<?php

declare(strict_types=1);

namespace TCB;

use TCB\Credentials;
use TCB\HttpServer;
use TCB\Request;
use TCB\Response;
use TCB\TokenStorage;

final class TokenManager
{
    private string $authorisationCode;

    public function __construct(
        private readonly Credentials $credentials,
        private readonly HttpServer $httpServer,
        private readonly TokenStorage $storage,
    ) {}

    public function getAccessToken(): string
    {
        if ($this->storage->accessToken === '' || $this->storage->refreshToken === '') {
            $this->authorise();
            $this->requestAccessToken();
        }

        if ($this->storage->expiresOn < time()) {
            $this->refreshAccessToken();
        }

        return $this->storage->accessToken;
    }

    private function authorise(): void
    {
        $this->authorisationCode = '';

        $this->httpServer->get(
            '/callback',
            function (Request $request, HttpServer $server): Response {
                $server->closeAfterResponse();

                if (
                    !array_key_exists('state', $request->params)
                    || $request->params['state'] !== $this->credentials->state
                ) {
                    $body = 'State mismatch.';
                } elseif (array_key_exists('error', $request->params)) {
                    $body = "Error from Spotify: {$request->params['error']}";
                } elseif (!array_key_exists('code', $request->params)) {
                    $body = "Missing authorisation code from Spotify.";
                } else {
                    $this->authorisationCode = $request->params['code'];
                    $body = 'Authorisation code received from Spotify. You can close this page and go back to the terminal.';
                }

                return new Response(
                    statusCode: 200,
                    contentType: 'text/plain; charset=UTF-8',
                    body: htmlspecialchars($body, ENT_QUOTES),
                );
            },
        );

        $query = http_build_query([
            'response_type' => 'code',
            'client_id' => $this->credentials->clientID,
            'redirect_uri' => $this->credentials->redirectURI,
            'state' => $this->credentials->state,
            'scope' => 'playlist-read-private',
            'show_dialog' => false,
        ]);

        echo "Visit the below URL in your browser to authorise access to Spotify.\n";
        echo "https://accounts.spotify.com/authorize?$query\n";
        echo "Waiting for authorisation from Spotify...\n";

        $this->httpServer->run();

        if ($this->authorisationCode === '') {
            echo "Failed to get authorisation code from Spotify.\n";
            exit(1);
        }
    }

    private function requestAccessToken(): void
    {
        echo "Requesting an access token from Spotify.\n";

        $ch = curl_init();

        curl_setopt_array($ch, [
            CURLOPT_URL => 'https://accounts.spotify.com/api/token',
            CURLOPT_POST => true,
            CURLOPT_HTTPHEADER => [
                'Authorization: Basic ' . base64_encode($this->credentials->clientID . ':' . $this->credentials->clientSecret),
                'Content-Type: application/x-www-form-urlencoded',
            ],
            CURLOPT_POSTFIELDS => http_build_query([
                'grant_type'  => 'authorization_code',
                'code' => $this->authorisationCode,
                'redirect_uri' => $this->credentials->redirectURI,
            ]),
            CURLOPT_RETURNTRANSFER => true,
        ]);

        $response = curl_exec($ch);
        $statusCode = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);

        if ($statusCode !== 200) {
            echo "Non 200 response from Spotify: $statusCode $response\n";
            exit(1);
        }

        $data = json_decode($response, true) ?? [];

        $accessToken = $data['access_token'] ?? '';
        $refreshToken = $data['refresh_token'] ?? '';
        $expiresIn = $data['expires_in'] ?? 0;

        if ($accessToken === '' || $refreshToken === '') {
            echo "Failed to get access token from Spotify.\n";
            exit(1);
        }

        $this->storage->accessToken = $accessToken;
        $this->storage->refreshToken = $refreshToken;
        $this->storage->expiresOn = time() + $expiresIn;
        $this->storage->save();
    }

    private function refreshAccessToken(): void
    {
        echo "Refreshing the Spotify access token.\n";

        $ch = curl_init();

        curl_setopt_array($ch, [
            CURLOPT_URL => 'https://accounts.spotify.com/api/token',
            CURLOPT_POST => true,
            CURLOPT_HTTPHEADER => [
                'Authorization: Basic ' . base64_encode($this->credentials->clientID . ':' . $this->credentials->clientSecret),
                'Content-Type: application/x-www-form-urlencoded',
            ],
            CURLOPT_POSTFIELDS => http_build_query([
                'grant_type'  => 'refresh_token',
                'refresh_token' => $this->storage->refreshToken,
            ]),
            CURLOPT_RETURNTRANSFER => true,
        ]);

        $response = curl_exec($ch);
        $statusCode = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);

        if ($statusCode !== 200) {
            echo "Non 200 response from Spotify: $statusCode $response\n";
            exit(1);
        }

        $data = json_decode($response, true) ?? [];

        $accessToken = $data['access_token'] ?? '';
        $refreshToken = $data['refresh_token'] ?? $this->storage->refreshToken;
        $expiresIn = $data['expires_in'] ?? 0;

        if ($accessToken === '' || $refreshToken === '') {
            echo "Failed to refresh the Spotify access token.\n";
            exit(1);
        }

        $this->storage->accessToken = $accessToken;
        $this->storage->refreshToken = $refreshToken;
        $this->storage->expiresOn = time() + $expiresIn;
        $this->storage->save();
    }
}