Add expr source

pkg/expr/expr.go

@@ -0,0 +1,115 @@
+package expr
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+
+	"github.com/AlexxIT/go2rtc/pkg/tcp"
+	"github.com/antonmedv/expr"
+)
+
+func newRequest(method, url string, headers map[string]any) (*http.Request, error) {
+	if method == "" {
+		method = "GET"
+	}
+
+	req, err := http.NewRequest(method, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	for k, v := range headers {
+		req.Header.Set(k, fmt.Sprintf("%v", v))
+	}
+
+	return req, nil
+}
+
+func regExp(params ...any) (*regexp.Regexp, error) {
+	exp := params[0].(string)
+	if len(params) >= 2 {
+		// support:
+		//   i  case-insensitive (default false)
+		//   m  multi-line mode: ^ and $ match begin/end line (default false)
+		//   s  let . match \n (default false)
+		// https://pkg.go.dev/regexp/syntax
+		flags := params[1].(string)
+		exp = "(?" + flags + ")" + exp
+	}
+	return regexp.Compile(exp)
+}
+
+var Options = []expr.Option{
+	expr.Function(
+		"fetch",
+		func(params ...any) (any, error) {
+			var req *http.Request
+			var err error
+
+			url := params[0].(string)
+
+			if len(params) == 2 {
+				options := params[1].(map[string]any)
+				method, _ := options["method"].(string)
+				headers, _ := options["headers"].(map[string]any)
+				req, err = newRequest(method, url, headers)
+			} else {
+				req, err = http.NewRequest("GET", url, nil)
+			}
+
+			if err != nil {
+				return nil, err
+			}
+
+			res, err := tcp.Do(req)
+			if err != nil {
+				return nil, err
+			}
+
+			b, _ := io.ReadAll(res.Body)
+
+			return map[string]any{
+				"ok":     res.StatusCode < 400,
+				"status": res.Status,
+				"text":   string(b),
+				"json": func() (v any) {
+					_ = json.Unmarshal(b, &v)
+					return
+				},
+			}, nil
+		},
+		//new(func(url string) map[string]any),
+		//new(func(url string, options map[string]any) map[string]any),
+	),
+	expr.Function(
+		"match",
+		func(params ...any) (any, error) {
+			re, err := regExp(params[1:]...)
+			if err != nil {
+				return nil, err
+			}
+			str := params[0].(string)
+			return re.FindStringSubmatch(str), nil
+		},
+		//new(func(str, expr string) []string),
+		//new(func(str, expr, flags string) []string),
+	),
+	expr.Function(
+		"RegExp",
+		func(params ...any) (any, error) {
+			return regExp(params)
+		},
+	),
+}
+
+func Run(input string) (any, error) {
+	program, err := expr.Compile(input, Options...)
+	if err != nil {
+		return nil, err
+	}
+
+	return expr.Run(program, nil)
+}