Local queries (#641)

* Read local queries from pgweb home directory
* Refactor local query functionality
* Allow picking local query in the query tab
* WIP
* Disable local query dropdown during execution
* Only allow local queries running in a single session mode
* Add middleware to enforce local query endpoint availability
* Fix query check
* Add query store tests
* Make query store errors portable
* Skip building specific tests on windows

pkg/queries/store.go

@@ -0,0 +1,88 @@
+package queries
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	ErrQueryDirNotExist  = errors.New("queries directory does not exist")
+	ErrQueryFileNotExist = errors.New("query file does not exist")
+)
+
+type Store struct {
+	dir string
+}
+
+func NewStore(dir string) *Store {
+	return &Store{
+		dir: dir,
+	}
+}
+
+func (s Store) Read(id string) (*Query, error) {
+	path := filepath.Join(s.dir, fmt.Sprintf("%s.sql", id))
+	return readQuery(path)
+}
+
+func (s Store) ReadAll() ([]Query, error) {
+	entries, err := os.ReadDir(s.dir)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			err = ErrQueryDirNotExist
+		}
+		return nil, err
+	}
+
+	queries := []Query{}
+
+	for _, entry := range entries {
+		name := entry.Name()
+		if filepath.Ext(name) != ".sql" {
+			continue
+		}
+
+		path := filepath.Join(s.dir, name)
+		query, err := readQuery(path)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "[WARN] skipping %q query file due to error: %v\n", name, err)
+			continue
+		}
+		if query == nil {
+			continue
+		}
+
+		queries = append(queries, *query)
+	}
+
+	return queries, nil
+}
+
+func readQuery(path string) (*Query, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return nil, ErrQueryFileNotExist
+		}
+		return nil, err
+	}
+	dataStr := string(data)
+
+	meta, err := parseMetadata(dataStr)
+	if err != nil {
+		return nil, err
+	}
+	if meta == nil {
+		return nil, nil
+	}
+
+	return &Query{
+		ID:   strings.Replace(filepath.Base(path), ".sql", "", 1),
+		Path: path,
+		Meta: meta,
+		Data: sanitizeMetadata(dataStr),
+	}, nil
+}