#include "plstring.h"

#include <string.h>

Object charVal(Object* params, unused int length, unused struct Environment* env)
{
    checkTypes(charVal)
    Object test = params[0];

    return numberObject(test.string[0]);
}

Object chars(Object* params, unused int length, unused struct Environment* env)
{
    checkTypes(chars)
    char c[2];
    c[1] = '\0';
    int i = 0;
    Object list = listObject();
    while (params[0].string[i]) {
        c[0] = params[0].string[i];
        nf_addToList(&list, stringFromSlice(c, 1));
        i++;
    }
    return list;
}

size_t literalLen(const char* pattern)
{
    const char* cursor = pattern;
    while (*cursor != '*' && *cursor != '\0') {
        cursor++;
    }
    return cursor - pattern;
}

/// Returns 1 on match, 0 otherwise
int stringComp(const char* string, const char* pattern)
{
    const char* cursor = string;
    const char* patternCursor = pattern;

    while (*patternCursor) {
        size_t len = literalLen(patternCursor);
        if (len == 0) {
            patternCursor += 1;
            while (!stringComp(cursor, patternCursor)) {
                cursor++;
                if (*cursor == '\0') {
                    return 0;
                }
            }
        } else {
            if (strncmp(patternCursor, cursor, len) != 0) {
                return 0;
            }
            patternCursor += len;
        }
    }
    return 1;
}

Object matches(Object* params, int length, unused struct Environment* env)
{
    checkTypes(matches)
    return boolObject(stringComp(params[0].string, params[1].string));
}

Object slen(Object* params, int length, unused struct Environment* env)
{
    checkTypes(slen)
    return numberObject(strlen(params[0].string));
}

Object substring(Object* params, int length, unused struct Environment* env)
{
    checkTypes(substring)
    Object start = params[0]; // First char to include
    Object end = params[1];   // First char to exclude
    Object string = params[2];

    long len = end.number - start.number;
    size_t stringLen = strlen(string.string);
    if (len < 0) {
        throw(BAD_PARAMS, "substr start index (%ld) is higher than its end index (%ld)!", start.number, end.number);
    }
    if (start.number > stringLen) {
        throw(BAD_PARAMS, "substr start index (%ld) is higher than the string length (%lu)", start.number, stringLen);
    }

    if (len > stringLen - start.number) {
        len = stringLen - start.number;
    }

    Object substr = withLen(len, TYPE_STRING);
    snprintf(substr.string, len + 1, "%s", string.string + start.number);
    return substr;
}

Object charAt(Object* params, unused int length, unused struct Environment* env)
{
    checkTypes(charAt)
    Object string = params[0];
    Object at = params[1];

    Object c = withLen(1, string.type);
    c.string[1] = '\0';

    for (int i = 0; i < at.number; i++) {
        if (string.string[i] == '\0') {
            c.string[0] = '\0';
            return c;
        }
    }

    c.string[0] = string.string[at.number];
    return c;
}