<?php

namespace MwgAuth\Core;

use PDO;
use PDOStatement;

class Model
{
    private static $database = null;
    private static $lastErrorMessage = '';

    private static function connect(): void
    {
        if (null === self::$database) {
            $config = Config::getSection('database');
            self::$database = new PDO(
                'mysql:host=' . $config['host'] . ';dbname=' . $config['database'],
                $config['username'],
                $config['password'],
            );
        }
    }

    protected static function delete(string $table, array $conditions): bool
    {
        $where = $parameters = [];
        foreach ($conditions as $condition) {
            switch (count($condition)) {
                case 1:
                    $where[] = '`' . $condition[0] . '`';
                    break;
                case 2:
                    $where[] = '`' . $condition[0] . '`=:' . $condition[0];
                    $parameters[':' . $condition[0]] = $condition[1];
                    break;
                case 3:
                    $where[] = '`' . $condition[0] . '`' . $condition[1] . ':' . $condition[0];
                    $parameters[':' . $condition[0]] = $condition[2];
                    break;
                default:
                    return false;
            }
        }
        $sql = "DELETE FROM `$table` WHERE (" . implode(") AND (", $where) . ")";
        $statement = self::prepare($sql, $parameters);
        return self::execute($statement);
    }

    private static function execute(PDOStatement $statement): bool
    {
        if ($ret = $statement->execute()) {
            self::$lastErrorMessage = '';
        } else {
            $errorInfo = $statement->errorInfo();
            self::$lastErrorMessage = $errorInfo[0] . ': ' . $errorInfo[2];
        }
        return $ret;
    }

    protected static function getLastErrorMessage(): string
    {
        return self::$lastErrorMessage;
    }

    private static function getParameters(array $conditions): array
    {
        $parameters = [];
        foreach ($conditions as $field => $value) {
            $parameters[":$field"] = $value;
        }
        return $parameters;
    }

    private static function getSelectQuery(string $table, array $fields, array $conditions): string
    {
        $where = [];
        foreach ($conditions as $field => $value) {
            $where[] = "(`$field`=:$field)";
        }
        return "SELECT `" . implode('`,`', $fields) . "` FROM `$table` WHERE " . implode(' AND ', $where);
    }

    protected static function insert(string $table, array $fields): bool
    {
        $fields['created_at'] = $fields['modified_at'] = date('Y-m-d H:i:s');
        $parameters = self::getParameters($fields);
        $sql = "INSERT INTO `$table`(`" . implode('`,`', array_keys($fields)) . "`) VALUES (" .
            implode(',', array_keys($parameters)) . ')';
        $statement = self::prepare($sql, $parameters);
        return self::execute($statement);
    }

    private static function prepare(string $sql, array $parameters): PDOStatement
    {
        self::connect();
        $statement = self::$database->prepare($sql);
        foreach ($parameters as $name => $value) {
            if (is_bool($value)) {
                $type = PDO::PARAM_BOOL;
            } elseif (is_int($value)) {
                $type = PDO::PARAM_INT;
            } else {
                $type = PDO::PARAM_STR;
            }
            $statement->bindValue($name, $value, $type);
        }
        return $statement;
    }

    protected static function select(string $table, array $fields, array $conditions): ?array
    {
        $parameters = self::getParameters($conditions);
        $sql = self::getSelectQuery($table, $fields, $conditions);
        $statement = self::prepare($sql, $parameters);
        self::execute($statement);
        $ret = $statement->fetchAll(PDO::FETCH_ASSOC);
        $statement->closeCursor();
        return false === $ret ? null : $ret;
    }

    protected static function selectOne(string $table, array $fields, array $conditions): ?array
    {
        $parameters = self::getParameters($conditions);
        $sql = self::getSelectQuery($table, $fields, $conditions) . ' LIMIT 1';
        $statement = self::prepare($sql, $parameters);
        self::execute($statement);
        $ret = $statement->fetch(PDO::FETCH_ASSOC);
        $statement->closeCursor();
        return false === $ret ? null : $ret;
    }

    protected static function selectSingleValue(string $table, string $field, array $conditions)
    {
        $parameters = self::getParameters($conditions);
        $sql = self::getSelectQuery($table, [$field], $conditions) . ' LIMIT 1';
        $statement = self::prepare($sql, $parameters);
        self::execute($statement);
        $ret = $statement->fetchColumn();
        $statement->closeCursor();
        return false === $ret ? null : $ret;
    }

    protected static function update(string $table, array $fields, array $conditions): bool
    {
        $fields['modified_at'] = date('Y-m-d H:i:s');
        $where = $parameters = $set = [];
        foreach ($fields as $field => $value) {
            $set[] = "`$field`=:p$field";
            $parameters[":p$field"] = $value;
        }
        foreach ($conditions as $field => $value) {
            $where[] = "(`$field`=:w$field)";
            $parameters[":w$field"] = $value;
        }
        $sql = "UPDATE `$table` SET " . implode(',', $set) . " WHERE " . implode(',', $where);
        $statement = self::prepare($sql, $parameters);
        return self::execute($statement);
    }
}