package networkconfig

import (
	"context"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

type successfulRunner struct {
	calls        []string
	failContains string
}

func (r *successfulRunner) Run(_ context.Context, name string, args ...string) ([]byte, error) {
	call := name + " " + strings.Join(args, " ")
	r.calls = append(r.calls, call)
	if r.failContains != "" && strings.Contains(call, r.failContains) {
		return nil, errors.New("injected command failure")
	}
	return nil, nil
}

func testOSController(t *testing.T) (*OSController, *successfulRunner, map[string]string) {
	t.Helper()
	root := t.TempDir()
	paths := map[string]string{
		"interfaces": filepath.Join(root, "etc", "network", "interfaces"),
		"routing":    filepath.Join(root, "etc", "network", "if-up.d", "20-tera-active-active"),
		"config":     filepath.Join(root, "var", "lib", "tera-network", "config.json"),
		"pending":    filepath.Join(root, "var", "lib", "tera-network", "pending.json"),
		"hostname":   filepath.Join(root, "etc", "hostname"),
		"sys":        filepath.Join(root, "sys", "class", "net"),
	}
	for _, path := range paths {
		if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
			t.Fatal(err)
		}
	}
	if err := os.WriteFile(paths["interfaces"], []byte("old interfaces\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(paths["routing"], []byte("#!/bin/sh\n# old route\n"), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(paths["hostname"], []byte("old-console\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	runner := &successfulRunner{}
	controller, err := NewOSController(OSOptions{
		InterfacesPath: paths["interfaces"], RoutingPath: paths["routing"], ConfigPath: paths["config"], PendingPath: paths["pending"], HostnamePath: paths["hostname"],
		HostnameCommandPath: filepath.Join(root, "bin", "hostname"),
		IfdownPath:          filepath.Join(root, "sbin", "ifdown"), IfupPath: filepath.Join(root, "sbin", "ifup"), IPPath: filepath.Join(root, "sbin", "ip"), ShellPath: filepath.Join(root, "bin", "sh"), SysClassRoot: paths["sys"],
		Runner: runner, Now: func() time.Time { return time.Date(2026, 7, 30, 9, 0, 0, 0, time.UTC) },
	})
	if err != nil {
		t.Fatal(err)
	}
	return controller, runner, paths
}

func TestRenderRoutingScriptBuildsECMPAndSourceRules(t *testing.T) {
	config := testConfig()
	config.Interfaces[0].Role = RoleExternal
	config.Interfaces[0].Gateway = "192.168.0.1"
	script, err := RenderRoutingScript(config, "/sbin/ip")
	if err != nil {
		t.Fatal(err)
	}
	text := string(script)
	for _, expected := range []string{
		"if $IP -4 rule show >/dev/null 2>&1; then",
		"network_ready()",
		"if network_ready eth0 192.168.0.223; then",
		"deferring IPv4 policy route for eth1 until 192.168.78.55 is configured",
		"from 192.168.0.223/32 lookup 100",
		"from 192.168.78.55/32 lookup 101",
		"route flush table 100",
		"route add 192.168.0.0/24 dev eth0 src 192.168.0.223 table 100",
		"while $IP -4 route del default 2>/dev/null; do :; done",
		"route add default nexthop via 192.168.0.1 dev eth0 weight 1 nexthop via 192.168.78.1 dev eth1 weight 1",
	} {
		if !strings.Contains(text, expected) {
			t.Fatalf("routing script missing %q:\n%s", expected, text)
		}
	}
	if !strings.Contains(text, "kernel lacks IPv4 policy routing required for dual-external active/active") {
		t.Fatalf("dual-external kernel capability guard is missing:\n%s", text)
	}
	if strings.Contains(text, "route replace") {
		t.Fatalf("routing script must remain compatible with the target route implementation:\n%s", text)
	}
}

func TestRenderRoutingScriptFallsBackForSingleExternalWithoutPolicyRouting(t *testing.T) {
	script, err := RenderRoutingScript(testConfig(), "/sbin/ip")
	if err != nil {
		t.Fatal(err)
	}
	text := string(script)
	if !strings.Contains(text, "IPv4 policy routing unavailable; using connected routes plus one main default") {
		t.Fatalf("single-external fallback is missing:\n%s", text)
	}
	if strings.Contains(text, "kernel lacks IPv4 policy routing required for dual-external active/active") {
		t.Fatalf("single-external configuration must not use the dual-external rejection:\n%s", text)
	}
	if !strings.Contains(text, "route add default via 192.168.78.1 dev eth1") {
		t.Fatalf("single-external main default is missing:\n%s", text)
	}
	if !strings.Contains(text, "if network_ready eth1 192.168.78.55; then") {
		t.Fatalf("single-external main default is not guarded until eth1 has its address:\n%s", text)
	}
}

func TestOOBHealthThresholdActivatesFallbackAndRestoresPrimary(t *testing.T) {
	controller, runner, paths := testOSController(t)
	for _, device := range []string{"eth0", "eth1"} {
		directory := filepath.Join(paths["sys"], device)
		if err := os.MkdirAll(directory, 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filepath.Join(directory, "carrier"), []byte("1\n"), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	config := testConfig()
	config.OperatingMode = OperatingModeOOB
	config.OOBPrimaryInterface = "Interface-1"
	config.OOBFallbackInterface = "Interface-2"
	config.Interfaces[0].Gateway = "192.168.0.1"
	config.OOBHealthCheckTarget = "9.9.9.9"
	config.OOBFailureThreshold = 2
	if config.Interfaces[0].Name != Interface1Name || config.Interfaces[0].Device != Interface1Device ||
		config.Interfaces[1].Name != Interface2Name || config.Interfaces[1].Device != Interface2Device {
		t.Fatalf("test configuration does not use fixed interface mapping: %+v", config.Interfaces)
	}
	if _, err := controller.Apply(context.Background(), config); err != nil {
		t.Fatal(err)
	}
	runner.failContains = "ping"
	controller.checkOOBHealth(context.Background())
	controller.checkOOBHealth(context.Background())
	status, err := controller.Status(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if !status.OOB.FallbackActive || status.OOB.FailoverReason != "primary_failure_threshold_reached" || status.OOB.LastFailoverAt == nil {
		t.Fatalf("fallback status = %+v", status.OOB)
	}
	if !strings.Contains(strings.Join(runner.calls, "\n"), "route replace default via 192.168.78.1 dev eth1") {
		t.Fatalf("fallback route command missing: %v", runner.calls)
	}
	runner.failContains = ""
	controller.checkOOBHealth(context.Background())
	status, _ = controller.Status(context.Background())
	if status.OOB.FallbackActive || status.OOB.FailoverReason != "primary_restored" {
		t.Fatalf("restored status = %+v", status.OOB)
	}
	if !strings.Contains(strings.Join(runner.calls, "\n"), "route replace default via 192.168.0.1 dev eth0") {
		t.Fatalf("primary route restore command missing: %v", runner.calls)
	}
}

func TestRenderInterfacesSupportsDHCPDNSAndIPv6(t *testing.T) {
	config := testConfig()
	config.Interfaces[0].DNSServers = []string{"192.168.0.1", "8.8.8.8"}
	config.Interfaces[0].IPv6Mode = IPv6ModeStatic
	config.Interfaces[0].IPv6Address = "2001:db8::223/64"
	config.Interfaces[0].IPv6Gateway = "2001:db8::1"
	config.Interfaces[0].IPv6DNSServers = []string{"2001:4860:4860::8888"}
	config.Interfaces[1].AddressMode = AddressModeDHCP
	config.Interfaces[1].Address = ""
	config.Interfaces[1].Gateway = ""

	payload, err := RenderInterfaces(config, "/etc/network/if-up.d/20-tera-network")
	if err != nil {
		t.Fatal(err)
	}
	text := string(payload)
	if strings.Contains(text, "inet6 auto") {
		t.Fatalf("BusyBox-incompatible IPv6 auto method emitted:\n%s", text)
	}
	for _, expected := range []string{
		"iface eth0 inet static",
		"dns-nameservers 192.168.0.1 8.8.8.8",
		"iface eth0 inet6 static",
		"address 2001:db8::223",
		"netmask 64",
		"gateway 2001:db8::1",
		"dns-nameservers 2001:4860:4860::8888",
		"iface eth1 inet dhcp",
	} {
		if !strings.Contains(text, expected) {
			t.Fatalf("interfaces file missing %q:\n%s", expected, text)
		}
	}

	routing, err := RenderRoutingScript(config, "/sbin/ip")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(string(routing), "DHCP owns the dynamic default route") {
		t.Fatalf("routing script overwrites DHCP default route:\n%s", routing)
	}
}

func TestRenderInterfacesBuildsBondingFromInterfaceOne(t *testing.T) {
	config := testConfig()
	config.Advanced = AdvancedConfig{Mode: AdvancedModeBonding, BondMode: "active-backup", BondMii: 50}
	payload, err := RenderInterfaces(config, "/etc/network/if-up.d/20-tera-network")
	if err != nil {
		t.Fatal(err)
	}
	text := string(payload)
	for _, expected := range []string{
		"iface eth0 inet manual",
		"iface eth1 inet manual",
		"auto bond0",
		"iface bond0 inet static",
		"address 192.168.0.223",
		"link add name bond0 type bond",
		"type bond mode active-backup miimon 50",
		"link set dev eth0 master bond0",
		"link set dev eth1 master bond0",
	} {
		if !strings.Contains(text, expected) {
			t.Fatalf("bonding interfaces file missing %q:\n%s", expected, text)
		}
	}
	if strings.Contains(text, "address 192.168.78.55") {
		t.Fatalf("Interface-2 layer-3 address leaked into bond configuration:\n%s", text)
	}
	routing, err := RenderRoutingScript(config, "/sbin/ip")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(string(routing), "dev bond0") || strings.Contains(string(routing), "dev eth1") {
		t.Fatalf("bond routing does not use bond0 exclusively:\n%s", routing)
	}
}

func TestRenderInterfacesBuildsBridgeAndSTP(t *testing.T) {
	config := testConfig()
	config.Advanced = AdvancedConfig{Mode: AdvancedModeBridge, BridgeSTP: true}
	payload, err := RenderInterfaces(config, "/etc/network/if-up.d/20-tera-network")
	if err != nil {
		t.Fatal(err)
	}
	text := string(payload)
	for _, expected := range []string{
		"auto br0",
		"iface br0 inet static",
		"link add name br0 type bridge",
		"type bridge stp_state 1",
		"link set dev eth0 master br0",
		"link set dev eth1 master br0",
	} {
		if !strings.Contains(text, expected) {
			t.Fatalf("bridge interfaces file missing %q:\n%s", expected, text)
		}
	}
}

func TestApplyAdvancedModeBringsUpAggregateDevice(t *testing.T) {
	controller, runner, _ := testOSController(t)
	config := testConfig()
	config.Advanced = AdvancedConfig{Mode: AdvancedModeBonding, BondMode: "balance-rr", BondMii: 100}
	if _, err := controller.Apply(context.Background(), config); err != nil {
		t.Fatal(err)
	}
	calls := strings.Join(runner.calls, "\n")
	if !strings.Contains(calls, "ifup bond0") {
		t.Fatalf("aggregate interface was not brought up: %s", calls)
	}
}

func TestChangedNetworkDevicesIncludesDNSAndIPv6ButSkipsHostnameOnly(t *testing.T) {
	current := testConfig()
	next := current
	next.Interfaces = append([]Interface(nil), current.Interfaces...)
	next.Interfaces[0].DNSServers = []string{"8.8.8.8"}
	next.Interfaces[0].IPv6Mode = IPv6ModeStatic
	next.Interfaces[0].IPv6Address = "2001:db8::223/64"
	changed := changedNetworkDevices(current, next)
	if !changed["eth0"] || changed["eth1"] {
		t.Fatalf("changed devices = %#v", changed)
	}

	hostOnly := current
	hostOnly.HostName = "new-console"
	changed = changedNetworkDevices(current, hostOnly)
	if changed["eth0"] || changed["eth1"] {
		t.Fatalf("hostname-only update bounced interfaces: %#v", changed)
	}
}

func TestApplyConfirmPersistsConfigurationAndClearsRollback(t *testing.T) {
	controller, runner, paths := testOSController(t)
	result, err := controller.Apply(context.Background(), testConfig())
	if err != nil {
		t.Fatal(err)
	}
	if result.State != "pending_confirmation" || result.TransactionID == "" {
		t.Fatalf("apply result = %+v", result)
	}
	interfaces, _ := os.ReadFile(paths["interfaces"])
	if !strings.Contains(string(interfaces), "address 192.168.78.55") || len(runner.calls) < 5 {
		t.Fatalf("configuration not applied: %s calls=%v", interfaces, runner.calls)
	}
	hostname, _ := os.ReadFile(paths["hostname"])
	if string(hostname) != "iconsole-server\n" || !strings.Contains(strings.Join(runner.calls, "\n"), "hostname iconsole-server") {
		t.Fatalf("hostname not applied: %q calls=%v", hostname, runner.calls)
	}
	status, err := controller.Confirm(context.Background(), result.TransactionID)
	if err != nil || status.State != "confirmed" {
		t.Fatalf("confirm = %+v, %v", status, err)
	}
	if _, err := os.Stat(paths["pending"]); !os.IsNotExist(err) {
		t.Fatalf("pending transaction still exists: %v", err)
	}
}

func TestRollbackRestoresExactPreviousFiles(t *testing.T) {
	controller, _, paths := testOSController(t)
	result, err := controller.Apply(context.Background(), testConfig())
	if err != nil {
		t.Fatal(err)
	}
	status, err := controller.Rollback(context.Background(), result.TransactionID)
	if err != nil || !strings.HasPrefix(status.State, "rolled_back") {
		t.Fatalf("rollback = %+v, %v", status, err)
	}
	content, _ := os.ReadFile(paths["interfaces"])
	if string(content) != "old interfaces\n" {
		t.Fatalf("interfaces after rollback = %q", content)
	}
	hostname, _ := os.ReadFile(paths["hostname"])
	if string(hostname) != "old-console\n" {
		t.Fatalf("hostname after rollback = %q", hostname)
	}
	if _, err := os.Stat(paths["config"]); !os.IsNotExist(err) {
		t.Fatalf("new config was not removed: %v", err)
	}
}

func TestRecoverRollsBackUnconfirmedTransactionAfterRestart(t *testing.T) {
	controller, runner, paths := testOSController(t)
	if _, err := controller.Apply(context.Background(), testConfig()); err != nil {
		t.Fatal(err)
	}
	restarted, err := NewOSController(OSOptions{
		InterfacesPath: paths["interfaces"], RoutingPath: paths["routing"], ConfigPath: paths["config"], PendingPath: paths["pending"], HostnamePath: paths["hostname"],
		HostnameCommandPath: filepath.Join(filepath.Dir(paths["interfaces"]), "hostname"),
		IfdownPath:          filepath.Join(filepath.Dir(paths["interfaces"]), "ifdown"), IfupPath: filepath.Join(filepath.Dir(paths["interfaces"]), "ifup"), IPPath: filepath.Join(filepath.Dir(paths["interfaces"]), "ip"), ShellPath: filepath.Join(filepath.Dir(paths["interfaces"]), "sh"), SysClassRoot: paths["sys"], Runner: runner,
	})
	if err != nil {
		t.Fatal(err)
	}
	if err := restarted.Recover(context.Background()); err != nil {
		t.Fatal(err)
	}
	content, _ := os.ReadFile(paths["interfaces"])
	if string(content) != "old interfaces\n" {
		t.Fatalf("interfaces after recovery = %q", content)
	}
}