#include "interpreter.h"
#include "program.h"

#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void loop_end(Program* program) {
    uint32_t count = 1;
    Symbol s;

    while (true) {
        program_next(program, &s);
        if (s == StartLoop) {
            count++;
        } else if (s == EndLoop) {
            count--;
        } else if (s == Eof) {
            return;
        }

        if (count == 0) return;
    }
}

static void loop_start(Program* program) {
    uint32_t count = 1;
    Symbol s;

    program_last(program, &s);
    while (true) {
        program_last(program, &s);
        if (s == StartLoop) {
            count--;
        } else if (s == EndLoop) {
            count++;
        } else if (s == Eof) {
            return;
        }

        if (count == 0) {
            return;
        };
    }
}

static void recurse_program(Program* program, Tape* tape) {
    Symbol s;

next:
    program_next(program, &s);

    // printf("[");
    // for(uint32_t i = 0; i < tape->len; i++) {
    //     printf("0x%02x ", tape->data[i]);
    // }
    // printf("\b]\n ");
    // for(uint32_t i = 0; i < tape->len; i++) {
    //     if (i == tape->index) {
    //         printf("  ^  ");
    //     } else {
    //         printf("     ");
    //     }
    // }
    // printf(" \ + tape->indexn");

    switch (s) {
        case MoveLeft:
            tape_left(tape);
            break;
        case MoveRight:
            tape_right(tape);
            break;
        case Increment:
            tape_set(tape, tape_get(tape) + 1);
            break;
        case Decrement:
            tape_set(tape, tape_get(tape) - 1);
            break;
        case StartLoop:
            if (tape_get(tape) == 0)
                loop_end(program);
            break;
        case EndLoop:
            if (tape_get(tape) != 0)
                loop_start(program);
            break;
        case PutChar: {
            printf("%c", tape_get(tape));
            break;
        }
        case GetChar: {
            uint8_t c = (uint8_t) getchar();
            tape_set(tape, c);
            break;
        }
        case Allocate: {
            uint8_t len = tape_get(tape);
            Tape* new = malloc(sizeof(Tape));
            tape_init(len, new);
            void* ptr = (void*) tape_ptr(tape);
            memcpy(ptr, &new, sizeof(Tape*));
            break;
        }
        case Free: {
            Tape* old;
            void* ptr = (void*) tape_ptr(tape);
            memcpy(&old, ptr, sizeof(Tape*));
            memset(ptr, 0, sizeof(Tape*));
            tape_free(tape);
            free(old);
            break;
        }
        case EnterTape: {
            Tape* cur;
            void* ptr = (void*) tape_ptr(tape);
            memcpy(&cur, ptr, sizeof(Tape*));
            recurse_program(program, cur);
            break;
        }
        case GetString: {
            uint8_t len = tape_get(tape);
            void* ptr = (void*) tape_ptr(tape);
            fgets(ptr, len, stdin);
            break;
        }
        case PutString: {
            char* ptr = (char*) tape_ptr(tape);
            printf("%s", ptr);
            break;
        }
        case Clear:
            printf("\033c");
            break;
        case LeaveTape:
        case Eof:
            return;
    }

    goto next;
}

void run_program(Program* program) {
    Tape tape;
    tape_init(sizeof(void*), &tape);
    recurse_program(program, &tape);
    tape_free(&tape);
}