#include "gc.h"
#include "objects.h"

//
// Constructors.
//

Object *
make_fixnum(ssize_t num) {
    Object *obj = alloc_object(OBJ_TYPE_FIXNUM);
    obj->fixnum = num;
    return obj;
}

Object *
make_procedure(Object *(*proc)(struct Environment *, struct Object *args)) {
    Object *obj = alloc_object(OBJ_TYPE_PROCEDURE);
    obj->proc = proc;
    return obj;
}

Object *
make_pair(Object *car, Object *cdr) {
    Object *obj = alloc_object(OBJ_TYPE_PAIR);
    obj->car = car;
    obj->cdr = cdr;
    return  obj;
}

Object *
make_symbol(StringView sv) {
    Object *obj = alloc_object(OBJ_TYPE_SYMBOL);
    obj->symbol = malloc(sizeof(char) * sv.n);
    memcpy(obj->symbol, sv.start, sv.n);
    obj->symbol_n = sv.n;
    return obj;
}

Object *
make_string(void) {
    Object *obj = alloc_object(OBJ_TYPE_STRING);
    obj->string = NULL;
    obj->string_n = 0;
    return obj;
}

void
append_string(Object *obj, const StringView sv) {
    assert(obj != NULL);
    assert(obj->type == OBJ_TYPE_STRING);
    if (sv.n == 0) {
        return;
    }
    obj->string = realloc(obj->string, (obj->string_n + sv.n) * sizeof(char));
    memcpy(obj->string + obj->string_n, sv.start, sv.n);
    obj->string_n += sv.n;
}

void
display_pair(Object *root) {
    display(root->car);
    if (root->cdr->type == OBJ_TYPE_PAIR) {
        printf(" ");
        display_pair(root->cdr);
    } else if (root->cdr == obj_nil) {
        return;
    } else {
        printf(" . ");
        display(root->cdr);
    }
}

void
display(Object *root) {
    switch (root->type) {
        case OBJ_TYPE_FIXNUM: {
            printf("%zd", root->fixnum);
        } break;
        case OBJ_TYPE_BOOL: {
            if (root == obj_true) {
                printf("true");
            } else {
                printf("false");
            }
        } break;
        case OBJ_TYPE_NIL: {
            printf("()");
        } break;
        case OBJ_TYPE_STRING: {
            printf("\"%.*s\"", (int)root->string_n, root->string);
        } break;
        case OBJ_TYPE_SYMBOL: {
            printf(":%.*s", (int)root->symbol_n, root->symbol);
        } break;
        case OBJ_TYPE_PAIR: {
            printf("(");
            display_pair(root);
            printf(")");
        } break;
        case OBJ_TYPE_LAMBDA:
        case OBJ_TYPE_PROCEDURE: {
            printf("#{procedure}");
        } break;
        case OBJ_TYPE_ERR: {
            printf("#{error}");
        } break;
    }
    return;
}

bool
obj_eq(Object *a, Object* b) {
    if (a->type != b->type) {
        return false;
    }
    switch (a->type) {
        case OBJ_TYPE_FIXNUM: {
            return a->fixnum == b->fixnum;
        } break;
        case OBJ_TYPE_STRING: {
            if (a->string_n != b->string_n) {
                return false;
            }
            for (size_t i = 0; i < a->string_n; i++) {
                if (a->string[i] != b->string[i]) {
                    return false;
                }
            }
        } break;
        case OBJ_TYPE_SYMBOL: {
            if (a->symbol_n != b->symbol_n) {
                return false;
            }
            for (size_t i = 0; i < a->symbol_n; i++) {
                if (a->symbol[i] != b->symbol[i]) {
                    return false;
                }
            }
        } break;
        default: {
            return a == b;
        } break;
    }
    return true;
}