package tools

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func readIn(t *testing.T, input string, files map[string]string) (string, error) {
	t.Helper()
	dir := t.TempDir()
	for name, content := range files {
		p := filepath.Join(dir, name)
		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(p, []byte(content), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	reg := NewRegistry()
	for _, tl := range BuiltinIn(dir, NewFence(), nil) {
		if err := reg.Register(tl); err != nil {
			t.Fatal(err)
		}
	}
	r, _ := reg.Get("read")
	res, err := r.Run(context.Background(), input)
	return res.Text, err
}

// TestReadSmallFileUnchanged：不分页的小文件保持原样，不加头尾。
func TestReadSmallFileUnchanged(t *testing.T) {
	got, err := readIn(t, `{"path":"f.txt"}`, map[string]string{"f.txt": "a\nb\nc\n"})
	if err != nil {
		t.Fatal(err)
	}
	if got != "a\nb\nc\n" {
		t.Fatalf("got %q", got)
	}
}

func TestReadOffsetLimit(t *testing.T) {
	got, err := readIn(t, `{"path":"f.txt","offset":2,"limit":2}`,
		map[string]string{"f.txt": "l1\nl2\nl3\nl4\nl5\n"})
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(got, "lines 2-3 of 5") || !strings.Contains(got, "l2\nl3") {
		t.Fatalf("got %q", got)
	}
	if !strings.Contains(got, "continue with offset: 4") {
		t.Fatalf("missing continuation: %q", got)
	}
	if strings.Contains(got, "l1") || strings.Contains(got, "l4") {
		t.Fatalf("paging leaked other lines: %q", got)
	}
}

func TestReadBeyondEOF(t *testing.T) {
	got, err := readIn(t, `{"path":"f.txt","offset":99}`, map[string]string{"f.txt": "a\nb\n"})
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(got, "beyond EOF") {
		t.Fatalf("got %q", got)
	}
}

func TestReadDirectoryListing(t *testing.T) {
	got, err := readIn(t, `{"path":".","offset":2,"limit":1}`, map[string]string{
		"a.txt":    "x",
		"sub/b.go": "y",
	})
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(got, "entries 2-2 of 2") || !strings.Contains(got, "sub/") {
		t.Fatalf("got %q", got)
	}
	if strings.Contains(got, "a.txt") {
		t.Fatalf("paging leaked other entries: %q", got)
	}
}

func TestReadRejectsBinary(t *testing.T) {
	dir := t.TempDir()
	p := filepath.Join(dir, "bin")
	if err := os.WriteFile(p, []byte{'a', 0, 'b'}, 0o644); err != nil {
		t.Fatal(err)
	}
	reg := NewRegistry()
	for _, tl := range BuiltinIn(dir, NewFence(), nil) {
		if err := reg.Register(tl); err != nil {
			t.Fatal(err)
		}
	}
	r, _ := reg.Get("read")
	if _, err := r.Run(context.Background(), `{"path":"bin"}`); err == nil ||
		!strings.Contains(err.Error(), "binary") {
		t.Fatalf("want binary error, got %v", err)
	}
}