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

package apply

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

	"krino/internal/plan"
	"krino/internal/scan"
)

// planned writes body to root/rel and returns the chain a plan would build
// for it, identity included, with steps.
func planned(t *testing.T, root, rel, body string, steps ...plan.Step) plan.Chain {
	t.Helper()
	p := filepath.Join(root, rel)
	if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
		t.Fatal(err)
	}
	info, err := os.Lstat(p)
	if err != nil {
		t.Fatal(err)
	}
	return plan.Chain{File: scan.NewFile(p, rel, info), Steps: steps}
}

// TestChainRefusesSourceSwappedForSymlink: a file replaced by a symlink
// between plan and apply - even to a file of the same size and modification
// time - is not acted on, so a copy never reads through the link.
func TestChainRefusesSourceSwappedForSymlink(t *testing.T) {
	root := t.TempDir()
	p := filepath.Join(root, "a.txt")
	out := filepath.Join(root, "Out", "a.txt")
	c := planned(t, root, "a.txt", "12345", plan.Step{Kind: plan.Copy, Src: p, Dst: out})
	target := filepath.Join(root, "secret.txt")
	if err := os.WriteFile(target, []byte("54321"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.Chtimes(target, c.File.ModTime, c.File.ModTime); err != nil {
		t.Fatal(err)
	}
	if err := os.Remove(p); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink(target, p); err != nil {
		t.Fatal(err)
	}
	res := Chain(c)
	if res[0].Status != "failed" || !strings.HasPrefix(res[0].Detail, "changed since plan") {
		t.Fatalf("step = %s %q, want failed: changed since plan", res[0].Status, res[0].Detail)
	}
	if _, err := os.Lstat(out); !os.IsNotExist(err) {
		t.Errorf("the copy was made through the symlink: %v", err)
	}
}

// TestChainRefusesSourceReplacedByAnotherFile: another file renamed into
// the planned path, with the same size and modification time, has another
// inode: it is not the file that was planned.
func TestChainRefusesSourceReplacedByAnotherFile(t *testing.T) {
	root := t.TempDir()
	p := filepath.Join(root, "a.txt")
	c := planned(t, root, "a.txt", "12345", plan.Step{Kind: plan.Move, Src: p, Dst: filepath.Join(root, "Out", "a.txt")})
	other := filepath.Join(root, "other.txt")
	if err := os.WriteFile(other, []byte("54321"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.Chtimes(other, c.File.ModTime, c.File.ModTime); err != nil {
		t.Fatal(err)
	}
	if err := os.Rename(other, p); err != nil {
		t.Fatal(err)
	}
	res := Chain(c)
	if res[0].Status != "failed" || !strings.HasPrefix(res[0].Detail, "changed since plan") {
		t.Fatalf("step = %s %q, want failed: changed since plan", res[0].Status, res[0].Detail)
	}
	if b, err := os.ReadFile(p); err != nil || string(b) != "54321" {
		t.Errorf("the replacement was moved: %q, %v", b, err)
	}
}

// TestChainFollowsItsOwnFile: the file's identity check does not stop a
// chain that renames and then moves the planned file itself.
func TestChainFollowsItsOwnFile(t *testing.T) {
	root := t.TempDir()
	p := filepath.Join(root, "a.txt")
	b := filepath.Join(root, "b.txt")
	c := planned(t, root, "a.txt", "12345",
		plan.Step{Kind: plan.Rename, Src: p, Dst: b},
		plan.Step{Kind: plan.Move, Src: b, Dst: filepath.Join(root, "Out", "b.txt")},
	)
	for i, r := range Chain(c) {
		if r.Status != "ok" {
			t.Errorf("step %d: %s %q", i+1, r.Status, r.Detail)
		}
	}
}