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middlewares.go
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middlewares.go
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package middlewares
import (
"fmt"
"net/http"
"strings"
)
// MiddlewareStack middlewares stack
type MiddlewareStack struct {
middlewares []*Middleware
}
// Use use middleware
func (stack *MiddlewareStack) Use(middleware Middleware) {
stack.middlewares = append(stack.middlewares, &middleware)
}
// Remove remove middleware by name
func (stack *MiddlewareStack) Remove(name string) {
registeredMiddlewares := stack.middlewares
for idx, middleware := range registeredMiddlewares {
if middleware.Name == name {
if idx > 0 {
stack.middlewares = stack.middlewares[0 : idx-1]
} else {
stack.middlewares = []*Middleware{}
}
if idx < len(registeredMiddlewares)-1 {
stack.middlewares = append(stack.middlewares, registeredMiddlewares[idx+1:]...)
}
}
}
}
// sortMiddlewares sort middlewares
func (stack *MiddlewareStack) sortMiddlewares() (sortedMiddlewares []*Middleware, err error) {
var (
errs []error
middlewareNames, sortedNames []string
middlewaresMap = map[string]*Middleware{}
sortMiddleware func(m *Middleware)
)
for _, middleware := range stack.middlewares {
middlewaresMap[middleware.Name] = middleware
middlewareNames = append(middlewareNames, middleware.Name)
}
for _, middleware := range stack.middlewares {
for _, require := range middleware.Requires {
if _, ok := middlewaresMap[require]; !ok {
errs = append(errs, fmt.Errorf("middleware %v requires %v, but it doesn't exist", middleware.Name, require))
}
}
for _, insertBefore := range middleware.InsertBefore {
if m, ok := middlewaresMap[insertBefore]; ok {
m.InsertAfter = uniqueAppend(m.InsertAfter, middleware.Name)
}
}
for _, insertAfter := range middleware.InsertAfter {
if m, ok := middlewaresMap[insertAfter]; ok {
m.InsertBefore = uniqueAppend(m.InsertBefore, middleware.Name)
}
}
}
if len(errs) > 0 {
return nil, fmt.Errorf("%v", errs)
}
sortMiddleware = func(m *Middleware) {
if _, found := getRIndex(sortedNames, m.Name); !found { // if not sorted
var minIndex = -1
// sort by InsertAfter
for _, insertAfter := range m.InsertAfter {
idx, found := getRIndex(sortedNames, insertAfter)
if !found {
if middleware, ok := middlewaresMap[insertAfter]; ok {
sortMiddleware(middleware)
idx, found = getRIndex(sortedNames, insertAfter)
}
}
if found && idx > minIndex {
minIndex = idx
}
}
// sort by InsertBefore
for _, insertBefore := range m.InsertBefore {
if idx, found := getRIndex(sortedNames, insertBefore); found {
if idx < minIndex {
sortedNames = append(sortedNames[:idx], sortedNames[idx+1:]...)
sortMiddleware(middlewaresMap[insertBefore])
return
}
}
}
if minIndex >= 0 {
sortedNames = append(sortedNames[:minIndex+1], append([]string{m.Name}, sortedNames[minIndex+1:]...)...)
} else if _, has := getRIndex(sortedNames, m.Name); !has {
// if current callback haven't been sorted, append it to last
sortedNames = append(sortedNames, m.Name)
}
}
}
for _, middleware := range stack.middlewares {
sortMiddleware(middleware)
}
for _, name := range sortedNames {
sortedMiddlewares = append(sortedMiddlewares, middlewaresMap[name])
}
return sortedMiddlewares, nil
}
func (stack *MiddlewareStack) String() string {
var (
sortedNames []string
sortedMiddlewares, err = stack.sortMiddlewares()
)
if err != nil {
fmt.Println(err)
}
for _, middleware := range sortedMiddlewares {
sortedNames = append(sortedNames, middleware.Name)
}
return fmt.Sprintf("MiddlewareStack: %v", strings.Join(sortedNames, ", "))
}
// Apply apply middlewares to handler
func (stack *MiddlewareStack) Apply(handler http.Handler) http.Handler {
var (
compiledHandler http.Handler
sortedMiddlewares, err = stack.sortMiddlewares()
)
if err != nil {
fmt.Println(err)
}
for idx := len(sortedMiddlewares) - 1; idx >= 0; idx-- {
middleware := sortedMiddlewares[idx]
if compiledHandler == nil {
compiledHandler = middleware.Handler(handler)
} else {
compiledHandler = middleware.Handler(compiledHandler)
}
}
return compiledHandler
}