<?php

namespace Ulmus;

use Ulmus\Common\EntityResolver;

class Repository
{
    use EventTrait, Repository\ConditionTrait;
    
    const DEFAULT_ALIAS = "this";

    public ? ConnectionAdapter $adapter;

    protected QueryBuilder $queryBuilder;

    protected EntityResolver $entityResolver;

    public string $alias;

    public string $entityClass;
    
    public array $events = [];
    
    public function __construct(string $entity, string $alias = self::DEFAULT_ALIAS, ConnectionAdapter $adapter = null) {
        $this->entityClass = $entity;
        $this->alias = $alias;
        $this->entityResolver = Ulmus::resolveEntity($entity);
        $this->adapter = $adapter ?? $this->entityResolver->databaseAdapter() ?? Ulmus::$defaultAdapter;
        $this->queryBuilder = new QueryBuilder();
    }
    
    public function __clone() 
    {
        #$this->queryBuilder = clone $this->queryBuilder;
    }

    public function loadOne() : ? object
    {
        return $this->limit(1)->collectionFromQuery()[0] ?? null;
    }

    public function loadOneFromField($field, $value) : ? object
    {
        return $this->where($field, $value)->loadOne();
    }
    
    public function loadFromPk($value, /* ? stringable */ $primaryKey = null) : ? object
    {
        return $primaryKey ? $this->loadOneFromField($primaryKey, $value) : $this->wherePrimaryKey($value)->loadOne();
    }
    
    public function loadAll() : EntityCollection
    {
        return $this->collectionFromQuery();
    }

    public function loadFromField($field, $value) : EntityCollection
    {
        return $this->where($field, $value)->collectionFromQuery();
    }
    
    public function count() : int
    {
        if ( null !== $select = $this->queryBuilder->getFragment(Query\Select::class) ) {
            $this->queryBuilder->removeFragment($select);
        }
        
        if ( $this->queryBuilder->getFragment(Query\GroupBy::class) ) {
            $this->select( "DISTINCT COUNT(*) OVER ()" );
        }
        else {
            $this->select(Common\Sql::function("COUNT", "*"));
        }
        
        $this->selectSqlQuery();

        $this->finalizeQuery();

        return Ulmus::runSelectQuery($this->queryBuilder, $this->adapter)->fetchColumn(0);
    }

    protected function deleteOne() 
    {
        return $this->limit(1)->deleteSqlQuery()->runQuery();
    }
    
    protected function deleteAll() 
    {    
        return $this->deleteSqlQuery()->runQuery();
    }

    public function deleteFromPk($value) : bool
    {
        if ( $value !== 0 && empty($value) ) {
            throw new Exception\EntityPrimaryKeyUnknown("A primary key value has to be defined to delete an item.");
        }
        
        return (bool) $this->wherePrimaryKey($value)->deleteOne()->rowCount();
    }
    
    public function destroy(object $entity) : bool
    {
        if ( ! $this->matchEntity($entity) ) {
            throw new \Exception("Your entity class `" . get_class($entity) . "` cannot match entity type of repository `{$this->entityClass}`");
        }
        
        $primaryKeyDefinition = Ulmus::resolveEntity($this->entityClass)->getPrimaryKeyField();

        if ( $primaryKeyDefinition === null ) {
            throw new \Exception(sprintf("No primary key found for entity %s", $this->entityClass));
        }
        else {
            $pkField = key($primaryKeyDefinition);
            
            return $this->deleteFromPk($entity->$pkField);
        }
        
        return false;
    }

    public function destroyAll(EntityCollection $collection) : void 
    {
        foreach($collection as $entity) {
            $this->destroy($entity);
        }
    }
    
    public function save(object $entity) : bool
    {        
        if ( ! $this->matchEntity($entity) ) {
            throw new \Exception("Your entity class `" . get_class($entity) . "` cannot match entity type of repository `{$this->entityClass}`");
        }

        $dataset = $entity->toArray();
        
        $primaryKeyDefinition = Ulmus::resolveEntity($this->entityClass)->getPrimaryKeyField();

        if ( ! $entity->isLoaded() ) {
            $statement = $this->insertSqlQuery($dataset)->runQuery();
            
            if ( ( 0 !== $statement->lastInsertId ) && 
               ( null !== $primaryKeyDefinition )) {
                $pkField = key($primaryKeyDefinition);
                $dataset[$pkField] = $statement->lastInsertId;
            }
            
            $entity->entityFillFromDataset($dataset, true);
            
            return true;
        }
        else {
            if ( $primaryKeyDefinition === null ) {
                throw new \Exception(sprintf("No primary key found for entity %s", $this->entityClass));
            }

            if ( [] !== $diff = $this->generateDatasetDiff($entity) ) {
                $pkField = key($primaryKeyDefinition);
                $pkFieldName = $primaryKeyDefinition[$pkField]->name ?? $pkField;
                $this->where($pkFieldName, $dataset[$pkFieldName]);

                $update = $this->updateSqlQuery($diff)->runQuery();
                $entity->entityFillFromDataset($dataset);
                
                return $update ? (bool) $update->rowCount() : false;
            }
        }
        
        return false;
    }
    
    public function saveAll(EntityCollection $collection) : void 
    {
        foreach($collection as $entity) {
            $this->save($entity);
        }
    }
    
    public function truncate(? string $table = null, ? string $alias = null, ? string $schema = null) : self
    {
        $schema = $schema ?: $this->entityResolver->schemaName();
        
        $this->queryBuilder->truncate($this->escapeTable($table ?: $this->entityResolver->tableName()), $alias ?: $this->alias, $this->escapeDatabase($this->adapter->adapter()->database), $schema ? $this->escapeSchema($schema) : null);
        
        $this->finalizeQuery();
        
        $result = Ulmus::runSelectQuery($this->queryBuilder, $this->adapter);
        
        return $this;
    }
    
    public function generateDatasetDiff(object $entity) : array
    {
        return array_diff_assoc( array_change_key_case($entity->toArray()), array_change_key_case($entity->entityGetDataset(false, true)) );
    }
  
    public function yield() : \Generator
    {
        $class = $this->entityClass;
        
        $this->selectSqlQuery();
        
        $this->finalizeQuery();

        foreach(Ulmus::iterateQueryBuilder($this->queryBuilder, $this->adapter) as $entityData) {
            yield ( new $class() )->entityFillFromDataset($entityData);
        }
    }

    public function select(/*array|Stringable*/ $fields) : self
    {
        $this->queryBuilder->select($fields);
        
        return $this;
    }

    public function insert(array $fieldlist, string $table, string $alias, ? string $schema) : self
    {
        $this->queryBuilder->insert($fieldlist, $this->escapeTable($table), $alias, $schema);
        
        return $this;
    }

    public function values(array $dataset) : self
    {
        $this->queryBuilder->values($dataset);
        
        return $this;
    }
    
    public function update(string $table, string $alias, ? string $schema) : self
    {
        $this->queryBuilder->update($this->escapeTable($table), $alias, $schema);
        
        return $this;
    }
    
    public function set(array $dataset) : self
    {
        $this->queryBuilder->set($dataset);
        
        return $this;
    }
    
    public function delete() : self
    {
        $this->queryBuilder->delete($this->alias);
        
        return $this;
    }

    public function from(string $table, ? string $alias, ? string $schema) : self
    {
        $this->queryBuilder->from($this->escapeTable($table), $alias, $this->escapeDatabase($this->adapter->adapter()->database), $schema ? $this->escapeSchema($schema) : null);
        
        return $this;
    }

    public function join(string $type, $table, $field, $value, ? string $alias = null, ? callable $callback = null) : self
    {
        $join = $this->queryBuilder->withJoin($type, $this->escapeTable($table), $field, $value, false, $alias);
        
        if ( $callback ) {
            $callback($join);
        }
        
        return $this;
    }

    public function outerJoin(string $type, $table, $field, $value, ? string $alias = null, ? callable $callback = null) : self
    {
        $join = $this->queryBuilder->withJoin($type, $this->escapeTable($table), $field, $value, true, $alias);
        
        if ( $callback ) {
            $callback($join);
        }
        
        return $this;
    }
    
    public function match() : self
    {

    }

    public function notMatch() : self
    {

    }

    public function between() : self
    {

    }

    public function notBetween() : self
    {

    }
    
    public function groupBy($field) : self
    {
        $this->queryBuilder->groupBy($field);
        
        return $this;
    }

    public function groups(array $groups) : self
    {
        foreach($groups as $field ) {
            $this->groupBy($field);
        }
        
        return $this;
    }
    
    public function orderBy($field, ? string $direction = null) : self
    {
        $this->queryBuilder->orderBy($field, $direction);
        
        return $this;
    }

    # @UNTESTED
    public function randomizeOrder() : self
    {
        $this->queryBuilder->orderBy(Common\Sql::function('RAND', Sql::identifier('CURDATE()+0')));
        
        return $this;
    }
    
    public function orders(array $orderList) : self
    {
        foreach($orderList as $field => $direction) {
            $this->orderBy($field, $direction);
        }
        
        return $this;
    }

    
    public function limit(int $value) : self
    {
        $this->queryBuilder->limit($value);
        
        return $this;
    }

    public function offset(int $value) : self
    {
        $this->queryBuilder->offset($value);
        
        return $this;
    }


    /* @TODO */
    public function commit() : self
    {
        return $this;
    }

    /* @TODO */
    public function rollback() : self
    {
        return $this;
    }

    public function wherePrimaryKey($value) : self
    {
        if ( null === $primaryKeyField = Ulmus::resolveEntity($this->entityClass)->getPrimaryKeyField() ) {
            throw new Exception\EntityPrimaryKeyUnknown("Entity has no field containing attributes 'primary_key'");
        }
        
        $pkField = key($primaryKeyField);
        
        return $this->where($primaryKeyField[$pkField]->name ?? $pkField, $value);
    }
 
    public function withJoin(/*stringable|array*/ $fields) : self
    {
        $resolvedEntity = Ulmus::resolveEntity($this->entityClass);
        
        if ( null === $this->queryBuilder->getFragment(Query\Select::class) ) {
            $this->select("{$this->alias}.*");
        }
        
        foreach((array) $fields as $item) {
            if ( null !== $join = $resolvedEntity->searchFieldAnnotation($item, new Annotation\Property\Join) ) {
                $alias = $join->alias ?? $item;
                $entity = $join->entity ?? $resolvedEntity->properties[$item]['type'];
                
                foreach($entity::resolveEntity()->fieldList(Common\EntityResolver::KEY_COLUMN_NAME, true) as $key => $field) {
                    $this->select("$alias.$key as {$alias}\${$field['name']}");
                }
                
                $key = is_string($join->key) ? $this->entityClass::field($join->key) : $join->key;
                $foreignKey = is_string($join->foreignKey) ? $entity::field($join->foreignKey, $alias) : $join->foreignKey;
                
                $this->join($join->type, $entity::resolveEntity()->tableName(), $key, $foreignKey, $alias);
            }
            else {
                throw new \Exception("You referenced field `$item` which do not exist or do not contain a valid @Join annotation.");
            }
        }
        
        return $this;
    }
    
    public function filterServerRequest(SearchRequest\SearchRequestInterface $searchRequest) : self 
    {
        $likes = $searchRequest->likes();
        $wheres = $searchRequest->wheres();
        $groups = $searchRequest->groups();
        
        $searchRequest->filter( $this )
            ->wheres($wheres, Query\Where::OPERATOR_EQUAL, Query\Where::CONDITION_AND)
            ->likes($likes, Query\Where::CONDITION_OR)
            ->groups($groups);
        
        $searchRequest->count = $searchRequest->skipCount ? 0 : (clone $this)->count();
        
        return $searchRequest
            ->filter($this)
            ->wheres($wheres, Query\Where::OPERATOR_EQUAL, Query\Where::CONDITION_AND)
            ->likes($likes, Query\Where::CONDITION_OR)
            ->groups($groups)
            ->orders($searchRequest->orders())
            ->offset($searchRequest->offset())
            ->limit($searchRequest->limit());
    }
    
    public function collectionFromQuery(? string $entityClass = null) : EntityCollection
    {
        $class = $entityClass ?: $this->entityClass;
        
        $entityCollection = $class::entityCollection();
        
        $this->selectSqlQuery();
        
        $this->finalizeQuery();

        foreach(Ulmus::iterateQueryBuilder($this->queryBuilder, $this->adapter) as $entityData) {
            $entityCollection->append( ( new $class() )->entityFillFromDataset($entityData) );
        }
        
        $this->eventExecute(Event\Repository\CollectionFromQueryInterface::class, $entityCollection);

        return $entityCollection;
    }
    
    public function arrayFromQuery() : array
    {
        $this->selectSqlQuery();
        
        $this->finalizeQuery();

        return Ulmus::datasetQueryBuilder($this->queryBuilder, $this->adapter);
    }

    public function runQuery() : ? \PDOStatement
    {
        $this->finalizeQuery();
        
        return Ulmus::runQuery($this->queryBuilder, $this->adapter);
    }
    
    public function resetQuery() : self
    {
        $this->queryBuilder->reset();
        
        return $this;
    }
    
    protected function insertSqlQuery(array $dataset) : self
    {
        if ( null === $this->queryBuilder->getFragment(Query\Insert::class) ) {
            $this->insert(array_keys($dataset), $this->entityResolver->tableName(), $this->alias, $this->entityResolver->schemaName());
        }

        $this->values($dataset);

        return $this;
    }
    
    protected function updateSqlQuery(array $dataset) : self
    {
        if ( null === $this->queryBuilder->getFragment(Query\Update::class) ) {
            $this->update($this->entityResolver->tableName(), $this->alias, $this->entityResolver->schemaName());
        }
        
        $this->set($dataset);

        return $this;
    }
    
    protected function selectSqlQuery() : self
    {
        if ( null === $this->queryBuilder->getFragment(Query\Select::class) ) {
            $this->select("{$this->alias}.*");
        }

        if ( null === $this->queryBuilder->getFragment(Query\From::class) ) {
            $this->from($this->entityResolver->tableName(), $this->alias, $this->entityResolver->schemaName());
        }

        return $this;
    }

    protected function deleteSqlQuery() : self
    {
        if ( null === $this->queryBuilder->getFragment(Query\Delete::class) ) {
            $this->delete();
        }

        if ( null === $this->queryBuilder->getFragment(Query\From::class) ) {
            $this->from($this->entityResolver->tableName(), null, $this->entityResolver->schemaName());
        }

        return $this;
    }
    
    protected function fromRow($row) : self
    {

    }

    protected function fromCollection($rows) : self
    {

    }
    
    public function instanciateEntityCollection(...$arguments) : EntityCollection
    {
        return $this->entityClass::entityCollection(...$arguments);
    }
    
    public function escapeTable(string $identifier) : string
    {
        return $this->adapter->adapter()->escapeIdentifier($identifier, Adapter\AdapterInterface::IDENTIFIER_TABLE);
    }
    
    public function escapeDatabase(string $identifier) : string
    {
        return $this->adapter->adapter()->escapeIdentifier($identifier, Adapter\AdapterInterface::IDENTIFIER_DATABASE);
    }
    
    public function escapeSchema(string $identifier) : string
    {
        return $this->adapter->adapter()->escapeIdentifier($identifier, Adapter\AdapterInterface::IDENTIFIER_SCHEMA);
    }
    
    protected function matchEntity(object $entity) {
        return get_class($entity) === $this->entityClass;
    }
    
    protected function finalizeQuery() : void {}
}