#include "ruby.h"

#include <mysql.h>
#include <errmsg.h>
#include <mysqld_error.h>

#define GetMysqlRes(obj) (Check_Type(obj, T_DATA), ((struct mysql_res*)DATA_PTR(obj))->res)
#define GetLongPtr(obj) (Check_Type(obj, T_DATA), (long*)DATA_PTR(obj))
#define GetCharPtr(obj) (Check_Type(obj, T_DATA), (char*)DATA_PTR(obj))
#define GetCharStarPtr(obj) (Check_Type(obj, T_DATA), (char**)DATA_PTR(obj))

VALUE cRowHash, cClass;

// from mysql/ruby
struct mysql_res {
  MYSQL_RES* res;
  char freed;
};

// row info
#define SLIM_IS_NULL (char)1
#define SLIM_IS_SET (char)2

static VALUE all_hashes(VALUE obj) {
  MYSQL_RES *res = GetMysqlRes(obj);
  MYSQL_FIELD *fields = mysql_fetch_fields(res);
  MYSQL_ROW row;
  VALUE all_hashes_ary, col_names_hsh, row_ary;
  my_ulonglong nr = mysql_num_rows(res);
  unsigned int nf = mysql_num_fields(res);
  unsigned int i, j, s;
  unsigned long *lengths;
  char *row_space, *row_info_space, **pointers_space;

  /* hash of column names */
  col_names_hsh = rb_hash_new();
  for (i=0; i<nf; i++) {
    rb_hash_aset(col_names_hsh, rb_str_new2(fields[i].name), INT2FIX(i));
  }

  /* array of result rows */
  all_hashes_ary = rb_ary_new2(nr);
  for (i=0; i<nr; i++) {
    VALUE frh;
    frh = rb_class_new_instance(0, NULL, cRowHash);
    rb_iv_set(frh, "@field_indexes", col_names_hsh);
    row = mysql_fetch_row(res);         // get the row

    row_ary = rb_ary_new();
    rb_iv_set(frh, "@row", row_ary);    // ready to hold fetched fields

    lengths = mysql_fetch_lengths(res); // get lengths
    for (s=j=0; j < nf; j++) s += lengths[j];  // s = total of lengths
    row_space = malloc(s);
    pointers_space = malloc((nf + 1) * sizeof(char *));
    row_info_space = calloc(nf, 1);
    for (s=j=0; j < nf; j++) {
      int len = lengths[j];
      char *p = row_space + s;
      s += len;
      pointers_space[j] = p;
      if (!row[j]) row_info_space[j] = SLIM_IS_NULL;
      else memcpy(p, row[j], len); // copy row data in
    }
    pointers_space[nf] = row_space + s;
    rb_iv_set(frh, "@pointers", Data_Wrap_Struct(cClass, 0, free, pointers_space));
    rb_iv_set(frh, "@row_info", Data_Wrap_Struct(cClass, 0, free, row_info_space));
    rb_iv_set(frh, "@raw_row", Data_Wrap_Struct(cClass, 0, free, row_space));  // @raw_row contains pointer to the the row data
    rb_ary_store(all_hashes_ary, i, frh);
  }
  return all_hashes_ary;
}

static VALUE fetch_by_index(VALUE obj, VALUE index) {
  VALUE row_ary, row_ary_contents, contents, row_info_obj;
  char *raw_row, *row_info, **pointers, *start;
  long col_number;
  unsigned int length;
  
  col_number = FIX2LONG(index);
  row_info_obj = rb_iv_get(obj, "@row_info");
  row_ary = rb_iv_get(obj, "@row");
  if (NIL_P(row_info_obj)) return rb_ary_entry(row_ary, col_number);  // was marshalled
  else {
    row_info = GetCharPtr(row_info_obj);
    if (row_info[col_number] == SLIM_IS_SET) return rb_ary_entry(row_ary, col_number);  // was set already, return array entry
  }

  if (row_info[col_number] == SLIM_IS_NULL) {  // return nil if null from db
    rb_ary_store(row_ary, col_number, Qnil);
    row_info[col_number] = SLIM_IS_SET;
    return Qnil;
  }
  
  pointers = GetCharStarPtr(rb_iv_get(obj, "@pointers"));
  start = pointers[col_number];
  length = pointers[col_number + 1] - start;
  contents = rb_tainted_str_new(start, length);
  rb_ary_store(row_ary, col_number, contents);
  row_info[col_number] = SLIM_IS_SET;
  return contents;
}

static VALUE slim_fetch(VALUE obj, VALUE name) {
  VALUE real_hash, hash_lookup;
  real_hash = rb_iv_get(obj, "@real_hash");
  if (!NIL_P(real_hash)) return rb_hash_aref(real_hash, name);
  hash_lookup = rb_hash_aref(rb_iv_get(obj, "@field_indexes"), name);
  if (NIL_P(hash_lookup)) return Qnil;
  return fetch_by_index(obj, hash_lookup);
}

static VALUE set_element(VALUE obj, VALUE name, VALUE val) {
  VALUE real_hash, hash_lookup;
  VALUE row_ary, row_info_obj;
  long col_number;

  real_hash = rb_iv_get(obj, "@real_hash");
  if (!NIL_P(real_hash)) return rb_hash_aset(real_hash, name, val);
  
  hash_lookup = rb_hash_aref(rb_iv_get(obj, "@field_indexes"), name);  
  if (NIL_P(hash_lookup)) return rb_funcall(rb_funcall(obj, rb_intern("to_hash"), 0), rb_intern("[]="), 2, name, val);
  row_ary = rb_iv_get(obj, "@row");
  col_number = FIX2LONG(hash_lookup);
  rb_ary_store(row_ary, col_number, val);
  row_info_obj = rb_iv_get(obj, "@row_info");
  if (!NIL_P(row_info_obj)) GetCharPtr(row_info_obj)[col_number] = SLIM_IS_SET;
  return val;
}

void Init_slim_attrib_ext() {
  VALUE c = rb_cObject;
  c = rb_const_get_at(c, rb_intern("Mysql"));
  c = rb_const_get_at(c, rb_intern("Result"));
  rb_define_method(c, "all_hashes", (VALUE(*)(ANYARGS))all_hashes, 0);
  cRowHash = rb_const_get_at(c, rb_intern("RowHash"));
  cClass = rb_define_class("CObjects", cRowHash);
  rb_define_method(cRowHash, "fetch_by_index", (VALUE(*)(ANYARGS))fetch_by_index, 1);
  rb_define_method(cRowHash, "[]", (VALUE(*)(ANYARGS))slim_fetch, 1);
  rb_define_method(cRowHash, "[]=", (VALUE(*)(ANYARGS))set_element, 2);
}