<?php

function connectToDb() {
    static $db = null;

    if ($db === null) {
        $dsn = "pgsql:host=" . DB_HOST . ";port=" . DB_PORT . ";dbname=" . DB_NAME;

        try {
            $db = new PDO($dsn, DB_USER, DB_PASSWORD);
            $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch (PDOException $e) {
            die("❌ Connection failed: " . $e->getMessage());
        }
    }

    return $db;
}

function insertInto($table, $data) {
    $db = connectToDb();

    $columns = '"' . implode('","', array_keys($data)) . '"';
    $placeholders = ':' . implode(', :', array_keys($data));

    $sql = "INSERT INTO \"$table\" ($columns) VALUES ($placeholders)";

    $stmt = $db->prepare($sql);
    $stmt->execute($data);

    return $db->lastInsertId();
}

function selectFrom($table, $conditions = []) {
    $db = connectToDb();

    $whereClause = '';
    if (!empty($conditions)) {
        $clauses = [];
        foreach ($conditions as $key => $value) {
            $clauses[] = "\"$key\" = :$key";
        }
        $whereClause = 'WHERE ' . implode(' AND ', $clauses);
    }

    $sql = "SELECT * FROM \"$table\" $whereClause";

    $stmt = $db->prepare($sql);
    $stmt->execute($conditions);

    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

function update($table, $data, $conditions) {
    $db = connectToDb();

    $setParts = [];
    foreach ($data as $key => $value) {
        $setParts[] = "\"$key\" = :set_$key";
    }
    $setClause = implode(', ', $setParts);

    $whereParts = [];
    foreach ($conditions as $key => $value) {
        $whereParts[] = "\"$key\" = :where_$key";
    }
    $whereClause = implode(' AND ', $whereParts);

    $sql = "UPDATE \"$table\" SET $setClause WHERE $whereClause";

    $params = [];
    foreach ($data as $key => $value) {
        $params['set_' . $key] = $value;
    }
    foreach ($conditions as $key => $value) {
        $params['where_' . $key] = $value;
    }

    $stmt = $db->prepare($sql);
    return $stmt->execute($params);
}
function upsert($table, $data, $conflictColumns) {
    $db = connectToDb();

    $columns = '"' . implode('","', array_keys($data)) . '"';
    $placeholders = ':' . implode(', :', array_keys($data));

    $updateParts = [];
    foreach ($data as $key => $value) {
        $updateParts[] = "\"$key\" = EXCLUDED.\"$key\"";
    }
    $updateClause = implode(', ', $updateParts);

    $conflicts = '"' . implode('","', (array)$conflictColumns) . '"';

    $sql = "INSERT INTO \"$table\" ($columns) VALUES ($placeholders)
            ON CONFLICT ($conflicts) DO UPDATE SET $updateClause";

    $stmt = $db->prepare($sql);
    return $stmt->execute($data);
}