#include "dstring.h"
#include "aliases.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// Use this scalar to allocate extra memory in order to avoid having to
// constantly reallocate
#define CAPACITY_SCALAR 8

struct dstring {
  u64 capacity;
  u64 size;
  char buf[];
};

dstr_t *dstr_with_capacity(u64 capacity) {
  dstr_t *out = (dstr_t *)malloc(sizeof(dstr_t) + capacity + 1);

  if (!out) {
    return NULL;
  }

  out->capacity = capacity;
  out->size = 0;
  memset(out->buf, 0, capacity + 1);

  return out;
}

dstr_t *dstr_from_string(const char *str) {
  u64 length = strlen(str);

  u64 capacity = length * CAPACITY_SCALAR;

  dstr_t *out = dstr_with_capacity(capacity);

  if (!out) {
    return NULL;
  }

  out->size = length;
  strncpy(out->buf, str, length);

  return out;
}

void dstr_update(dstr_t **dst, const char *src) {
  if (!(*dst)) {
    return;
  }

  u64 length = strlen(src);

  dstr_t *str = *dst;

  if (length <= str->capacity) {
    memset(str->buf, 0, str->capacity);

    str->size = length;

    strncpy(str->buf, src, length);
  } else {
    u64 capacity = length * CAPACITY_SCALAR;

    dstr_t *tmp = (dstr_t *)realloc(*dst, sizeof(dstr_t) + capacity + 1);

    if (!tmp) {
      return;
    }

    tmp->capacity = capacity;
    tmp->size = length;
    strncpy(tmp->buf, src, length);

    *dst = tmp;
  }
}

void dstr_free(dstr_t **str) {
  if (!(*str)) {
    return;
  }

  free(*str);
  *str = NULL;
}

void dstr_concat(dstr_t **dst, const char *src) {
  if (!(*dst)) {
    return;
  }

  u64 src_length = strlen(src);

  if (src_length == 0) {
    return;
  }

  u64 new_length = (*dst)->size + src_length;

  char str[new_length + 1];
  memset(str, 0, new_length + 1);

  strncpy(str, (*dst)->buf, (*dst)->size);
  strncat(str, src, src_length);

  dstr_update(dst, str);
}

void dstr_append(dstr_t **dst, char c) {
  if (!(*dst)) {
    return;
  }

  u64 new_length = (*dst)->size + 1;

  char str[new_length + 1];
  memset(str, 0, new_length + 1);

  strncpy(str, (*dst)->buf, (*dst)->size);
  str[(*dst)->size] = c;

  dstr_update(dst, str);
}

void dstr_resize(dstr_t **str) {
  u64 capacity = (*str)->size;

  dstr_t *tmp = (dstr_t *)realloc(*str, sizeof(dstr_t) + capacity + 1);

  if (!tmp) {
    return;
  }

  tmp->capacity = capacity;

  *str = tmp;
}

void dstr_clear(dstr_t *str) {
  if (!str || str->size == 0) {
    return;
  }

  memset(str->buf, 0, str->capacity);
  str->size = 0;
}

void dstr_print(const dstr_t *str) {
  if (!str) {
    return;
  }

  printf("%s\n", str->buf);
}

i64 dstr_find(const dstr_t *str, const char *substr) {
  if (!str || !substr) {
    return -1;
  }

  u64 substr_length = strlen(substr);

  if (substr_length == 0 || substr_length > str->size) {
    return -1;
  }

  char buf[substr_length + 1];
  memset(buf, 0, substr_length + 1);

  for (i64 i = 0; i < str->size; ++i) {
    if (i + substr_length >= str->size) {
      break;
    }

    for (u64 j = 0; j < substr_length; ++j) {
      buf[j] = str->buf[i + j];
    }

    if (strcmp(buf, substr) == 0) {
      return i;
    }
  }

  return -1;
}

u64 dstr_length(const dstr_t *str) {
  if (!str) {
    return 0;
  }

  return str->size;
}

u64 dstr_capacity(const dstr_t *str) {
  if (!str) {
    return 0;
  }

  return str->capacity;
}

const char *dstr_to_cstr(const dstr_t *str) {
  if (!str) {
    return "";
  }

  return str->buf;
}