<?php
defined( 'ABSPATH' ) || exit;

/**
 * Sara REST endpoint. Provides the LLM round-trip from the JS bubble.
 *
 * Endpoint: POST /sa-orch/v1/sara/invoke
 * Body:     { surface: string|null, ref: string|null, prompt: string }
 * Returns:  { response: string, context: {...} }   on success
 *           { error: string, message: string }    on failure (HTTP 502)
 *
 * Capability: manage_options. Same gate as the rest of the SA-Orch admin.
 *
 * No DB writes. No mutation. Pure round-trip to the configured LLM
 * provider via SA_Orch_Sara_Service.
 */
class SA_Orch_Sara_Rest {

    public static function register_routes() {
        register_rest_route( 'sa-orch/v1', '/sara/invoke', [
            'methods'  => 'POST',
            'callback' => [ __CLASS__, 'invoke' ],
            'permission_callback' => function () {
                return current_user_can( 'manage_options' );
            },
            'args' => [
                'surface'       => [ 'type' => 'string', 'required' => false ],
                'ref'           => [ 'type' => 'string', 'required' => false ],
                'page'          => [ 'type' => 'string', 'required' => false ],
                'prompt'        => [ 'type' => 'string', 'required' => true ],
                'history'       => [ 'type' => 'array',  'required' => false ],
                'asterion_file' => [ 'type' => 'string', 'required' => false ], // Board #28
            ],
        ] );
    }

    public static function invoke( WP_REST_Request $request ) {
        $surface       = sanitize_text_field( (string) $request->get_param( 'surface' ) );
        $ref           = sanitize_text_field( (string) $request->get_param( 'ref' ) );
        $page          = sanitize_text_field( (string) $request->get_param( 'page' ) );
        $prompt        = (string) $request->get_param( 'prompt' );
        $asterion_file = sanitize_text_field( (string) $request->get_param( 'asterion_file' ) );
        $history       = $request->get_param( 'history' );
        if ( ! is_array( $history ) ) {
            $history = [];
        }

        if ( trim( $prompt ) === '' ) {
            return new WP_REST_Response( [
                'error'   => 'empty_prompt',
                'message' => 'prompt is required',
            ], 400 );
        }

        $context = [
            'surface' => $surface !== '' ? $surface : null,
            'ref'     => $ref     !== '' ? $ref     : null,
        ];

        $result = SA_Orch_Sara_Service::invoke( $context, $prompt, $history, $page, $asterion_file );

        if ( is_wp_error( $result ) ) {
            return new WP_REST_Response( [
                'error'   => $result->get_error_code(),
                'message' => $result->get_error_message(),
            ], 502 );
        }

        // Service now returns a wrapping shape: { response, usage, log_id }.
        // Pass the structured response through as-is for backward-compat with
        // the existing JS contract; surface usage + log_id alongside for Board #16.
        return new WP_REST_Response( [
            'response' => $result['response'],
            'usage'    => $result['usage']  ?? null,
            'log_id'   => $result['log_id'] ?? null,
            'context'  => $context,
            'page'     => $page !== '' ? $page : null,
            'turn'     => count( $history ) / 2 + 1,  // 1-indexed turn number for UI feedback
        ], 200 );
    }
}