research.c

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/****************************************************************************
 Freeciv - Copyright (C) 2004 - The Freeciv Team
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
****************************************************************************/
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
/* utility */
#include "iterator.h"
#include "log.h"
#include "shared.h"
#include "string_vector.h"
#include "support.h"
 
/* common */
#include "fc_types.h"
#include "game.h"
#include "nation.h"
#include "player.h"
#include "name_translation.h"
#include "team.h"
#include "tech.h"
 
#include "research.h"
 
 
struct research_iter {
  struct iterator vtable;
  int index;
};
#define RESEARCH_ITER(p) ((struct research_iter *) p)
 
struct research_player_iter {
  struct iterator vtable;
  union {
    struct player *pplayer;
    struct player_list_link *plink;
  };
};
#define RESEARCH_PLAYER_ITER(p) ((struct research_player_iter *) p)
 
#define RESEARCH_ARRAY_SIZE MAX(MAX_NUM_PLAYER_SLOTS, MAX_NUM_TEAM_SLOTS)
static struct research research_array[RESEARCH_ARRAY_SIZE];
 
static struct name_translation advance_unset_name = NAME_INIT;
static struct name_translation advance_future_name = NAME_INIT;
static struct name_translation advance_unknown_name = NAME_INIT;
 
static struct strvec *future_rule_name;
static struct strvec *future_name_translation;
 
/************************************************************************/
void researches_init(void)
{
  int i;
 
  /* Ensure we have enough space for players or teams. */
  fc_assert(ARRAY_SIZE(research_array) >= team_slot_count());
  fc_assert(ARRAY_SIZE(research_array) >= player_slot_count());
 
  memset(research_array, 0, sizeof(research_array));
  for (i = 0; i < ARRAY_SIZE(research_array); i++) {
    research_array[i].tech_goal = A_UNSET;
    research_array[i].researching = A_UNSET;
    research_array[i].researching_saved = A_UNKNOWN;
    research_array[i].future_tech = 0;
    research_array[i].inventions[A_NONE].state = TECH_KNOWN;
    advance_index_iterate(A_FIRST, j) {
      research_array[i].inventions[j].bulbs_researched_saved = 0;
    } advance_index_iterate_end;
  }
 
  game.info.global_advances[A_NONE] = TRUE;
 
  /* Set technology names. */
  /* TRANS: "None" tech */
  name_set(&advance_unset_name, nullptr, N_("?tech:None"));
  name_set(&advance_future_name, nullptr, N_("Future Tech."));
  /* TRANS: "Unknown" advance/technology */
  name_set(&advance_unknown_name, nullptr, N_("(Unknown)"));
 
  future_rule_name = strvec_new();
  future_name_translation = strvec_new();
}
 
/************************************************************************/
void researches_free(void)
{
  strvec_destroy(future_rule_name);
  strvec_destroy(future_name_translation);
}
 
/************************************************************************/
int research_number(const struct research *presearch)
{
  fc_assert_ret_val(presearch != nullptr, -1);
 
  return presearch - research_array;
}
 
/************************************************************************/
struct research *research_by_number(int number)
{
  fc_assert_ret_val(0 <= number, nullptr);
  fc_assert_ret_val(ARRAY_SIZE(research_array) > number, nullptr);
 
  return &research_array[number];
}
 
/************************************************************************/
struct research *research_get(const struct player *pplayer)
{
  if (pplayer == nullptr) {
    /* Special case used at client side. */
    return nullptr;
  } else if (game.info.team_pooled_research) {
    return &research_array[team_number(pplayer->team)];
  } else {
    return &research_array[player_number(pplayer)];
  }
}
 
/************************************************************************/
const char *research_rule_name(const struct research *presearch)
{
  if (game.info.team_pooled_research) {
    return team_rule_name(team_by_number(research_number(presearch)));
  } else {
    return player_name(player_by_number(research_number(presearch)));
  }
}
 
/************************************************************************/
const char *research_name_translation(const struct research *presearch)
{
  if (game.info.team_pooled_research) {
    return team_name_translation(team_by_number(research_number(presearch)));
  } else {
    return player_name(player_by_number(research_number(presearch)));
  }
}
 
/************************************************************************/
int research_pretty_name(const struct research *presearch, char *buf,
                         size_t buf_len)
{
  const struct player *pplayer;
 
  if (game.info.team_pooled_research) {
    const struct team *pteam = team_by_number(research_number(presearch));
 
    if (1 != player_list_size(team_members(pteam))) {
      char buf2[buf_len];
 
      team_pretty_name(pteam, buf2, sizeof(buf2));
      /* TRANS: e.g. "members of team 1", or even "members of team Red".
       * Used in many places where a nation plural might be used. */
      return fc_snprintf(buf, buf_len, _("members of %s"), buf2);
    } else {
      pplayer = player_list_front(team_members(pteam));
    }
  } else {
    pplayer = player_by_number(research_number(presearch));
  }
 
  return fc_strlcpy(buf, nation_plural_for_player(pplayer), buf_len);
}
 
/************************************************************************/
static inline const struct name_translation *
research_advance_name(Tech_type_id tech)
{
  if (A_UNSET == tech) {
    return &advance_unset_name;
  } else if (A_FUTURE == tech) {
    return &advance_future_name;
  } else if (A_UNKNOWN == tech) {
    return &advance_unknown_name;
  } else {
    const struct advance *padvance = advance_by_number(tech);
 
    fc_assert_ret_val(padvance != nullptr, nullptr);
 
    return &padvance->name;
  }
}
 
/************************************************************************/
static const char *research_future_set_name(struct strvec *psv, int no,
                                            const char *new_name)
{
  if (strvec_size(psv) <= no) {
    /* Increase the size of the vector if needed. */
    strvec_reserve(psv, no + 1);
  }
 
  /* Set in vector. */
  strvec_set(psv, no, new_name);
 
  /* Return duplicate of 'new_name'. */
  return strvec_get(psv, no);
}
 
/************************************************************************/
const char *research_advance_rule_name(const struct research *presearch,
                                       Tech_type_id tech)
{
  if (A_FUTURE == tech && presearch != nullptr) {
    const int no = presearch->future_tech;
    const char *name;
 
    name = strvec_get(future_rule_name, no);
    if (name == nullptr) {
      char buffer[256];
 
      /* NB: 'presearch->future_tech == 0' means "Future Tech. 1". */
      fc_snprintf(buffer, sizeof(buffer), "%s %d",
                  rule_name_get(&advance_future_name),
                  no + 1);
      name = research_future_set_name(future_rule_name, no, buffer);
    }
 
    fc_assert(name != nullptr);
 
    return name;
  }
 
  return rule_name_get(research_advance_name(tech));
}
 
/************************************************************************/
const char *
research_advance_name_translation(const struct research *presearch,
                                  Tech_type_id tech)
{
  if (A_FUTURE == tech && presearch != nullptr) {
    const int no = presearch->future_tech;
    const char *name;
 
    name = strvec_get(future_name_translation, no);
    if (name == nullptr) {
      char buffer[256];
 
      /* NB: 'presearch->future_tech == 0' means "Future Tech. 1". */
      fc_snprintf(buffer, sizeof(buffer), _("Future Tech. %d"), no + 1);
      name = research_future_set_name(future_name_translation, no, buffer);
    }
 
    fc_assert(name != nullptr);
 
    return name;
  }
 
  return name_translation_get(research_advance_name(tech));
}
 
/************************************************************************/
static bool reqs_may_activate(const struct req_context *context,
                              const struct req_context *other_context,
                              const struct requirement_vector *reqs,
                              const enum   req_problem_type prob_type)
{
  requirement_vector_iterate(reqs, preq) {
    if (is_req_preventing(context, other_context, preq, prob_type)) {
      return FALSE;
    }
  } requirement_vector_iterate_end;
  return TRUE;
}
 
/************************************************************************/
static bool
research_allowed(const struct research *presearch,
                 Tech_type_id tech,
                 bool (*reqs_eval)(const struct req_context *context,
                                   const struct req_context *ocontext,
                                   const struct requirement_vector *reqs,
                                   const enum   req_problem_type ptype))
{
  struct advance *adv;
 
  adv = valid_advance_by_number(tech);
 
  if (adv == nullptr) {
    /* Not a valid advance. */
    return FALSE;
  }
 
  research_players_iterate(presearch, pplayer) {
    if (reqs_eval(&(const struct req_context) { .player = pplayer },
                  nullptr, &(adv->research_reqs), RPT_CERTAIN)) {
      /* It is enough that one player that shares research is allowed to
       * research it.
       * Reasoning: Imagine a tech with that requires a nation in the
       * player range. If the requirement applies to all players sharing
       * research it will be illegal in research sharing games. To require
       * that the player that fulfills the requirement must order it to be
       * researched creates unnecessary bureaucracy. */
      return TRUE;
    }
  } research_players_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
#define research_is_allowed(presearch, tech)                              \
  research_allowed(presearch, tech, are_reqs_active)
 
/************************************************************************/
#define research_may_become_allowed(presearch, tech)                      \
  research_allowed(presearch, tech, reqs_may_activate)
 
/************************************************************************/
static bool research_get_reachable_rreqs(const struct research *presearch,
                                         Tech_type_id tech)
{
  bv_techs done;
  Tech_type_id techs[game.control.num_tech_types];
  enum tech_req req;
  int techs_num;
  int i;
 
  techs[0] = tech;
  BV_CLR_ALL(done);
  BV_SET(done, A_NONE);
  BV_SET(done, tech);
  techs_num = 1;
 
  /* Check that all recursive requirements have their research_reqs
   * in order. */
  for (i = 0; i < techs_num; i++) {
    if (presearch->inventions[techs[i]].state == TECH_KNOWN) {
      /* This tech is already reached. What is required to research it and
       * the techs it depends on is therefore irrelevant. */
      continue;
    }
 
    if (!research_may_become_allowed(presearch, techs[i])) {
      /* It will always be illegal to start researching this tech because
       * of unchanging requirements. Since it isn't already known and can't
       * be researched it must be unreachable. */
      return FALSE;
    }
 
    /* Check if required techs are research_reqs reachable. */
    for (req = 0; req < AR_SIZE; req++) {
      Tech_type_id req_tech = advance_required(techs[i], req);
 
      if (valid_advance_by_number(req_tech) == nullptr) {
        return FALSE;
      } else if (!BV_ISSET(done, req_tech)) {
        fc_assert(techs_num < ARRAY_SIZE(techs));
        techs[techs_num] = req_tech;
        techs_num++;
 
        BV_SET(done, req_tech);
      }
    }
  }
 
  return TRUE;
}
 
/************************************************************************/
static bool research_get_reachable(const struct research *presearch,
                                   Tech_type_id tech)
{
  if (valid_advance_by_number(tech) == nullptr) {
    return FALSE;
  } else {
    advance_root_req_iterate(advance_by_number(tech), proot) {
      if (advance_requires(proot, AR_ROOT) == proot) {
        /* This tech requires itself; it can only be reached by special
         * means (init_techs, lua script, ...).
         * If you already know it, you can "reach" it; if not, not. (This
         * case is needed for descendants of this tech.) */
        if (presearch->inventions[advance_number(proot)].state != TECH_KNOWN) {
          return FALSE;
        }
      } else {
        enum tech_req req;
 
        for (req = 0; req < AR_SIZE; req++) {
          if (valid_advance(advance_requires(proot, req)) == nullptr) {
            return FALSE;
          }
        }
      }
    } advance_root_req_iterate_end;
  }
 
  /* Check research reqs reachability. */
  if (!research_get_reachable_rreqs(presearch, tech)) {
    return FALSE;
  }
 
  return TRUE;
}
 
/************************************************************************/
static bool research_get_root_reqs_known(const struct research *presearch,
                                         Tech_type_id tech)
{
  advance_root_req_iterate(advance_by_number(tech), proot) {
    if (presearch->inventions[advance_number(proot)].state != TECH_KNOWN) {
      return FALSE;
    }
  } advance_root_req_iterate_end;
 
  return TRUE;
}
 
/************************************************************************/
void research_update(struct research *presearch)
{
  enum tech_flag_id flag;
  int techs_researched;
  Tech_type_id ac = advance_count();
 
  advance_index_iterate_max(A_FIRST, i, ac) {
    enum tech_state state = presearch->inventions[i].state;
    bool root_reqs_known = TRUE;
    bool reachable = research_get_reachable(presearch, i);
 
    /* Finding if the root reqs of an unreachable tech isn't redundant.
     * A tech can be unreachable via research but have known root reqs
     * because of unfilfilled research_reqs. Unfulfilled research_reqs
     * doesn't prevent the player from acquiring the tech by other means. */
    root_reqs_known = research_get_root_reqs_known(presearch, i);
 
    if (reachable) {
      if (state != TECH_KNOWN) {
        /* Update state. */
        state = (root_reqs_known
                 && (presearch->inventions[advance_required(i, AR_ONE)].state
                     == TECH_KNOWN)
                 && (presearch->inventions[advance_required(i, AR_TWO)].state
                     == TECH_KNOWN)
                 && research_is_allowed(presearch, i)
                 ? TECH_PREREQS_KNOWN : TECH_UNKNOWN);
      }
    } else {
      /* We used to assert here that state already is TECH_UNKNOWN. However, there is
       * a special case where it can be e.g. TECH_PREREQS_KNOWN and still
       * unreachable (like in above research_get_reachable() call) because
       * player is dead. Dead player's don't research anything. More accurately
       * research_players_iterate() for a dead player's research iterates over
       * zero players in research_allowed(), so it falls through to default of FALSE.
       *
       * Now we set the state to TECH_UNKNOWN instead of asserting that it already is. */
      state = TECH_UNKNOWN;
    }
    presearch->inventions[i].state = state;
    presearch->inventions[i].reachable = reachable;
    presearch->inventions[i].root_reqs_known = root_reqs_known;
 
    /* Updates required_techs, num_required_techs and bulbs_required. */
    BV_CLR_ALL(presearch->inventions[i].required_techs);
    presearch->inventions[i].num_required_techs = 0;
    presearch->inventions[i].bulbs_required = 0;
 
    if (!reachable || state == TECH_KNOWN) {
      continue;
    }
 
    techs_researched = presearch->techs_researched;
    advance_req_iterate(valid_advance_by_number(i), preq) {
      Tech_type_id j = advance_number(preq);
 
      if (TECH_KNOWN == research_invention_state(presearch, j)) {
        continue;
      }
 
      BV_SET(presearch->inventions[i].required_techs, j);
      presearch->inventions[i].num_required_techs++;
      presearch->inventions[i].bulbs_required +=
          research_total_bulbs_required(presearch, j, FALSE);
      /* This is needed to get a correct result for the
       * research_total_bulbs_required() call when
       * game.info.game.info.tech_cost_style is TECH_COST_CIV1CIV2. */
      presearch->techs_researched++;
    } advance_req_iterate_end;
    presearch->techs_researched = techs_researched;
  } advance_index_iterate_max_end;
 
#ifdef FREECIV_DEBUG
  advance_index_iterate_max(A_FIRST, i, ac) {
    char buf[advance_count() + 1];
 
    advance_index_iterate_max(A_NONE, j, ac) {
      if (BV_ISSET(presearch->inventions[i].required_techs, j)) {
        buf[j] = '1';
      } else {
        buf[j] = '0';
      }
    } advance_index_iterate_max_end;
    buf[advance_count()] = '\0';
 
    log_debug("%s: [%3d] %-25s => %s%s%s",
              research_rule_name(presearch),
              i,
              advance_rule_name(advance_by_number(i)),
              tech_state_name(research_invention_state(presearch, i)),
              presearch->inventions[i].reachable ? "" : " [unreachable]",
              presearch->inventions[i].root_reqs_known
              ? "" : " [root reqs aren't known]");
    log_debug("%s: [%3d] %s", research_rule_name(presearch), i, buf);
  } advance_index_iterate_max_end;
#endif /* FREECIV_DEBUG */
 
  for (flag = 0; flag <= tech_flag_id_max(); flag++) {
    /* Iterate over all possible tech flags (0..max). */
    presearch->num_known_tech_with_flag[flag] = 0;
 
    advance_index_iterate_max(A_NONE, i, ac) {
      if (TECH_KNOWN == research_invention_state(presearch, i)
          && advance_has_flag(i, flag)) {
        presearch->num_known_tech_with_flag[flag]++;
      }
    } advance_index_iterate_max_end;
  }
}
 
/************************************************************************/
enum tech_state research_invention_state(const struct research *presearch,
                                         Tech_type_id tech)
{
  fc_assert_ret_val(valid_advance_by_number(tech) != nullptr,
                    tech_state_invalid());
 
  if (presearch != nullptr) {
    return presearch->inventions[tech].state;
  } else if (game.info.global_advances[tech]) {
    return TECH_KNOWN;
  } else {
    return TECH_UNKNOWN;
  }
}
 
/************************************************************************/
enum tech_state research_invention_set(struct research *presearch,
                                       Tech_type_id tech,
                                       enum tech_state value)
{
  enum tech_state old;
 
  fc_assert_ret_val(valid_advance_by_number(tech) != nullptr, -1);
 
  old = presearch->inventions[tech].state;
  if (old == value) {
    return old;
  }
  presearch->inventions[tech].state = value;
 
  if (value == TECH_KNOWN) {
    if (!game.info.global_advances[tech]) {
      game.info.global_advances[tech] = TRUE;
      game.info.global_advance_count++;
    }
  }
 
  return old;
}
 
/************************************************************************/
bool research_invention_reachable(const struct research *presearch,
                                  const Tech_type_id tech)
{
  if (valid_advance_by_number(tech) == nullptr) {
    return FALSE;
  } else if (presearch != nullptr) {
    return presearch->inventions[tech].reachable;
  } else {
    researches_iterate(research_iter) {
      if (research_iter->inventions[tech].reachable) {
        return TRUE;
      }
    } researches_iterate_end;
 
    return FALSE;
  }
}
 
/************************************************************************/
bool research_invention_gettable(const struct research *presearch,
                                 const Tech_type_id tech,
                                 bool allow_holes)
{
  if (valid_advance_by_number(tech) == nullptr) {
    return FALSE;
  } else if (presearch != nullptr) {
    return (allow_holes
            ? presearch->inventions[tech].root_reqs_known
            : presearch->inventions[tech].state == TECH_PREREQS_KNOWN);
  } else {
    researches_iterate(research_iter) {
      if (allow_holes
          ? research_iter->inventions[tech].root_reqs_known
          : research_iter->inventions[tech].state == TECH_PREREQS_KNOWN) {
        return TRUE;
      }
    } researches_iterate_end;
 
    return FALSE;
  }
}
 
/************************************************************************/
Tech_type_id research_goal_step(const struct research *presearch,
                                Tech_type_id goal)
{
  const struct advance *pgoal = valid_advance_by_number(goal);
 
  if (pgoal == nullptr
      || !research_invention_reachable(presearch, goal)) {
    return A_UNSET;
  }
 
  advance_req_iterate(pgoal, preq) {
    switch (research_invention_state(presearch, advance_number(preq))) {
    case TECH_PREREQS_KNOWN:
      return advance_number(preq);
    case TECH_KNOWN:
    case TECH_UNKNOWN:
       break;
    };
  } advance_req_iterate_end;
  return A_UNSET;
}
 
/************************************************************************/
int research_goal_unknown_techs(const struct research *presearch,
                                Tech_type_id goal)
{
  const struct advance *pgoal = valid_advance_by_number(goal);
 
  if (pgoal == nullptr) {
    return 0;
  } else if (presearch != nullptr) {
    return presearch->inventions[goal].num_required_techs;
  } else {
    return pgoal->num_reqs;
  }
}
 
/************************************************************************/
int research_goal_bulbs_required(const struct research *presearch,
                                 Tech_type_id goal)
{
  const struct advance *pgoal = valid_advance_by_number(goal);
 
  if (pgoal == nullptr) {
    return 0;
  } else if (presearch != nullptr) {
    return presearch->inventions[goal].bulbs_required;
  } else if (game.info.tech_cost_style == TECH_COST_CIV1CIV2) {
    int base_cost = game.info.base_tech_cost * pgoal->num_reqs
      * (pgoal->num_reqs + 1) / 2;
 
    if (base_cost < game.info.min_tech_cost) {
      return game.info.min_tech_cost;
    } else {
      return base_cost;
    }
  } else {
    int bulbs_required = 0;
 
    advance_req_iterate(pgoal, preq) {
      bulbs_required += preq->cost;
    } advance_req_iterate_end;
 
    return bulbs_required;
  }
}
 
/************************************************************************/
bool research_goal_tech_req(const struct research *presearch,
                            Tech_type_id goal, Tech_type_id tech)
{
  const struct advance *pgoal, *ptech;
 
  if (tech == goal
      || (pgoal = valid_advance_by_number(goal)) == nullptr
      || (ptech = valid_advance_by_number(tech)) == nullptr) {
    return FALSE;
  } else if (presearch != nullptr) {
    return BV_ISSET(presearch->inventions[goal].required_techs, tech);
  } else {
    advance_req_iterate(pgoal, preq) {
      if (preq == ptech) {
        return TRUE;
      }
    } advance_req_iterate_end;
 
    return FALSE;
  }
}
 
/************************************************************************/
int research_total_bulbs_required(const struct research *presearch,
                                  Tech_type_id tech, bool loss_value)
{
  enum tech_cost_style tech_cost_style = game.info.tech_cost_style;
  int members;
  double base_cost, total_cost;
  bool leakage = FALSE;
 
  if (valid_advance_by_number(tech) == nullptr) {
    return 0;
  }
 
  if (!loss_value
      && presearch != nullptr
      && !is_future_tech(tech)
      && research_invention_state(presearch, tech) == TECH_KNOWN) {
    /* A non-future tech which is already known costs nothing. */
    return 0;
  }
 
  if (is_future_tech(tech)) {
    /* Future techs use style TECH_COST_CIV1CIV2. */
    tech_cost_style = TECH_COST_CIV1CIV2;
  }
 
  fc_assert_msg(tech_cost_style_is_valid(tech_cost_style),
                "Invalid tech_cost_style %d", tech_cost_style);
  base_cost = 0.0;
  switch (tech_cost_style) {
  case TECH_COST_CIV1CIV2:
    if (presearch != nullptr) {
      base_cost = game.info.base_tech_cost * presearch->techs_researched;
      break;
    }
 
    fc_assert(presearch != nullptr);
    fc__fallthrough; /* No break; Fallback to using preset cost. */
  case TECH_COST_CLASSIC:
  case TECH_COST_CLASSIC_PRESET:
  case TECH_COST_EXPERIMENTAL:
  case TECH_COST_EXPERIMENTAL_PRESET:
  case TECH_COST_LINEAR:
    {
      const struct advance *padvance = valid_advance_by_number(tech);
 
      if (padvance != nullptr) {
        base_cost = padvance->cost;
      } else {
        fc_assert(padvance != nullptr); /* Always fails. */
      }
    }
    break;
  }
 
  total_cost = 0.0;
  members = 0;
  research_players_iterate(presearch, pplayer) {
    members++;
    total_cost += (base_cost
                   * get_player_bonus(pplayer, EFT_TECH_COST_FACTOR));
    if (!leakage && get_player_bonus(pplayer, EFT_TECH_LEAKAGE)) {
      leakage = TRUE;
    }
  } research_players_iterate_end;
  if (0 == members) {
    /* There is no more alive players for this research, no need to apply
     * complicated modifiers. */
    return base_cost * (double) game.info.sciencebox / 100.0;
  }
  base_cost = total_cost / members;
 
  if (leakage) {
    double leak = 0.0;
 
    fc_assert_msg(tech_leakage_style_is_valid(game.info.tech_leakage),
                  "Invalid tech_leakage %d", game.info.tech_leakage);
 
    switch (game.info.tech_leakage) {
    case TECH_LEAKAGE_NONE:
      /* No change */
      break;
 
    case TECH_LEAKAGE_EMBASSIES:
      {
        int players = 0, players_with_tech_and_embassy = 0;
 
        players_iterate_alive(aplayer) {
          const struct research *aresearch = research_get(aplayer);
 
          players++;
          if (aresearch == presearch
              || (A_FUTURE == tech
                  ? aresearch->future_tech <= presearch->future_tech
                  : TECH_KNOWN != research_invention_state(aresearch, tech))) {
            continue;
          }
 
          research_players_iterate(presearch, pplayer) {
            if (player_has_embassy(pplayer, aplayer)) {
              players_with_tech_and_embassy++;
              break;
            }
          } research_players_iterate_end;
        } players_iterate_alive_end;
 
        fc_assert_ret_val(0 < players, base_cost);
        fc_assert(players >= players_with_tech_and_embassy);
        leak = base_cost * players_with_tech_and_embassy
          * game.info.tech_leak_pct / players / 100;
      }
      break;
 
    case TECH_LEAKAGE_PLAYERS:
      {
        int players = 0, players_with_tech = 0;
 
        players_iterate_alive(aplayer) {
          players++;
          if (A_FUTURE == tech
              ? research_get(aplayer)->future_tech > presearch->future_tech
              : TECH_KNOWN == research_invention_state(research_get(aplayer),
                                                       tech)) {
            players_with_tech++;
          }
        } players_iterate_alive_end;
 
        fc_assert_ret_val(0 < players, base_cost);
        fc_assert(players >= players_with_tech);
        leak = base_cost * players_with_tech * game.info.tech_leak_pct
          / players / 100;
      }
      break;
 
    case TECH_LEAKAGE_NO_BARBS:
      {
        int players = 0, players_with_tech = 0;
 
        players_iterate_alive(aplayer) {
          if (is_barbarian(aplayer)) {
            continue;
          }
          players++;
          if (A_FUTURE == tech
              ? research_get(aplayer)->future_tech > presearch->future_tech
              : TECH_KNOWN == research_invention_state(research_get(aplayer),
                                                       tech)) {
            players_with_tech++;
          }
        } players_iterate_alive_end;
 
        fc_assert_ret_val(0 < players, base_cost);
        fc_assert(players >= players_with_tech);
        leak = base_cost * players_with_tech * game.info.tech_leak_pct
          / players / 100;
      }
      break;
    }
 
    if (leak > base_cost) {
      base_cost = 0.0;
    } else {
      base_cost -= leak;
    }
  }
 
  /* Assign a science penalty to the AI at easier skill levels. This code
   * can also be adopted to create an extra-hard AI skill level where the AI
   * gets science benefits. */
 
  total_cost = 0.0;
  research_players_iterate(presearch, pplayer) {
    if (is_ai(pplayer)) {
      fc_assert(0 < pplayer->ai_common.science_cost);
      total_cost += base_cost * pplayer->ai_common.science_cost / 100.0;
    } else {
      total_cost += base_cost;
    }
  } research_players_iterate_end;
  base_cost = total_cost / members;
 
  base_cost *= (double) game.info.sciencebox / 100.0;
 
  return MAX(base_cost, 1);
}
 
 
/************************************************************************/
int player_tech_upkeep(const struct player *pplayer)
{
  const struct research *presearch = research_get(pplayer);
  int f = presearch->future_tech, t = presearch->techs_researched;
  double tech_upkeep = 0.0;
  double total_research_factor;
  int members;
 
  if (TECH_UPKEEP_NONE == game.info.tech_upkeep_style) {
    return 0;
  }
 
  total_research_factor = 0.0;
  members = 0;
  research_players_iterate(presearch, contributor) {
    total_research_factor += (get_player_bonus(contributor, EFT_TECH_COST_FACTOR)
                              + (is_ai(contributor)
                                 ? contributor->ai_common.science_cost / 100.0
                                 : 1));
    members++;
  } research_players_iterate_end;
  if (0 == members) {
    /* No player still alive. */
    return 0;
  }
 
  /* Upkeep cost for 'normal' techs (t). */
  fc_assert_msg(tech_cost_style_is_valid(game.info.tech_cost_style),
                "Invalid tech_cost_style %d", game.info.tech_cost_style);
  switch (game.info.tech_cost_style) {
  case TECH_COST_CIV1CIV2:
    /* sum_1^t x = t * (t + 1) / 2 */
    tech_upkeep += game.info.base_tech_cost * t * (t + 1) / 2;
    break;
  case TECH_COST_CLASSIC:
  case TECH_COST_CLASSIC_PRESET:
  case TECH_COST_EXPERIMENTAL:
  case TECH_COST_EXPERIMENTAL_PRESET:
  case TECH_COST_LINEAR:
    advance_iterate(padvance) {
      if (TECH_KNOWN == research_invention_state(presearch,
                                                 advance_number(padvance))) {
        tech_upkeep += padvance->cost;
      }
    } advance_iterate_end;
    if (0 < f) {
      /* Upkeep cost for future techs (f) are calculated using style 0:
       * sum_t^(t+f) x = (f * (2 * t + f + 1) + 2 * t) / 2 */
      tech_upkeep += (double) (game.info.base_tech_cost
                               * (f * (2 * t + f + 1) + 2 * t) / 2);
    }
    break;
  }
 
  tech_upkeep *= total_research_factor / members;
  tech_upkeep *= (double) game.info.sciencebox / 100.0;
  /* We only want to calculate the upkeep part of one player, not the
   * whole team! */
  tech_upkeep /= members;
  tech_upkeep /= game.info.tech_upkeep_divider;
 
  switch (game.info.tech_upkeep_style) {
  case TECH_UPKEEP_BASIC:
    tech_upkeep -= get_player_bonus(pplayer, EFT_TECH_UPKEEP_FREE);
    break;
  case TECH_UPKEEP_PER_CITY:
    tech_upkeep -= get_player_bonus(pplayer, EFT_TECH_UPKEEP_FREE);
    tech_upkeep *= city_list_size(pplayer->cities);
    break;
  case TECH_UPKEEP_NONE:
    fc_assert(game.info.tech_upkeep_style != TECH_UPKEEP_NONE);
    tech_upkeep = 0.0;
  }
 
  if (0.0 > tech_upkeep) {
    tech_upkeep = 0.0;
  }
 
  log_debug("[%s (%d)] tech upkeep: %d", player_name(pplayer),
            player_number(pplayer), (int) tech_upkeep);
  return (int) tech_upkeep;
}
 
 
/************************************************************************/
size_t research_iter_sizeof(void)
{
  return sizeof(struct research_iter);
}
 
/************************************************************************/
static void *research_iter_get(const struct iterator *it)
{
  return &research_array[RESEARCH_ITER(it)->index];
}
 
/************************************************************************/
static void research_iter_team_next(struct iterator *it)
{
  struct research_iter *rit = RESEARCH_ITER(it);
 
  if (team_slots_initialised()) {
    do {
      rit->index++;
    } while (rit->index < ARRAY_SIZE(research_array) && !it->valid(it));
  }
}
 
/************************************************************************/
static bool research_iter_team_valid(const struct iterator *it)
{
  struct research_iter *rit = RESEARCH_ITER(it);
 
  return (0 <= rit->index
          && ARRAY_SIZE(research_array) > rit->index
          && team_by_number(rit->index) != nullptr);
}
 
/************************************************************************/
static void research_iter_player_next(struct iterator *it)
{
  struct research_iter *rit = RESEARCH_ITER(it);
 
  if (player_slots_initialised()) {
    do {
      rit->index++;
    } while (rit->index < ARRAY_SIZE(research_array) && !it->valid(it));
  }
}
 
/************************************************************************/
static bool research_iter_player_valid(const struct iterator *it)
{
  struct research_iter *rit = RESEARCH_ITER(it);
 
  return (0 <= rit->index
          && ARRAY_SIZE(research_array) > rit->index
          && player_by_number(rit->index) != nullptr);
}
 
/************************************************************************/
struct iterator *research_iter_init(struct research_iter *it)
{
  struct iterator *base = ITERATOR(it);
 
  base->get = research_iter_get;
  it->index = -1;
 
  if (game.info.team_pooled_research) {
    base->next = research_iter_team_next;
    base->valid = research_iter_team_valid;
  } else {
    base->next = research_iter_player_next;
    base->valid = research_iter_player_valid;
  }
 
  base->next(base);
  return base;
}
 
/************************************************************************/
size_t research_player_iter_sizeof(void)
{
  return sizeof(struct research_player_iter);
}
 
/************************************************************************/
static inline bool research_player_iter_valid_state(struct iterator *it)
{
  const struct player *pplayer = iterator_get(it);
 
  return (pplayer == nullptr || pplayer->is_alive);
}
 
/************************************************************************/
static void *research_player_iter_pooled_get(const struct iterator *it)
{
  return player_list_link_data(RESEARCH_PLAYER_ITER(it)->plink);
}
 
/************************************************************************/
static void research_player_iter_pooled_next(struct iterator *it)
{
  struct research_player_iter *rpit = RESEARCH_PLAYER_ITER(it);
 
  do {
    rpit->plink = player_list_link_next(rpit->plink);
  } while (!research_player_iter_valid_state(it));
}
 
/************************************************************************/
static bool research_player_iter_pooled_valid(const struct iterator *it)
{
  return RESEARCH_PLAYER_ITER(it)->plink != nullptr;
}
 
/************************************************************************/
static void *research_player_iter_not_pooled_get(const struct iterator *it)
{
  return RESEARCH_PLAYER_ITER(it)->pplayer;
}
 
/************************************************************************/
static void research_player_iter_not_pooled_next(struct iterator *it)
{
  RESEARCH_PLAYER_ITER(it)->pplayer = nullptr;
}
 
/************************************************************************/
static bool research_player_iter_not_pooled_valid(const struct iterator *it)
{
  return RESEARCH_PLAYER_ITER(it)->pplayer != nullptr;
}
 
/************************************************************************/
struct iterator *research_player_iter_init(struct research_player_iter *it,
                                           const struct research *presearch)
{
  struct iterator *base = ITERATOR(it);
 
  if (game.info.team_pooled_research && presearch != nullptr) {
    base->get = research_player_iter_pooled_get;
    base->next = research_player_iter_pooled_next;
    base->valid = research_player_iter_pooled_valid;
    it->plink = player_list_head(team_members(team_by_number(research_number
                                                             (presearch))));
  } else {
    base->get = research_player_iter_not_pooled_get;
    base->next = research_player_iter_not_pooled_next;
    base->valid = research_player_iter_not_pooled_valid;
    it->pplayer = (presearch != nullptr
                   ? player_by_number(research_number(presearch)) : nullptr);
  }
 
  /* Ensure we have consistent data. */
  if (!research_player_iter_valid_state(base)) {
    iterator_next(base);
  }
 
  return base;
}
 
/************************************************************************/
int research_count(void)
{
  /* TODO: Should have the value stored at the time researches are created */
  int count = 0;
 
  researches_iterate(dummy) {
    (void) dummy; /* To silence warning about unused 'dummy' */
    count++;
  } researches_iterate_end;
 
  return count;
}
 
/************************************************************************/
int recalculate_techs_researched(const struct research *presearch)
{
  int techs = 1; /* A_NONE known, and not part of below iteration */
 
  advance_iterate(t) {
    if (valid_advance(t) != nullptr
        && research_invention_state(presearch, advance_number(t)) == TECH_KNOWN) {
      techs++;
    }
  } advance_iterate_end;
 
  return techs + presearch->future_tech;
}
 
/************************************************************************/
bool research_future_next(const struct research *presearch)
{
  advance_index_iterate(A_FIRST, i) {
    if (research_invention_state(presearch, i) != TECH_KNOWN) {
      return FALSE;
    }
  } advance_index_iterate_end;
 
  return TRUE;
}