94 lines
2.4 KiB
Go
94 lines
2.4 KiB
Go
package plugins
|
|
|
|
import (
|
|
"context"
|
|
"fmt"
|
|
"net/http"
|
|
"path"
|
|
"reflect"
|
|
"strings"
|
|
|
|
"github.com/mitchellh/mapstructure"
|
|
)
|
|
|
|
// Build builds a middleware plugin.
|
|
func (b Builder) Build(pName string, config map[string]interface{}, middlewareName string) (Constructor, error) {
|
|
if b.middlewareDescriptors == nil {
|
|
return nil, fmt.Errorf("no plugin definition in the static configuration: %s", pName)
|
|
}
|
|
|
|
descriptor, ok := b.middlewareDescriptors[pName]
|
|
if !ok {
|
|
return nil, fmt.Errorf("unknown plugin type: %s", pName)
|
|
}
|
|
|
|
m, err := newMiddleware(descriptor, config, middlewareName)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return m.NewHandler, err
|
|
}
|
|
|
|
// Middleware is a HTTP handler plugin wrapper.
|
|
type Middleware struct {
|
|
middlewareName string
|
|
fnNew reflect.Value
|
|
config reflect.Value
|
|
}
|
|
|
|
func newMiddleware(descriptor pluginContext, config map[string]interface{}, middlewareName string) (*Middleware, error) {
|
|
basePkg := descriptor.BasePkg
|
|
if basePkg == "" {
|
|
basePkg = strings.ReplaceAll(path.Base(descriptor.Import), "-", "_")
|
|
}
|
|
|
|
vConfig, err := descriptor.interpreter.Eval(basePkg + `.CreateConfig()`)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to eval CreateConfig: %w", err)
|
|
}
|
|
|
|
cfg := &mapstructure.DecoderConfig{
|
|
DecodeHook: mapstructure.StringToSliceHookFunc(","),
|
|
WeaklyTypedInput: true,
|
|
Result: vConfig.Interface(),
|
|
}
|
|
|
|
decoder, err := mapstructure.NewDecoder(cfg)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to create configuration decoder: %w", err)
|
|
}
|
|
|
|
err = decoder.Decode(config)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to decode configuration: %w", err)
|
|
}
|
|
|
|
fnNew, err := descriptor.interpreter.Eval(basePkg + `.New`)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to eval New: %w", err)
|
|
}
|
|
|
|
return &Middleware{
|
|
middlewareName: middlewareName,
|
|
fnNew: fnNew,
|
|
config: vConfig,
|
|
}, nil
|
|
}
|
|
|
|
// NewHandler creates a new HTTP handler.
|
|
func (m *Middleware) NewHandler(ctx context.Context, next http.Handler) (http.Handler, error) {
|
|
args := []reflect.Value{reflect.ValueOf(ctx), reflect.ValueOf(next), m.config, reflect.ValueOf(m.middlewareName)}
|
|
results := m.fnNew.Call(args)
|
|
|
|
if len(results) > 1 && results[1].Interface() != nil {
|
|
return nil, results[1].Interface().(error)
|
|
}
|
|
|
|
handler, ok := results[0].Interface().(http.Handler)
|
|
if !ok {
|
|
return nil, fmt.Errorf("invalid handler type: %T", results[0].Interface())
|
|
}
|
|
|
|
return handler, nil
|
|
}
|