package sidecar

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"testing"
)

func TestAppendCreatesPrivateUnrelatedSidecar(t *testing.T) {
	repo := testRepo(t)
	// Store must be independent of a user's restrictive auto-track setting.
	testJJ(t, repo, "config", "set", "--repo", "snapshot.auto-track", `"none()"`)
	testJJ(t, repo, "config", "set", "--repo", "git.private-commits", `"description(glob:'secret:*')"`)
	before := testJJ(t, repo, "status")
	store, err := Open(repo)
	if err != nil {
		t.Fatal(err)
	}

	if err := store.Append(func(current []byte) ([]byte, error) {
		if len(current) != 0 {
			t.Fatalf("new store contained %q", current)
		}
		return []byte("one\n"), nil
	}); err != nil {
		t.Fatal(err)
	}
	if err := store.Append(func(current []byte) ([]byte, error) {
		if string(current) != "one\n" {
			t.Fatalf("second append saw %q", current)
		}
		return []byte("two\n"), nil
	}); err != nil {
		t.Fatal(err)
	}

	got, err := store.Read()
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != "one\ntwo\n" {
		t.Fatalf("sidecar log = %q", got)
	}
	if after := testJJ(t, repo, "status"); after != before {
		t.Fatalf("working copy changed:\n--- before\n%s--- after\n%s", before, after)
	}
	if _, err := os.Stat(filepath.Join(repo, LogFile)); !os.IsNotExist(err) {
		t.Fatalf("log materialized in the project working copy: %v", err)
	}

	alias := strings.TrimSpace(testJJ(t, repo, "config", "get", "revset-aliases."+Alias))
	if alias == "" {
		t.Fatal("repo-local sidecar alias was not configured")
	}
	private := testJJ(t, repo, "config", "get", "git.private-commits")
	if !containsRevsetName(private, Alias) {
		t.Fatalf("private commits = %q, missing %s", private, Alias)
	}
	if !strings.Contains(private, "secret:*") {
		t.Fatalf("private commits = %q, previous setting was overwritten", private)
	}
	parent := strings.TrimSpace(testJJ(t, repo, "log", "-G", "-r", "exactly("+Alias+", 1)",
		"-T", "parents.map(|p| p.commit_id()).join(\"\")"))
	if parent != strings.Repeat("0", 40) {
		t.Fatalf("sidecar parent = %q, want virtual root", parent)
	}
}

func TestLegacyLogIsReadThenImportedOnFirstAppend(t *testing.T) {
	repo := testRepo(t)
	legacy := []byte("legacy\n")
	if err := os.WriteFile(filepath.Join(repo, LogFile), legacy, 0o644); err != nil {
		t.Fatal(err)
	}
	store, err := Open(repo)
	if err != nil {
		t.Fatal(err)
	}
	if got, err := store.Read(); err != nil || string(got) != string(legacy) {
		t.Fatalf("pre-migration read = %q, %v", got, err)
	}
	if err := store.Append(func(current []byte) ([]byte, error) {
		if string(current) != string(legacy) {
			t.Fatalf("migration callback saw %q", current)
		}
		return []byte("sidecar\n"), nil
	}); err != nil {
		t.Fatal(err)
	}
	if got, err := store.Read(); err != nil || string(got) != "legacy\nsidecar\n" {
		t.Fatalf("migrated log = %q, %v", got, err)
	}
}

func TestConcurrentAppendsAreSerialized(t *testing.T) {
	repo := testRepo(t)
	store, err := Open(repo)
	if err != nil {
		t.Fatal(err)
	}
	const writers = 6
	errCh := make(chan error, writers)
	var wg sync.WaitGroup
	for range writers {
		wg.Add(1)
		go func() {
			defer wg.Done()
			errCh <- store.Append(func(current []byte) ([]byte, error) {
				id := len(strings.Fields(string(current))) + 1
				return []byte(fmt.Sprintf("%d\n", id)), nil
			})
		}()
	}
	wg.Wait()
	close(errCh)
	for err := range errCh {
		if err != nil {
			t.Fatal(err)
		}
	}
	got, err := store.Read()
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != "1\n2\n3\n4\n5\n6\n" {
		t.Fatalf("serialized appends = %q", got)
	}
}

func testRepo(t *testing.T) string {
	t.Helper()
	if _, err := exec.LookPath("jj"); err != nil {
		t.Skip("jj not installed")
	}
	home := t.TempDir()
	t.Setenv("HOME", home)
	t.Setenv("JJ_USER", "test")
	t.Setenv("JJ_EMAIL", "test@example.com")
	repo := filepath.Join(home, "repo")
	if err := os.Mkdir(repo, 0o755); err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command("jj", "git", "init")
	cmd.Dir = repo
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("jj git init: %v\n%s", err, out)
	}
	return repo
}

func testJJ(t *testing.T, repo string, args ...string) string {
	t.Helper()
	cmd := exec.Command("jj", append([]string{"--ignore-working-copy", "--no-pager"}, args...)...)
	cmd.Dir = repo
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("jj %s: %v\n%s", strings.Join(args, " "), err, out)
	}
	return string(out)
}