package toolsrv_test

import (
	"context"
	"encoding/json"
	"testing"

	"ollie/toolsrv"
)

// stubRunner is a minimal Runner used to verify the contract.
type stubRunner struct {
	name  string
	tools []toolsrv.ToolInfo
}

func (s *stubRunner) ListTools() ([]toolsrv.ToolInfo, error) { return s.tools, nil }
func (s *stubRunner) CallTool(_ context.Context, tool string, _ json.RawMessage) (json.RawMessage, error) {
	return json.RawMessage(`{"tool":"` + tool + `"}`), nil
}

func newStub(name string, toolNames ...string) *stubRunner {
	var ti []toolsrv.ToolInfo
	for _, n := range toolNames {
		ti = append(ti, toolsrv.ToolInfo{Name: n, Description: n + " desc"})
	}
	return &stubRunner{name: name, tools: ti}
}

// checkRunnerContract verifies Runner invariants.
func checkRunnerContract(t *testing.T, r toolsrv.Runner) {
	t.Helper()
	tl, err := r.ListTools()
	if err != nil {
		t.Fatalf("ListTools: %v", err)
	}
	if tl == nil {
		t.Fatal("ListTools returned nil")
	}
	for _, ti := range tl {
		res, err := r.CallTool(context.Background(), ti.Name, json.RawMessage(`{}`))
		if err != nil {
			t.Errorf("CallTool(%q): %v", ti.Name, err)
		}
		if len(res) == 0 {
			t.Errorf("CallTool(%q) returned empty result", ti.Name)
		}
	}
}

func TestStubRunnerContract(t *testing.T) {
	checkRunnerContract(t, newStub("s", "a", "b"))
}