package bootstrap

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"testing"
	"time"
)

// Step 8 is the pivot's hinge (novox/hq ADR 0067): the carried image gets a manifest digest, which
// is the first one it has ever had, and that is what lets the control plane be named the way every
// other module is named. These tests defend how that digest is learned, because a wrong one pins
// the mesh to an image nothing on this machine serves.

func publishing(t *testing.T, fetch func(string) (int, string, error),
	run func(name string, args []string) (string, error)) (Options, Deps, *asked) {
	t.Helper()
	runtime := &asked{answer: run}
	return Options{
		Registry: "127.0.0.1:5000",
		Timeout:  time.Second,
		Wait:     0,
	}, Deps{
		Run: runtime.run,
		Fetch: func(_ context.Context, url string) (int, string, error) {
			return fetch(url)
		},
	}, runtime
}

// Nothing has ever been pushed under this name, so the registry says 404 — and that is an answer,
// not a failure. An installer that treated it as one would refuse on the first run of the step it
// exists to perform.
func TestAnImageNoRegistryHasEverHeldIsPushed(t *testing.T) {
	pushed := false
	o, d, runtime := publishing(t,
		func(string) (int, string, error) {
			if !pushed {
				return http.StatusNotFound, "", nil
			}
			return http.StatusOK, `{"name":"mesh-controller","tags":["genesis"]}`, nil
		},
		func(_ string, args []string) (string, error) {
			switch args[0] {
			case "tag":
				return "", nil
			case "push":
				pushed = true
				return "", nil
			case "image":
				return `["127.0.0.1:5000/mesh-controller@sha256:` + strings.Repeat("a", 64) + `"]`, nil
			}
			return "", fmt.Errorf("unexpected: %v", args)
		})

	out, err := PublishControlPlane(context.Background(), o, d, held, func(string) {})
	if err != nil {
		t.Fatal(err)
	}
	if out.Already {
		t.Error("an image no registry held was reported as already published")
	}
	if !strings.HasPrefix(out.Reference, "127.0.0.1:5000/mesh-controller@sha256:") {
		t.Errorf("the control plane is pinned as %q", out.Reference)
	}
	if !runtime.ran("docker push 127.0.0.1:5000/mesh-controller:genesis") {
		t.Errorf("nothing was pushed: %v", runtime.commands)
	}
}

// An image the registry already serves is not pushed again, and says so. Blobs are named by their
// content, so re-pushing is asking a registry to store what it already has under the name it
// already has — and the installer is run over and over.
func TestAnImageTheRegistryAlreadyServesIsNotPushedAgain(t *testing.T) {
	o, d, runtime := publishing(t,
		func(string) (int, string, error) {
			return http.StatusOK, `{"name":"mesh-controller","tags":["genesis"]}`, nil
		},
		func(_ string, args []string) (string, error) {
			if args[0] == "image" {
				return `["127.0.0.1:5000/mesh-controller@sha256:` + strings.Repeat("b", 64) + `"]`, nil
			}
			return "", fmt.Errorf("unexpected: %v", args)
		})

	out, err := PublishControlPlane(context.Background(), o, d, held, func(string) {})
	if err != nil {
		t.Fatal(err)
	}
	if !out.Already {
		t.Error("an image the registry already serves was not reported as already published")
	}
	if runtime.ran("docker push") {
		t.Errorf("it was pushed again: %v", runtime.commands)
	}
}

// **The digest is chosen by repository, not taken as element zero.** An image that has been pushed
// to more than one registry has more than one entry, and element zero is whichever the runtime
// listed first — which would pin this mesh's control plane to somebody else's registry, silently,
// which is the dependency the whole pivot exists to remove.
func TestTheDigestComesFromThisMeshsOwnRegistry(t *testing.T) {
	elsewhere := "some.other.registry/mesh-controller@sha256:" + strings.Repeat("c", 64)
	ours := "127.0.0.1:5000/mesh-controller@sha256:" + strings.Repeat("d", 64)

	o, d, _ := publishing(t,
		func(string) (int, string, error) {
			return http.StatusOK, `{"tags":["genesis"]}`, nil
		},
		func(_ string, args []string) (string, error) {
			if args[0] == "image" {
				return `["` + elsewhere + `","` + ours + `"]`, nil
			}
			return "", fmt.Errorf("unexpected: %v", args)
		})

	out, err := PublishControlPlane(context.Background(), o, d, held, func(string) {})
	if err != nil {
		t.Fatal(err)
	}
	if out.Reference != ours {
		t.Errorf("the control plane is pinned as %q, and this mesh's registry serves %q",
			out.Reference, ours)
	}
}

// A push that produced no digest this mesh's registry serves is refused, and the refusal says what
// depends on it. The next step names the control plane's module by that digest, so there would be
// nothing to name — and finding that out one step later would mean registering a module pinned to
// an empty string.
func TestAPushThatProducedNoDigestIsRefused(t *testing.T) {
	pushed := false
	o, d, _ := publishing(t,
		func(string) (int, string, error) {
			if !pushed {
				return http.StatusNotFound, "", nil
			}
			// Pushed, and the registry still does not list it.
			return http.StatusOK, `{"tags":[]}`, nil
		},
		func(_ string, args []string) (string, error) {
			if args[0] == "push" {
				pushed = true
			}
			return "", nil
		})

	_, err := PublishControlPlane(context.Background(), o, d, held, func(string) {})
	if err == nil {
		t.Fatal("a push that produced no digest was accepted")
	}
	if !strings.Contains(err.Error(), "does not serve it") {
		t.Errorf("the refusal does not say what is missing: %v", err)
	}
}

// A tag is not a pin. If the runtime answers with something that is not pinned by digest, it is
// not used — a tag can be made to point at a different image, and this reference is applied on
// machines with no mesh to ask about anything (novox/hq ADR 0006).
func TestATagIsNotAPin(t *testing.T) {
	o, d, _ := publishing(t,
		func(string) (int, string, error) {
			return http.StatusOK, `{"tags":["genesis"]}`, nil
		},
		func(_ string, args []string) (string, error) {
			if args[0] == "image" {
				return `["127.0.0.1:5000/mesh-controller:genesis"]`, nil
			}
			return "", nil
		})

	out, err := PublishControlPlane(context.Background(), o, d, held, func(string) {})
	if err == nil {
		t.Fatalf("a tag was accepted as a pin: %q", out.Reference)
	}
}

// A registry that cannot be reached at all is said so plainly rather than becoming a push that
// fails for a reason nobody can read.
func TestARegistryThatCannotBeAskedIsSaidSo(t *testing.T) {
	o, d, _ := publishing(t,
		func(string) (int, string, error) {
			return 0, "", errors.New("connection refused")
		},
		func(string, []string) (string, error) { return "", nil })

	_, err := PublishControlPlane(context.Background(), o, d, held, func(string) {})
	if err == nil {
		t.Fatal("a registry that refused the connection was treated as empty")
	}
	if !strings.Contains(err.Error(), "cannot ask the registry") {
		t.Errorf("the refusal does not say the registry could not be asked: %v", err)
	}
}