init(db): add persons get func

internal/db/db.go

@@ -3,8 +3,11 @@ package db
 import (
 	"context"
 	"fmt"
+	"net/http"
+	"strings"
 	"time"
 
+	"github.com/H1K0/Kiraku/internal/models"
 	"github.com/jackc/pgx/v5/pgxpool"
 )
 
@@ -44,3 +47,91 @@ func UserAuth(ctx context.Context, user_id string) (ok, editor bool) {
 }
 
 //#endregion Users
+
+//#region Persons
+
+func PersonsGet(ctx context.Context, user_id, filter, sort string, limit, offset int) (persons models.Persons, statusCode int, err error) {
+	if ok, _ := UserAuth(ctx, user_id); !ok {
+		err = fmt.Errorf("Unauthorized")
+		statusCode = http.StatusUnauthorized
+		return
+	}
+	queryGet := "SELECT id, name, coalesce(sort_name, '') FROM persons WHERE position($1 in lower(name))>0 OR position($1 in lower(sort_name))>0"
+	if sort != "" {
+		sort_options := strings.Split(sort, ",")
+		queryGet += " ORDER BY "
+		for i, sort_option := range sort_options {
+			sort_order := sort_option[:1]
+			sort_field := sort_option[1:]
+			switch sort_order {
+			case "+":
+				sort_order = "ASC"
+			case "-":
+				sort_order = "DESC"
+			default:
+				err = fmt.Errorf("invalid sorting order mark: %q", sort)
+				statusCode = http.StatusBadRequest
+				return
+			}
+			switch sort_field {
+			case "name":
+			case "sortName":
+				sort_field = "coalesce(sort_name, name)"
+			case "birthdate":
+			case "deathdate":
+			default:
+				err = fmt.Errorf("invalid sorting field: %q", sort_field)
+				statusCode = http.StatusBadRequest
+				return
+			}
+			if i > 0 {
+				queryGet += ", "
+			}
+			queryGet += fmt.Sprintf("%s %s NULLS LAST", sort_field, sort_order)
+		}
+	}
+	queryCount := queryGet
+	if limit >= 0 {
+		queryGet += fmt.Sprintf(" LIMIT %d", limit)
+	}
+	if offset > 0 {
+		queryGet += fmt.Sprintf(" OFFSET %d", offset)
+	}
+	filter = strings.ToLower(filter)
+	rows, err := connPool.Query(ctx, queryGet, filter)
+	if err != nil {
+		statusCode = http.StatusInternalServerError
+		return
+	}
+	count := 0
+	for rows.Next() {
+		var person models.PersonBrief
+		err = rows.Scan(&person.ID, &person.Name, &person.SortName)
+		if err != nil {
+			err = fmt.Errorf("error while fetching persons: %w", err)
+			statusCode = http.StatusInternalServerError
+			return
+		}
+		persons.Persons = append(persons.Persons, person)
+		count++
+	}
+	err = rows.Err()
+	if err != nil {
+		statusCode = http.StatusInternalServerError
+		return
+	}
+	persons.Pagination.Limit = limit
+	persons.Pagination.Offset = offset
+	persons.Pagination.Count = count
+	queryCount = fmt.Sprintf("SELECT count(*) FROM (%s) tmp", queryCount)
+	row := connPool.QueryRow(ctx, queryCount, filter)
+	err = row.Scan(&persons.Pagination.Total)
+	if err != nil {
+		statusCode = http.StatusInternalServerError
+	} else {
+		statusCode = http.StatusOK
+	}
+	return
+}
+
+//#endregion Persons