<?php
namespace Civi\ContactCats;

use CRM_Contactcats_ExtensionUtil as E;
use Civi;
use Civi\Api4\Activity;
use Civi\Api4\ContactCategoryDefinition;
use Civi\Api4\Group;
use Civi\Api4\SavedSearch;
use CRM_Core_DAO;
use CRM_Core_Exception;

class Processor {

  protected array $categories = [];

  protected array $groupDetails = [];

  protected array $searchDetails = [];

  protected ?int $contact_id = NULL;

  public function __construct(?int $contact_id = NULL) {

    $this->contact_id = $contact_id;

    $this->categories = ContactCategoryDefinition::get(FALSE)
      ->addOrderBy('execution_order')
      ->execute()->indexBy('id')->getArrayCopy();

    // Check the last item is the 'default' one.
    if ((end($this->categories)['search_type'] ?? '') !== 'default') {
      throw new CRM_Core_Exception("ContactCategoryDefinition unconfigured; no default category.");
    }

    // Identify groups and searches used by definitions.
    $groupIDs = $searchIDs = [];
    foreach ($this->categories as $cat) {
      if ($cat['search_type'] === 'group') {
        $groupIDs[] = (int) $cat['search_data']['group_id'];
      }
      elseif ($cat['search_type'] === 'search') {
        $searchIDs[] = (int) $cat['search_data']['saved_search_id'];
      }
    }

    // Load group details; ensure all groups still exist.
    $this->groupDetails = [];
    if ($groupIDs) {
      $this->groupDetails = Group::get(FALSE)
        ->addWhere('id', 'IN', $groupIDs)
        ->execute()->indexBy('id')->getArrayCopy();
      foreach ($this->categories as $cat) {
        if ($cat['search_type'] === 'group') {
          if (!isset($this->groupDetails[$cat['search_data']['group_id'] ?? 0])) {
            throw new CRM_Core_Exception("ContactCategoryDefinition $cat[id] $cat[label] references invalid Group: " . $cat['search_data']['group_id']);
          }
        }
      }
    }

    // Load all searches
    $this->searchDetails = [];
    if ($searchIDs) {
      $this->searchDetails = SavedSearch::get(FALSE)
        ->addWhere('id', 'IN', $searchIDs)
        ->execute()->indexBy('id')->getArrayCopy();
      foreach ($this->categories as $cat) {
        if ($cat['search_type'] === 'search') {
          if (!isset($this->searchDetails[$cat['search_data']['saved_search_id'] ?? 0])) {
            throw new CRM_Core_Exception("ContactCategoryDefinition $cat[id] $cat[label] references invalid Search: " . $cat['search_data']['saved_search_id']);
          }
          $search = $this->searchDetails[$cat['search_data']['saved_search_id']];
          if (!isset($search['api_params']) || !isset($search['api_entity'])) {
            throw new CRM_Core_Exception("ContactCategoryDefinition $cat[id] $cat[label] uses search $search[id] which does not look appropriate.");
          }
        }
      }
    }

    // TODO: check things like searches that group by contact_id
  }

  /**
   * Main calling point.
   */
  public function run() {
    $this->refreshSmartGroups();
    $summary = [];
    \CRM_Core_Transaction::create()->run(function($tx) use (&$summary) {
      $this->resetTable();
      foreach ($this->categories as $cat) {
        try {
          if ($cat['search_type'] === 'group') {
            $this->assignCategoryFromGroup($cat);
          }
          elseif ($cat['search_type'] === 'search') {
            $this->assignCategoryFromSearch($cat);
          }
          elseif ($cat['search_type'] === 'default') {
            $this->assignDefaultCategory($cat);
          }
          else {
            throw new CRM_Core_Exception("Invalid search_type: $cat[search_type] for category $cat[id]");
          }
        }
        catch (\Exception $e) {
          throw new CRM_Core_Exception(
            "ContactCats failed to run category $cat[id] $cat[search_type] $cat[label]: " . $e->getMessage(),
            0,
            [],
            $e);
        }
        // future...
      }
      $summary = $this->createChangeActivities();
    });

    return $summary;
  }

  /**
   * Creates change activities and actually updates the current category data.
   */
  protected function createChangeActivities() {
    $singleContactClause = $this->contact_id ? "AND id = $this->contact_id" : "";
    Civi::log()->debug("Calculate changes", ['=' => 'timed', '=start' => "changes"]);
    $changes = CRM_Core_DAO::executeQuery(<<<SQL
      SELECT id, category_definition_id, next_category
      FROM civicrm_contact_category
      WHERE (category_definition_id IS NULL OR next_category <> category_definition_id) $singleContactClause
      ORDER BY category_definition_id, next_category
      SQL);
    $lastChange = [0, 0];
    $batch = [];
    $n = 0;
    $domainContactID = \CRM_Core_BAO_Domain::getDomain()->contact_id;
    $writeBatch = function() use (&$lastChange, &$batch, $domainContactID) {
      if (empty($batch)) {
        return;
      }
      $oldCategoryId = (int) ($lastChange[0] ?? 0);
      $newCategoryId = (int) ($lastChange[1] ?? 0);
      $oldName = $this->categories[$oldCategoryId]['label'] ?? E::ts('(Unknown)');
      $subject = "$oldName → " . $this->categories[$newCategoryId]['label'];
      // Create activity on the first contact
      $a = Activity::create(FALSE)
        ->addValue('target_contact_id', $batch[0])
        ->addValue('activity_type_id:name', 'changed_contact_category')
        ->addValue('source_contact_id', $domainContactID)
        ->addValue('status_id:name', 'Completed')
        ->addValue('subject', $subject)
        ->addValue('Category_changes.previous_category_id', $oldCategoryId)
        ->addValue('Category_changes.new_category_id', $newCategoryId)
        ->execute()->first();
      $activityID = (int) $a['id'];
      // Join activity to all relevant contacts
      CRM_Core_DAO::executeQuery("INSERT INTO civicrm_activity_contact (contact_id, activity_id, record_type_id)
        SELECT id contact_id, $activityID activity_id, 3 record_type_id
        FROM civicrm_contact_category cc
        WHERE COALESCE(cc.category_definition_id, 0) = $oldCategoryId
          AND cc.next_category = $newCategoryId
          AND cc.id <> $batch[0]
        ")->free();
      Civi::log()->debug(count($batch) . " changes: $subject");
    };

    while ($changes->fetch()) {
      $n++;
      if ($lastChange[0] !== $changes->category_definition_id || $lastChange[1] !== $changes->next_category) {
        $writeBatch();
        $lastChange = [$changes->category_definition_id, $changes->next_category];
        $batch = [];
      }
      $batch[] = $changes->id;
    }
    $changes->free();
    $writeBatch();

    Civi::log()->debug('Apply changes', ['=change' => 'applyChanges', '=timed' => 1]);
    CRM_Core_DAO::executeQuery("UPDATE civicrm_contact_category
      SET category_definition_id = next_category
      WHERE (category_definition_id IS NULL OR category_definition_id <> next_category) $singleContactClause")->free();
    Civi::log()->debug('', ['=pop' => 1]);

    $singleContactClause = $this->contact_id ? "WHERE id = $this->contact_id" : "";
    $summary = CRM_Core_DAO::executeQuery("SELECT next_category, count(*) from civicrm_contact_category $singleContactClause GROUP BY next_category")->fetchAll();
    $summary['changes'] = $n;
    $_ = memory_get_peak_usage(TRUE);
    $summary['memory_use'] = @round($_ / pow(1024, ($i = floor(log($_, 1024)))), 2) . ' ' . ['b', 'kb', 'mb', 'gb', 'tb', 'pb'][$i];
    return $summary;

  }

  protected function refreshSmartGroups() {
    $smartGroups = [];
    foreach ($this->groupDetails as $groupID => $group) {
      if (!empty($group['saved_search_id'])) {
        $smartGroups[] = $groupID;
      }
    }
    if ($smartGroups) {
      Civi::log()->debug('Refreshing smart groups', ['=' => 'timed,start', 'groups' => $smartGroups]);
      \CRM_Contact_BAO_GroupContactCache::loadAll($smartGroups);
      Civi::log()->debug('', ['=' => 'pop']);
    }
  }

  /**
   * Ensure we have one category row per not-trashed contact and zero the next_category field.
   */
  protected function resetTable() {
    Civi::log()->debug('Resetting table', ['=' => 'start,timed']);

    $singleContactClause = $this->contact_id ? "WHERE cat.id = $this->contact_id" : "";

    // Delete our data for deleted contacts.
    $dao = CRM_Core_DAO::executeQuery(<<<SQL
      DELETE cat
      FROM civicrm_contact_category cat
      INNER JOIN civicrm_contact ct ON ct.id = cat.id AND ct.is_deleted = 1
      $singleContactClause
      SQL);
    if ($dao->N) {
      Civi::log()->debug("Deleted category data for {$dao->N} trashed contacts");
    }
    $dao->free();

    // Zero our internal next_category field.
    CRM_Core_DAO::executeQuery("UPDATE civicrm_contact_category cat SET next_category = 0 $singleContactClause;")->free();
    Civi::log()->debug('stage 2');

    // ensure we have all our contacts covered.
    // Q: is it quicker to do a WHERE NOT EXISTS? A: nope.
    $singleContactClause = $this->contact_id ? "AND id = $this->contact_id" : "";
    CRM_Core_DAO::executeQuery(<<<SQL
      INSERT INTO civicrm_contact_category
      SELECT id, NULL AS category_definition_id, 0 AS next_category
      FROM civicrm_contact
      WHERE is_deleted = 0 $singleContactClause
      AND NOT EXISTS (SELECT id FROM civicrm_contact_category WHERE id = civicrm_contact.id)
    SQL)->free();
    Civi::log()->debug('Done resetting table', ['=' => 'pop']);
  }

  /**
   *
   */
  protected function assignCategoryFromGroup(array $cat) {
    $groupID = (int) $cat['search_data']['group_id'];
    $group = $this->groupDetails[$groupID];

    // Put unclaimed contacts in this group into this category.
    $isSmart = !empty($group['saved_search_id']);
    Civi::log()->debug($group['title'] . ($isSmart ? '(smart)' : ''), ['=' => 'timed', '=start' => "group$groupID"]);
    $table = $isSmart ? 'civicrm_group_contact_cache' : 'civicrm_group_contact';
    $statusWhere = $isSmart ? '' : 'AND gc.status = "Added"';
    $andContactIdCriterion = $this->contact_id ? "AND cc.id=$this->contact_id" : '';
    $sql = <<<SQL
        UPDATE civicrm_contact_category cc
        INNER JOIN $table gc ON gc.contact_id = cc.id AND group_id = $groupID $statusWhere
        SET next_category = {$cat['id']}
        WHERE next_category = 0 $andContactIdCriterion
    SQL;
    CRM_Core_DAO::executeQuery($sql)->free();
    Civi::log()->debug('', ['=' => 'pop']);
  }

  /**
   *
   */
  protected function assignCategoryFromSearch(array $cat) {
    $search = $this->searchDetails[$cat['search_data']['saved_search_id']];
    Civi::log()->debug("Doing $cat[id] $cat[label]", ['=' => 'timed', '=start' => "ss" . $cat['search_data']['saved_search_id']]);

    $apiParams = $search['api_params'];
    if ($search['api_entity'] === 'Contact' && in_array('id', $apiParams['select'] ?? [])) {
      $contactIdKey = 'id';
      if ($this->contact_id) {
        // Limit to one contact.
        $apiParams['where'][] = ['id', '=', $this->contact_id];
      }
    }
    else {
      throw new CRM_Core_Exception("can't figure out contactID in search: " . json_encode($search));
    }
    // We don't need them ordered.
    unset($apiParams['orderBy']);
    $apiParams['checkPermissions'] = FALSE;

    $contactIDs = civicrm_api4($search['api_entity'], 'get', $apiParams)->column($contactIdKey);
    // Unsure if this batching is needed.
    // It would be better if we could access the select SQL directly and do it all in an SQL update.
    $batchSize = 10000;
    while ($batch = array_splice($contactIDs, 0, $batchSize)) {
      $batch = implode(',', $batch);
      if (!preg_match('/^[0-9,]+$/', $batch)) {
        // Surely this can never happen.
        throw new CRM_Core_Exception("Erm, received non-integer contact IDs from Search $search[id]!");
      }
      $sql = <<<SQL
        UPDATE civicrm_contact_category cc
        SET next_category = {$cat['id']}
        WHERE next_category = 0 AND id IN ($batch)
        SQL;
      CRM_Core_DAO::executeQuery($sql)->free();
    }
    Civi::log()->debug('Done', ['=' => 'pop']);
  }

  protected function assignDefaultCategory(array $cat) {
    $id = (int) $cat['id'];
    CRM_Core_DAO::executeQuery("UPDATE civicrm_contact_category SET next_category = $id WHERE next_category = 0;")->free();
  }

}