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

#include "lsm.h"
#include "lsm/str_internal.h"

#define MIN(x, y) (((x) < (y)) ? (x) : (y))

lsm_error lsm_str_init(lsm_str **ptr, char *s) {
  lsm_str *str = calloc(1, sizeof(lsm_str));

  if (str == NULL) {
    return lsm_error_failed_alloc;
  }

  lsm_str_overwrite(str, s);

  *ptr = str;

  return lsm_error_ok;
}

lsm_error lsm_str_init_zero(lsm_str **ptr) {
  lsm_str *str = calloc(1, sizeof(lsm_str));

  if (str == NULL) {
    return lsm_error_failed_alloc;
  }

  *ptr = str;

  return lsm_error_ok;
}

lsm_error lsm_str_init_copy(lsm_str **ptr, const char *s) {
  lsm_str *str = calloc(1, sizeof(lsm_str));

  if (str == NULL) {
    return lsm_error_failed_alloc;
  }

  lsm_str_overwrite_copy(str, s);

  *ptr = str;

  return lsm_error_ok;
}

lsm_error lsm_str_init_copy_n(lsm_str **ptr, const char *s, uint64_t len) {
  lsm_str *str = calloc(1, sizeof(lsm_str));

  if (str == NULL) {
    return lsm_error_failed_alloc;
  }

  lsm_str_overwrite_copy_n(str, s, len);

  *ptr = str;

  return lsm_error_ok;
}

void lsm_str_overwrite(lsm_str *str, char *s) {
  str->len = strlen(s);

  if (str->len <= 8) {
    memcpy(str->data.val, s, str->len);
    free(s);
  } else {
    str->data.ptr = s;
  }
}

lsm_error lsm_str_overwrite_copy(lsm_str *str, const char *s) {
  return lsm_str_overwrite_copy_n(str, s, strlen(s));
}

lsm_error lsm_str_overwrite_copy_n(lsm_str *str, const char *s, uint64_t len) {
  if (len <= 8) {
    memcpy(str->data.val, s, len);
  } else {
    char *buf = malloc(len * sizeof(char));

    if (buf == NULL) {
      return lsm_error_failed_alloc;
    }

    memcpy(buf, s, len);
    str->data.ptr = buf;
  }

  str->len = len;

  return lsm_error_ok;
}

void lsm_str_zero(lsm_str *str) {
  if (str->len > 8) {
    free(str->data.ptr);
  }

  str->len = 0;
}

void lsm_str_free(lsm_str *str) {
  lsm_str_zero(str);
  free(str);
}

uint64_t lsm_str_len(const lsm_str *str) { return str->len; }

const char *lsm_str_ptr(lsm_str *str) {
  if (str->len <= 8) {
    return str->data.val;
  } else {
    return str->data.ptr;
  }
}

char lsm_str_char(lsm_str *str, uint64_t index) {
  if (str->len <= 8) {
    return str->data.val[index];
  } else {
    return str->data.ptr[index];
  }
}

lsm_error lsm_str_substr(lsm_str *out, lsm_str *str, uint64_t start,
                         uint64_t end) {
  // A substring that starts past the string's length will have length 0
  uint64_t len = start < str->len ? end - start : 0;
  const char *str_ptr = lsm_str_ptr(str);

  if (len <= 8) {
    /* lsm_str_zero(out); */
    memcpy(out->data.val, &str_ptr[start], len);
  } else {
    char *buf = malloc(len * sizeof(char));

    if (buf == NULL) {
      return lsm_error_failed_alloc;
    }

    memcpy(buf, &str_ptr[start], len);

    /* lsm_str_zero(out); */
    out->data.ptr = buf;
  }

  out->len = len;

  return lsm_error_ok;
}

uint64_t lsm_str_cmp(lsm_str *s1, uint64_t s1_offset, lsm_str *s2,
                     uint64_t s2_offset) {
  uint64_t index = 0;
  uint64_t max_len = MIN(s1->len - s1_offset, s2->len - s2_offset);

  while ((index < max_len) && (lsm_str_char(s1, s1_offset + index) ==
                               lsm_str_char(s2, s2_offset + index))) {
    index++;
  }

  return index;
}

lsm_error lsm_str_truncate(lsm_str *s, uint64_t new_len) {
  if (new_len >= s->len) {
    return lsm_error_ok;
  }

  if (new_len <= 8) {
    char *s_buf = s->data.ptr;

    memcpy(s->data.val, lsm_str_ptr(s), new_len);

    if (s->len > 8) {
      free(s_buf);
    }
  } else {
    char *buf = malloc(new_len * sizeof(char));

    if (buf == NULL) {
      return lsm_error_failed_alloc;
    }

    memcpy(buf, s->data.ptr, new_len);
    free(s->data.ptr);

    s->data.ptr = buf;
  }

  s->len = new_len;

  return lsm_error_ok;
}

lsm_error lsm_str_split(lsm_str *s, lsm_str *s2, uint64_t index) {
  lsm_error res = lsm_str_substr(s2, s, index, s->len);

  if (res != lsm_error_ok) {
    return res;
  }

  return lsm_str_truncate(s, index);
}

bool lsm_str_eq(lsm_str *s1, lsm_str *s2) {
  if (s1->len != s2->len) {
    return false;
  }

  return memcmp(lsm_str_ptr(s1), lsm_str_ptr(s2), s1->len) == 0;
}

lsm_error lsm_str_append(lsm_str *s, lsm_str *s2) {
  if (s2->len == 0) {
    return lsm_error_ok;
  }

  uint64_t new_len = s->len + s2->len;

  if (new_len <= 8) {
    memcpy(&s->data.val[s->len], s2->data.val, s2->len);
  } else {
    char *buf;

    if (s->len <= 8) {
      buf = malloc(new_len * sizeof(char));

      if (buf == NULL) {
        return lsm_error_failed_alloc;
      }

      memcpy(buf, s->data.val, s->len);
    } else {
      buf = realloc(s->data.ptr, new_len * sizeof(char));

      if (buf == NULL) {
        return lsm_error_failed_alloc;
      }
    }

    memcpy(&buf[s->len], lsm_str_ptr(s2), s2->len);
    s->data.ptr = buf;
  }

  s->len += s2->len;

  return lsm_error_ok;
}