<?php

declare(strict_types=1);

namespace TCB;

use TCB\TokenManager;
use TCB\HistoryStorage;

final class SpotifyApiClient
{
    public function __construct(
        private readonly TokenManager $tokenManager,
        private readonly HistoryStorage $historyStorage,
    ) {}

    public function pickRandomSongFromPlaylist(string $playlistName): array
    {
        echo "Picking a random song from the playlist $playlistName.\n";

        if (
            !array_key_exists($playlistName, $this->historyStorage->playlists)
            || $this->historyStorage->playlists[$playlistName] === ''
        ) {
            $this->getPlaylistID($playlistName);
        }

        $items = $this->getPlaylistItems($this->historyStorage->playlists[$playlistName]);

        if (!count($items)) {
            echo "Playlist appears empty.\n";
            exit(1);
        }

        $items = array_values(array_filter($items, function (array $item): bool {
            return !array_key_exists($item['id'], $this->historyStorage->history);
        }));

        if (!count($items)) {
            echo "No songs left to pick.\n";
            exit(1);
        }

        $key = array_rand($items);

        $song = $items[$key];

        $this->historyStorage->saveSong($song);

        return $song;
    }

    private function getPlaylistID(string $playlistName): void
    {
        echo "Looking up the Spotify playlist ID.\n";

        $url = 'https://api.spotify.com/v1/me/playlists?limit=50';

        $ch = curl_init();

        while ($url !== null) {
            curl_setopt_array($ch, [
                CURLOPT_URL => $url,
                CURLOPT_HTTPGET => true,
                CURLOPT_HTTPHEADER => [
                    "Authorization: Bearer {$this->tokenManager->getAccessToken()}",
                ],
                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) ?? [];

            foreach ($data['items'] ?? [] as $item) {
                if ($item['name'] === $playlistName) {
                    $this->historyStorage->playlists[$playlistName] = $item['id'];
                    $this->historyStorage->save();

                    return;
                }
            }

            $url = $data['next'] ?? null;
        }

        echo "Unable to find a playlist named $playlistName.\n";
        exit(1);
    }

    private function getPlaylistItems(string $playlistID): array
    {
        $items = [];

        $query = http_build_query([
            'fields' => 'next,items(item(id,name,artists(name)))',
        ]);

        $url = "https://api.spotify.com/v1/playlists/$playlistID/items?limit=50&$query";

        $ch = curl_init();

        while ($url !== null) {
            curl_setopt_array($ch, [
                CURLOPT_URL => $url,
                CURLOPT_HTTPGET => true,
                CURLOPT_HTTPHEADER => [
                    "Authorization: Bearer {$this->tokenManager->getAccessToken()}",
                ],
                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) ?? [];

            foreach ($data['items'] ?? [] as $item) {
                if (isset($item['item'])) {
                    $items[] = $item['item'];
                }
            }

            $url = $data['next'] ?? null;
        }

        return $items;
    }
}