdmin) FormAfterCreate(ctx context.Context, model any) error {
	return materialAfterCommit(ctx, model, false)
}

// FormAfterUpdate syncs the material once the save transaction commits.
func (materialsAdmin) FormAfterUpdate(ctx context.Context, model any) error {
	return materialAfterCommit(ctx, model, false)
}

// FormAfterDelete removes the material's document once the delete commits.
func (materialsAdmin) FormAfterDelete(ctx context.Context, model any) error {
	return materialAfterCommit(ctx, model, true)
}

// materialAfterCommit schedules the index work of an admin save on the save
// transaction. Only a model that is not a material is an error: the index
// never fails a save.
func materialAfterCommit(ctx context.Context, model any, remove bool) error {
	m, ok := model.(*models.Material)
	if !ok || m == nil {
		return errors.New("materials admin: form model is not a material")
	}
	ix := installedMaterialIndex()
	if ix == nil || m.ID == 0 {
		return nil
	}
	tx, _ := cabana.TxFromContext(ctx)
	if remove {
		ix.RemoveAfterCommit(ctx, tx, m.ID)
	} else {
		ix.SyncAfterCommit(ctx, tx, m.ID)
	}
	return nil
}