Add mailer system

Signed-off-by: gearnode <bryan@frimin.fr>

pkg/coredata/email.go

@@ -0,0 +1,133 @@
+// Copyright (c) 2025 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 coredata
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/getprobo/probo/pkg/gid"
+	"github.com/jackc/pgx/v5"
+	"go.gearno.de/kit/pg"
+)
+
+type (
+	Email struct {
+		ID             gid.GID    `db:"id"`
+		RecipientEmail string     `db:"recipient_email"`
+		RecipientName  string     `db:"recipient_name"`
+		Subject        string     `db:"subject"`
+		TextBody       string     `db:"text_body"`
+		CreatedAt      time.Time  `db:"created_at"`
+		UpdatedAt      time.Time  `db:"updated_at"`
+		SentAt         *time.Time `db:"sent_at"`
+	}
+)
+
+var (
+	ErrNoUnsentEmail = errors.New("no unsent email found")
+)
+
+func NewEmail(
+	recipientName string,
+	recipientEmail string,
+	subject string,
+	body string,
+) *Email {
+	return &Email{
+		ID:             gid.New(gid.NilTenant, EmailEntityType),
+		RecipientName:  recipientName,
+		RecipientEmail: recipientEmail,
+		Subject:        subject,
+		TextBody:       body,
+	}
+}
+
+func (e *Email) Insert(
+	ctx context.Context,
+	conn pg.Conn,
+) error {
+	q := `
+INSERT INTO emails (id, recipient_email, recipient_name, subject, text_body, created_at, updated_at)
+VALUES (@id, @recipient_email, @recipient_name, @subject, @text_body, @created_at, @updated_at)
+	`
+
+	args := pgx.StrictNamedArgs{
+		"id":              e.ID,
+		"recipient_email": e.RecipientEmail,
+		"recipient_name":  e.RecipientName,
+		"subject":         e.Subject,
+		"text_body":       e.TextBody,
+		"created_at":      e.CreatedAt,
+		"updated_at":      e.UpdatedAt,
+	}
+
+	_, err := conn.Exec(ctx, q, args)
+	return err
+}
+
+func (e *Email) LoadNextUnsentForUpdate(
+	ctx context.Context,
+	conn pg.Conn,
+) error {
+	q := `
+SELECT id, recipient_email, recipient_name, subject, text_body, created_at, updated_at, sent_at
+FROM emails
+WHERE sent_at IS NULL
+ORDER BY created_at ASC
+LIMIT 1
+FOR UPDATE
+	`
+
+	rows, err := conn.Query(ctx, q)
+	if err != nil {
+		return err
+	}
+
+	email, err := pgx.CollectExactlyOneRow(rows, pgx.RowToStructByName[Email])
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return ErrNoUnsentEmail
+		}
+
+		return fmt.Errorf("cannot collect email: %w", err)
+	}
+
+	*e = email
+
+	return nil
+}
+
+func (e *Email) Update(
+	ctx context.Context,
+	conn pg.Conn,
+) error {
+	q := `
+UPDATE emails
+SET sent_at = @sent_at, updated_at = @updated_at
+WHERE id = @id
+	`
+
+	args := pgx.StrictNamedArgs{
+		"id":         e.ID,
+		"sent_at":    e.SentAt,
+		"updated_at": e.UpdatedAt,
+	}
+
+	_, err := conn.Exec(ctx, q, args)
+	return err
+}