#include <stdlib.h>
#include <string.h>
#include "types.h"

extern long memory[MEM_SIZE];
extern int sp;
extern int bp;
extern int pc;
extern long ax;
extern int return_flag;
extern Symbol locals[VAR_MAX];
extern int loc_cnt;

ExecutionContext* context_create() {
    ExecutionContext *ctx = (ExecutionContext*)calloc(1, sizeof(ExecutionContext));
    if (!ctx) return NULL;

    ctx->memory_size = MEM_SIZE;
    ctx->memory = (long*)calloc(MEM_SIZE, sizeof(long));
    if (!ctx->memory) {
        free(ctx);
        return NULL;
    }

    ctx->loc_capacity = VAR_MAX;
    ctx->locals = (Symbol*)calloc(VAR_MAX, sizeof(Symbol));
    if (!ctx->locals) {
        free(ctx->memory);
        free(ctx);
        return NULL;
    }

    ctx->pc = 0;
    ctx->sp = 0;
    ctx->bp = 0;
    ctx->ax = 0;
    ctx->return_flag = 0;
    ctx->loc_cnt = 0;

    return ctx;
}

void context_destroy(ExecutionContext *ctx) {
    if (!ctx) return;

    if (ctx->memory) {
        free(ctx->memory);
    }
    if (ctx->locals) {
        free(ctx->locals);
    }
    free(ctx);
}

ExecutionContext* context_snapshot() {
    ExecutionContext *ctx = context_create();
    if (!ctx) return NULL;

    int safe_sp = sp;
    if (safe_sp < 0) safe_sp = 0;
    if (safe_sp > MEM_SIZE) safe_sp = MEM_SIZE;

    for (int i = 0; i < safe_sp; i++) {
        ctx->memory[i] = memory[i];
    }

    int safe_loc_cnt = loc_cnt;
    if (safe_loc_cnt < 0) safe_loc_cnt = 0;
    if (safe_loc_cnt > VAR_MAX) safe_loc_cnt = VAR_MAX;

    for (int i = 0; i < safe_loc_cnt; i++) {
        ctx->locals[i] = locals[i];
    }

    ctx->pc = pc;
    ctx->sp = safe_sp;
    ctx->bp = bp;
    ctx->ax = ax;
    ctx->return_flag = return_flag;
    ctx->loc_cnt = safe_loc_cnt;

    return ctx;
}

void context_restore(ExecutionContext *ctx) {
    if (!ctx) return;

    int safe_sp = ctx->sp;
    if (safe_sp < 0) safe_sp = 0;
    if (safe_sp > MEM_SIZE) safe_sp = MEM_SIZE;

    for (int i = 0; i < safe_sp; i++) {
        memory[i] = ctx->memory[i];
    }

    int safe_loc_cnt = ctx->loc_cnt;
    if (safe_loc_cnt < 0) safe_loc_cnt = 0;
    if (safe_loc_cnt > VAR_MAX) safe_loc_cnt = VAR_MAX;

    for (int i = 0; i < safe_loc_cnt; i++) {
        locals[i] = ctx->locals[i];
    }

    pc = ctx->pc;
    sp = safe_sp;
    bp = ctx->bp;
    ax = ctx->ax;
    return_flag = ctx->return_flag;
    loc_cnt = safe_loc_cnt;
}