package config

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

func writeInstanceSettings(t *testing.T, root, body string) {
	t.Helper()
	if err := os.MkdirAll(root, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(root, "instance-settings.json"), []byte(body), 0o600); err != nil {
		t.Fatal(err)
	}
}

func TestInstanceSettingsFinalLayerWins(t *testing.T) {
	root := t.TempDir()
	t.Setenv("CONFIG_ROOT", root)
	writeInstanceSettings(t, root, `{"revision":3,"settings":{"http_port":9000,"agent_backend":"stub","agent_timeout":"15m"}}`)

	cfg, src, err := LoadWithSources("", func(c *Config) { c.HTTPPort = 8888 }) // CLI 也被实例设置覆盖
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if cfg.HTTPPort != 9000 || cfg.AgentBackend != "stub" || cfg.AgentTimeout.String() != "15m0s" {
		t.Fatalf("instance settings not applied: port=%d backend=%s timeout=%s", cfg.HTTPPort, cfg.AgentBackend, cfg.AgentTimeout)
	}
	if src["http_port"].Layer != "instance-settings" {
		t.Fatalf("http_port layer=%s want instance-settings", src["http_port"].Layer)
	}
	if src["agent_timeout"].Layer != "instance-settings" {
		t.Fatalf("agent_timeout layer=%s", src["agent_timeout"].Layer)
	}
}

func TestInstanceSettingsIgnoredMode(t *testing.T) {
	root := t.TempDir()
	t.Setenv("CONFIG_ROOT", root)
	t.Setenv("SETTINGS_MODE", "ignore")
	writeInstanceSettings(t, root, `{"settings":{"http_port":9000}}`)
	cfg, err := Load("")
	if err != nil {
		t.Fatal(err)
	}
	if cfg.HTTPPort == 9000 {
		t.Fatal("SETTINGS_MODE=ignore must skip the instance settings layer")
	}
}

func TestInstanceSettingsBootstrapDeny(t *testing.T) {
	root := t.TempDir()
	t.Setenv("CONFIG_ROOT", root)
	writeInstanceSettings(t, root, `{"settings":{"env":"main"}}`)
	if _, err := Load(""); err == nil {
		t.Fatal("bootstrap field override must fail closed")
	}
}

func TestInstanceSettingsTypeMismatchFails(t *testing.T) {
	root := t.TempDir()
	t.Setenv("CONFIG_ROOT", root)
	writeInstanceSettings(t, root, `{"settings":{"http_port":"not-a-number"}}`)
	if _, err := Load(""); err == nil {
		t.Fatal("type mismatch must fail closed")
	}
}

func TestInstanceSettingsPermissiveFileRejected(t *testing.T) {
	root := t.TempDir()
	t.Setenv("CONFIG_ROOT", root)
	p := filepath.Join(root, "instance-settings.json")
	_ = os.WriteFile(p, []byte(`{"settings":{"http_port":9000}}`), 0o600)
	_ = os.Chmod(p, 0o666) // 显式置位：WriteFile 的 mode 受 umask 侵蚀（CI 022 下 0666→0644）
	if _, err := Load(""); err == nil {
		t.Fatal("group/world writable instance settings must be rejected")
	}
}