<?php
/**
 * Local Backend Provider
 *
 * Connects to user's local Claude CLI proxy for AI inference
 *
 * @package WP_Agentic_Writer
 */

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

class WP_Agentic_Writer_Local_Backend_Provider implements WP_Agentic_Writer_AI_Provider_Interface {

	/**
	 * Local backend base URL
	 *
	 * @var string
	 */
	private $base_url = '';

	/**
	 * API key (dummy for local backend)
	 *
	 * @var string
	 */
	private $api_key = 'dummy';

	/**
	 * Model identifier
	 *
	 * @var string
	 */
	private $model = 'claude-local';

	/**
	 * Constructor
	 */
	public function __construct() {
		$settings = get_option( 'wp_agentic_writer_settings', array() );
		$this->base_url = $settings['local_backend_url'] ?? '';
		$this->api_key = $settings['local_backend_key'] ?? 'dummy';
		$this->model = $settings['local_backend_model'] ?? 'claude-local';
	}

	/**
	 * Non-streaming chat completion
	 *
	 * @param array  $messages Array of message objects.
	 * @param array  $options  Optional parameters.
	 * @param string $type     Task type.
	 * @return array|WP_Error Response with content, model, tokens, cost.
	 */
	public function chat( $messages, $options = array(), $type = 'planning' ) {
		if ( ! $this->is_configured() ) {
			return new WP_Error(
				'not_configured',
				__( 'Local Backend URL not configured.', 'wp-agentic-writer' )
			);
		}

		$start_time = microtime( true );

		$response = wp_remote_post(
			$this->base_url . '/v1/messages',
			array(
				'headers' => array(
					'Content-Type' => 'application/json',
					'Authorization' => 'Bearer ' . $this->api_key,
				),
				'body' => wp_json_encode(
					array(
						'messages' => $messages,
					)
				),
				'timeout' => 120, // Long timeout for local processing
				'sslverify' => false, // Local network
			)
		);

		$generation_time = microtime( true ) - $start_time;

		if ( is_wp_error( $response ) ) {
			return new WP_Error(
				'connection_failed',
				sprintf(
					/* translators: %s: error message */
					__( 'Local Backend connection failed: %s', 'wp-agentic-writer' ),
					$response->get_error_message()
				)
			);
		}

		$code = wp_remote_retrieve_response_code( $response );
		if ( 200 !== $code ) {
			$body = wp_remote_retrieve_body( $response );
			return new WP_Error(
				'api_error',
				sprintf(
					/* translators: %1$d: HTTP status code, %2$s: response body */
					__( 'Local Backend error (%1$d): %2$s', 'wp-agentic-writer' ),
					$code,
					$body
				)
			);
		}

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

		if ( ! isset( $body['choices'][0]['message']['content'] ) ) {
			return new WP_Error(
				'invalid_response',
				__( 'Invalid response format from Local Backend', 'wp-agentic-writer' )
			);
		}

		$content = $body['choices'][0]['message']['content'];

		return array(
			'content' => $content,
			'model' => $this->model,
			'input_tokens' => 0, // Local backend doesn't track tokens
			'output_tokens' => 0,
			'total_tokens' => 0,
			'cost' => 0, // Free for local backend
			'generation_time' => $generation_time,
		);
	}

	/**
	 * Streaming chat completion (not supported yet)
	 *
	 * @param array    $messages Array of message objects.
	 * @param array    $options  Optional parameters.
	 * @param string   $type     Task type.
	 * @param callable $callback Function to call with each chunk.
	 * @return array|WP_Error Response or error.
	 */
	public function chat_stream( $messages, $options = array(), $type = 'planning', $callback = null ) {
		if ( ! $this->is_configured() ) {
			return new WP_Error(
				'not_configured',
				__( 'Local Backend URL not configured.', 'wp-agentic-writer' )
			);
		}

		$body = array(
			'messages' => $messages,
			'stream' => true,
		);

		$accumulated_content = '';
		$accumulated_usage = array();
		$buffer = '';

		$accumulating_callback = function( $chunk, $is_complete ) use ( &$accumulated_content, $callback ) {
			if ( ! $is_complete && ! empty( $chunk ) ) {
				$accumulated_content .= $chunk;
			}

			if ( $callback ) {
				call_user_func( $callback, $chunk, $is_complete, $accumulated_content );
			}
		};

		$ch = curl_init( $this->base_url . '/v1/messages' );

		curl_setopt_array( $ch, array(
			CURLOPT_POST => true,
			CURLOPT_RETURNTRANSFER => false,
			CURLOPT_SSL_VERIFYPEER => false,
			CURLOPT_SSL_VERIFYHOST => false,
			CURLOPT_WRITEFUNCTION => function( $curl, $data ) use ( &$buffer, $accumulating_callback, &$accumulated_usage ) {
				$buffer .= $data;

				while ( true ) {
					$newline_pos = strpos( $buffer, "\n" );
					if ( false === $newline_pos ) {
						break;
					}

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

					$line = trim( $line );
					if ( empty( $line ) || ! str_starts_with( $line, 'data: ' ) ) {
						continue;
					}

					$json_str = substr( $line, 6 );

					if ( '[DONE]' === $json_str || '"[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'] ) && is_string( $chunk['choices'][0]['delta']['content'] ) ) {
						$content = $chunk['choices'][0]['delta']['content'];
						call_user_func( $accumulating_callback, $content, false );
					}
					// Also support Anthropic format if proxy uses it
					if ( isset( $chunk['type'] ) && 'content_block_delta' === $chunk['type'] && isset( $chunk['delta']['text'] ) ) {
						$content = $chunk['delta']['text'];
						call_user_func( $accumulating_callback, $content, false );
					}

					if ( isset( $chunk['usage'] ) ) {
						$accumulated_usage = $chunk['usage'];
					}
				}

				return strlen( $data );
			},
			CURLOPT_HTTPHEADER => array(
				'Content-Type: application/json',
				'Authorization: Bearer ' . $this->api_key,
			),
			CURLOPT_POSTFIELDS => wp_json_encode( $body ),
			CURLOPT_TIMEOUT => 300,
		) );

		$start_time = microtime( true );
		$result = curl_exec( $ch );
		$http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
		$curl_error = curl_error( $ch );
		curl_close( $ch );

		// Debug logging
		error_log( 'WPAW Local Backend chat_stream: HTTP=' . $http_code . ', curl_result=' . ( $result ? 'true' : 'false' ) . ', curl_error=' . $curl_error . ', accumulated_content_len=' . strlen( $accumulated_content ) . ', buffer_len=' . strlen( $buffer ) );

		if ( false === $result && ! empty( $curl_error ) ) {
			return new WP_Error( 'curl_error', 'cURL error: ' . $curl_error );
		}

		if ( $http_code >= 400 ) {
			return new WP_Error( 'api_error', sprintf( 'API error (%d): %s', $http_code, $buffer ) );
		}

		// FALLBACK: If no SSE chunks were parsed, the proxy likely returned a plain JSON response.
		// Try to parse the leftover buffer as a standard OpenAI/Anthropic JSON response.
		if ( empty( $accumulated_content ) && ! empty( $buffer ) ) {
			error_log( 'WPAW Local Backend: No SSE chunks parsed. Attempting raw JSON fallback. Buffer preview: ' . substr( $buffer, 0, 500 ) );
			$raw_json = json_decode( $buffer, true );
			if ( is_array( $raw_json ) ) {
				// OpenAI format: choices[0].message.content
				if ( isset( $raw_json['choices'][0]['message']['content'] ) ) {
					$accumulated_content = $raw_json['choices'][0]['message']['content'];
					error_log( 'WPAW Local Backend: Extracted content via OpenAI format fallback (' . strlen( $accumulated_content ) . ' chars)' );
				}
				// Anthropic format: content[0].text
				elseif ( isset( $raw_json['content'][0]['text'] ) ) {
					$accumulated_content = $raw_json['content'][0]['text'];
					error_log( 'WPAW Local Backend: Extracted content via Anthropic format fallback (' . strlen( $accumulated_content ) . ' chars)' );
				}
				// Simple format: content string
				elseif ( isset( $raw_json['content'] ) && is_string( $raw_json['content'] ) ) {
					$accumulated_content = $raw_json['content'];
					error_log( 'WPAW Local Backend: Extracted content via simple format fallback (' . strlen( $accumulated_content ) . ' chars)' );
				}

				if ( ! empty( $accumulated_content ) && $callback ) {
					// Emit the full content as a single chunk so the SSE handler picks it up
					call_user_func( $callback, $accumulated_content, false, $accumulated_content );
					call_user_func( $callback, '', true, $accumulated_content );
				}

				// Extract usage if available
				if ( isset( $raw_json['usage'] ) ) {
					$accumulated_usage = $raw_json['usage'];
				}
			} else {
				error_log( 'WPAW Local Backend: Buffer is not valid JSON. First 300 chars: ' . substr( $buffer, 0, 300 ) );
			}
		}

		return array(
			'content' => $accumulated_content,
			'model' => $this->model,
			'input_tokens' => $accumulated_usage['prompt_tokens'] ?? 0,
			'output_tokens' => $accumulated_usage['completion_tokens'] ?? 0,
			'total_tokens' => $accumulated_usage['total_tokens'] ?? 0,
			'cost' => 0,
			'generation_time' => microtime( true ) - $start_time,
		);
	}

	/**
	 * Generate image (not supported by local backend)
	 *
	 * @param string $prompt Image prompt.
	 * @param string $model  Model to use.
	 * @param array  $options Optional parameters.
	 * @return WP_Error Error indicating not supported.
	 */
	public function generate_image( $prompt, $model = null, $options = array() ) {
		return new WP_Error(
			'not_supported',
			__( 'Image generation not supported by Local Backend. Use OpenRouter for images.', 'wp-agentic-writer' )
		);
	}

	/**
	 * Check if provider is configured
	 *
	 * @return bool True if base URL is set.
	 */
	public function is_configured() {
		return ! empty( $this->base_url );
	}

	/**
	 * Test connection to local backend
	 *
	 * @return array|WP_Error Success array or error.
	 */
	public function test_connection() {
		if ( ! $this->is_configured() ) {
			return new WP_Error(
				'not_configured',
				__( 'Local Backend URL not configured', 'wp-agentic-writer' )
			);
		}

		// Test /ping endpoint
		$ping_response = wp_remote_get(
			$this->base_url . '/ping',
			array(
				'timeout' => 5,
				'sslverify' => false,
			)
		);

		if ( is_wp_error( $ping_response ) ) {
			return new WP_Error(
				'ping_failed',
				sprintf(
					/* translators: %s: error message */
					__( 'Cannot reach proxy: %s. Is it running?', 'wp-agentic-writer' ),
					$ping_response->get_error_message()
				)
			);
		}

		$ping_body = wp_remote_retrieve_body( $ping_response );
		if ( 'pong' !== $ping_body ) {
			return new WP_Error(
				'invalid_ping',
				__( 'Proxy responded but with unexpected format', 'wp-agentic-writer' )
			);
		}

		// Test actual inference with simple prompt
		$test_response = wp_remote_post(
			$this->base_url . '/v1/messages',
			array(
				'headers' => array(
					'Content-Type' => 'application/json',
				),
				'body' => wp_json_encode(
					array(
						'messages' => array(
							array(
								'role' => 'user',
								'content' => 'Reply with exactly: Connection test successful',
							),
						),
					)
				),
				'timeout' => 30,
				'sslverify' => false,
			)
		);

		if ( is_wp_error( $test_response ) ) {
			return new WP_Error(
				'inference_failed',
				sprintf(
					/* translators: %s: error message */
					__( 'Inference test failed: %s', 'wp-agentic-writer' ),
					$test_response->get_error_message()
				)
			);
		}

		$test_body = json_decode( wp_remote_retrieve_body( $test_response ), true );
		if ( ! isset( $test_body['choices'][0]['message']['content'] ) ) {
			return new WP_Error(
				'invalid_response',
				__( 'Claude CLI not responding correctly. Check proxy logs.', 'wp-agentic-writer' )
			);
		}

		return array(
			'success' => true,
			'message' => __( 'Connected! Proxy responding correctly.', 'wp-agentic-writer' ),
			'sample_response' => $test_body['choices'][0]['message']['content'],
		);
	}

	/**
	 * Check if provider supports task type
	 *
	 * @param string $type Task type.
	 * @return bool True if supported (all text tasks).
	 */
	public function supports_task_type( $type ) {
		// Local backend supports all text tasks, but not images
		return in_array(
			$type,
			array( 'chat', 'clarity', 'planning', 'writing', 'refinement' ),
			true
		);
	}
}