<?php
/**
 * OpenRouter API Provider
 *
 * Handles all communication with OpenRouter API, including chat completion
 * and image generation.
 *
 * @package WP_Agentic_Writer
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Class WP_Agentic_Writer_OpenRouter_Provider
 *
 * @since 0.1.0
 */
class WP_Agentic_Writer_OpenRouter_Provider {

	/**
	 * API key.
	 *
	 * @var string
	 */
	private $api_key = '';

	/**
	 * Chat model (discussion, research, recommendations).
	 *
	 * @var string
	 */
	private $chat_model = 'google/gemini-2.5-flash';

	/**
	 * Clarity model (prompt analysis, quiz generation).
	 *
	 * @var string
	 */
	private $clarity_model = 'google/gemini-2.5-flash';

	/**
	 * Planning model (article outline generation).
	 *
	 * @var string
	 */
	private $planning_model = 'google/gemini-2.5-flash';

	/**
	 * Writing model (article draft generation).
	 *
	 * @var string
	 */
	private $writing_model = 'anthropic/claude-3.5-sonnet';

	/**
	 * Refinement model (paragraph edits, rewrites).
	 *
	 * @var string
	 */
	private $refinement_model = 'anthropic/claude-3.5-sonnet';

	/**
	 * Image model.
	 *
	 * @var string
	 */
	private $image_model = 'openai/gpt-4o';

	/**
	 * Web search enabled.
	 *
	 * @var bool
	 */
	private $web_search_enabled = false;

	/**
	 * Search depth.
	 *
	 * @var string
	 */
	private $search_depth = 'medium';

	/**
	 * Search engine.
	 *
	 * @var string
	 */
	private $search_engine = 'auto';

	/**
	 * API endpoint.
	 *
	 * @var string
	 */
	private $api_endpoint = 'https://openrouter.ai/api/v1/chat/completions';

	/**
	 * Get cached models from OpenRouter API.
	 *
	 * @since 0.1.0
	 * @return array|WP_Error Models array or WP_Error on failure.
	 */
	public function get_cached_models() {
		// Check if we have cached models.
		$cached_models = get_transient( 'wpaw_openrouter_models' );
		if ( false !== $cached_models ) {
			return $cached_models;
		}

		// Check API key.
		if ( empty( $this->api_key ) ) {
			return new WP_Error(
				'no_api_key',
				__( 'OpenRouter API key is not configured.', 'wp-agentic-writer' )
			);
		}

		// Fetch all models from OpenRouter API.
		$response = wp_remote_get(
			'https://openrouter.ai/api/v1/models',
			array(
				'headers' => array(
					'Authorization' => 'Bearer ' . $this->api_key,
				),
				'timeout' => 30,
			)
		);

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$body = wp_remote_retrieve_body( $response );
		$data = json_decode( $body, true );

		if ( isset( $data['error'] ) ) {
			return new WP_Error(
				'api_error',
				$data['error']['message'] ?? __( 'Unknown API error', 'wp-agentic-writer' )
			);
		}

		$models = $data['data'] ?? array();

		// Debug: Log model count and categorize by output_modalities
		if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
			error_log( 'OpenRouter API total models: ' . count( $models ) );
			
			// Count models by output modality
			$text_count = 0;
			$image_count = 0;
			$image_model_ids = array();
			
			foreach ( $models as $model ) {
				$output_modalities = $model['architecture']['output_modalities'] ?? array();
				if ( in_array( 'text', $output_modalities, true ) ) {
					$text_count++;
				}
				if ( in_array( 'image', $output_modalities, true ) ) {
					$image_count++;
					$image_model_ids[] = $model['id'] . ' (' . ( $model['name'] ?? 'N/A' ) . ')';
				}
			}
			
			error_log( "OpenRouter models by output_modalities: TEXT={$text_count}, IMAGE={$image_count}" );
			error_log( 'Image generation models: ' . implode( ', ', array_slice( $image_model_ids, 0, 20 ) ) );
		}

		// Cache for 24 hours.
		set_transient( 'wpaw_openrouter_models', $models, DAY_IN_SECONDS );

		return $models;
	}

	/**
	 * Fetch models and refresh cache when requested.
	 *
	 * @since 0.1.0
	 * @param bool $force_refresh Whether to refresh cache.
	 * @return array|WP_Error Models array or WP_Error on failure.
	 */
	public function fetch_and_cache_models( $force_refresh = false ) {
		if ( $force_refresh ) {
			delete_transient( 'wpaw_openrouter_models' );
		}

		return $this->get_cached_models();
	}

	/**
	 * Get writing model name (legacy: execution model).
	 *
	 * @since 0.1.0
	 * @return string
	 */
	public function get_execution_model() {
		return $this->writing_model;
	}

	/**
	 * Get model for a specific task type.
	 *
	 * @since 0.1.0
	 * @param string $type Task type (chat, clarity, planning, writing, execution, refinement).
	 * @param array  $options Options array that may contain 'model' override.
	 * @return string Model ID.
	 */
	private function get_model_for_type( $type, $options = array() ) {
		if ( isset( $options['model'] ) ) {
			return $options['model'];
		}

		switch ( $type ) {
			case 'chat':
				return $this->chat_model;
			case 'clarity':
				return $this->clarity_model;
			case 'writing':
			case 'execution':
				return $this->writing_model;
			case 'refinement':
				return $this->refinement_model;
			case 'planning':
			default:
				return $this->planning_model;
		}
	}

	/**
	 * Get singleton instance.
	 *
	 * @since 0.1.0
	 * @return WP_Agentic_Writer_OpenRouter_Provider
	 */
	public static function get_instance() {
		static $instance = null;

		if ( null === $instance ) {
			$instance = new self();
		}

		return $instance;
	}

	/**
	 * Constructor.
	 *
	 * @since 0.1.0
	 */
	private function __construct() {
		// Get settings from the unified settings array.
		$settings = get_option( 'wp_agentic_writer_settings', array() );
		$this->api_key = $settings['openrouter_api_key'] ?? '';

		// Get models from settings (6 models per model-preset-brief.md).
		$this->chat_model = $settings['chat_model'] ?? $this->chat_model;
		$this->clarity_model = $settings['clarity_model'] ?? $this->clarity_model;
		$this->planning_model = $settings['planning_model'] ?? $this->planning_model;
		$this->writing_model = $settings['writing_model'] ?? ( $settings['execution_model'] ?? $this->writing_model );
		$this->refinement_model = $settings['refinement_model'] ?? $this->refinement_model;
		$this->image_model = $settings['image_model'] ?? $this->image_model;

		// Get web search settings.
		$this->web_search_enabled = isset( $settings['web_search_enabled'] ) && '1' === $settings['web_search_enabled'];
		$this->search_depth = $settings['search_depth'] ?? 'medium';
		$this->search_engine = $settings['search_engine'] ?? 'auto';
	}

	/**
	 * Chat completion (non-streaming).
	 *
	 * @since 0.1.0
	 * @param array  $messages Chat messages.
	 * @param array  $options Additional options (model, max_tokens, etc.).
	 * @param string $type Request type (planning or execution).
	 * @return array|WP_Error Response array or WP_Error on failure.
	 */
	public function chat( $messages, $options = array(), $type = 'planning' ) {
		// Check API key.
		if ( empty( $this->api_key ) ) {
			return new WP_Error(
				'no_api_key',
				__( 'OpenRouter API key is not configured.', 'wp-agentic-writer' )
			);
		}

		$web_search_enabled = $this->web_search_enabled;
		if ( is_array( $options ) && array_key_exists( 'web_search_enabled', $options ) ) {
			$web_search_enabled = (bool) $options['web_search_enabled'];
		}
		$search_depth = $options['search_depth'] ?? $this->search_depth;
		$search_engine = $options['search_engine'] ?? $this->search_engine;

		// Determine model based on type (6 models per model-preset-brief.md).
		$model = $this->get_model_for_type( $type, $options );

		// Add :online suffix if web search is enabled.
		if ( $web_search_enabled && 'planning' === $type ) {
			$model .= ':online';
		}

		// Build request body.
		$body = array(
			'model' => $model,
			'messages' => $messages,
			'usage' => array(
				'include' => true,
			),
		);

		// Add optional parameters.
		if ( isset( $options['max_tokens'] ) ) {
			$body['max_tokens'] = $options['max_tokens'];
		}

		if ( isset( $options['temperature'] ) ) {
			$body['temperature'] = $options['temperature'];
		}

		// Add web search options if enabled.
		if ( $web_search_enabled && 'planning' === $type ) {
			$body['plugins'] = array(
				array(
					'id' => 'web',
					'web_search_options' => array(
						'search_context_size' => $search_depth,
						'max_results' => 5,
					),
				),
			);

			// Set search engine if specified.
			if ( 'auto' !== $search_engine ) {
				$body['plugins'][0]['web_search_options']['engine'] = $search_engine;
			}
		}

		// Send request.
		$response = wp_remote_post(
			$this->api_endpoint,
			array(
				'headers' => array(
					'Authorization' => 'Bearer ' . $this->api_key,
					'Content-Type' => 'application/json',
					'HTTP-Referer' => home_url(),
					'X-Title' => 'WP Agentic Writer',
				),
				'body' => wp_json_encode( $body ),
				'timeout' => 120, // 2 minutes timeout.
			)
		);

		// Check for errors.
		if ( is_wp_error( $response ) ) {
			return $response;
		}

		// Get response body.
		$body = wp_remote_retrieve_body( $response );
		$data = json_decode( $body, true );

		// Check for API errors.
		if ( isset( $data['error'] ) ) {
			return new WP_Error(
				'api_error',
				$data['error']['message'] ?? __( 'Unknown API error', 'wp-agentic-writer' )
			);
		}

		// Extract response data.
		$content = $data['choices'][0]['message']['content'] ?? '';
		$input_tokens = $data['usage']['prompt_tokens'] ?? 0;
		$output_tokens = $data['usage']['completion_tokens'] ?? 0;
		$cost = $data['usage']['cost'] ?? 0.0;

		// Extract web search results if available.
		$web_search_results = array();
		if ( isset( $data['choices'][0]['message']['annotations'] ) ) {
			foreach ( $data['choices'][0]['message']['annotations'] as $annotation ) {
				if ( isset( $annotation['url'] ) ) {
					$web_search_results[] = array(
						'url' => $annotation['url'],
						'title' => $annotation['title'] ?? '',
						'description' => $annotation['description'] ?? '',
					);
				}
			}
		}

		return array(
			'content' => $content,
			'input_tokens' => $input_tokens,
			'output_tokens' => $output_tokens,
			'total_tokens' => $input_tokens + $output_tokens,
			'cost' => $cost,
			'model' => $model,
			'web_search_results' => $web_search_results,
		);
	}

	/**
	 * Stream chat completion with callback for each chunk.
	 *
	 * This method streams the AI response token by token, calling the callback
	 * function with each accumulated chunk. This provides real-time feedback
	 * to the user instead of waiting for the complete response.
	 *
	 * @since 0.1.0
	 * @param array    $messages Chat messages.
	 * @param array    $options Additional options (model, max_tokens, etc.).
	 * @param string   $type Request type (planning or execution).
	 * @param callable $callback Callback function( $chunk, $is_complete, $full_content ).
	 * @return array|WP_Error Response array or WP_Error on failure.
	 */
	public function chat_stream( $messages, $options = array(), $type = 'planning', $callback = null ) {
		// Check API key.
		if ( empty( $this->api_key ) ) {
			return new WP_Error(
				'no_api_key',
				__( 'OpenRouter API key is not configured.', 'wp-agentic-writer' )
			);
		}

		$web_search_enabled = $this->web_search_enabled;
		if ( is_array( $options ) && array_key_exists( 'web_search_enabled', $options ) ) {
			$web_search_enabled = (bool) $options['web_search_enabled'];
		}
		$search_depth = $options['search_depth'] ?? $this->search_depth;
		$search_engine = $options['search_engine'] ?? $this->search_engine;

		// Determine model based on type (6 models per model-preset-brief.md).
		$model = $this->get_model_for_type( $type, $options );

		// Add :online suffix if web search is enabled (for planning or execution/chat).
		if ( $web_search_enabled ) {
			$model .= ':online';
		}

		// Build request body.
		$body = array(
			'model' => $model,
			'messages' => $messages,
			'stream' => true, // Enable streaming!
			'stream_options' => array(
				'include_usage' => true,
			),
			'usage' => array(
				'include' => true,
			),
		);

		// Add optional parameters.
		if ( isset( $options['max_tokens'] ) ) {
			$body['max_tokens'] = $options['max_tokens'];
		}

		if ( isset( $options['temperature'] ) ) {
			$body['temperature'] = $options['temperature'];
		}

		// Add web search options if enabled.
		if ( $web_search_enabled ) {
			$body['plugins'] = array(
				array(
					'id' => 'web',
					'web_search_options' => array(
						'search_context_size' => $search_depth,
						'max_results' => 5,
					),
				),
			);

			// Set search engine if specified.
			if ( 'auto' !== $search_engine ) {
				$body['plugins'][0]['web_search_options']['engine'] = $search_engine;
			}
		}

		// Accumulators for content and usage
		$accumulated_content = '';
		$accumulated_usage = array();
		$buffer = ''; // Buffer for incomplete lines

		// Wrapper callback to accumulate content and call user callback
		$accumulating_callback = function( $chunk, $is_complete ) use ( &$accumulated_content, &$accumulated_usage, $callback ) {
			if ( ! $is_complete && ! empty( $chunk ) ) {
				$accumulated_content .= $chunk;
			}

			// Call user callback if provided
			if ( $callback ) {
				call_user_func( $callback, $chunk, $is_complete, $accumulated_content );
			}
		};

		// Use cURL for streaming support (wp_remote_post doesn't support streaming)
		$ch = curl_init( $this->api_endpoint );

		$json_body = wp_json_encode( $body );

		// Set up cURL options with write function
		curl_setopt_array( $ch, array(
			CURLOPT_POST => true,
			CURLOPT_RETURNTRANSFER => false,
			CURLOPT_WRITEFUNCTION => function( $curl, $data ) use ( &$buffer, $accumulating_callback, &$accumulated_usage ) {
				// Append new data to buffer
				$buffer .= $data;

				// Process all complete lines
				while ( true ) {
					$newline_pos = strpos( $buffer, "\n" );
					if ( false === $newline_pos ) {
						// No complete lines, wait for more data
						break;
					}

					// Extract one line
					$line = substr( $buffer, 0, $newline_pos );
					$buffer = substr( $buffer, $newline_pos + 1 );

					$line = trim( $line );
					if ( empty( $line ) ) {
						continue;
					}

					if ( ! str_starts_with( $line, 'data: ' ) ) {
						continue;
					}

					$json_str = substr( $line, 6 );

					if ( '[DONE]' === $json_str ) {
						call_user_func( $accumulating_callback, '', true );
						return strlen( $data );
					}

					$chunk = json_decode( $json_str, true );
					if ( isset( $chunk['choices'][0]['delta']['content'] ) ) {
						$content = $chunk['choices'][0]['delta']['content'];
						call_user_func( $accumulating_callback, $content, false );
					}

					// Accumulate usage data from final chunk
					if ( isset( $chunk['usage'] ) ) {
						$accumulated_usage = $chunk['usage'];
					}
				}

				return strlen( $data );
			},
			CURLOPT_HTTPHEADER => array(
				'Authorization: Bearer ' . $this->api_key,
				'Content-Type: application/json',
				'HTTP-Referer: ' . home_url(),
				'X-Title: WP Agentic Writer',
			),
			CURLOPT_POSTFIELDS => $json_body,
			CURLOPT_TIMEOUT => 180, // 3 minutes timeout for slower models
		) );

		// Execute request
		$result = curl_exec( $ch );
		$http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
		$curl_error = curl_error( $ch );
		curl_close( $ch );

		// Check for errors
		if ( $result === false && ! empty( $curl_error ) ) {
			return new WP_Error(
				'curl_error',
				__( 'cURL error: ', 'wp-agentic-writer' ) . $curl_error
			);
		}

		if ( $http_code >= 400 ) {
			return new WP_Error(
				'api_error',
				sprintf( __( 'API error: HTTP %d', 'wp-agentic-writer' ), $http_code )
			);
		}

		// Calculate cost from usage data
		$input_tokens = $accumulated_usage['prompt_tokens'] ?? 0;
		$output_tokens = $accumulated_usage['completion_tokens'] ?? 0;
		$cost = $accumulated_usage['cost'] ?? 0.0;

		return array(
			'content' => $accumulated_content,
			'input_tokens' => $input_tokens,
			'output_tokens' => $output_tokens,
			'total_tokens' => $input_tokens + $output_tokens,
			'cost' => $cost,
			'model' => $model,
			'web_search_results' => array(), // Streaming doesn't return web search results
		);
	}

	/**
	 * Generate image.
	 *
	 * @since 0.1.0
	 * @param string $prompt Image prompt.
	 * @return array|WP_Error Response array with image URL or WP_Error on failure.
	 */
	public function generate_image( $prompt ) {
		// Check API key.
		if ( empty( $this->api_key ) ) {
			return new WP_Error(
				'no_api_key',
				__( 'OpenRouter API key is not configured.', 'wp-agentic-writer' )
			);
		}

		$messages = array(
			array(
				'role' => 'user',
				'content' => sprintf(
					'Generate an image based on this prompt: %s. Return only the image URL.',
					$prompt
				),
			),
		);

		$response = $this->chat( $messages, array( 'model' => $this->image_model ), 'image' );

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		// Extract image URL from response.
		$content = $response['content'];
		$url = '';

		// Try to extract URL from content.
		if ( preg_match( '/https?:\/\/[^\s]+\.(?:png|jpg|jpeg|gif|webp)/i', $content, $matches ) ) {
			$url = $matches[0];
		}

		return array(
			'url' => $url,
			'prompt' => $prompt,
			'cost' => $response['cost'],
			'model' => $response['model'],
		);
	}
}