<?php
/** @license MIT
 * Copyright 2017 J. King, Dustin Wilson et al.
 * See LICENSE and AUTHORS files for details */

declare(strict_types=1);
namespace JKingWeb\Arsse\Db\SQLite3;

use JKingWeb\Arsse\Arsse;
use JKingWeb\Arsse\Db\Exception;
use JKingWeb\Arsse\Db\ExceptionInput;
use JKingWeb\Arsse\Db\ExceptionTimeout;

class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
    use ExceptionBuilder;

    const SQLITE_BUSY = 5;
    const SQLITE_CONSTRAINT = 19;
    const SQLITE_MISMATCH = 20;

    protected $db;

    public function __construct(string $dbFile = null, string $dbKey = null) {
        // check to make sure required extension is loaded
        if (!static::requirementsMet()) {
            throw new Exception("extMissing", static::driverName()); // @codeCoverageIgnore
        }
        // if no database file is specified in the configuration, use a suitable default
        $dbFile = $dbFile ?? Arsse::$conf->dbSQLite3File ?? \JKingWeb\Arsse\BASE."arsse.db";
        $dbKey = $dbKey ?? Arsse::$conf->dbSQLite3Key;
        $timeout = Arsse::$conf->dbSQLite3Timeout * 1000;
        try {
            $this->makeConnection($dbFile, $dbKey);
            // set the timeout; parameters are not allowed for pragmas, but this usage should be safe
            $this->exec("PRAGMA busy_timeout = $timeout");
            // set other initial options
            $this->exec("PRAGMA foreign_keys = yes");
        } catch (\Throwable $e) {
            // if opening the database doesn't work, check various pre-conditions to find out what the problem might be
            $files = [
                $dbFile,        // main database file
                $dbFile."-wal", // write-ahead log journal
                $dbFile."-shm", // shared memory index
            ];
            foreach ($files as $file) {
                if (!file_exists($file) && !is_writable(dirname($file))) {
                    throw new Exception("fileUncreatable", $file);
                } elseif (!is_readable($file) && !is_writable($file)) {
                    throw new Exception("fileUnusable", $file);
                } elseif (!is_readable($file)) {
                    throw new Exception("fileUnreadable", $file);
                } elseif (!is_writable($file)) {
                    throw new Exception("fileUnwritable", $file);
                }
            }
            // otherwise the database is probably corrupt
            throw new Exception("fileCorrupt", $dbFile);
        }
    }

    public static function requirementsMet(): bool {
        return class_exists("SQLite3");
    }

    protected function makeConnection(string $file, string $key) {
        $this->db = new \SQLite3($file, \SQLITE3_OPEN_READWRITE | \SQLITE3_OPEN_CREATE, $key);
        // enable exceptions
        $this->db->enableExceptions(true);
    }

    public function __destruct() {
        try {
            $this->db->close();
        } catch (\Exception $e) { // @codeCoverageIgnore
        }
        unset($this->db);
    }

    /** @codeCoverageIgnore */
    public static function create(): \JKingWeb\Arsse\Db\Driver {
        if (self::requirementsMet()) {
            return new self;
        } elseif (PDODriver::requirementsMet()) {
            return new PDODriver;
        } else {
            throw new Exception("extMissing", self::driverName());
        }
    }


    public static function driverName(): string {
        return Arsse::$lang->msg("Driver.Db.SQLite3.Name");
    }

    public static function schemaID(): string {
        return "SQLite3";
    }

    public function schemaVersion(): int {
        return (int) $this->query("PRAGMA user_version")->getValue();
    }

    public function schemaUpdate(int $to, string $basePath = null): bool {
        // turn off foreign keys
        $this->exec("PRAGMA foreign_keys = no");
        // run the generic updater
        try {
            parent::schemaUpdate($to, $basePath);
        } catch (\Throwable $e) {
            // turn foreign keys back on
            $this->exec("PRAGMA foreign_keys = yes");
            // pass the exception up
            throw $e;
        }
        // turn foreign keys back on
        $this->exec("PRAGMA foreign_keys = yes");
        return true;
    }

    public function charsetAcceptable(): bool {
        // SQLite 3 databases are UTF-8 internally, thus always acceptable
        return true;
    }

    protected function getError(): string {
        return $this->db->lastErrorMsg();
    }

    public function exec(string $query): bool {
        try {
            return (bool) $this->db->exec($query);
        } catch (\Exception $e) {
            list($excClass, $excMsg, $excData) = $this->exceptionBuild();
            throw new $excClass($excMsg, $excData);
        }
    }

    public function query(string $query): \JKingWeb\Arsse\Db\Result {
        try {
            $r = $this->db->query($query);
        } catch (\Exception $e) {
            list($excClass, $excMsg, $excData) = $this->exceptionBuild();
            throw new $excClass($excMsg, $excData);
        }
        $changes = $this->db->changes();
        $lastId = $this->db->lastInsertRowID();
        return new Result($r, [$changes, $lastId]);
    }

    public function prepareArray(string $query, array $paramTypes): \JKingWeb\Arsse\Db\Statement {
        try {
            $s = $this->db->prepare($query);
        } catch (\Exception $e) {
            list($excClass, $excMsg, $excData) = $this->exceptionBuild();
            throw new $excClass($excMsg, $excData);
        }
        return new Statement($this->db, $s, $paramTypes);
    }

    protected function lock(): bool {
        $this->exec("BEGIN EXCLUSIVE TRANSACTION");
        return true;
    }

    protected function unlock(bool $rollback = false): bool {
        $this->exec((!$rollback) ? "COMMIT" : "ROLLBACK");
        return true;
    }
}