<?php
// models/User.php

class User {
    private $conn;
    private $table_name = "users";

    public function __construct($db) {
        $this->conn = $db;
    }

    // --- 1. INSCRIPTION ---
    public function register($username, $email, $password) {
        // On vérifie si l'email ou le pseudo existe déjà
        if ($this->emailExists($email) || $this->usernameExists($username)) {
            return ["success" => false, "message" => "Pseudo ou email déjà utilisé."];
        }

        // Génération d'un code de liaison unique (ex: WG-X89F2)
        $pairing_code = $this->generateUniquePairingCode();

        // Hachage sécurisé du mot de passe
        $hashed_password = password_hash($password, PASSWORD_BCRYPT);

        $query = "INSERT INTO " . $this->table_name . " 
                  SET username = :username, email = :email, password = :password, pairing_code = :pairing_code";

        $stmt = $this->conn->prepare($query);

        $stmt->bindParam(":username", $username);
        $stmt->bindParam(":email", $email);
        $stmt->bindParam(":password", $hashed_password);
        $stmt->bindParam(":pairing_code", $pairing_code);

        if ($stmt->execute()) {
            return [
                "success" => true, 
                "message" => "Utilisateur créé avec succès.",
                "pairing_code" => $pairing_code
            ];
        }
        return ["success" => false, "message" => "Erreur lors de l'inscription."];
    }

    // --- 2. CONNEXION ---
    public function login($email, $password) {
        $query = "SELECT id, username, email, password, pairing_code, partner_id FROM " . $this->table_name . " WHERE email = :email LIMIT 0,1";
        $stmt = $this->conn->prepare($query);
        $stmt->bindParam(":email", $email);
        $stmt->execute();

        if ($stmt->rowCount() > 0) {
            $row = $stmt->fetch();
            
            // Vérification du mot de passe
            if (password_verify($password, $row['password'])) {
                return [
                    "success" => true,
                    "user" => [
                        "id" => $row['id'],
                        "username" => $row['username'],
                        "email" => $row['email'],
                        "pairing_code" => $row['pairing_code'],
                        "partner_id" => $row['partner_id']
                    ]
                ];
            }
        }
        return ["success" => false, "message" => "Identifiants incorrects."];
    }

    // --- 3. LIAISON DE DEUX COMPTES ---
    public function linkPartner($current_user_id, $partner_code) {
        // 1. Trouver le partenaire qui possède ce code
        $query = "SELECT id, partner_id FROM " . $this->table_name . " WHERE pairing_code = :partner_code LIMIT 0,1";
        $stmt = $this->conn->prepare($query);
        $stmt->bindParam(":partner_code", $partner_code);
        $stmt->execute();

        if ($stmt->rowCount() == 0) {
            return ["success" => false, "message" => "Code de liaison invalide."];
        }

        $partner = $stmt->fetch();
        $partner_id = $partner['id'];

        // Sécurité : On ne peut pas se lier à soi-même
        if ($partner_id == $current_user_id) {
            return ["success" => false, "message" => "Tu ne peux pas te lier à ton propre compte."];
        }

        // Sécurité : Vérifier si le partenaire est déjà pris
        if (!is_null($partner['partner_id'])) {
            return ["success" => false, "message" => "Ce partenaire est déjà lié à quelqu'un d'autre."];
        }

        try {
            // On commence une transaction SQL pour être sûr que les deux updates passent (ou aucun)
            $this->conn->beginTransaction();

            // Update de l'utilisateur actuel
            $query1 = "UPDATE " . $this->table_name . " SET partner_id = :partner_id WHERE id = :current_id";
            $stmt1 = $this->conn->prepare($query1);
            $stmt1->bindParam(":partner_id", $partner_id);
            $stmt1->bindParam(":current_id", $current_user_id);
            $stmt1->execute();

            // Update du partenaire (réciprocité)
            $query2 = "UPDATE " . $this->table_name . " SET partner_id = :current_id WHERE id = :partner_id";
            $stmt2 = $this->conn->prepare($query2);
            $stmt2->bindParam(":current_id", $current_user_id);
            $stmt2->bindParam(":partner_id", $partner_id);
            $stmt2->execute();

            $this->conn->commit();
            return ["success" => true, "message" => "Comptes liés avec succès !"];

        } catch (Exception $e) {
            $this->conn->rollBack();
            return ["success" => false, "message" => "Erreur lors de la liaison."];
        }
    }
    
    // --- 4. RÉCUPÉRER LE STATUT DE PAIRAGE ---
    public function getPairingStatus($user_id) {
        // On récupère les infos de l'utilisateur et de son partenaire s'il existe
        $query = "SELECT u1.pairing_code, u1.partner_id, u2.username AS partner_username 
                FROM " . $this->table_name . " u1
                LEFT JOIN " . $this->table_name . " u2 ON u1.partner_id = u2.id
                WHERE u1.id = :user_id LIMIT 1";
                
        $stmt = $this->conn->prepare($query);
        $stmt->bindParam(":user_id", $user_id);
        $stmt->execute();

        if ($stmt->rowCount() > 0) {
            return ["success" => true, "data" => $stmt->fetch()];
        }
        return ["success" => false, "message" => "Utilisateur introuvable."];
    }

    // --- 5. CASSER LE LIEN (DÉLIAISON) ---
    public function unlinkPartner($user_id) {
        // 1. On cherche d'abord l'ID du partenaire actuel
        $query = "SELECT partner_id FROM " . $this->table_name . " WHERE id = :user_id LIMIT 1";
        $stmt = $this->conn->prepare($query);
        $stmt->bindParam(":user_id", $user_id);
        $stmt->execute();
        
        $user = $stmt->fetch();
        if (!$user || is_null($user['partner_id'])) {
            return ["success" => false, "message" => "Tu n'es lié à personne."];
        }

        $partner_id = $user['partner_id'];

        try {
            $this->conn->beginTransaction();

            // On passe le partner_id à NULL pour les deux utilisateurs
            $query1 = "UPDATE " . $this->table_name . " SET partner_id = NULL WHERE id = :user_id";
            $stmt1 = $this->conn->prepare($query1);
            $stmt1->bindParam(":user_id", $user_id);
            $stmt1->execute();

            $query2 = "UPDATE " . $this->table_name . " SET partner_id = NULL WHERE id = :partner_id";
            $stmt2 = $this->conn->prepare($query2);
            $stmt2->bindParam(":partner_id", $partner_id);
            $stmt2->execute();

            $this->conn->commit();
            return ["success" => true, "message" => "Comptes déliés avec succès."];
        } catch (Exception $e) {
            $this->conn->rollBack();
            return ["success" => false, "message" => "Erreur lors de la déliaison."];
        }
    }

    // --- UTILS / VALIDATIONS ---
    private function emailExists($email) {
        $query = "SELECT id FROM " . $this->table_name . " WHERE email = :email LIMIT 1";
        $stmt = $this->conn->prepare($query);
        $stmt->bindParam(":email", $email);
        $stmt->execute();
        return $stmt->rowCount() > 0;
    }

    private function usernameExists($username) {
        $query = "SELECT id FROM " . $this->table_name . " WHERE username = :username LIMIT 1";
        $stmt = $this->conn->prepare($query);
        $stmt->bindParam(":username", $username);
        $stmt->execute();
        return $stmt->rowCount() > 0;
    }

    private function generateUniquePairingCode() {
        $characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        do {
            $code = 'WG-';
            for ($i = 0; $i < 6; $i++) {
                $code .= $characters[rand(0, strlen($characters) - 1)];
            }
            
            // On vérifie en BDD que le code n'existe pas déjà par pur hasard
            $query = "SELECT id FROM " . $this->table_name . " WHERE pairing_code = :code LIMIT 1";
            $stmt = $this->conn->prepare($query);
            $stmt->bindParam(":code", $code);
            $stmt->execute();
            $exists = $stmt->rowCount() > 0;
        } while ($exists);

        return $code;
    }
}