/**
 * @file unidiff.c
 *
 * @brief Handles the application and removal of 'diffs' to the universe.
 *
 * Diffs allow changing planets, fleets, factions etc.. in the universe.
 * These are meant to be applied after the player triggers them, mostly
 * through missions.
 */

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

#include "lephisto.h"
#include "log.h"
#include "lxml.h"
#include "space.h"
#include "ldata.h"
#include "unidiff.h"

#define CHUNK_SIZE    32                    /**< Size of chunk to allocate. */
#define DIFF_DATA     "../dat/unidiff.xml"  /**< Unidff XML file. */

/**
 * @enum UniHunkTargetType_t
 *
 * @brief Represents the possible hunk targets.
 */
typedef enum UniHunkTargetType_ {
  HUNK_TARGET_NONE,
  HUNK_TARGET_SYSTEM
} UniHunkTargetType_t;

/**
 * @struct UniHunkTarget_t
 *
 * @brief Represents the hunks target.
 */
typedef struct UniHunkTarget_ {
  UniHunkTargetType_t type;
  union {
    char* name;
  } u;
} UniHunkTarget_t;

/**
 * @enum UniHunkType_t
 *
 * @brief Represents the different type of hunk actions.
 */
typedef enum UniHunkType_ {
  HUNK_TYPE_NONE,
  /* Target should be system. */
  HUNK_TYPE_PLANET_ADD,
  HUNK_TYPE_PLANET_REMOVE,
  HUNK_TYPE_FLEET_ADD,
  HUNK_TYPE_FLEET_REMOVE
} UniHunkType_t;

/**
 * @struct UniHunk_t
 *
 * @brief Represents a single hunk in the diff.
 */
typedef struct UniHunk_ {
  UniHunkTarget_t target; /**< Hunk's target. */
  
  UniHunkType_t type; /**< Type of hunk it is. */
  union {
    char* name;
    SystemFleet fleet;
  } u; /* Actual data to patch. */
} UniHunk_t;

/**
 * @struct UniDiff_t
 *
 * @brief Represents each Universe Diff.
 */
typedef struct UniDiff_ {
  char* name;           /**< Name of the diff. */

  UniHunk_t* applied;   /**< Applied hunks. */
  int napplied;         /**< Number of applied hunks. */
  int mapplied;         /**< Memory of applied hunks. */

  UniHunk_t* failed;    /**< Failed hunks. */
  int nfailed;          /**< Number of failed hunks. */
  int mfailed;          /**< Memory of failed hunks. */
} UniDiff_t;

/* Diff stack. */
static UniDiff_t* diff_stack = NULL;  /**< Currently applied universe diffs. */
static int diff_nstack = 0;           /**< Number of diffs in the stack. */
static int diff_mstack = 0;           /**< Currently allocated diffs. */

static UniDiff_t* diff_get(char* name);
static UniDiff_t* diff_newDiff(void);
static int diff_removeDiff(UniDiff_t* diff);
static int diff_patch(xmlNodePtr parent);
static int diff_patchHunk(UniHunk_t* hunk);
static void diff_hunkFailed(UniDiff_t* diff, UniHunk_t* hunk);
static void diff_hunkSuccess(UniDiff_t* diff, UniHunk_t* hunk);
static void diff_cleanup(UniDiff_t* diff);
static void diff_cleanupHunk(UniHunk_t* hunk);
/* Externed. */
int diff_save(xmlTextWriterPtr writer);
int diff_load(xmlNodePtr parent);

/**
 * @fn int diff_isApplied(char* name)
 *
 * @brief Check if a diff is currently applied.
 *    @param name Diff to check.
 *    @return 0 if it's not applied, 1 if it is.
 */
int diff_isApplied(char* name) {
  if(diff_get(name) != NULL)
    return 1;
  return 0;
}

/**
 * @fn static UniDiff_t* diff_get(char* name)
 *
 * @brief Get a diff by name.
 *    @param name Name of the diff to get.
 *    @return The diff if found or NULL if not found.
 */
static UniDiff_t* diff_get(char* name) {
  int i;
  for(i = 0; i < diff_nstack; i++)
    if(strcmp(diff_stack[i].name, name)==0)
      return &diff_stack[i];
  return NULL;
}

/**
 * @fn int diff_apply(char* name)
 *
 * @brief Applies a diff to the universe.
 *    @param name Diff to apply.
 *    @return 0 on success.
 */
int diff_apply(char* name) {
  xmlNodePtr node;
  xmlDocPtr doc;
  uint32_t bufsize;
  char* buf;
  char* diffname;

  /* Check if already applied. */
  if(diff_isApplied(name))
    return 0;

  buf = ldata_read(DIFF_DATA, &bufsize);
  doc = xmlParseMemory(buf, bufsize);

  node = doc->xmlChildrenNode;
  if(strcmp((char*)node->name, "unidiffs")) {
    WARN("Malformed unidiff file: missing root element 'unidiffs'");
    return 0;
  }

  node = node->xmlChildrenNode; /* First system node. */
  if(node == NULL) {
    ERR("Malformed unidiff file: does not contain elements");
    return 0;
  }

  do {
    if(xml_isNode(node, "unidiff")) {
      /* Check to see if it's the diff we're looking for. */
      xmlr_attr(node, "name", diffname);
      if(strcmp(diffname, name)==0) {
        /* Apply it. */
        diff_patch(node);

        /* Clean up. */
        free(diffname);
        xmlFreeDoc(doc);
        free(buf);

        return 0;
      }
      free(diffname);
    }
  } while(xml_nextNode(node));

  /* More clean up. */
  xmlFreeDoc(doc);
  free(buf);

  WARN("UniDiff '%s' not found in "DIFF_DATA".", name);
  return -1;
}

/**
 * @fn static int diff_patch(xmlNodePtr parent)
 *
 * @brief Actually applies a diff in XML node form.
 *    @param parent Node containing the diff information.
 *    @return 0 on success.
 */
static int diff_patch(xmlNodePtr parent) {
  int i;
  UniDiff_t* diff;
  UniHunk_t base, hunk, *fail;
  xmlNodePtr node, cur;
  char* buf, *target;

  /* Prepare it. */
  diff = diff_newDiff();
  memset(diff, 0, sizeof(UniDiff_t));
  xmlr_attr(parent, "name", diff->name);

  node = parent->xmlChildrenNode;
  do {
    if(xml_isNode(node, "system")) {
      /* Set the target. */
      memset(&base, 0, sizeof(UniHunk_t));
      base.target.type = HUNK_TARGET_SYSTEM;
      xmlr_attr(node, "name", base.target.u.name);
      if(base.target.u.name == NULL)
        WARN("UniDiff '%s' has a system node without a 'name' tag", diff->name);

      /* Now parse the possible changes. */
      cur = node->xmlChildrenNode;
      do {
        if(xml_isNode(cur, "planet")) {
          hunk.target.type    = base.target.type;
          hunk.target.u.name  = strdup(base.target.u.name);

          /* Get the planet to modify. */
          xmlr_attr(cur, "name", hunk.u.name);

          /* Get the type. */
          buf = xml_get(cur);
          if(strcmp(buf, "add")==0) {
            hunk.type = HUNK_TYPE_PLANET_ADD;
          }
          else if(strcmp(buf, "remove")==0) {
            hunk.type = HUNK_TYPE_PLANET_REMOVE;
          }

          if(diff_patchHunk(&hunk) < 0)
            diff_hunkFailed(diff, &hunk);
          else
            diff_hunkSuccess(diff, &hunk);
        }
        else if(xml_isNode(cur, "fleet")) {
          hunk.target.type    = base.target.type;
          hunk.target.u.name  = strdup(base.target.u.name);

          /* Get the fleet properties. */
          xmlr_attr(cur, "name", buf);
          hunk.u.fleet.fleet = fleet_get(buf);
          free(buf);
          xmlr_attr(cur, "chance", buf);
          hunk.u.fleet.chance = atoi(buf);
          free(buf);

          /* Get the type. */
          buf = xml_get(cur);
          if(strcmp(buf, "add")==0) {
            hunk.type = HUNK_TYPE_FLEET_ADD;
          }
          else if(strcmp(buf, "remove")==0) {
            hunk.type = HUNK_TYPE_FLEET_REMOVE;
          }

          if(diff_patchHunk(&hunk) < 0)
            diff_hunkFailed(diff, &hunk);
          else
            diff_hunkSuccess(diff, &hunk);
        }
      } while(xml_nextNode(cur));

      /* Clean up some stuff. */
      free(base.target.u.name);
      base.target.u.name = NULL;
    }
  } while(xml_nextNode(node));

  if(diff->nfailed > 0) {
    DEBUG("Unidiff '%s' failed %d hunks.", diff->name, diff->nfailed);
    for(i = 0; i < diff->nfailed; i++) {
      fail = &diff->failed[i];
      target = fail->target.u.name;
      switch(fail->type) {
        case HUNK_TYPE_PLANET_ADD:
          DEBUG("   [%s] planet add: '%s'", target, fail->u.name);
          break;
        case HUNK_TYPE_PLANET_REMOVE:
          DEBUG("   [%s] planet remove: '%s'", target, fail->u.name);
          break;
        case HUNK_TYPE_FLEET_ADD:
          DEBUG("   [%s] fleet add: '%s' (%d%% chance)", target,
              fail->u.fleet.fleet->name, fail->u.fleet.chance);
          break;
        case HUNK_TYPE_FLEET_REMOVE:
          DEBUG("   [%s] fleet remove: '%s' (%d%% chance)", target,
              fail->u.fleet.fleet->name, fail->u.fleet.chance);
          break;
          
        default:
          DEBUG("   Unkown hunk '%d'", fail->type);
          break;
      }
    }
  }

  return 0;
}

/**
 * @fn static int diff_patchHunk(UniHunk_t* hunk)
 *
 * @brief Applies a hunk and adds it to the diff.
 *    @param diff Diff to which the hunk belongs.
 *    @param hunk Hunk to apply.
 */
static int diff_patchHunk(UniHunk_t* hunk) {
  switch(hunk->type) {
    /* Adding a planet. */
    case HUNK_TYPE_PLANET_ADD:
      return system_addPlanet(system_get(hunk->target.u.name), hunk->u.name);
    /* Removing a planet. */
    case HUNK_TYPE_PLANET_REMOVE:
      return system_rmPlanet(system_get(hunk->target.u.name), hunk->u.name);

    /* Adding a fleet. */
    case HUNK_TYPE_FLEET_ADD:
      return system_addFleet(system_get(hunk->target.u.name), &hunk->u.fleet);

    /* Removing a fleet. */
    case HUNK_TYPE_FLEET_REMOVE:
      return system_rmFleet(system_get(hunk->target.u.name), &hunk->u.fleet);

    default:
      WARN("Unkown hunk type '%d'.", hunk->type);
      break;
  }
  return -1;
}

/**
 * @fn static void diff_hunkFailed(UniDiff_t* diff, UniHunk_t* hunk)
 *
 * @brief Add a hunk to the failed list.
 *    @param diff Diff to add hunk to.
 *    @param hunk Hunk that failed to apply.
 */
static void diff_hunkFailed(UniDiff_t* diff, UniHunk_t* hunk) {
  if(diff == NULL)
    return;

  diff->nfailed++;
  if(diff->nfailed > diff->mfailed) {
    diff->mfailed += CHUNK_SIZE;
    diff->failed = realloc(diff->failed, sizeof(UniHunk_t) * diff->mfailed);
  }
  memcpy(&diff->failed[diff->nfailed-1], hunk, sizeof(UniHunk_t));
}

/**
 * @fn static void diff_hunkSuccess(UniDiff_t* diff, UniHunk_t* hunk)
 *
 * @brief Add a hunk to the applied list.
 *    @param diff Diff to add hunk to.
 *    @param hunk Hunk that applied correctly.
 */
static void diff_hunkSuccess(UniDiff_t* diff, UniHunk_t* hunk) {
  if(diff == NULL)
    return;

  diff->napplied++;
  if(diff->napplied > diff->mapplied) {
    diff->mapplied += CHUNK_SIZE;
    diff->applied = realloc(diff->applied, sizeof(UniHunk_t) * diff->mapplied);
  }
  memcpy(&diff->applied[diff->napplied-1], hunk, sizeof(UniHunk_t));
}

/**
 * @fn void diff_remove(char* name)
 *
 * @brief Remove a diff from the universe.
 *    @param name Diff to remove.
 */
void diff_remove(char* name) {
  UniDiff_t* diff;

  /* check if already applied. */
  diff = diff_get(name);
  if(diff == NULL)
    return;

  diff_removeDiff(diff);
}

/**
 * @fn void diff_clear(void)
 */
void diff_clear(void) {
  while(diff_nstack > 0) {
    diff_removeDiff(&diff_stack[diff_nstack-1]);
  }
}

/**
 * @fn static UniDiff_t* diff_newDiff(void)
 *
 * @brief Creates a new UniDiff_t for usage.
 *    @return A newly created UniDiff_t.
 */
static UniDiff_t* diff_newDiff(void) {
  /* Check if needs initialization. */
  if(diff_stack == NULL) {
    diff_mstack = CHUNK_SIZE;
    diff_stack = malloc(diff_mstack * sizeof(UniDiff_t));
    diff_nstack = 1;
    return &diff_stack[0];
  }

  diff_nstack++;
  /* Check if need to grow. */
  if(diff_nstack > diff_mstack) {
    diff_mstack += CHUNK_SIZE;
    diff_stack = realloc(diff_stack, diff_mstack * sizeof(UniDiff_t));
  }

  return &diff_stack[diff_nstack-1];
}

/**
 * @fn static int diff_removeDiff(UniDiff_t* diff)
 *
 * @brief Removes a diff.
 *    @param diff Diff to remove.
 *    @return 0 on success.
 */
static int diff_removeDiff(UniDiff_t* diff) {
  int i;
  UniHunk_t hunk;

  for(i = 0; i < diff->napplied; i++) {
    memcpy(&hunk, &diff->applied[i], sizeof(UniHunk_t));
    /* Invert the type for reverting. */
    switch(hunk.type) {
      case HUNK_TYPE_PLANET_ADD:
        hunk.type = HUNK_TYPE_PLANET_REMOVE;
        break;

      case HUNK_TYPE_PLANET_REMOVE:
        hunk.type = HUNK_TYPE_PLANET_ADD;
        break;

      case HUNK_TYPE_FLEET_ADD:
        hunk.type = HUNK_TYPE_FLEET_REMOVE;
        break;

      case HUNK_TYPE_FLEET_REMOVE:
        hunk.type = HUNK_TYPE_FLEET_ADD;
        break;
      
      default:
        WARN("Unkown Hunk type '%d'.", hunk.type);
        continue;
    }

    diff_patchHunk(&hunk);
  }

  diff_cleanup(diff);
  diff_nstack--;
  i = diff - diff_stack;
  memmove(&diff_stack[i], &diff_stack[i+1], sizeof(UniDiff_t) * (diff_nstack-i));

  return 0;  
}

/**
 * @fn static void diff_cleanup(UniDiff_t* diff)
 *
 * @brief Clean up a diff.
 *    @param diff Diff to clean up.
 */
static void diff_cleanup(UniDiff_t* diff) {
  int i;

  free(diff->name);
  for(i = 0; i < diff->napplied; i++)
    diff_cleanupHunk(&diff->applied[i]);
  if(diff->applied != NULL)
    free(diff->applied);
  for(i = 0; i < diff->nfailed; i++)
    diff_cleanupHunk(&diff->failed[i]);
  if(diff->failed != NULL)
    free(diff->failed);
  memset(diff, 0, sizeof(UniDiff_t));
}

/**
 * @fn static void diff_cleanupHunk(UniHunk_t* hunk)
 *
 * @brief Clean up a hunk.
 *    @param hunk Hunk to clean up.
 */
static void diff_cleanupHunk(UniHunk_t* hunk) {
  if(hunk->target.u.name != NULL)
    free(hunk->target.u.name);
  
  switch(hunk->type) {
    case HUNK_TYPE_PLANET_ADD:
    case HUNK_TYPE_PLANET_REMOVE:
      if(hunk->u.name != NULL)
        free(hunk->u.name);
      break;
    default:
      break;
  }

  memset(hunk, 0, sizeof(UniHunk_t));
}

/**
 * @fn int diff_save(xmlTextWriterPtr writer)
 *
 * @brief Save the active diffs.
 *    @param writer XML Writer to use.
 *    @return 0 on success.
 */
int diff_save(xmlTextWriterPtr writer) {
  int i;
  UniDiff_t* diff;

  xmlw_startElem(writer, "diffs");
  for(i = 0; i < diff_nstack; i++) {
    diff = &diff_stack[i];

    xmlw_elem(writer, "diff", diff->name);
  }
  xmlw_endElem(writer); /* "diffs" */

  return 0;
}

/**
 * @fn int diff_load(xmlNodePtr parent)
 *
 * @brief Loads the diffs.
 *    @param parent Parent node containing diffs.
 *    @return 0 on success.
 */
int diff_load(xmlNodePtr parent) {
  xmlNodePtr node, cur;

  diff_clear();

  node = parent->xmlChildrenNode;
  do {
    if(xml_isNode(node, "diffs")) {
      cur = node->xmlChildrenNode;
      do {
        if(xml_isNode(cur, "diff"))
          diff_apply(xml_get(cur));
      } while(xml_nextNode(cur));
    }
  } while(xml_nextNode(node));
  return 0;
}