package resolver

import (
	"context"
	"errors"
	"testing"

	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/config"
	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/netbox"
)

// stubStrategy is a test double for Strategy.
type stubStrategy struct {
	name string
	ip   string
	err  error
}

func (s *stubStrategy) Name() string { return s.name }
func (s *stubStrategy) Resolve(_ context.Context, _ *netbox.HostEntry, _ *netbox.Client) (string, error) {
	return s.ip, s.err
}

func TestChain_FirstStrategySucceeds(t *testing.T) {
	c := &Chain{strategies: []Strategy{
		&stubStrategy{name: "first", ip: "10.0.0.1"},
		&stubStrategy{name: "second", ip: "10.0.0.2"},
	}}
	ip, err := c.Resolve(context.Background(), &netbox.HostEntry{Name: "host"}, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if ip != "10.0.0.1" {
		t.Errorf("got %q, want first strategy's IP %q", ip, "10.0.0.1")
	}
}

func TestChain_FallsBackToNextStrategy(t *testing.T) {
	c := &Chain{strategies: []Strategy{
		&stubStrategy{name: "first", err: ErrNoIP},
		&stubStrategy{name: "second", ip: "10.0.0.2"},
	}}
	ip, err := c.Resolve(context.Background(), &netbox.HostEntry{Name: "host"}, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if ip != "10.0.0.2" {
		t.Errorf("got %q, want second strategy's IP %q", ip, "10.0.0.2")
	}
}

func TestChain_AllStrategiesFail(t *testing.T) {
	c := &Chain{strategies: []Strategy{
		&stubStrategy{name: "a", err: ErrNoIP},
		&stubStrategy{name: "b", err: errors.New("api error")},
	}}
	_, err := c.Resolve(context.Background(), &netbox.HostEntry{Name: "host"}, nil)
	if err == nil {
		t.Error("expected error when all strategies fail")
	}
}

func TestChain_EmptyStrategies(t *testing.T) {
	c := &Chain{}
	_, err := c.Resolve(context.Background(), &netbox.HostEntry{Name: "host"}, nil)
	if err == nil {
		t.Error("empty chain should return an error")
	}
}

func TestNew_PrimaryIP(t *testing.T) {
	cfg := config.ResolverConfig{Strategies: []string{"primary_ip"}}
	c, err := New(cfg)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if len(c.strategies) != 1 {
		t.Errorf("got %d strategies, want 1", len(c.strategies))
	}
	if c.strategies[0].Name() != "primary_ip" {
		t.Errorf("strategy name: got %q, want %q", c.strategies[0].Name(), "primary_ip")
	}
}

func TestNew_ManagementSubnet(t *testing.T) {
	cfg := config.ResolverConfig{
		Strategies:        []string{"management_subnet"},
		ManagementSubnets: []string{"10.0.0.0/8"},
	}
	c, err := New(cfg)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if c.strategies[0].Name() != "management_subnet" {
		t.Errorf("strategy name: got %q, want %q", c.strategies[0].Name(), "management_subnet")
	}
}

func TestNew_ManagementSubnet_InvalidCIDR(t *testing.T) {
	cfg := config.ResolverConfig{
		Strategies:        []string{"management_subnet"},
		ManagementSubnets: []string{"not-a-cidr"},
	}
	_, err := New(cfg)
	if err == nil {
		t.Error("invalid CIDR should return an error")
	}
}

func TestNew_InterfaceName(t *testing.T) {
	cfg := config.ResolverConfig{
		Strategies:    []string{"interface_name"},
		InterfaceName: "mgmt0",
	}
	c, err := New(cfg)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if c.strategies[0].Name() != "interface_name" {
		t.Errorf("strategy name: got %q", c.strategies[0].Name())
	}
}

func TestNew_InterfaceName_MissingConfig(t *testing.T) {
	cfg := config.ResolverConfig{
		Strategies:    []string{"interface_name"},
		InterfaceName: "", // not set
	}
	_, err := New(cfg)
	if err == nil {
		t.Error("interface_name without config should return an error")
	}
}

func TestNew_UnknownStrategy(t *testing.T) {
	cfg := config.ResolverConfig{Strategies: []string{"nonexistent"}}
	_, err := New(cfg)
	if err == nil {
		t.Error("unknown strategy should return an error")
	}
}

func TestNew_MultipleStrategies(t *testing.T) {
	cfg := config.ResolverConfig{
		Strategies:        []string{"management_subnet", "primary_ip"},
		ManagementSubnets: []string{"10.0.0.0/8"},
	}
	c, err := New(cfg)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if len(c.strategies) != 2 {
		t.Errorf("got %d strategies, want 2", len(c.strategies))
	}
}