package session

import (
	"fmt"
	"testing"

	"github.com/firebase/genkit/go/ai"
)

// The command is recognised as typed at a prompt: surrounding whitespace and
// the trailing newline an editor keeps must not hide it, and anything after
// the word is a question, not the command.
func TestIsNewCommandTrimsButDoesNotGuess(t *testing.T) {
	cases := map[string]bool{
		"/new":         true,
		"  /new  ":     true,
		"/new\n":       true,
		"/new please":  false,
		"/News":        false,
		"new":          false,
		"":             false,
		"/compact":     false,
		"/new\tthings": false,
	}
	for in, want := range cases {
		if got := IsNewCommand(in); got != want {
			t.Errorf("IsNewCommand(%q) = %v, want %v", in, got, want)
		}
	}
}

// A fresh session is the system prompt alone, with the text given.
func TestFreshIsTheSystemPromptAlone(t *testing.T) {
	msgs := Fresh("you are bob")
	if len(msgs) != 1 {
		t.Fatalf("Fresh: %d message(s), want 1", len(msgs))
	}
	if msgs[0].Role != ai.RoleSystem {
		t.Errorf("Fresh: role %q, want %q", msgs[0].Role, ai.RoleSystem)
	}
	if got := msgs[0].Text(); got != "you are bob" {
		t.Errorf("Fresh: text %q, want %q", got, "you are bob")
	}
}

// Two fresh sessions must not share their backing array: appending to one
// would otherwise leak into the other (one process, several ACP sessions).
func TestFreshReturnsIndependentSlices(t *testing.T) {
	a := Fresh("s")
	b := Fresh("s")
	a = append(a, ai.NewUserTextMessage("hello"))
	if len(a) != 2 {
		t.Fatalf("appending to a fresh session: %d message(s), want 2", len(a))
	}
	if len(b) != 1 {
		t.Errorf("appending to one fresh session changed another: %d message(s)", len(b))
	}
}

// Forgotten counts what a reset drops: every message but the system prompt,
// tool turns included. A fresh session forgets nothing.
func TestForgottenCountsEverythingButTheSystemPrompt(t *testing.T) {
	if got := Forgotten(Fresh("s")); got != 0 {
		t.Errorf("Forgotten(fresh) = %d, want 0", got)
	}
	if got := Forgotten(nil); got != 0 {
		t.Errorf("Forgotten(nil) = %d, want 0", got)
	}
	msgs := append(Fresh("s"),
		ai.NewUserTextMessage("ls"),
		ai.NewModelMessage(ai.NewToolRequestPart(&ai.ToolRequest{Name: "bash", Input: map[string]any{"command": "ls"}})),
		ai.NewMessage(ai.RoleTool, nil, ai.NewToolResponsePart(&ai.ToolResponse{Name: "bash", Output: "main.go"})),
		ai.NewModelTextMessage("There is one file."),
	)
	if got := Forgotten(msgs); got != 4 {
		t.Errorf("Forgotten = %d, want 4", got)
	}
}

func ExampleIsNewCommand() {
	fmt.Println(IsNewCommand("/new"), IsNewCommand("/new please"))
	// Output: true false
}

func ExampleFresh() {
	msgs := Fresh("You are a coding agent.")
	fmt.Println(len(msgs), msgs[0].Role, Forgotten(msgs))
	// Output: 1 system 0
}