<?php

declare(strict_types=1);

namespace Core\Mod\Agentic\Tests\Unit;

use Core\Mod\Agentic\Services\AgenticResponse;
use Core\Mod\Agentic\Services\GeminiService;
use Illuminate\Support\Facades\Http;
use RuntimeException;
use Tests\TestCase;

/**
 * Tests for the GeminiService AI provider.
 *
 * Uses mocked HTTP responses to test the service without real API calls.
 */
class GeminiServiceTest extends TestCase
{
    private const API_URL = 'https://generativelanguage.googleapis.com/v1beta/models';

    // =========================================================================
    // Service Configuration Tests
    // =========================================================================

    public function test_name_returns_gemini(): void
    {
        $service = new GeminiService('test-api-key');

        $this->assertEquals('gemini', $service->name());
    }

    public function test_default_model_returns_configured_model(): void
    {
        $service = new GeminiService('test-api-key', 'gemini-1.5-pro');

        $this->assertEquals('gemini-1.5-pro', $service->defaultModel());
    }

    public function test_default_model_uses_flash_when_not_specified(): void
    {
        $service = new GeminiService('test-api-key');

        $this->assertEquals('gemini-2.0-flash', $service->defaultModel());
    }

    public function test_is_available_returns_true_with_api_key(): void
    {
        $service = new GeminiService('test-api-key');

        $this->assertTrue($service->isAvailable());
    }

    public function test_is_available_returns_false_without_api_key(): void
    {
        $service = new GeminiService('');

        $this->assertFalse($service->isAvailable());
    }

    // =========================================================================
    // Generate Tests
    // =========================================================================

    public function test_generate_returns_agentic_response(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    [
                        'content' => [
                            'parts' => [['text' => 'Hello, world!']],
                        ],
                        'finishReason' => 'STOP',
                    ],
                ],
                'usageMetadata' => [
                    'promptTokenCount' => 10,
                    'candidatesTokenCount' => 5,
                ],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('You are helpful.', 'Say hello');

        $this->assertInstanceOf(AgenticResponse::class, $response);
        $this->assertEquals('Hello, world!', $response->content);
        $this->assertEquals('gemini-2.0-flash', $response->model);
        $this->assertEquals(10, $response->inputTokens);
        $this->assertEquals(5, $response->outputTokens);
        $this->assertEquals('STOP', $response->stopReason);
    }

    public function test_generate_sends_correct_request_body(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $service->generate('System prompt', 'User prompt');

        Http::assertSent(function ($request) {
            $body = $request->data();

            return $body['systemInstruction']['parts'][0]['text'] === 'System prompt'
                && $body['contents'][0]['parts'][0]['text'] === 'User prompt'
                && $body['generationConfig']['maxOutputTokens'] === 4096
                && $body['generationConfig']['temperature'] === 1.0;
        });
    }

    public function test_generate_uses_model_in_url(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key', 'gemini-1.5-pro');
        $service->generate('System', 'User');

        Http::assertSent(function ($request) {
            return str_contains($request->url(), 'gemini-1.5-pro:generateContent');
        });
    }

    public function test_generate_uses_custom_config(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $service->generate('System', 'User', [
            'model' => 'gemini-1.5-pro',
            'max_tokens' => 8192,
            'temperature' => 0.5,
        ]);

        Http::assertSent(function ($request) {
            $body = $request->data();

            return str_contains($request->url(), 'gemini-1.5-pro')
                && $body['generationConfig']['maxOutputTokens'] === 8192
                && $body['generationConfig']['temperature'] === 0.5;
        });
    }

    public function test_generate_sends_api_key_in_query(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key-123');
        $service->generate('System', 'User');

        Http::assertSent(function ($request) {
            return str_contains($request->url(), 'key=test-api-key-123');
        });
    }

    public function test_generate_tracks_duration(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertIsInt($response->durationMs);
        $this->assertGreaterThanOrEqual(0, $response->durationMs);
    }

    public function test_generate_includes_raw_response(): void
    {
        $rawResponse = [
            'candidates' => [
                ['content' => ['parts' => [['text' => 'Response']]]],
            ],
            'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
        ];

        Http::fake([
            self::API_URL.'/*' => Http::response($rawResponse, 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertArrayHasKey('candidates', $response->raw);
        $this->assertArrayHasKey('usageMetadata', $response->raw);
    }

    // =========================================================================
    // Error Handling Tests
    // =========================================================================

    public function test_generate_throws_on_client_error(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'error' => ['message' => 'Invalid API key'],
            ], 401),
        ]);

        $service = new GeminiService('invalid-key');

        $this->expectException(RuntimeException::class);
        $this->expectExceptionMessage('Gemini API error');

        $service->generate('System', 'User');
    }

    public function test_generate_retries_on_rate_limit(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::sequence()
                ->push(['error' => ['message' => 'Rate limited']], 429)
                ->push([
                    'candidates' => [
                        ['content' => ['parts' => [['text' => 'Success after retry']]]],
                    ],
                    'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
                ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertEquals('Success after retry', $response->content);
    }

    public function test_generate_retries_on_server_error(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::sequence()
                ->push(['error' => ['message' => 'Server error']], 500)
                ->push([
                    'candidates' => [
                        ['content' => ['parts' => [['text' => 'Success after retry']]]],
                    ],
                    'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
                ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertEquals('Success after retry', $response->content);
    }

    public function test_generate_throws_after_max_retries(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response(['error' => ['message' => 'Server error']], 500),
        ]);

        $service = new GeminiService('test-api-key');

        $this->expectException(RuntimeException::class);

        $service->generate('System', 'User');
    }

    // =========================================================================
    // Stream Tests
    // =========================================================================

    public function test_stream_is_generator(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response('', 200),
        ]);

        $service = new GeminiService('test-api-key');
        $generator = $service->stream('System', 'User');

        $this->assertInstanceOf(\Generator::class, $generator);
    }

    public function test_stream_uses_stream_endpoint(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response('', 200),
        ]);

        $service = new GeminiService('test-api-key');
        iterator_to_array($service->stream('System', 'User'));

        Http::assertSent(function ($request) {
            return str_contains($request->url(), ':streamGenerateContent');
        });
    }

    // =========================================================================
    // Response Handling Edge Cases
    // =========================================================================

    public function test_handles_empty_candidates(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 0],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertEquals('', $response->content);
    }

    public function test_handles_missing_usage_metadata(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertEquals(0, $response->inputTokens);
        $this->assertEquals(0, $response->outputTokens);
    }

    public function test_handles_missing_finish_reason(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => [['text' => 'Response']]]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 5],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertNull($response->stopReason);
    }

    public function test_handles_empty_parts(): void
    {
        Http::fake([
            self::API_URL.'/*' => Http::response([
                'candidates' => [
                    ['content' => ['parts' => []]],
                ],
                'usageMetadata' => ['promptTokenCount' => 10, 'candidatesTokenCount' => 0],
            ], 200),
        ]);

        $service = new GeminiService('test-api-key');
        $response = $service->generate('System', 'User');

        $this->assertEquals('', $response->content);
    }
}