<?php
namespace nur\sery\db\sqlite;

use nur\sery\cl;
use nur\sery\db\CapacitorChannel;
use nur\sery\db\CapacitorStorage;
use nur\sery\php\func;
use nur\sery\ValueException;

/**
 * Class SqliteCapacitor
 */
class SqliteCapacitor extends CapacitorStorage {
  function __construct($sqlite) {
    $this->sqlite = Sqlite::with($sqlite);
  }

  /** @var Sqlite */
  protected $sqlite;

  function sqlite(): Sqlite {
    return $this->sqlite;
  }

  protected function _create(CapacitorChannel $channel): void {
    if (!$channel->isCreated()) {
      $columns = cl::merge([
        "_id" => "integer primary key autoincrement",
        "_item" => "text",
        "_sum" => "varchar(40)",
        "_created" => "datetime",
        "_modified" => "datetime",
      ], $channel->getKeyDefinitions());
      $this->sqlite->exec([
        "create table if not exists",
        "table" => $channel->getTableName(),
        "cols" => $columns,
      ]);
      $channel->setCreated();
    }
  }

  /** @var CapacitorChannel[] */
  protected $channels;

  function addChannel(CapacitorChannel $channel): CapacitorChannel {
    $this->_create($channel);
    $this->channels[$channel->getName()] = $channel;
    return $channel;
  }

  protected function getChannel(?string $name): CapacitorChannel {
    $name = CapacitorChannel::verifix_name($name);
    $channel = $this->channels[$name] ?? null;
    if ($channel === null) {
      $channel = $this->addChannel(new CapacitorChannel($name));
    }
    return $channel;
  }

  function _exists(CapacitorChannel $channel): bool {
    $tableName = $this->sqlite->get([
      "select name from sqlite_schema",
      "where" => [
        "name" => $channel->getTableName(),
      ],
    ]);
    return $tableName !== null;
  }

  function _ensureExists(CapacitorChannel $channel): void {
    $this->_create($channel);
  }

  function _reset(CapacitorChannel $channel): void {
    $this->sqlite->exec([
      "drop table if exists",
      $channel->getTableName(),
    ]);
    $channel->setCreated(false);
  }

  function _charge(CapacitorChannel $channel, $item, ?callable $func, ?array $args): int {
    $this->_create($channel);
    $now = date("Y-m-d H:i:s");
    $_item = serialize($item);
    $_sum = sha1($_item);
    $values = cl::merge([
      "_item" => $_item,
      "_sum" => $_sum,
    ], $channel->getKeyValues($item));
    $row = null;
    $id = $values["_id"] ?? null;
    if ($id !== null) {
      # modification
      $row = $this->sqlite->one([
        "select _item, _sum, _created, _modified",
        "from" => $channel->getTableName(),
        "where" => ["_id" => $id],
      ]);
    }
    $insert = null;
    if ($row === null) {
      # création
      $values = cl::merge($values, [
        "_created" => $now,
        "_modified" => $now,
      ]);
      $insert = true;
    } elseif ($_sum !== $row["_sum"]) {
      # modification
      $values = cl::merge($values, [
        "_modified" => $now,
      ]);
      $insert = false;
    }

    if ($func === null) $func = [$channel, "onCharge"];
    $onCharge = func::_prepare($func);
    $args ??= [];
    $updates = func::_call($onCharge, [$item, $values, $row, ...$args]);
    if (is_array($updates)) {
      if (array_key_exists("_item", $updates)) {
        $_item = serialize($updates["_item"]);
        $updates["_item"] = $_item;
        $updates["_sum"] = sha1($_item);
        if (!array_key_exists("_modified", $updates)) {
          $updates["_modified"] = $now;
        }
      }
      $values = cl::merge($values, $updates);
    }

    if ($insert === null) {
      # aucune modification
      return 0;
    } elseif ($insert) {
      $this->sqlite->exec([
        "insert",
        "into" => $channel->getTableName(),
        "values" => $values,
      ]);
    } else {
      $this->sqlite->exec([
        "update",
        "table" => $channel->getTableName(),
        "values" => $values,
        "where" => ["_id" => $id],
      ]);
    }
    return 1;
  }

  function _count(CapacitorChannel $channel, $filter): int {
    if ($filter !== null && !is_array($filter)) $filter = ["_id" => $filter];
    return $this->sqlite->get([
      "select count(*)",
      "from" => $channel->getTableName(),
      "where" => $filter,
    ]);
  }

  function _discharge(CapacitorChannel $channel, $filter, ?bool $reset): iterable {
    if ($filter !== null && !is_array($filter)) $filter = ["_id" => $filter];
    if ($reset === null) $reset = $filter === null;
    $rows = $this->sqlite->all([
      "select _item",
      "from" => $channel->getTableName(),
      "where" => $filter,
    ]);
    foreach ($rows as $row) {
      $item = unserialize($row['_item']);
      yield $item;
    }
    if ($reset) $this->_reset($channel);
  }

  function _get(CapacitorChannel $channel, $filter) {
    if ($filter === null) throw ValueException::null("keys");
    if (!is_array($filter)) $filter = ["_id" => $filter];
    $row = $this->sqlite->one([
      "select _item",
      "from" => $channel->getTableName(),
      "where" => $filter,
    ]);
    if ($row === null) return null;
    else return unserialize($row["_item"]);
  }

  function _each(CapacitorChannel $channel, $filter, ?callable $func, ?array $args): int {
    if ($func === null) $func = [$channel, "onEach"];
    $onEach = func::_prepare($func);
    if ($filter !== null && !is_array($filter)) $filter = ["_id" => $filter];
    $sqlite = $this->sqlite;
    $tableName = $channel->getTableName();
    $commited = false;
    $count = 0;
    $sqlite->beginTransaction();
    $commitThreshold = $channel->getEachCommitThreshold();
    try {
      $rows = $sqlite->all([
        "select",
        "from" => $tableName,
        "where" => $filter,
      ]);
      $args ??= [];
      foreach ($rows as $row) {
        $item = unserialize($row['_item']);
        $updates = func::_call($onEach, [$item, $row, ...$args]);
        if (is_array($updates)) {
          if (array_key_exists("_item", $updates)) {
            $updates["_item"] = serialize($updates["_item"]);
          }
          $sqlite->exec([
            "update",
            "table" => $tableName,
            "values" => $updates,
            "where" => ["_id" => $row["_id"]],
          ]);
          if ($commitThreshold !== null) {
            $commitThreshold--;
            if ($commitThreshold == 0) {
              $sqlite->commit();
              $commitThreshold = $channel->getEachCommitThreshold();
            }
          }
        }
        $count++;
      }
      $sqlite->commit();
      $commited = true;
      return $count;
    } finally {
      if (!$commited) $sqlite->rollback();
    }
  }

  function close(): void {
    $this->sqlite->close();
  }
}