// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

package mailman

import (
	"context"
	"errors"
	"fmt"
	"time"

	"go.gearno.de/kit/log"
	"go.gearno.de/kit/pg"
	"go.gearno.de/kit/worker"
	"go.probo.inc/probo/pkg/coredata"
)

type mailingListHandler struct {
	service    *Service
	pg         *pg.Client
	logger     *log.Logger
	staleAfter time.Duration
}

func NewMailingListWorker(
	service *Service,
	pgClient *pg.Client,
	logger *log.Logger,
	opts ...worker.Option,
) *worker.Worker[coredata.MailingListUpdate] {
	h := &mailingListHandler{
		service:    service,
		pg:         pgClient,
		logger:     logger,
		staleAfter: 5 * time.Minute,
	}

	return worker.New(
		"mailing-list-worker",
		h,
		logger,
		opts...,
	)
}

func (h *mailingListHandler) Claim(ctx context.Context) (coredata.MailingListUpdate, error) {
	var mlu coredata.MailingListUpdate

	if err := h.pg.WithTx(
		ctx,
		func(ctx context.Context, tx pg.Tx) error {
			if err := mlu.LoadNextEnqueuedForUpdateSkipLocked(ctx, tx); err != nil {
				return err
			}

			scope := coredata.NewScopeFromObjectID(mlu.ID)
			mlu.Status = coredata.MailingListUpdateStatusProcessing
			mlu.UpdatedAt = time.Now()

			if err := mlu.Update(ctx, tx, scope); err != nil {
				return fmt.Errorf("cannot claim mailing list update: %w", err)
			}

			return nil
		},
	); err != nil {
		if errors.Is(err, coredata.ErrResourceNotFound) {
			return coredata.MailingListUpdate{}, worker.ErrNoTask
		}
		return coredata.MailingListUpdate{}, err
	}

	return mlu, nil
}

func (h *mailingListHandler) Process(ctx context.Context, mlu coredata.MailingListUpdate) error {
	if err := h.sendAndCommit(ctx, &mlu); err != nil {
		h.logger.ErrorCtx(
			ctx,
			"cannot send mailing list update",
			log.Error(err),
			log.String("mailing_list_update_id", mlu.ID.String()),
		)

		if err := h.resetEnqueued(ctx, &mlu); err != nil {
			h.logger.ErrorCtx(
				ctx,
				"cannot reset mailing list update to enqueued",
				log.Error(err),
				log.String("mailing_list_update_id", mlu.ID.String()),
			)
		}

		return err
	}

	return nil
}

func (h *mailingListHandler) RecoverStale(ctx context.Context) error {
	return h.pg.WithTx(
		ctx,
		func(ctx context.Context, tx pg.Tx) error {
			if err := coredata.ResetStaleProcessingMailingListUpdates(ctx, tx, h.staleAfter); err != nil {
				return fmt.Errorf("cannot reset stale processing mailing list updates: %w", err)
			}
			return nil
		},
	)
}

func (h *mailingListHandler) sendAndCommit(ctx context.Context, mlu *coredata.MailingListUpdate) error {
	if err := h.service.CreateUpdateEmails(ctx, mlu.MailingListID, mlu.ID, mlu.Title, mlu.Body); err != nil {
		return fmt.Errorf("cannot create update emails: %w", err)
	}

	return h.pg.WithTx(
		ctx,
		func(ctx context.Context, tx pg.Tx) error {
			scope := coredata.NewScopeFromObjectID(mlu.ID)

			var current coredata.MailingListUpdate
			if err := current.LoadByID(ctx, tx, scope, mlu.ID); err != nil {
				return fmt.Errorf("cannot reload mailing list update: %w", err)
			}

			if current.Status != coredata.MailingListUpdateStatusProcessing {
				return fmt.Errorf("unexpected status %s, expected PROCESSING", current.Status)
			}

			mlu.Status = coredata.MailingListUpdateStatusSent
			mlu.UpdatedAt = time.Now()

			if err := mlu.Update(ctx, tx, scope); err != nil {
				return fmt.Errorf("cannot mark mailing list update as sent: %w", err)
			}

			return nil
		},
	)
}

func (h *mailingListHandler) resetEnqueued(ctx context.Context, mlu *coredata.MailingListUpdate) error {
	return h.pg.WithTx(
		ctx,
		func(ctx context.Context, tx pg.Tx) error {
			scope := coredata.NewScopeFromObjectID(mlu.ID)
			mlu.Status = coredata.MailingListUpdateStatusEnqueued
			mlu.UpdatedAt = time.Now()

			if err := mlu.Update(ctx, tx, scope); err != nil {
				return fmt.Errorf("cannot reset mailing list update: %w", err)
			}

			return nil
		},
	)
}