<?php

declare(strict_types=1);

// phpcs:disable WordPress.Security.EscapeOutput -- No HTML output in this file; exception messages are not rendered.

namespace WordPress\CloudflareWorkersAiProvider\Models;

use WordPress\AiClient\Common\Exception\InvalidArgumentException;
use WordPress\AiClient\Common\Exception\RuntimeException;
use WordPress\AiClient\Messages\DTO\MessagePart;
use WordPress\AiClient\Messages\Enums\MessagePartChannelEnum;
use WordPress\AiClient\Providers\Http\DTO\Request;
use WordPress\AiClient\Providers\Http\DTO\RequestOptions;
use WordPress\AiClient\Providers\Http\DTO\Response;
use WordPress\AiClient\Providers\Http\Enums\HttpMethodEnum;
use WordPress\AiClient\Providers\Http\Contracts\HttpTransporterInterface;
use WordPress\AiClient\Providers\OpenAiCompatibleImplementation\AbstractOpenAiCompatibleTextGenerationModel;
use WordPress\CloudflareWorkersAiProvider\Gateway;
use WordPress\CloudflareWorkersAiProvider\Http\CloudflareTransporter;
use WordPress\CloudflareWorkersAiProvider\Routing\TaskContext;
use WordPress\CloudflareWorkersAiProvider\Usage\UsageTracker;

class CloudflareWorkersAiTextGenerationModel extends AbstractOpenAiCompatibleTextGenerationModel
{
    private const MAX_INLINE_IMAGE_BYTES = 10 * 1024 * 1024;

    private const DEFAULT_TIMEOUT = 60.0;

    protected function createRequest(
        HttpMethodEnum $method,
        string $path,
        array $headers = [],
        $data = null
    ): Request {
        $modelId   = is_array($data) && isset($data['model']) ? (string) $data['model'] : $this->metadata()->getId();
        $cacheable = CloudflareTransporter::isDeterministic(is_array($data) ? $data : null);
        $url       = $path === 'chat/completions'
            ? Gateway::chatUrl()
            : Gateway::directUrl(Gateway::chatUrl()); // Only chat is used by this model.

        // Vision: Cloudflare's OpenAI-compatible endpoint rejects image parts for
        // Llama 3.2 Vision ("Unable to add image when there are no ... messages",
        // code 3030). The native run endpoint accepts the same messages plus a
        // top-level base64 `image`, so image prompts are re-shaped and sent there.
        if (is_array($data) && $this->hasImagePart($data)) {
            $data = $this->toNativeVisionBody($data);
            $url  = Gateway::runUrl(strpos($modelId, 'workers-ai/') === 0 ? substr($modelId, 11) : $modelId);
        }

        $headers = $headers + Gateway::headers(TaskContext::current(), $cacheable, $modelId);

        return new Request($method, $url, $headers, $data, $this->effectiveRequestOptions());
    }

    private function hasImagePart(array $data): bool
    {
        foreach ((array) ($data['messages'] ?? []) as $m) {
            if (is_array($m) && isset($m['content']) && is_array($m['content'])) {
                foreach ($m['content'] as $part) {
                    if (is_array($part) && ($part['type'] ?? '') === 'image_url') {
                        return true;
                    }
                }
            }
        }
        return false;
    }

    private function toNativeVisionBody(array $data): array
    {
        $messages = [];
        $image    = null;
        foreach ((array) ($data['messages'] ?? []) as $m) {
            if (!is_array($m)) {
                continue;
            }
            $text = '';
            if (isset($m['content']) && is_array($m['content'])) {
                foreach ($m['content'] as $part) {
                    if (!is_array($part)) {
                        continue;
                    }
                    if (($part['type'] ?? '') === 'text') {
                        $text .= (string) ($part['text'] ?? '');
                    } elseif (($part['type'] ?? '') === 'image_url' && $image === null) {
                        $url   = (string) ($part['image_url']['url'] ?? '');
                        $comma = strpos($url, 'base64,');
                        $image = $comma !== false ? substr($url, $comma + 7) : $url;
                    }
                }
            } else {
                $text = (string) ($m['content'] ?? '');
            }
            if ($text !== '' || ($m['role'] ?? '') === 'system') {
                $messages[] = ['role' => (string) ($m['role'] ?? 'user'), 'content' => $text];
            }
        }
        if ($messages === []) {
            $messages[] = ['role' => 'user', 'content' => 'Describe this image.'];
        }
        // The native endpoint rejects messages+image without a system message
        // ("Unable to add image when there are no ... system-supplied messages").
        $hasSystem = false;
        foreach ($messages as $m) {
            if ($m['role'] === 'system') {
                $hasSystem = true;
                break;
            }
        }
        if (!$hasSystem) {
            $sys = \WordPress\CloudflareWorkersAiProvider\Prompts::render('vision_system');
            array_unshift($messages, ['role' => 'system', 'content' => $sys !== '' ? $sys : 'You are a helpful assistant.']);
        }

        // Cloudflare accepts `messages` + image as a byte array, or `prompt` +
        // image as base64 - but not `messages` + base64 (error 3030). Byte
        // arrays keep the system/user roles but cost ~16 bytes of PHP memory per
        // image byte, so use them only for small images; above that fold the
        // roles into a single prompt.
        $bytes    = $image !== null ? base64_decode($image, true) : false; // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode -- image bytes for the vision endpoint
        $maxBytes = (int) apply_filters('aipcf_vision_byte_array_max', 512 * 1024);
        if ($bytes !== false && strlen($bytes) <= $maxBytes) {
            $byteArray = unpack('C*', $bytes) ?: [];
            unset($bytes);
            $body = [
                'messages' => $messages,
                'image'    => array_values($byteArray),
            ];
            unset($byteArray);
        } else {
            $prompt = '';
            foreach ($messages as $m) {
                $prompt .= ($prompt === '' ? '' : "\n\n") . $m['content'];
            }
            $body = ['prompt' => $prompt !== '' ? $prompt : 'Describe this image.'];
            if ($image !== null) {
                $body['image'] = $image;
            }
        }
        foreach (['max_tokens', 'temperature', 'top_p'] as $k) {
            if (isset($data[$k])) {
                $body[$k] = $data[$k];
            }
        }
        return $body;
    }

    protected function parseResponseToGenerativeAiResult(Response $response): \WordPress\AiClient\Results\DTO\GenerativeAiResult
    {
        $data = $response->getData();
        if (is_array($data) && isset($data['result']) && is_array($data['result']) && array_key_exists('response', $data['result'])) {
            $r     = $data['result'];
            $usage = isset($r['usage']) && is_array($r['usage']) ? $r['usage'] : [];
            $shape = [
                'id'      => '',
                'model'   => $this->metadata()->getId(),
                'choices' => [[
                    'index'         => 0,
                    'message'       => ['role' => 'assistant', 'content' => is_scalar($r['response']) ? (string) $r['response'] : (string) wp_json_encode($r['response'])],
                    'finish_reason' => 'stop',
                ]],
                'usage'   => [
                    'prompt_tokens'     => (int) ($usage['prompt_tokens'] ?? 0),
                    'completion_tokens' => (int) ($usage['completion_tokens'] ?? 0),
                    'total_tokens'      => (int) ($usage['total_tokens'] ?? 0),
                    'neurons'           => $usage['neurons'] ?? 0,
                ],
            ];
            $response = new Response($response->getStatusCode(), $response->getHeaders(), (string) wp_json_encode($shape));
        }
        return parent::parseResponseToGenerativeAiResult($response);
    }

    public function getHttpTransporter(): HttpTransporterInterface
    {
        return new CloudflareTransporter(parent::getHttpTransporter(), $this->metadata()->getId());
    }

    private function effectiveRequestOptions(): RequestOptions
    {
        $options = $this->getRequestOptions();
        if ($options !== null && $options->getTimeout() !== null) {
            return $options;
        }

        $timeout = (float) apply_filters('aipcf_request_timeout', self::DEFAULT_TIMEOUT, $this->metadata()->getId());

        $merged = $options !== null ? clone $options : new RequestOptions();
        $merged->setTimeout($timeout > 0 ? $timeout : self::DEFAULT_TIMEOUT);

        return $merged;
    }

    protected function prepareMessagesParam(array $messages, ?string $systemInstruction = null): array
    {
        if ($systemInstruction !== null && $systemInstruction !== '') {
            $systemInstruction .= $this->systemInstructionSuffix();
        }

        $prepared = parent::prepareMessagesParam($messages, $systemInstruction);

        foreach ($prepared as &$message) {
            if (!isset($message['content']) || !is_array($message['content'])) {
                continue;
            }

            $text        = '';
            $allTextOnly = true;
            foreach ($message['content'] as $part) {
                if (is_array($part) && ($part['type'] ?? '') === 'text' && isset($part['text'])) {
                    $text .= (string) $part['text'];
                    continue;
                }
                $allTextOnly = false;
                break;
            }

            if ($allTextOnly) {
                $message['content'] = $text;
            }
        }
        unset($message);

        return $prepared;
    }

    protected function prepareGenerateTextParams(array $prompt): array
    {
        $params  = parent::prepareGenerateTextParams($prompt);
        $modelId = $this->metadata()->getId();

        // Budget guard (stop mode) - before anything is sent.
        if (UsageTracker::overBudget() && UsageTracker::budgetAction() === 'stop') {
            throw new RuntimeException(sprintf(
                /* translators: 1: neurons used today, 2: daily budget */
                __('The daily budget is used up (%1$s of %2$s neurons). Requests resume at midnight UTC. To allow more, raise the daily budget under AIPCF > Settings > Budget.', 'aipcf-ai-provider-for-cloudflare'),
                number_format(UsageTracker::todayNeurons(), 0),
                number_format(UsageTracker::budget())
            ));
        }

        if ($this->hasImagePart($params)) {
            // Image prompts go to the native run endpoint of this exact vision model: a
            // text model cannot read the image and a dynamic route has no run URL.
            // There is no cheaper vision model, so "cheapest" pauses here as well.
            if (UsageTracker::overBudget()) {
                throw new RuntimeException(__('The daily budget is used up. Image reading resumes at midnight UTC. To allow more, raise the daily budget under AIPCF > Settings > Budget.', 'aipcf-ai-provider-for-cloudflare'));
            }
            $params['model'] = $modelId;
        } else {
            // Light-model routing / budget downgrade, then gateway model naming.
            $modelId         = TaskContext::routeTextModel($modelId);
            $params['model'] = Gateway::modelParam($modelId);
        }

        if (!isset($params['max_tokens'])) {
            $default = (int) apply_filters('aipcf_default_max_tokens', 2048, $modelId);
            if ($default > 0) {
                $params['max_tokens'] = $default;
            }
        }

        if (isset($params['chat_template_kwargs'])) {
            return $params;
        }

        // Mistral tokenizers reject chat_template_kwargs outright (HTTP 400),
        // Llama/Granite/Nemotron ignore it, so this stays an allowlist.

        $supportsSwitch = (bool) preg_match('#/(gemma-4|glm-|qwen3|deepseek-v4|nemotron-)#i', $modelId);

        if (apply_filters('aipcf_disable_thinking', $supportsSwitch, $modelId)) {
            $params['chat_template_kwargs'] = ['enable_thinking' => false];
        }

        return $params;
    }

    private function systemInstructionSuffix(): string
    {
        $text   = \WordPress\CloudflareWorkersAiProvider\Prompts::render('system_suffix');
        $suffix = $text !== '' ? "\n\n" . $text : '';

        return (string) apply_filters('aipcf_system_instruction_suffix', $suffix, $this->metadata()->getId());
    }

    protected function getMessagePartContentData(MessagePart $part): ?array
    {
        $file = $part->getType()->isFile() ? $part->getFile() : null;

        if ($file !== null && $file->isRemote() && $file->isImage()) {
            $url = (string) $file->getUrl();
            return [
                'type'      => 'image_url',
                'image_url' => ['url' => $this->fetchImageAsDataUri($url)],
            ];
        }

        return parent::getMessagePartContentData($part);
    }

    private function fetchImageAsDataUri(string $url): string
    {
        $response = wp_remote_get(
            $url,
            [
                'timeout'             => 20,
                'limit_response_size' => self::MAX_INLINE_IMAGE_BYTES,
            ]
        );

        if (is_wp_error($response)) {
            throw new InvalidArgumentException(
                /* translators: 1: image URL, 2: error message */
                sprintf(__('Could not fetch the remote image "%1$s": %2$s', 'aipcf-ai-provider-for-cloudflare'), $url, $response->get_error_message())
            );
        }

        $status = (int) wp_remote_retrieve_response_code($response);
        $body   = (string) wp_remote_retrieve_body($response);
        if ($status < 200 || $status >= 300 || $body === '') {
            throw new InvalidArgumentException(
                /* translators: 1: image URL, 2: HTTP status code */
                sprintf(__('Could not fetch the remote image "%1$s" (HTTP %2$d).', 'aipcf-ai-provider-for-cloudflare'), $url, $status)
            );
        }

        $mime = (string) wp_remote_retrieve_header($response, 'content-type');
        $mime = strtolower(trim(explode(';', $mime)[0]));
        if (strpos($mime, 'image/') !== 0) {
            $detected = function_exists('finfo_open') ? (string) (new \finfo(FILEINFO_MIME_TYPE))->buffer($body) : '';
            $mime     = strpos($detected, 'image/') === 0 ? $detected : 'image/jpeg';
        }

        return 'data:' . $mime . ';base64,' . base64_encode($body); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode -- Workers AI only accepts inline images
    }

    protected function parseResponseChoiceMessageParts(array $messageData, int $index): array
    {
        // The AI plugin's alt-text ability expects the exact token [[DECORATIVE_ALT]]
        // when an image needs empty alt text; Llama wraps it in prose ("The alt
        // text for this image is: [[DECORATIVE_ALT]]"), which the ability would
        // then store verbatim as alt text. Normalise to the bare token.
        if (
            isset($messageData['content']) && is_string($messageData['content'])
            && stripos($messageData['content'], '[[DECORATIVE_ALT]]') !== false
        ) {
            $messageData['content'] = '[[DECORATIVE_ALT]]';
        }

        $parts = parent::parseResponseChoiceMessageParts($messageData, $index);

        $hasReasoningContent = isset($messageData['reasoning_content'])
            && is_string($messageData['reasoning_content'])
            && $messageData['reasoning_content'] !== '';

        if (
            !$hasReasoningContent
            && isset($messageData['reasoning'])
            && is_string($messageData['reasoning'])
            && $messageData['reasoning'] !== ''
        ) {
            array_unshift($parts, new MessagePart($messageData['reasoning'], MessagePartChannelEnum::thought()));
        }

        return $parts;
    }

    protected function throwIfNotSuccessful(Response $response): void
    {
        if ($response->isSuccessful()) {
            return;
        }

        if ($response->getStatusCode() === 429) {
            $d = $response->getData();
            $m = is_array($d) ? ($d['errors'][0]['message'] ?? $d['error']['message'] ?? $d['error'] ?? '') : '';
            $m = is_scalar($m) ? (string) $m : '';
            throw new RuntimeException(
                'Cloudflare Workers AI request was rate-limited (HTTP 429)'
                . ($m !== '' ? ': ' . $m : ' - an AI Gateway rate limit or spend limit was reached, or Workers AI is throttling this account.')
            );
        }

        $data = $response->getData();
        if (Gateway::isLicenceGate($data)) {
            $modelId = $this->metadata()->getId();
            Gateway::recordLicenceGate($modelId, (string) ($data['errors'][0]['message'] ?? ''));
            throw new RuntimeException(Gateway::licenceInstructions($modelId));
        }
        if (is_array($data) && isset($data['errors']) && is_array($data['errors']) && $data['errors'] !== []) {
            $first   = $data['errors'][0];
            $message = is_array($first) && isset($first['message']) ? (string) $first['message'] : '';
            $code    = is_array($first) && isset($first['code']) ? (string) $first['code'] : '';
            if ($message !== '') {
                throw new RuntimeException(
                    sprintf(
                        'Cloudflare Workers AI request failed (HTTP %d%s): %s',
                        $response->getStatusCode(),
                        $code !== '' ? ', code ' . $code : '',
                        $message
                    )
                );
            }
        }

        parent::throwIfNotSuccessful($response);
    }

    protected function parseResponseChoiceToCandidate(array $choiceData, int $index): \WordPress\AiClient\Results\DTO\Candidate
    {
        $msg = isset($choiceData['message']) && is_array($choiceData['message']) ? $choiceData['message'] : [];
        $hasText = isset($msg['content']) && is_string($msg['content']) && trim($msg['content']) !== '';
        $hasReasoning = (isset($msg['reasoning']) && is_string($msg['reasoning']) && $msg['reasoning'] !== '')
            || (isset($msg['reasoning_content']) && is_string($msg['reasoning_content']) && $msg['reasoning_content'] !== '');
        // Qwen3 with thinking switched off returns its answer under `reasoning`
        // with an empty `content`. A completed reply with only reasoning is the
        // answer, not a thought - promote it.
        if (!$hasText && $hasReasoning && ($choiceData['finish_reason'] ?? '') === 'stop' && empty($msg['tool_calls'])) {
            $answer = isset($msg['content']) && is_string($msg['content']) && trim($msg['content']) !== ''
                ? $msg['content']
                : (string) ($msg['reasoning'] ?? $msg['reasoning_content'] ?? '');
            $choiceData['message']['content'] = trim($answer);
            $choiceData['message'] = array_diff_key((array) $choiceData['message'], ['reasoning' => 1, 'reasoning_content' => 1]);
        }

        if (!$hasText && $hasReasoning && ($choiceData['finish_reason'] ?? '') === 'length' && empty($msg['tool_calls'])) {
            throw new RuntimeException(sprintf(
                /* translators: %s: model ID */
                __('The Cloudflare Workers AI model "%s" used all its tokens on reasoning and returned no answer. Raise the maximum tokens for this request or choose a model without reasoning.', 'aipcf-ai-provider-for-cloudflare'),
                $this->metadata()->getId()
            ));
        }

        if (isset($choiceData['finish_reason'])) {
            $known = ['stop', 'length', 'content_filter', 'tool_calls'];
            if (!is_string($choiceData['finish_reason']) || !in_array($choiceData['finish_reason'], $known, true)) {
                $choiceData['finish_reason'] = 'stop';
            }
        } else {
            $choiceData['finish_reason'] = 'stop';
        }

        return parent::parseResponseChoiceToCandidate($choiceData, $index);
    }
}