package greeter

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"os"
	"strings"
	"testing"

	"git.golem15.com/golem15/summercms/backpack"
	"git.golem15.com/golem15/summercms/bonfire"
	"git.golem15.com/golem15/summercms/compass"
	"git.golem15.com/golem15/summercms/pact"
)

type testOut struct{ bytes.Buffer }

func (o *testOut) Write(p []byte) (int, error) { return o.Buffer.Write(p) }
func (o *testOut) Println(a ...any)            { fmt.Fprintln(&o.Buffer, a...) }
func (o *testOut) Printf(format string, a ...any) {
	fmt.Fprintf(&o.Buffer, format, a...)
}

var _ bonfire.Output = (*testOut)(nil)
var _ io.Writer = (*testOut)(nil)

type extraMsg struct{ msg string }

func (e extraMsg) Message() string { return e.msg }

func TestBootSkipsAbsentOptionalPlugin(t *testing.T) {
	app := backpack.New(&compass.Config{})
	app.SetPlugins([]string{"golem15.hello", "golem15.greeter"})
	p := &Plugin{}
	if err := p.Boot(app); err != nil {
		t.Fatalf("Boot: %v", err)
	}
	out := runHelloCmd(t, p)
	if strings.Contains(out, "hello-from-optional") {
		t.Fatalf("absent optional leaked into output: %q", out)
	}
	if !strings.Contains(out, "extra=") {
		t.Fatalf("output %q should include extra=", out)
	}
}

func TestBootUsesPublishedOptionalService(t *testing.T) {
	app := backpack.New(&compass.Config{})
	app.SetPlugins([]string{"golem15.hello", "golem15.greeter", "golem15.optional"})
	if err := app.Publish[pact.OptionalMessage](extraMsg{msg: "hello-from-optional"}); err != nil {
		t.Fatalf("Publish: %v", err)
	}
	p := &Plugin{}
	if err := p.Boot(app); err != nil {
		t.Fatalf("Boot: %v", err)
	}
	out := runHelloCmd(t, p)
	if !strings.Contains(out, "extra=hello-from-optional") {
		t.Fatalf("output = %q, want extra=hello-from-optional", out)
	}
}

func TestGreeterSourceDoesNotImportOptional(t *testing.T) {
	body, err := os.ReadFile("plugin.go")
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(body), "plugins/optional") {
		t.Fatal("greeter must not import the optional plugin module")
	}
}

func runHelloCmd(t *testing.T, p *Plugin) string {
	t.Helper()
	cmds := p.Commands()
	if len(cmds) == 0 {
		t.Fatal("no commands")
	}
	var out testOut
	if err := cmds[0].Run(context.Background(), nil, &out); err != nil {
		t.Fatalf("Run: %v", err)
	}
	return strings.TrimSpace(out.String())
}