/**
 *  environment/environment.c
 *
 *  Initialise a MINIMAL environment.
 *
 *  (c) 2026 Simon Brooke <simon@journeyman.cc>
 *  Licensed under GPL version 2.0, or, at your option, any later version.
 */

#include <stdbool.h>

#include "debug.h"

#include "memory/memory.h"
#include "memory/node.h"
#include "memory/pointer.h"
#include "memory/pso.h"
#include "memory/pso2.h"
#include "memory/tags.h"

#include "ops/bind.h"
#include "ops/string_ops.h"

#include "payloads/cons.h"
#include "payloads/exception.h"
#include "payloads/psse_string.h"

/**
 * @brief Flag to prevent re-initialisation.
 */
bool environment_initialised = false;

/**
 * @brief Initialise a minimal environment, so that Lisp can be bootstrapped.
 * 
 * @param node theindex of the node we are initialising.
 * @return struct pso_pointer t on success, else an exception.
 */

struct pso_pointer initialise_environment( uint32_t node ) {
    struct pso_pointer result = initialise_memory( node );

    if ( !exceptionp( result ) ) {
        debug_print( L"Initialising `nil`... ", DEBUG_BOOTSTRAP, 0);
        struct pso_pointer n = allocate( NILTAG, 2 );

        if ( ( n.page == 0 ) && ( n.offset == 0 ) ) {
            struct pso2 *object = pointer_to_object( n );
            object->payload.cons.car = nil;
            object->payload.cons.cdr = nil;

            nil = n;
            debug_print( L"success\n", DEBUG_BOOTSTRAP, 0);
        } else {
            result =
                make_exception( c_string_to_lisp_string
                                ( L"Unexpected cell while allocating `nil`." ),
                                nil, n );
            debug_print( L"fail\n", DEBUG_BOOTSTRAP, 0);
        }
    }
    if ( !exceptionp( result ) ) {
        debug_print( L"Initialising `t`... ", DEBUG_BOOTSTRAP, 0);
        struct pso_pointer n = allocate( TRUETAG, 2 );

        if ( ( n.page == 0 ) && ( n.offset == 1 ) ) {
            struct pso2 *object = pointer_to_object( n );
            object->payload.string.character = L't';
            object->payload.cons.cdr = t;

            t = n;
            debug_print( L"success\n", DEBUG_BOOTSTRAP, 0);
        } else {
            result =
                make_exception( c_string_to_lisp_string
                                ( L"Unexpected cell while allocating `t`." ),
                                nil, n );
            debug_print( L"fail\n", DEBUG_BOOTSTRAP, 0);
        }
    }
    if ( !exceptionp( result ) ) {
        result = c_bind( c_string_to_lisp_symbol( L"nil" ), nil, nil );
        result = c_bind( c_string_to_lisp_symbol( L"t" ), t, result );

        environment_initialised = true;
    }

    return result;
}