fixed route not being updated on restart, added experimental middleware compose support

internal/net/http/middleware/middleware_builder.go

@@ -0,0 +1,104 @@
+package middleware
+
+import (
+	"net/http"
+	"os"
+
+	E "github.com/yusing/go-proxy/internal/error"
+	"gopkg.in/yaml.v3"
+)
+
+func BuildMiddlewaresFromYAML(filePath string) (middlewares map[string]*Middleware, outErr E.NestedError) {
+	b := E.NewBuilder("middlewares compile errors")
+	defer b.To(&outErr)
+
+	var data map[string][]map[string]any
+	fileContent, err := os.ReadFile(filePath)
+	if err != nil {
+		b.Add(E.FailWith("read file", err))
+		return
+	}
+	err = yaml.Unmarshal(fileContent, &data)
+	if err != nil {
+		b.Add(E.FailWith("toml unmarshal", err))
+		return
+	}
+	middlewares = make(map[string]*Middleware)
+	for name, defs := range data {
+		chainErr := E.NewBuilder("errors in middleware chain %s", name)
+		chain := make([]*Middleware, 0, len(defs))
+		for i, def := range defs {
+			if def["use"] == nil || def["use"].(string) == "" {
+				chainErr.Add(E.Missing("use").Subjectf("%s.%d", name, i))
+				continue
+			}
+			baseName := def["use"].(string)
+			base, ok := Get(baseName)
+			if !ok {
+				chainErr.Add(E.NotExist("middleware", baseName).Subjectf("%s.%d", name, i))
+				continue
+			}
+			delete(def, "use")
+			m, err := base.withOptions(def)
+			if err != nil {
+				chainErr.Add(err.Subjectf("%s.%d", name, i))
+				continue
+			}
+			chain = append(chain, m)
+		}
+		if chainErr.HasError() {
+			b.Add(chainErr.Build())
+		} else {
+			name = name + "@file"
+			middlewares[name] = BuildMiddlewareFromChain(name, chain)
+		}
+	}
+	return
+}
+
+// TODO: check conflict or duplicates
+func BuildMiddlewareFromChain(name string, chain []*Middleware) *Middleware {
+	var (
+		befores  []BeforeFunc
+		rewrites []RewriteFunc
+		modResps []ModifyResponseFunc
+	)
+	for _, m := range chain {
+		if m.before != nil {
+			befores = append(befores, m.before)
+		}
+		if m.rewrite != nil {
+			rewrites = append(rewrites, m.rewrite)
+		}
+		if m.modifyResponse != nil {
+			modResps = append(modResps, m.modifyResponse)
+		}
+	}
+
+	m := &Middleware{name: name}
+	if len(befores) > 0 {
+		m.before = func(next http.Handler, w ResponseWriter, r *Request) {
+			for _, before := range befores {
+				before(next, w, r)
+			}
+		}
+	}
+	if len(rewrites) > 0 {
+		m.rewrite = func(r *Request) {
+			for _, rewrite := range rewrites {
+				rewrite(r)
+			}
+		}
+	}
+	if len(modResps) > 0 {
+		m.modifyResponse = func(res *Response) error {
+			b := E.NewBuilder("errors in middleware %s", name)
+			for _, mr := range modResps {
+				b.AddE(mr(res))
+			}
+			return b.Build().Error()
+		}
+	}
+
+	return m
+}