// Copyright (c) 2025-2026 Probo Inc <hello@probo.com>.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package keys_test

import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rsa"
	"errors"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.probo.inc/probo/pkg/crypto/keys"
)

func TestGenerate(t *testing.T) {
	tests := []struct {
		name        string
		keyType     keys.Type
		checkFunc   func(t *testing.T, key any)
		expectError bool
	}{
		{
			name:    "EC256",
			keyType: keys.TypeEC256,
			checkFunc: func(t *testing.T, key any) {
				ecKey, ok := key.(*ecdsa.PrivateKey)
				require.True(t, ok, "expected *ecdsa.PrivateKey, got %T", key)
				assert.Equal(t, elliptic.P256(), ecKey.Curve, "expected P256 curve")
			},
		},
		{
			name:    "EC384",
			keyType: keys.TypeEC384,
			checkFunc: func(t *testing.T, key any) {
				ecKey, ok := key.(*ecdsa.PrivateKey)
				require.True(t, ok, "expected *ecdsa.PrivateKey, got %T", key)
				assert.Equal(t, elliptic.P384(), ecKey.Curve, "expected P384 curve")
			},
		},
		{
			name:    "RSA2048",
			keyType: keys.TypeRSA2048,
			checkFunc: func(t *testing.T, key any) {
				rsaKey, ok := key.(*rsa.PrivateKey)
				require.True(t, ok, "expected *rsa.PrivateKey, got %T", key)

				bitSize := rsaKey.N.BitLen()
				assert.GreaterOrEqual(t, bitSize, 2047, "RSA key too small")
				assert.LessOrEqual(t, bitSize, 2048, "RSA key too large")
			},
		},
		{
			name:    "RSA4096",
			keyType: keys.TypeRSA4096,
			checkFunc: func(t *testing.T, key any) {
				rsaKey, ok := key.(*rsa.PrivateKey)
				require.True(t, ok, "expected *rsa.PrivateKey, got %T", key)

				bitSize := rsaKey.N.BitLen()
				assert.GreaterOrEqual(t, bitSize, 4095, "RSA key too small")
				assert.LessOrEqual(t, bitSize, 4096, "RSA key too large")
			},
		},
		{
			name:        "Invalid key type",
			keyType:     keys.Type("INVALID"),
			expectError: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			key, err := keys.Generate(tt.keyType)

			if tt.expectError {
				assert.Error(t, err, "expected error")
				return
			}

			require.NoError(t, err, "unexpected error")
			require.NotNil(t, key, "expected key, got nil")

			// Verify the key can be used for signing (crypto.Signer has Public() method)
			assert.NotNil(t, key.Public(), "key.Public() returned nil")

			if tt.checkFunc != nil {
				tt.checkFunc(t, key)
			}
		})
	}
}

func TestGenerateConcurrency(t *testing.T) {
	// Test that key generation is safe for concurrent use
	keyTypes := []keys.Type{
		keys.TypeEC256,
		keys.TypeEC384,
		keys.TypeRSA2048,
		keys.TypeRSA4096,
	}

	for _, keyType := range keyTypes {
		t.Run(string(keyType), func(t *testing.T) {
			t.Parallel()

			const numGoroutines = 10

			errorsChan := make(chan error, numGoroutines)

			for range numGoroutines {
				go func() {
					key, err := keys.Generate(keyType)
					if err != nil {
						errorsChan <- err
						return
					}

					if key == nil {
						errorsChan <- errors.New("generated key is nil")
						return
					}

					errorsChan <- nil
				}()
			}

			for range numGoroutines {
				err := <-errorsChan
				assert.NoError(t, err, "concurrent generation failed")
			}
		})
	}
}

func BenchmarkGenerate(b *testing.B) {
	benchmarks := []struct {
		name    string
		keyType keys.Type
	}{
		{"EC256", keys.TypeEC256},
		{"EC384", keys.TypeEC384},
		{"RSA2048", keys.TypeRSA2048},
		{"RSA4096", keys.TypeRSA4096},
	}

	for _, bm := range benchmarks {
		b.Run(bm.name, func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				_, err := keys.Generate(bm.keyType)
				if err != nil {
					b.Fatal(err)
				}
			}
		})
	}
}