package challenge

import (
	"errors"
	"testing"
	"time"
)

func TestNewConfig(t *testing.T) {
	tests := []struct {
		name        string
		opts        []configOption
		wantErr     bool
		expectedErr error
		validate    func(*Config) error
	}{
		{
			name:    "default config",
			opts:    nil,
			wantErr: false,
			validate: func(c *Config) error {
				if c.DefaultDifficulty != 4 {
					return errors.New("expected default difficulty 4")
				}
				if c.RandomBytes != 6 {
					return errors.New("expected random bytes 6")
				}
				if len(c.HMACSecret) == 0 {
					return errors.New("expected HMAC secret to be generated")
				}
				return nil
			},
		},
		{
			name:    "custom difficulty",
			opts:    []configOption{WithDefaultDifficulty(8)},
			wantErr: false,
			validate: func(c *Config) error {
				if c.DefaultDifficulty != 8 {
					return errors.New("expected custom difficulty 8")
				}
				return nil
			},
		},
		{
			name:        "invalid random bytes - too low",
			opts:        []configOption{WithRandomBytes(0)},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
		{
			name:        "invalid random bytes - too high",
			opts:        []configOption{WithRandomBytes(50)},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
		{
			name:        "invalid difficulty - min too low",
			opts:        []configOption{WithMinDifficulty(0)},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
		{
			name: "invalid difficulty - max less than min",
			opts: []configOption{
				WithMinDifficulty(5),
				WithMaxDifficulty(3),
			},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
		{
			name: "invalid difficulty - default out of range",
			opts: []configOption{
				WithMinDifficulty(5),
				WithMaxDifficulty(10),
				WithDefaultDifficulty(15),
			},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
		{
			name:        "empty HMAC secret",
			opts:        []configOption{WithHMACSecret(nil)},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
		{
			name:        "negative TTL",
			opts:        []configOption{WithChallengeTTL(-time.Minute)},
			wantErr:     true,
			expectedErr: ErrInvalidConfig,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			config, err := NewConfig(tt.opts...)

			if tt.wantErr {
				if err == nil {
					t.Fatal("expected error but got none")
				}
				if !errors.Is(err, tt.expectedErr) {
					t.Fatalf("expected error %v, got %v", tt.expectedErr, err)
				}
				return
			}

			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}

			if tt.validate != nil {
				if err := tt.validate(config); err != nil {
					t.Fatal(err)
				}
			}
		})
	}
}

func TestConfigOptions(t *testing.T) {
	secret := []byte("test-secret")
	config, err := NewConfig(
		WithDefaultDifficulty(6),
		WithMaxDifficulty(12),
		WithMinDifficulty(2),
		WithChallengeTTL(10*time.Minute),
		WithHMACSecret(secret),
		WithResource("api"),
		WithRandomBytes(8),
		WithLoadAdjustmentBits(2),
		WithFailurePenaltyBits(3),
		WithMaxFailurePenaltyBits(9),
	)

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if config.DefaultDifficulty != 6 {
		t.Errorf("expected DefaultDifficulty 6, got %d", config.DefaultDifficulty)
	}
	if config.MaxDifficulty != 12 {
		t.Errorf("expected MaxDifficulty 12, got %d", config.MaxDifficulty)
	}
	if config.MinDifficulty != 2 {
		t.Errorf("expected MinDifficulty 2, got %d", config.MinDifficulty)
	}
	if config.ChallengeTTL != 10*time.Minute {
		t.Errorf("expected ChallengeTTL 10m, got %v", config.ChallengeTTL)
	}
	if string(config.HMACSecret) != string(secret) {
		t.Errorf("expected HMACSecret %s, got %s", secret, config.HMACSecret)
	}
	if config.Resource != "api" {
		t.Errorf("expected Resource 'api', got %s", config.Resource)
	}
	if config.RandomBytes != 8 {
		t.Errorf("expected RandomBytes 8, got %d", config.RandomBytes)
	}
}