// Package storagefixture supplies a bounded protocol fixture, not a cloud service.
package storagefixture

import (
	"crypto/md5"
	"fmt"
	"io"
	"net/http"
	"sync"
	"time"
)

type value struct {
	data        []byte
	contentType string
	etag        string
}

func Handler() http.Handler {
	var mu sync.Mutex
	values := map[string]value{}
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		mu.Lock()
		defer mu.Unlock()
		if r.Header.Get("Authorization") == "" && r.URL.Query().Get("X-Amz-Signature") == "" && r.URL.Query().Get("x-oss-signature") == "" {
			http.Error(w, "signature required", 403)
			return
		}
		key := r.URL.Path
		switch r.Method {
		case "PUT":
			data, err := io.ReadAll(io.LimitReader(r.Body, 1025))
			if err != nil || len(data) > 1024 {
				http.Error(w, "too large", 413)
				return
			}
			v := value{data: data, contentType: r.Header.Get("Content-Type"), etag: fmt.Sprintf("%x", md5.Sum(data))}
			values[key] = v
			w.Header().Set("ETag", `"`+v.etag+`"`)
			w.WriteHeader(200)
		case "DELETE":
			delete(values, key)
			w.WriteHeader(204)
		case "GET", "HEAD":
			v, ok := values[key]
			if !ok {
				w.Header().Set("Content-Type", "application/xml")
				w.WriteHeader(404)
				fmt.Fprint(w, `<Error><Code>NoSuchKey</Code><Message>not found</Message></Error>`)
				return
			}
			w.Header().Set("Content-Length", fmt.Sprint(len(v.data)))
			w.Header().Set("Content-Type", v.contentType)
			w.Header().Set("ETag", `"`+v.etag+`"`)
			w.Header().Set("Last-Modified", time.Now().UTC().Format(http.TimeFormat))
			if r.Method == "GET" {
				w.Write(v.data)
			}
		default:
			http.Error(w, "unsupported", 405)
		}
	})
}