//go:build integration
// +build integration

package main

import (
	"bytes"
	_ "embed"
	"fmt"
	"os"
	"os/exec"
	"strings"
	"testing"

	"github.com/alecthomas/assert/v2"
)

//go:embed testdata/package.nix
var packageNix []byte

//go:embed testdata/configuration.nix
var configurationNix []byte

func TestDiffNixPackage(t *testing.T) {
	tempDir := t.TempDir()
	os.WriteFile(tempDir+"/default.nix", packageNix, 0644)
	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.3")
	copySymlink(tempDir+"/result", tempDir+"/old-result")
	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.4")

	var sb strings.Builder
	innerMain(&sb, tempDir+"/old-result", tempDir+"/result")
	assert.Equal(t, sb.String(), strings.TrimLeft(`
Version changed:
  test-dependency: 1.2.3 -> 1.2.4

  test-indirect-dependency: 1.2.3 -> 1.2.4
`, "\n"))
}

func TestDiffNixPackageDrv(t *testing.T) {
	tempDir := t.TempDir()
	os.WriteFile(tempDir+"/default.nix", packageNix, 0644)
	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.3")
	copySymlink(tempDir+"/result", tempDir+"/old-result")
	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.4")

	out, _ := runIn(tempDir, "nix-store", "--query", "--deriver", "old-result", "result")
	lines := strings.Split(out, "\n")

	var sb strings.Builder
	innerMain(&sb, lines[0], lines[1])
	assert.Equal(t, sb.String(), strings.TrimLeft(`
Version changed:
  test-dependency: 1.2.3 -> 1.2.4

  test-indirect-dependency: 1.2.3 -> 1.2.4
`, "\n"))
}

func TestDiffNixSystem(t *testing.T) {
	tempDir := t.TempDir()
	os.WriteFile(tempDir+"/package.nix", packageNix, 0644)
	os.WriteFile(tempDir+"/configuration.nix", configurationNix, 0644)
	os.WriteFile(tempDir+"/version.nix", []byte("\"1.2.3\""), 0644)
	runIn(tempDir, "nixos-rebuild", "build", "-I", "nixos-config=configuration.nix", "-I", "pkg-version=./version.nix")
	err := copySymlink(tempDir+"/result", tempDir+"/old-result")
	assert.NoError(t, err)
	os.WriteFile(tempDir+"/version.nix", []byte("\"1.2.4\""), 0644)
	runIn(tempDir, "nixos-rebuild", "build", "-I", "nixos-config=configuration.nix", "-I", "pkg-version=./version.nix")

	var sb strings.Builder
	innerMain(&sb, tempDir+"/old-result", tempDir+"/result")
	assert.Equal(t, sb.String(), strings.TrimLeft(`
Version changed:
  test-package: 1.2.3 -> 1.2.4
  user-package: 1.2.3 -> 1.2.4

  test-dependency: 1.2.3 -> 1.2.4
  test-indirect-dependency: 1.2.3 -> 1.2.4
`, "\n"))
}

func runIn(dir string, name string, args ...string) (string, error) {
	cmd := exec.Command(name, args...)
	cmd.Dir = dir
	var stderr bytes.Buffer
	cmd.Stderr = &stderr
	out, err := cmd.Output()
	if err != nil {
		return "", fmt.Errorf("%s failed: %v: %s", name, err, stderr.String())
	}
	return string(out), nil
}

func copySymlink(src, dst string) error {
	target, err := os.Readlink(src)
	if err != nil {
		return err
	}

	return os.Symlink(target, dst)
}