#ifndef BDL_OBJECTS_H
#define BDL_OBJECTS_H

#include "string_view.h"
#include "darray.h"

typedef enum ObjectType {
    OBJ_TYPE_NIL,
    OBJ_TYPE_TRUE,
    OBJ_TYPE_FALSE,
    OBJ_TYPE_FIXNUM,
    OBJ_TYPE_SYMBOL,
    OBJ_TYPE_STRING,
    OBJ_TYPE_PAIR,
    OBJ_TYPE_LAMBDA,
    OBJ_TYPE_ERR,
} ObjectType;

struct Environment;

typedef struct Object {
    ObjectType type;
    bool marked;
    union {
        // OBJ_TYPE_FIXNUM
        ssize_t fixnum;

        // OBJ_TYPE_STRING
        // OBJ_TYPE_SYMBOL
        struct {
            char *text;
        };

        // OBJ_TYPE_PAIR
        // struct {
        //     struct Object *car;
        //     struct Object *cdr;
        // };

        // OBJ_TYPE_LAMBDA
        // struct {
        //     struct Object *params;
        //     struct Object *body;
        //     struct Environment *env;
        // };
    };
} Object;

void display(Object obj);

// Value initialization.
#define NIL_VAL         ((Object){.type = OBJ_TYPE_NIL})
#define TRUE_VAL        ((Object){.type = OBJ_TYPE_TRUE})
#define FALSE_VAL       ((Object){.type = OBJ_TYPE_FALSE})
#define FIXNUM_VAL(VAL) ((Object){.type = OBJ_TYPE_FIXNUM, .fixnum = VAL})
#define BOOL_VAL(VAL)   ((VAL) ? TRUE_VAL : FALSE_VAL)

// Value extraction.
#define AS_FIXNUM(VAL) ((VAL).fixnum)

// Type checking.
#define IS_TRUE(VAL)   ((VAL).type != OBJ_TYPE_FALSE)
#define IS_FALSE(VAL)  ((VAL).type == OBJ_TYPE_FALSE)
#define IS_FIXNUM(VAL) ((VAL).type == OBJ_TYPE_FIXNUM)
#define IS_STRING(VAL) ((VAL).type == OBJ_TYPE_STRING)
#define IS_SYMBOL(VAL) ((VAL).type == OBJ_TYPE_SYMBOL)

Object make_string(StringView sv) {
    Object obj = {
        .type = OBJ_TYPE_STRING,
        .text = NULL,
    };
    array_init(obj.text, sv.n);
    array_insert(obj.text, sv.start, sv.n);
    return obj;
}

Object make_symbol(StringView sv) {
    Object obj = {
        .type = OBJ_TYPE_SYMBOL,
        .text = NULL,
    };
    array_init(obj.text, sv.n);
    array_insert(obj.text, sv.start, sv.n);
    return obj;
}

void
display(Object obj) {
    switch (obj.type) {
        case OBJ_TYPE_FIXNUM: {
            printf("%zd", obj.fixnum);
        } break;
        case OBJ_TYPE_TRUE: {
            printf("true");
        } break;
        case OBJ_TYPE_FALSE: {
            printf("false");
        } break;
        case OBJ_TYPE_NIL: {
            printf("()");
        } break;
        case OBJ_TYPE_STRING: {
            printf("\"%.*s\"", (int)array_size(obj.text), obj.text);
        } break;
        case OBJ_TYPE_SYMBOL: {
            printf(":%.*s", (int)array_size(obj.text), obj.text);
        } break;
        case OBJ_TYPE_PAIR: {
            // printf("(");
            // display_pair(obj);
            // printf(")");
        } break;
        case OBJ_TYPE_LAMBDA: {
            printf("#{procedure}");
        } break;
        case OBJ_TYPE_ERR: {
            printf("#{error}");
        } break;
    }
    return;
}

void
object_free(Object obj) {
    if (IS_STRING(obj) || IS_SYMBOL(obj)) {
        array_free(obj.text);
    }
}

bool
object_equal(Object a, Object b) {
    if (a.type != b.type) {
        return false;
    }
    switch (a.type) {
        case OBJ_TYPE_TRUE:
        case OBJ_TYPE_FALSE: {
            return true;
        } break;
        case OBJ_TYPE_FIXNUM: {
            return a.fixnum == b.fixnum;
        } break;
        case OBJ_TYPE_SYMBOL:
        case OBJ_TYPE_STRING: {
            if (array_size(a.text) != array_size(b.text)) {
                return false;
            }
            for (size_t i = 0; i < array_size(a.text); i++) {
                if (a.text[i] != b.text[i]) {
                    return false;
                }
            }
        } break;
        default: {
            return false;
        } break;
    }
    return true;
}

#endif // BDL_OBJECTS_H