// SPDX-License-Identifier: GPL-3.0-or-later

package model

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

// TestPreviewKinds: a text file comes back as text, a picture as a picture,
// and something krino cannot show says so instead of guessing.
func TestPreviewKinds(t *testing.T) {
	dir := t.TempDir()
	write := func(name string, body []byte) string {
		p := filepath.Join(dir, name)
		if err := os.WriteFile(p, body, 0o644); err != nil {
			t.Fatal(err)
		}
		return p
	}
	text := write("notes.txt", []byte("first line\nsecond line\n"))
	png := write("a.png", []byte("\x89PNG\r\n\x1a\nnot really, but the name is what counts here"))
	binary := write("a.bin", []byte{0, 1, 2, 3, 0})
	tmp := t.TempDir()

	if p := MakePreview(context.Background(), text, tmp); p.Kind != PreviewText ||
		!strings.Contains(p.Text, "second line") {
		t.Errorf("text preview = %+v", p)
	}
	if p := MakePreview(context.Background(), png, tmp); p.Kind != PreviewImage || p.Image != png {
		t.Errorf("image preview = %+v", p)
	}
	if p := MakePreview(context.Background(), binary, tmp); p.Kind != PreviewNone ||
		!strings.Contains(p.Note, "no preview") {
		t.Errorf("binary preview = %+v", p)
	}
	if p := MakePreview(context.Background(), filepath.Join(dir, "gone.txt"), tmp); p.Kind != PreviewNone {
		t.Errorf("a missing file = %+v", p)
	}
	if p := MakePreview(context.Background(), dir, tmp); p.Kind != PreviewNone {
		t.Errorf("a directory = %+v", p)
	}
}

// TestPreviewReadsOnly: looking at a file changes nothing about it, and
// nothing is left beside it.
func TestPreviewReadsOnly(t *testing.T) {
	dir := t.TempDir()
	p := filepath.Join(dir, "notes.txt")
	body := []byte("one\ntwo\n")
	if err := os.WriteFile(p, body, 0o644); err != nil {
		t.Fatal(err)
	}
	before, err := os.Stat(p)
	if err != nil {
		t.Fatal(err)
	}
	MakePreview(context.Background(), p, t.TempDir())
	after, err := os.Stat(p)
	if err != nil {
		t.Fatal(err)
	}
	if !before.ModTime().Equal(after.ModTime()) || before.Size() != after.Size() {
		t.Error("the file changed")
	}
	if entries, _ := os.ReadDir(dir); len(entries) != 1 {
		t.Errorf("the directory holds %d files, want the one", len(entries))
	}
	if on, _ := os.ReadFile(p); string(on) != string(body) {
		t.Error("the contents changed")
	}
}

// TestPreviewShowsOnlyTheHead: a long file is cut, and says it was.
func TestPreviewShowsOnlyTheHead(t *testing.T) {
	dir := t.TempDir()
	p := filepath.Join(dir, "long.txt")
	var b strings.Builder
	for i := 0; i < previewLines*2; i++ {
		b.WriteString("line\n")
	}
	if err := os.WriteFile(p, []byte(b.String()), 0o644); err != nil {
		t.Fatal(err)
	}
	pv := MakePreview(context.Background(), p, t.TempDir())
	if pv.Kind != PreviewText {
		t.Fatalf("preview = %+v", pv)
	}
	if n := strings.Count(pv.Text, "\n"); n > previewLines+1 {
		t.Errorf("%d lines shown, want at most %d", n, previewLines)
	}
	if !strings.HasSuffix(pv.Text, "...") {
		t.Error("a cut file does not say it was cut")
	}
}