#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "types.h"
#include "interpreter.h"
#include "parser.h"

void error(char *msg) {
    if (pc >= 0 && pc < MAX_TOK && pc < tk_idx) {
        printf("Error at token %d ('%c'): %s\n", pc, tokens[pc].type, msg);
    } else {
        printf("Error at token %d: %s\n", pc, msg);
    }
    exit(1);
}

void match(int type) {
    if (pc >= MAX_TOK || pc >= tk_idx) {
        error("Token index out of bounds in match");
    }
    if (tokens[pc].type == type) pc++;
    else error("Unexpected token");
}

int find_local(char *name, int len) {
    if (!name || len < 0 || len >= 32) return -1;
    if (loc_cnt > VAR_MAX) loc_cnt = VAR_MAX;
    for (int i = loc_cnt - 1; i >= 0; i--) {
        if (!strncmp(locals[i].name, name, len) && locals[i].name[len] == 0)
            return i;
    }
    return -1;
}

int find_func(char *name, int len) {
    if (!name || len < 0 || len >= 32) return -1;
    if (func_cnt > 100) func_cnt = 100;
    for (int i = 0; i < func_cnt; i++) {
        if (!strncmp(funcs[i].name, name, len) && funcs[i].name[len] == 0)
            return i;
    }
    return -1;
}

int find_native_func(char *name, int len) {
    if (!name || len < 0 || len >= 32) return -1;
    if (native_func_cnt > 100) native_func_cnt = 100;
    for (int i = 0; i < native_func_cnt; i++) {
        if (!strncmp(native_funcs[i].name, name, len) && native_funcs[i].name[len] == 0)
            return i;
    }
    return -1;
}

void skip_block() {
    int brace = 0;
    do {
        if (pc >= MAX_TOK || pc >= tk_idx) {
            error("Token index out of bounds in skip_block");
        }
        if (tokens[pc].type == '{') brace++;
        if (tokens[pc].type == '}') brace--;
        pc++;
    } while (brace > 0 && pc < MAX_TOK && pc < tk_idx && tokens[pc].type != 0);
}

void statement() {
    if (pc >= MAX_TOK || pc >= tk_idx) {
        error("Token index out of bounds in statement");
    }
    if (tokens[pc].type == '{') {
        pc++;
        while (pc < MAX_TOK && pc < tk_idx && tokens[pc].type != '}' && tokens[pc].type != 0) {
            statement();
            if (ax == -999) break;
        }
        match('}');
    }
    else if (tokens[pc].type == Int || tokens[pc].type == Char) {
        pc++;
        while (pc < MAX_TOK && pc < tk_idx && tokens[pc].type != ';') {
            while (pc < MAX_TOK && pc < tk_idx && tokens[pc].type == '*') pc++;
            if (pc >= MAX_TOK || pc >= tk_idx) break;
            Token *t = &tokens[pc];
            match(Id);

            if (loc_cnt >= VAR_MAX) {
                error("Too many local variables");
            }
            if (sp >= MEM_SIZE) {
                error("Stack overflow");
            }
            int addr = sp;
            Symbol *s = &locals[loc_cnt++];
            strncpy(s->name, t->text, t->val); s->name[t->val] = 0;
            s->addr = addr;
            s->is_array = 0;

            if (pc < MAX_TOK && pc < tk_idx && tokens[pc].type == '[') {
                pc++;
                int size = (int)expression();
                match(']');
                s->is_array = 1;
                if (sp + size >= MEM_SIZE) {
                    error("Stack overflow during array allocation");
                }
                sp += size;
            } else {
                sp++;
            }

            if (pc < MAX_TOK && pc < tk_idx && tokens[pc].type == '=') {
                pc++;
                if (addr >= 0 && addr < MEM_SIZE) {
                    memory[addr] = expression();
                } else {
                    error("Memory access out of bounds");
                }
            }
            if (pc < MAX_TOK && pc < tk_idx && tokens[pc].type == ',') pc++;
        }
        match(';');
    }
    else if (tokens[pc].type == If) {
        pc++;
        match('(');
        long cond = expression();
        match(')');
        if (cond) {
            statement();
            if (ax == -999) return;
            if (pc < MAX_TOK && pc < tk_idx && tokens[pc].type == Else) { pc++; skip_block(); }
        } else {
            skip_block();
            if (pc < MAX_TOK && pc < tk_idx && tokens[pc].type == Else) {
                pc++;
                statement();
                if (ax == -999) return;
            }
        }
    }
    else if (tokens[pc].type == While) {
        pc++;
        int loop_start = pc;
        match('(');
        long cond = expression();
        match(')');
        if (!cond) {
            skip_block();
        } else {
            int iteration_count = 0;
            while (1) {
                if (++iteration_count > 1000000) {
                    error("Potential infinite loop detected");
                }
                statement();
                if (ax == -999) return;
                int save_pc = pc;
                if (loop_start >= MAX_TOK || loop_start >= tk_idx) {
                    error("Loop start out of bounds");
                }
                pc = loop_start;
                match('(');
                cond = expression();
                match(')');
                if (!cond) { pc = save_pc; break; }
            }
        }
    }
    else if (tokens[pc].type == Return) {
        pc++;
        if (pc < MAX_TOK && pc < tk_idx && tokens[pc].type != ';') ax = expression();
        else ax = 0;
        match(';');
        ax = -999;
    }
    else if (tokens[pc].type == Printf) {
        pc++;
        match('(');
        if (pc >= MAX_TOK || pc >= tk_idx) {
            error("Token index out of bounds in printf");
        }
        char *fmt = tokens[pc].text;
        if (!fmt) fmt = "";
        match(Str);

        char *p = fmt;
        while (*p) {
            if (*p == '%' && (p[1] == 'd' || p[1] == 's')) {
                p++;
                match(',');
                long val = expression();
                if (*p == 'd') printf("%ld", val);
                else if (*p == 's') {
                    char *str = (char*)val;
                    if (str) printf("%s", str);
                }
                p++;
            } else {
                putchar(*p++);
            }
        }
        match(')');
        match(';');
    }
    else {
        expression();
        match(';');
    }
}

void scan_functions() {
    int i = 0;
    while (i < MAX_TOK && i < tk_idx && tokens[i].type != 0) {
        if (i + 2 < MAX_TOK && i + 2 < tk_idx &&
            (tokens[i].type == Int || tokens[i].type == Char) &&
            tokens[i+1].type == Id && tokens[i+2].type == '(') {

            if (func_cnt >= 100) {
                error("Too many functions defined");
            }
            Func *f = &funcs[func_cnt++];
            Token *name = &tokens[i+1];
            strncpy(f->name, name->text, name->val); f->name[name->val] = 0;

            i += 3;
            int params = 0;
            while(i < MAX_TOK && i < tk_idx && tokens[i].type != ')') {
                if (tokens[i].type == Int || tokens[i].type == Char) {
                    params++;
                    i++;
                    while (i < MAX_TOK && i < tk_idx && tokens[i].type == '*') i++;
                    if (i < MAX_TOK && i < tk_idx && tokens[i].type == Id) i++;
                } else i++;
            }
            f->param_count = params;
            if (i < MAX_TOK && i < tk_idx) i++;
            f->entry_point = i;

            int brace = 0;
            do {
                if (i >= MAX_TOK || i >= tk_idx) {
                    error("Token index out of bounds in scan_functions");
                }
                if (tokens[i].type == '{') brace++;
                if (tokens[i].type == '}') brace--;
                i++;
            } while (brace > 0 && i < MAX_TOK && i < tk_idx && tokens[i].type != 0);
        } else {
            i++;
        }
    }
}