package agents

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

	"codex-agent-manager/internal/codexhome"
)

func TestValidateInvalidTOMLReturnsInvalidAndDoesNotWrite(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")

	got, err := store.ValidateDraft("backend", `name = "未闭合`+"\n")
	if err != nil {
		t.Fatalf("ValidateDraft returned error: %v", err)
	}
	if got.Valid {
		t.Fatalf("validation should be invalid: %#v", got)
	}
	if len(got.Errors) == 0 {
		t.Fatalf("expected validation errors: %#v", got)
	}
	assertChineseTOMLError(t, got.Errors[0])
	assertFileContent(t, target, `name = "旧名称"`+"\n")
}

func TestValidateValidTOMLReturnsDiffAndCurrentHash(t *testing.T) {
	store, _ := writebackFixture(t, `name = "旧名称"`+"\ndescription = \"旧描述\"\n")

	got, err := store.ValidateDraft("backend", `name = "新名称"`+"\ndescription = \"旧描述\"\n")
	if err != nil {
		t.Fatalf("ValidateDraft returned error: %v", err)
	}
	if !got.Valid {
		t.Fatalf("validation should be valid: %#v", got)
	}
	if got.CurrentHash == "" {
		t.Fatalf("current hash must be returned: %#v", got)
	}
	if !strings.Contains(got.Diff, `-name = "旧名称"`) || !strings.Contains(got.Diff, `+name = "新名称"`) {
		t.Fatalf("diff does not show changed line: %q", got.Diff)
	}
	if len(got.FieldChanges) != 1 || got.FieldChanges[0].Field != "name" {
		t.Fatalf("unexpected field changes: %#v", got.FieldChanges)
	}
}

func TestWriteInvalidTOMLRejectsAndLeavesOriginal(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}

	_, err = store.WriteDraft("backend", `name = "未闭合`+"\n", validation.CurrentHash)
	if err == nil {
		t.Fatal("expected invalid TOML write to be rejected")
	}
	assertChineseTOMLError(t, err.Error())
	assertFileContent(t, target, `name = "旧名称"`+"\n")
}

func TestWriteExpectedHashMismatchRejectsAndLeavesOriginal(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(target, []byte(`name = "用户已改"`+"\n"), 0o644); err != nil {
		t.Fatal(err)
	}

	_, err = store.WriteDraft("backend", `name = "新名称"`+"\n", validation.CurrentHash)
	if !errors.Is(err, ErrWriteConflict) {
		t.Fatalf("expected conflict error, got %v", err)
	}
	assertFileContent(t, target, `name = "用户已改"`+"\n")
}

func TestWriteRejectsAgentsDirectoryReplacementBeforeBackup(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}
	root := filepath.Dir(filepath.Dir(target))
	agentsDir := filepath.Join(root, "agents")
	realAgentsDir := filepath.Join(root, "agents-real")
	externalDir := filepath.Join(root, "external")
	if err := os.MkdirAll(externalDir, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(externalDir, "backend.toml"), []byte(`name = "外部"`+"\n"), 0o644); err != nil {
		t.Fatal(err)
	}

	writebackTestHookBeforeBackup = func() {
		if err := os.Rename(agentsDir, realAgentsDir); err != nil {
			t.Fatal(err)
		}
		if err := os.Symlink(externalDir, agentsDir); err != nil {
			t.Fatal(err)
		}
	}
	defer func() { writebackTestHookBeforeBackup = nil }()

	_, err = store.WriteDraft("backend", `name = "新名称"`+"\n", validation.CurrentHash)
	if !errors.Is(err, ErrWriteConflict) && !errors.Is(err, codexhome.ErrForbiddenPath) {
		t.Fatalf("expected directory replacement to be rejected, got %v", err)
	}
	assertFileContent(t, filepath.Join(realAgentsDir, "backend.toml"), `name = "旧名称"`+"\n")
	assertFileContent(t, filepath.Join(externalDir, "backend.toml"), `name = "外部"`+"\n")
}

func TestWriteBindsBackupToAgentsDirectoryAfterFinalVerify(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}
	root := filepath.Dir(filepath.Dir(target))
	agentsDir := filepath.Join(root, "agents")
	realAgentsDir := filepath.Join(root, "agents-real")
	externalDir := filepath.Join(root, "external")
	if err := os.MkdirAll(externalDir, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(externalDir, "backend.toml"), []byte(`name = "外部"`+"\n"), 0o644); err != nil {
		t.Fatal(err)
	}

	writebackTestHookAfterVerifyBeforeBackup = func() {
		if err := os.Rename(agentsDir, realAgentsDir); err != nil {
			t.Fatal(err)
		}
		if err := os.Symlink(externalDir, agentsDir); err != nil {
			t.Fatal(err)
		}
	}
	defer func() { writebackTestHookAfterVerifyBeforeBackup = nil }()

	_, err = store.WriteDraft("backend", `name = "新名称"`+"\n", validation.CurrentHash)
	if !errors.Is(err, ErrWriteConflict) && !errors.Is(err, codexhome.ErrForbiddenPath) {
		t.Fatalf("expected post-verify directory replacement to be rejected, got %v", err)
	}
	assertFileContent(t, filepath.Join(realAgentsDir, "backend.toml"), `name = "旧名称"`+"\n")
	assertFileContent(t, filepath.Join(externalDir, "backend.toml"), `name = "外部"`+"\n")
	if backups, err := filepath.Glob(filepath.Join(externalDir, "*.bak-*")); err != nil {
		t.Fatal(err)
	} else if len(backups) != 0 {
		t.Fatalf("backup was created through replaced symlink directory: %#v", backups)
	}
}

func TestWriteRejectsTargetChangeAfterBackup(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}

	writebackTestHookAfterBackup = func() {
		if err := os.WriteFile(target, []byte(`name = "用户已改"`+"\n"), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	defer func() { writebackTestHookAfterBackup = nil }()

	_, err = store.WriteDraft("backend", `name = "新名称"`+"\n", validation.CurrentHash)
	if !errors.Is(err, ErrWriteConflict) {
		t.Fatalf("expected post-backup target change to be rejected, got %v", err)
	}
	assertFileContent(t, target, `name = "用户已改"`+"\n")
}

func TestWriteSuccessCreatesBackupAndAtomicallyWrites(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}

	got, err := store.WriteDraft("backend", `name = "新名称"`+"\n", validation.CurrentHash)
	if err != nil {
		t.Fatalf("WriteDraft returned error: %v", err)
	}
	if got.Status != "written" || got.TargetPath != target || got.BackupPath == "" {
		t.Fatalf("unexpected write result: %#v", got)
	}
	assertFileContent(t, target, `name = "新名称"`+"\n")
	assertFileContent(t, got.BackupPath, `name = "旧名称"`+"\n")
}

func TestWriteRejectsUnsafeIDAndSymlinks(t *testing.T) {
	store, target := writebackFixture(t, `name = "旧名称"`+"\n")
	validation, err := store.ValidateDraft("backend", `name = "新名称"`+"\n")
	if err != nil {
		t.Fatal(err)
	}

	for _, id := range []string{"../backend", "nested/backend", "/tmp/backend", "backend.toml"} {
		t.Run("unsafe id "+id, func(t *testing.T) {
			if _, err := store.ValidateDraft(id, `name = "x"`+"\n"); err == nil {
				t.Fatal("expected unsafe validate id to be rejected")
			}
			if _, err := store.WriteDraft(id, `name = "x"`+"\n", validation.CurrentHash); err == nil {
				t.Fatal("expected unsafe write id to be rejected")
			}
		})
	}

	if err := os.Remove(target); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink("../config.toml", target); err != nil {
		t.Fatal(err)
	}
	if _, err := store.WriteDraft("backend", `name = "新名称"`+"\n", validation.CurrentHash); err == nil {
		t.Fatal("expected symlink leaf to be rejected")
	}

	root := t.TempDir()
	if err := os.WriteFile(filepath.Join(root, "config.toml"), []byte(`name = "secret"`), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink(".", filepath.Join(root, "agents")); err != nil {
		t.Fatal(err)
	}
	symlinkedStore := Store{CodexHome: root}
	if _, err := symlinkedStore.WriteDraft("backend", `name = "x"`+"\n", validation.CurrentHash); err == nil {
		t.Fatal("expected symlinked agents directory to be rejected")
	}
}

func writebackFixture(t *testing.T, content string) (Store, string) {
	t.Helper()
	root := t.TempDir()
	agentsDir := filepath.Join(root, "agents")
	if err := os.MkdirAll(agentsDir, 0o755); err != nil {
		t.Fatal(err)
	}
	target := filepath.Join(agentsDir, "backend.toml")
	if err := os.WriteFile(target, []byte(content), 0o644); err != nil {
		t.Fatal(err)
	}
	return Store{CodexHome: root}, target
}

func assertFileContent(t *testing.T, path string, want string) {
	t.Helper()
	got, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != want {
		t.Fatalf("%s content = %q, want %q", path, string(got), want)
	}
}

func assertChineseTOMLError(t *testing.T, message string) {
	t.Helper()
	if strings.Contains(message, "invalid syntax") {
		t.Fatalf("TOML error leaked English parser text: %q", message)
	}
	if !strings.Contains(message, "字符串字段语法无效") {
		t.Fatalf("TOML error = %q, want Chinese string syntax error", message)
	}
}