<?php
namespace GraphQL;

use GraphQL\Error\Error;
use GraphQL\Executor\ExecutionResult;
use GraphQL\Executor\Executor;
use GraphQL\Executor\Promise\Adapter\SyncPromiseAdapter;
use GraphQL\Executor\Promise\Promise;
use GraphQL\Language\AST\DocumentNode;
use GraphQL\Language\Parser;
use GraphQL\Language\Source;
use GraphQL\Executor\Promise\PromiseAdapter;
use GraphQL\Type\Definition\Directive;
use GraphQL\Type\Definition\Type;
use GraphQL\Validator\DocumentValidator;
use GraphQL\Validator\Rules\AbstractValidationRule;
use GraphQL\Validator\Rules\QueryComplexity;

/**
 * This is the primary facade for fulfilling GraphQL operations.
 * See [related documentation](executing-queries.md).
 */
class GraphQL
{
    /**
     * Executes graphql query.
     *
     * More sophisticated GraphQL servers, such as those which persist queries,
     * may wish to separate the validation and execution phases to a static time
     * tooling step, and a server runtime step.
     *
     * Available options:
     *
     * schema:
     *    The GraphQL type system to use when validating and executing a query.
     * source:
     *    A GraphQL language formatted string representing the requested operation.
     * rootValue:
     *    The value provided as the first argument to resolver functions on the top
     *    level type (e.g. the query object type).
     * context:
     *    The value provided as the third argument to all resolvers.
     *    Use this to pass current session, user data, etc
     * variableValues:
     *    A mapping of variable name to runtime value to use for all variables
     *    defined in the requestString.
     * operationName:
     *    The name of the operation to use if requestString contains multiple
     *    possible operations. Can be omitted if requestString contains only
     *    one operation.
     * fieldResolver:
     *    A resolver function to use when one is not provided by the schema.
     *    If not provided, the default field resolver is used (which looks for a
     *    value on the source value with the field's name).
     * validationRules:
     *    A set of rules for query validation step. Default value is all available rules.
     *    Empty array would allow to skip query validation (may be convenient for persisted
     *    queries which are validated before persisting and assumed valid during execution)
     *
     * @api
     * @param \GraphQL\Type\Schema $schema
     * @param string|DocumentNode $source
     * @param mixed $rootValue
     * @param mixed $context
     * @param array|null $variableValues
     * @param string|null $operationName
     * @param callable $fieldResolver
     * @param array $validationRules
     *
     * @return ExecutionResult
     */
    public static function executeQuery(
        \GraphQL\Type\Schema $schema,
        $source,
        $rootValue = null,
        $context = null,
        $variableValues = null,
        $operationName = null,
        callable $fieldResolver = null,
        array $validationRules = null
    )
    {
        $promiseAdapter = new SyncPromiseAdapter();

        $promise = self::promiseToExecute($promiseAdapter, $schema, $source, $rootValue, $context,
            $variableValues, $operationName, $fieldResolver, $validationRules);

        return $promiseAdapter->wait($promise);
    }

    /**
     * Same as executeQuery(), but requires PromiseAdapter and always returns a Promise.
     * Useful for Async PHP platforms.
     *
     * @api
     * @param PromiseAdapter $promiseAdapter
     * @param \GraphQL\Type\Schema $schema
     * @param string|DocumentNode $source
     * @param mixed $rootValue
     * @param mixed $context
     * @param array|null $variableValues
     * @param string|null $operationName
     * @param callable $fieldResolver
     * @param array $validationRules
     *
     * @return Promise
     */
    public static function promiseToExecute(
        PromiseAdapter $promiseAdapter,
        \GraphQL\Type\Schema $schema,
        $source,
        $rootValue = null,
        $context = null,
        $variableValues = null,
        $operationName = null,
        callable $fieldResolver = null,
        array $validationRules = null
    )
    {
        try {
            if ($source instanceof DocumentNode) {
                $documentNode = $source;
            } else {
                $documentNode = Parser::parse(new Source($source ?: '', 'GraphQL'));
            }

            // FIXME
            if (!empty($validationRules)) {
                foreach ($validationRules as $rule) {
                    if ($rule instanceof QueryComplexity) {
                        $rule->setRawVariableValues($variableValues);
                    }
                }
            } else {
                /** @var QueryComplexity $queryComplexity */
                $queryComplexity = DocumentValidator::getRule(QueryComplexity::class);
                $queryComplexity->setRawVariableValues($variableValues);
            }

            $validationErrors = DocumentValidator::validate($schema, $documentNode, $validationRules);

            if (!empty($validationErrors)) {
                return $promiseAdapter->createFulfilled(
                    new ExecutionResult(null, $validationErrors)
                );
            } else {
                return Executor::promiseToExecute(
                    $promiseAdapter,
                    $schema,
                    $documentNode,
                    $rootValue,
                    $context,
                    $variableValues,
                    $operationName,
                    $fieldResolver
                );
            }
        } catch (Error $e) {
            return $promiseAdapter->createFulfilled(
                new ExecutionResult(null, [$e])
            );
        }
    }

    /**
     * @deprecated Use executeQuery()->toArray() instead
     *
     * @param \GraphQL\Type\Schema $schema
     * @param string|DocumentNode $source
     * @param mixed $rootValue
     * @param mixed $contextValue
     * @param array|null $variableValues
     * @param string|null $operationName
     * @return Promise|array
     */
    public static function execute(
        \GraphQL\Type\Schema $schema,
        $source,
        $rootValue = null,
        $contextValue = null,
        $variableValues = null,
        $operationName = null
    )
    {
        $result = self::promiseToExecute(
            $promiseAdapter = Executor::getPromiseAdapter(),
            $schema,
            $source,
            $rootValue,
            $contextValue,
            $variableValues,
            $operationName
        );

        if ($promiseAdapter instanceof SyncPromiseAdapter) {
            $result = $promiseAdapter->wait($result)->toArray();
        } else {
            $result = $result->then(function(ExecutionResult $r) {
                return $r->toArray();
            });
        }
        return $result;
    }

    /**
     * @deprecated renamed to executeQuery()
     *
     * @param \GraphQL\Type\Schema $schema
     * @param string|DocumentNode $source
     * @param mixed $rootValue
     * @param mixed $contextValue
     * @param array|null $variableValues
     * @param string|null $operationName
     *
     * @return ExecutionResult|Promise
     */
    public static function executeAndReturnResult(
        \GraphQL\Type\Schema $schema,
        $source,
        $rootValue = null,
        $contextValue = null,
        $variableValues = null,
        $operationName = null
    )
    {
        $result = self::promiseToExecute(
            $promiseAdapter = Executor::getPromiseAdapter(),
            $schema,
            $source,
            $rootValue,
            $contextValue,
            $variableValues,
            $operationName
        );
        if ($promiseAdapter instanceof SyncPromiseAdapter) {
            $result = $promiseAdapter->wait($result);
        }
        return $result;
    }

    /**
     * Returns directives defined in GraphQL spec
     *
     * @api
     * @return Directive[]
     */
    public static function getStandardDirectives()
    {
        return array_values(Directive::getInternalDirectives());
    }

    /**
     * Returns types defined in GraphQL spec
     *
     * @api
     * @return Type[]
     */
    public static function getStandardTypes()
    {
        return array_values(Type::getInternalTypes());
    }

    /**
     * Returns standard validation rules implementing GraphQL spec
     *
     * @api
     * @return AbstractValidationRule[]
     */
    public static function getStandardValidationRules()
    {
        return array_values(DocumentValidator::defaultRules());
    }

    /**
     * @param callable $fn
     */
    public static function setDefaultFieldResolver(callable $fn)
    {
        Executor::setDefaultFieldResolver($fn);
    }

    /**
     * @param PromiseAdapter|null $promiseAdapter
     */
    public static function setPromiseAdapter(PromiseAdapter $promiseAdapter = null)
    {
        Executor::setPromiseAdapter($promiseAdapter);
    }

    /**
     * Returns directives defined in GraphQL spec
     *
     * @deprecated Renamed to getStandardDirectives
     * @return Directive[]
     */
    public static function getInternalDirectives()
    {
        return self::getStandardDirectives();
    }
}
