<?php

namespace App\Services\Agent\OpenAi;

use App\Models\Message;
use App\Services\Agent\AgentContext;

class ChatCompletionsRequestBuilder
{
    public function __construct(
        private ?string $model = null,
        private ?float $temperature = null,
        private ?float $topP = null,
        private ?bool $includeUsage = null,
    ) {
        $this->model = $this->model ?? (string) config('agent.openai.model', 'gpt-4o-mini');
        $this->temperature = $this->temperature ?? (float) config('agent.openai.temperature', 0.7);
        $this->topP = $this->topP ?? (float) config('agent.openai.top_p', 1.0);
        $this->includeUsage = $this->includeUsage ?? (bool) config('agent.openai.include_usage', false);
    }

    /**
     * Builds an OpenAI-compatible Chat Completions payload from AgentContext.
     *
     * @param array<string, mixed> $options
     * @return array<string, mixed>
     */
    public function build(AgentContext $context, array $options = []): array
    {
        $payload = [
            'model' => (string) ($options['model'] ?? $this->model),
            'messages' => $this->buildMessages($context),
            'stream' => true,
        ];

        if (array_key_exists('temperature', $options)) {
            $payload['temperature'] = (float) $options['temperature'];
        } else {
            $payload['temperature'] = (float) $this->temperature;
        }

        if (array_key_exists('top_p', $options)) {
            $payload['top_p'] = (float) $options['top_p'];
        } else {
            $payload['top_p'] = (float) $this->topP;
        }

        if (array_key_exists('max_tokens', $options)) {
            $payload['max_tokens'] = (int) $options['max_tokens'];
        }

        if (array_key_exists('stop', $options)) {
            $payload['stop'] = $options['stop'];
        }

        if (array_key_exists('stream_options', $options)) {
            $payload['stream_options'] = $options['stream_options'];
        } elseif ($this->includeUsage) {
            $payload['stream_options'] = ['include_usage' => true];
        }

        if (array_key_exists('response_format', $options)) {
            $payload['response_format'] = $options['response_format'];
        }

        return $payload;
    }

    /**
     * @return array<int, array{role: string, content: string}>
     */
    private function buildMessages(AgentContext $context): array
    {
        $messages = [];

        if ($context->systemPrompt !== '') {
            $messages[] = [
                'role' => 'system',
                'content' => $context->systemPrompt,
            ];
        }

        foreach ($context->messages as $message) {
            $role = $this->mapRole((string) ($message['role'] ?? ''));
            $content = $message['content'] ?? null;

            if (! $role || ! is_string($content) || $content === '') {
                continue;
            }

            $messages[] = [
                'role' => $role,
                'content' => $content,
            ];
        }

        return $messages;
    }

    private function mapRole(string $role): ?string
    {
        return match ($role) {
            Message::ROLE_USER => 'user',
            Message::ROLE_AGENT => 'assistant',
            Message::ROLE_SYSTEM => 'system',
            default => null,
        };
    }
}