package buildstep

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
	"time"

	"git.novox.be/novox/mesh-sdk/go/delivery"
)

func digestOfBytes(b []byte) string {
	h := sha256.Sum256(b)
	return "sha256:" + hex.EncodeToString(h[:])
}

// registry is an artifact store as far as a blob push needs one: HEAD a blob, start an upload, PUT it with its digest.
type registry struct {
	mu    sync.Mutex
	blobs map[string][]byte
	calls []string
	put   int // the status a PUT answers, 201 when 0
}

func (r *registry) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.calls = append(r.calls, req.Method+" "+req.URL.Path)
	switch {
	case req.Method == http.MethodHead && strings.Contains(req.URL.Path, "/blobs/sha256:"):
		if _, ok := r.blobs[req.URL.Path[strings.LastIndex(req.URL.Path, "/")+1:]]; ok {
			w.WriteHeader(http.StatusOK)
			return
		}
		w.WriteHeader(http.StatusNotFound)
	case req.Method == http.MethodPost && strings.HasSuffix(req.URL.Path, "/blobs/uploads/"):
		w.Header().Set("Location", strings.TrimSuffix(req.URL.Path, "/")+"/u1?state=x")
		w.WriteHeader(http.StatusAccepted)
	case req.Method == http.MethodPut && strings.Contains(req.URL.Path, "/blobs/uploads/u1"):
		if r.put != 0 {
			w.WriteHeader(r.put)
			_, _ = io.WriteString(w, `{"errors":[{"code":"DIGEST_INVALID","message":"provided digest did not match uploaded content"}]}`)
			return
		}
		body, _ := io.ReadAll(req.Body)
		d := req.URL.Query().Get("digest")
		if req.URL.Query().Get("state") != "x" || d != digestOfBytes(body) {
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		r.blobs[d] = body
		w.WriteHeader(http.StatusCreated)
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

// A done build's bundle or archive is pushed to the artifact store by its build module (novox/hq ADR 0498 clauses 1
// and 2): a blob the store already holds is done with no upload; one it lacks is uploaded by digest; its reference is
// the artifact-store form the builder's key and the controller check.
func TestABlobIsPushedOnceByItsDigest(t *testing.T) {
	reg := &registry{blobs: map[string][]byte{}}
	srv := httptest.NewServer(reg)
	defer srv.Close()
	addr := strings.TrimPrefix(srv.URL, "http://")
	body := []byte("the packed bundle")
	d := digestOfBytes(body)
	if err := PushBlob(context.Background(), srv.Client(), addr, "mail/code", d, body); err != nil {
		t.Fatal(err)
	}
	if string(reg.blobs[d]) != string(body) {
		t.Fatalf("the store holds %q", reg.blobs[d])
	}
	reg.calls = nil
	if err := PushBlob(context.Background(), srv.Client(), addr, "mail/code", d, body); err != nil {
		t.Fatal(err)
	}
	if len(reg.calls) != 1 || !strings.HasPrefix(reg.calls[0], "HEAD ") {
		t.Fatalf("a blob the store holds was uploaded again: %v", reg.calls)
	}
	ref := BlobReference("mail", "code", d)
	if ref != "artifact-store://mail/code/blobs/"+d {
		t.Fatalf("BlobReference = %q", ref)
	}
	b := delivery.BuilderBuild{State: delivery.BuildDone, Manifest: strings.Repeat("4", 64),
		Artifacts: []delivery.BuiltArtifact{{Name: "code", Kind: "bundle", Digest: d, Reference: ref}}}
	if _, err := delivery.EncodeBuilderBuild(b); err != nil {
		t.Fatalf("the key refuses the reference BlobReference gives: %v", err)
	}
}

// A store that refuses the upload fails the push naming the store's own words; bytes that are not the digest are
// refused before anything is sent.
func TestAPushTheStoreRefusesSaysTheStoresWords(t *testing.T) {
	reg := &registry{blobs: map[string][]byte{}, put: http.StatusBadRequest}
	srv := httptest.NewServer(reg)
	defer srv.Close()
	addr := strings.TrimPrefix(srv.URL, "http://")
	body := []byte("x")
	err := PushBlob(context.Background(), srv.Client(), addr, "mail/code", digestOfBytes(body), body)
	if err == nil || !strings.Contains(err.Error(), "provided digest did not match") || !strings.Contains(err.Error(), "400") {
		t.Fatalf("a refused upload said %v", err)
	}
	reg.calls = nil
	err = PushBlob(context.Background(), srv.Client(), addr, "mail/code", digestOfBytes([]byte("other")), body)
	if err == nil || len(reg.calls) != 0 {
		t.Fatalf("bytes that are not their digest: %v, calls %v", err, reg.calls)
	}
}

// A store refusing connections (its nightly collection holds it still) is waited out, up to RegistryWait (issue 457).
func TestAPushWaitsOutAStoreRefusingConnections(t *testing.T) {
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	addr := l.Addr().String()
	l.Close() // refusing now
	reg := &registry{blobs: map[string][]byte{}}
	go func() {
		time.Sleep(300 * time.Millisecond)
		l2, err := net.Listen("tcp", addr)
		if err != nil {
			return
		}
		_ = http.Serve(l2, reg)
	}()
	beforeWait, beforePause := RegistryWait, RegistryFirstPause
	RegistryWait, RegistryFirstPause = 3*time.Second, 100*time.Millisecond
	defer func() { RegistryWait, RegistryFirstPause = beforeWait, beforePause }()
	body := []byte("late")
	if err := PushBlob(context.Background(), http.DefaultClient, addr, "mail/code", digestOfBytes(body), body); err != nil {
		t.Fatalf("a store that came back was not waited for: %v", err)
	}

	l3, _ := net.Listen("tcp", "127.0.0.1:0")
	gone := l3.Addr().String()
	l3.Close()
	RegistryWait = 300 * time.Millisecond
	err = PushBlob(context.Background(), http.DefaultClient, gone, "mail/code", digestOfBytes(body), body)
	if err == nil || !strings.Contains(err.Error(), "refused every connection") {
		t.Fatalf("a store that stayed down said %v", err)
	}
}