package wasmguest

// End-to-end proof that the guest capability stubs (package caps, wired into
// CoreServices by WO-WZ-003) marshal to the ABI, cross into a host over the
// generic host_call import, and return decoded values the plugin's unchanged
// service code consumes — all inside a real wazero-compiled wasm module.
//
// The host_call handler below is a throwaway fake capability table (like the
// WO-WZ-002 throwaway host), not the cms host. It answers exactly the three
// families the fixture's Load hook exercises.

import (
	"context"
	"testing"

	abiv1 "git.dev.alexdunmow.com/block/pluginsdk/abi/v1"
	"github.com/tetratelabs/wazero"
	"github.com/tetratelabs/wazero/api"
	"google.golang.org/protobuf/proto"
)

// installBlockninjaHost instantiates the "blockninja" import module exporting
// host_call, mirroring the guest calling convention in reverse (read a
// HostCallRequest from guest memory, answer it, write a HostCallResponse back
// via the guest's bn_alloc, return the packed pointer).
func installBlockninjaHost(t *testing.T, ctx context.Context, r wazero.Runtime) {
	t.Helper()
	_, err := r.NewHostModuleBuilder("blockninja").
		NewFunctionBuilder().
		WithFunc(func(ctx context.Context, mod api.Module, ptr, size uint32) uint64 {
			data, ok := mod.Memory().Read(ptr, size)
			if !ok {
				return 0
			}
			req := &abiv1.HostCallRequest{}
			if err := proto.Unmarshal(data, req); err != nil {
				return 0
			}
			out, err := proto.Marshal(fakeCapability(req.GetMethod(), req.GetPayload()))
			if err != nil {
				return 0
			}
			// Allocate the response in guest memory (bn_alloc may grow memory,
			// so req is already decoded — data is no longer referenced).
			res, err := mod.ExportedFunction("bn_alloc").Call(ctx, uint64(len(out)))
			if err != nil || len(res) == 0 || res[0] == 0 {
				return 0
			}
			respPtr := uint32(res[0])
			if !mod.Memory().Write(respPtr, out) {
				return 0
			}
			return uint64(respPtr)<<32 | uint64(uint32(len(out)))
		}).
		Export("host_call").
		Instantiate(ctx)
	if err != nil {
		t.Fatalf("instantiate blockninja host module: %v", err)
	}
}

// fakeCapability answers the three capability methods the fixture Load hook
// calls; everything else is UNIMPLEMENTED.
func fakeCapability(method string, payload []byte) *abiv1.HostCallResponse {
	pack := func(m proto.Message) *abiv1.HostCallResponse {
		b, err := proto.Marshal(m)
		if err != nil {
			return &abiv1.HostCallResponse{Error: &abiv1.AbiError{
				Code: abiv1.AbiErrorCode_ABI_ERROR_CODE_INTERNAL, Message: err.Error(),
			}}
		}
		return &abiv1.HostCallResponse{Payload: b}
	}
	switch method {
	case "content.get_page":
		return pack(&abiv1.ContentGetPageResponse{Page: &abiv1.PageInfo{Slug: "about", Title: "About Us"}})
	case "settings.get_site_settings":
		return pack(&abiv1.SettingsGetSiteSettingsResponse{SettingsJson: []byte(`{"site_name":"Fixture Site"}`)})
	case "bridge.get_service":
		return pack(&abiv1.BridgeGetServiceResponse{Available: false})
	default:
		return &abiv1.HostCallResponse{Error: &abiv1.AbiError{
			Code: abiv1.AbiErrorCode_ABI_ERROR_CODE_UNIMPLEMENTED, Message: "no fake for " + method,
		}}
	}
}

// TestWasmFixtureCapabilityRoundTrip drives HOOK_LOAD (which calls the
// capability stubs) then renders the report block that surfaces the results,
// proving deps.Content / deps.Settings / deps.Bridge cross the ABI end-to-end.
func TestWasmFixtureCapabilityRoundTrip(t *testing.T) {
	if testing.Short() {
		t.Skip("compiles a wasm module; skipped in -short")
	}
	w := instantiateFixture(t)

	resp := w.invoke(t, abiv1.Hook_HOOK_LOAD, &abiv1.LoadRequest{})
	if resp.GetError() != nil {
		t.Fatalf("LOAD error: %v", resp.GetError())
	}

	resp = w.invoke(t, abiv1.Hook_HOOK_RENDER_BLOCK, &abiv1.RenderBlockRequest{
		BlockKey:    "wasmfixture:greeting",
		ContentJson: []byte(`{"report":true}`),
	})
	if resp.GetError() != nil {
		t.Fatalf("RENDER_BLOCK error: %v", resp.GetError())
	}
	rb := &abiv1.RenderBlockResponse{}
	if err := proto.Unmarshal(resp.GetPayload(), rb); err != nil {
		t.Fatalf("unmarshal RenderBlockResponse: %v", err)
	}
	const want = "<p>capreport:page=About Us site=Fixture Site bridge_nil=true</p>"
	if rb.GetHtml() != want {
		t.Errorf("capability report html = %q, want %q", rb.GetHtml(), want)
	}
	t.Logf("capability round trip through wasm: %s", rb.GetHtml())
}