1 files changed, 141 insertions, 0 deletions
diff --git a/shrine/services/functions.go b/shrine/services/functions.go
new file mode 100644
index 0000000..f502ff6
--- /dev/null
+++ b/shrine/services/functions.go
@@ -0,0 +1,141 @@
+package services
+
+import (
+	"fmt"
+	"shrine/enums"
+	"shrine/messages"
+	"shrine/models"
+	"shrine/repositories"
+	"shrine/types/hypertext"
+	"shrine/types/letter"
+	"shrine/types/ticket"
+	"shrine/utils/sanitize"
+	"strings"
+)
+
+func ResolveUser(username string) (*models.User, *hypertext.ServiceError) {
+	citizen, err := repositories.FindUserByUsername(username)
+	if err != nil {
+		return nil, fail(enums.NotFound, messages.UserNotFound)
+	}
+	return citizen, nil
+}
+
+func mapRegistrationError(err error) *hypertext.ServiceError {
+	if strings.Contains(err.Error(), "users.username") {
+		return fail(enums.Conflict, messages.UsernameAlreadyExists)
+	}
+	if strings.Contains(err.Error(), "users.email") {
+		return fail(enums.Conflict, messages.EmailAlreadyExists)
+	}
+	return fail(enums.BadRequest, err.Error())
+}
+
+func assembleLetterResponse(record *models.Letter, viewerID uint) letter.LetterResponse {
+	participants := repositories.GetLetterParticipants(record.ID)
+	lastMessage := repositories.GetLastMessage(record.ID)
+	viewer, _ := repositories.GetParticipantRecord(record.ID, viewerID)
+
+	var unread bool
+	if viewer != nil && lastMessage != nil {
+		unread = viewer.LastReadAt == nil || lastMessage.CreatedAt.After(*viewer.LastReadAt)
+	}
+
+	var lastMessageResponse *letter.MessageResponse
+	if lastMessage != nil {
+		response := lastMessage.ToResponse()
+		lastMessageResponse = &response
+	}
+
+	return letter.LetterResponse{
+		Ref:          record.Ref,
+		Title:        computeTitle(record, participants, viewerID),
+		IsSystem:     record.IsSystem,
+		SystemRef:    record.SystemRef,
+		Participants: buildParticipantResponses(participants),
+		LastMessage:  lastMessageResponse,
+		Unread:       unread,
+		UpdatedAt:    record.UpdatedAt,
+	}
+}
+
+func computeTitle(record *models.Letter, participants []models.LetterParticipant, viewerID uint) string {
+	if record.Title != "" {
+		return record.Title
+	}
+
+	if record.IsSystem {
+		return "System Message"
+	}
+
+	var others []string
+	for _, participant := range participants {
+		if participant.UserID != viewerID {
+			others = append(others, participant.User.DisplayName)
+		}
+	}
+
+	switch len(others) {
+	case 0:
+		return "Empty Conversation"
+	case 1:
+		return others[0]
+	case 2:
+		return fmt.Sprintf("%s and %s", others[0], others[1])
+	default:
+		return fmt.Sprintf("%s, %s, and %d others", others[0], others[1], len(others)-2)
+	}
+}
+
+func buildParticipantResponses(participants []models.LetterParticipant) []letter.ParticipantResponse {
+	responses := make([]letter.ParticipantResponse, len(participants))
+	for index, participant := range participants {
+		responses[index] = participant.ToResponse()
+	}
+	return responses
+}
+
+func buildMessageResponses(letterMessages []models.LetterMessage) []letter.MessageResponse {
+	responses := make([]letter.MessageResponse, len(letterMessages))
+	for index, message := range letterMessages {
+		responses[index] = message.ToResponse()
+	}
+	return responses
+}
+
+func resolveLetter(ref string, userID uint) (*models.Letter, *hypertext.ServiceError) {
+	record, err := repositories.FindLetterByRef(ref)
+	if err != nil {
+		return nil, fail(enums.NotFound, messages.LetterNotFound)
+	}
+
+	if !repositories.IsLetterParticipant(record.ID, userID) {
+		return nil, fail(enums.NotFound, messages.LetterNotFound)
+	}
+
+	return record, nil
+}
+
+func resolveTicket(ref string) (*models.Ticket, *hypertext.ServiceError) {
+	record, err := repositories.FindTicketByRef(ref)
+	if err != nil {
+		return nil, fail(enums.NotFound, messages.TicketNotFound)
+	}
+	return record, nil
+}
+
+func sanitizeRequiredBody(body string) (string, *hypertext.ServiceError) {
+	sanitized := sanitize.HTML(body)
+	if sanitized == "" {
+		return "", fail(enums.BadRequest, messages.MessageBodyRequired)
+	}
+	return sanitized, nil
+}
+
+func buildTicketMessageResponses(ticketMessages []models.TicketMessage) []ticket.MessageResponse {
+	responses := make([]ticket.MessageResponse, len(ticketMessages))
+	for index, message := range ticketMessages {
+		responses[index] = message.ToResponse()
+	}
+	return responses
+}
+\ No newline at end of file