<?php

namespace FreeCryptoAPI;

/**
 * FreeCryptoAPI PHP Client
 *
 * A PHP client library for the FreeCryptoAPI cryptocurrency data service.
 *
 * @see https://freecryptoapi.com
 */
class FreeCryptoAPI
{
    /** @var string */
    private const BASE_URL = 'https://api.freecryptoapi.com/v1';

    /** @var string */
    private $apiKey;

    /** @var int Timeout in seconds for cURL requests */
    private $timeout;

    /**
     * Create a new FreeCryptoAPI client instance.
     *
     * @param string $apiKey  Your FreeCryptoAPI API key
     * @param int    $timeout Request timeout in seconds (default: 30)
     */
    public function __construct(string $apiKey, int $timeout = 30)
    {
        $this->apiKey  = $apiKey;
        $this->timeout = $timeout;
    }

    // ──────────────────────────────────────────────
    //  Market Data
    // ──────────────────────────────────────────────

    /**
     * Get a list of all available cryptocurrencies.
     *
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getCryptoList(): array
    {
        return $this->request('/getCryptoList');
    }

    /**
     * Get detailed data for a specific cryptocurrency.
     *
     * @param string $symbol Cryptocurrency symbol (e.g. "BTC")
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getData(string $symbol): array
    {
        return $this->request('/getData', ['symbol' => $symbol]);
    }

    /**
     * Get top cryptocurrencies by market cap.
     *
     * @param int|null $top Number of results to return (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getTop(?int $top = null): array
    {
        return $this->request('/getTop', ['top' => $top]);
    }

    /**
     * Get cryptocurrency data converted to a specific fiat currency.
     *
     * @param string $symbol Cryptocurrency symbol (e.g. "BTC")
     * @param string $local  Fiat currency code (e.g. "EUR")
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getDataCurrency(string $symbol, string $local): array
    {
        return $this->request('/getDataCurrency', [
            'symbol' => $symbol,
            'local'  => $local,
        ]);
    }

    /**
     * Get performance metrics for a cryptocurrency.
     *
     * @param string $symbol Cryptocurrency symbol (e.g. "BTC")
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getPerformance(string $symbol): array
    {
        return $this->request('/getPerformance', ['symbol' => $symbol]);
    }

    /**
     * Get volatility data.
     *
     * @param string|null $symbol Cryptocurrency symbol (optional)
     * @param int|null    $top    Number of results (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getVolatility(?string $symbol = null, ?int $top = null): array
    {
        return $this->request('/getVolatility', [
            'symbol' => $symbol,
            'top'    => $top,
        ]);
    }

    /**
     * Get all-time high and all-time low data.
     *
     * @param string|null $symbol Cryptocurrency symbol (optional)
     * @param int|null    $months Number of months to look back (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getATHATL(?string $symbol = null, ?int $months = null): array
    {
        return $this->request('/getATHATL', [
            'symbol' => $symbol,
            'months' => $months,
        ]);
    }

    /**
     * Get the current Fear & Greed Index.
     *
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getFearGreed(): array
    {
        return $this->request('/getFearGreed');
    }

    // ──────────────────────────────────────────────
    //  Technical Analysis
    // ──────────────────────────────────────────────

    /**
     * Get technical analysis indicators for a cryptocurrency.
     *
     * @param string $symbol Cryptocurrency symbol (e.g. "BTC")
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getTechnicalAnalysis(string $symbol): array
    {
        return $this->request('/getTechnicalAnalysis', ['symbol' => $symbol]);
    }

    /**
     * Get breakout signals.
     *
     * @param string|null $symbol Cryptocurrency symbol (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getBreakouts(?string $symbol = null): array
    {
        return $this->request('/getBreakouts', ['symbol' => $symbol]);
    }

    /**
     * Get correlation data between cryptocurrencies.
     *
     * @param string   $symbols Comma-separated cryptocurrency symbols (e.g. "BTC,ETH,SOL")
     * @param int|null $days    Number of days for correlation window (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getCorrelation(string $symbols, ?int $days = null): array
    {
        return $this->request('/getCorrelation', [
            'symbols' => $symbols,
            'days'    => $days,
        ]);
    }

    /**
     * Get support and resistance levels for a cryptocurrency.
     *
     * @param string   $symbol Cryptocurrency symbol (e.g. "BTC")
     * @param int|null $period Period in days (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getSupportResistance(string $symbol, ?int $period = null): array
    {
        return $this->request('/getSupportResistance', [
            'symbol' => $symbol,
            'period' => $period,
        ]);
    }

    /**
     * Get Moving Average Ribbon data.
     *
     * @param string   $symbol Cryptocurrency symbol (e.g. "BTC")
     * @param int|null $days   Number of days (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getMARibbon(string $symbol, ?int $days = null): array
    {
        return $this->request('/getMARibbon', [
            'symbol' => $symbol,
            'days'   => $days,
        ]);
    }

    /**
     * Get Bollinger Bands data.
     *
     * @param string     $symbol Cryptocurrency symbol (e.g. "BTC")
     * @param int|null   $days   Number of days (optional)
     * @param int|null   $period Bollinger period (optional)
     * @param float|null $stdDev Standard deviation multiplier (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getBollinger(string $symbol, ?int $days = null, ?int $period = null, ?float $stdDev = null): array
    {
        return $this->request('/getBollinger', [
            'symbol' => $symbol,
            'days'   => $days,
            'period' => $period,
            'stdDev' => $stdDev,
        ]);
    }

    // ──────────────────────────────────────────────
    //  Exchange Data
    // ──────────────────────────────────────────────

    /**
     * Get data for a specific exchange.
     *
     * @param string $exchange Exchange identifier (e.g. "binance")
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getExchange(string $exchange): array
    {
        return $this->request('/getExchange', ['exchange' => $exchange]);
    }

    // ──────────────────────────────────────────────
    //  Conversion
    // ──────────────────────────────────────────────

    /**
     * Convert an amount between two currencies.
     *
     * @param string $from   Source currency symbol (e.g. "BTC")
     * @param string $to     Target currency symbol (e.g. "ETH")
     * @param float  $amount Amount to convert
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getConversion(string $from, string $to, float $amount): array
    {
        return $this->request('/getConversion', [
            'from'   => $from,
            'to'     => $to,
            'amount' => $amount,
        ]);
    }

    // ──────────────────────────────────────────────
    //  Historical Data
    // ──────────────────────────────────────────────

    /**
     * Get historical price data for a cryptocurrency.
     *
     * @param string $symbol Cryptocurrency symbol (e.g. "BTC")
     * @param int    $days   Number of days of history
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getHistory(string $symbol, int $days): array
    {
        return $this->request('/getHistory', [
            'symbol' => $symbol,
            'days'   => $days,
        ]);
    }

    /**
     * Get price data for a specific time range.
     *
     * @param string $symbol Cryptocurrency symbol (e.g. "BTC")
     * @param string $start  Start date (YYYY-MM-DD)
     * @param string $end    End date (YYYY-MM-DD)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getTimeframe(string $symbol, string $start, string $end): array
    {
        return $this->request('/getTimeframe', [
            'symbol' => $symbol,
            'start'  => $start,
            'end'    => $end,
        ]);
    }

    /**
     * Get OHLC (Open, High, Low, Close) candlestick data.
     *
     * @param string      $symbol    Cryptocurrency symbol (e.g. "BTC")
     * @param int|null    $days      Number of days (optional)
     * @param string|null $startDate Start date in YYYY-MM-DD format (optional)
     * @param string|null $endDate   End date in YYYY-MM-DD format (optional)
     * @return array
     * @throws FreeCryptoAPIException
     */
    public function getOHLC(string $symbol, ?int $days = null, ?string $startDate = null, ?string $endDate = null): array
    {
        return $this->request('/getOHLC', [
            'symbol'    => $symbol,
            'days'      => $days,
            'startDate' => $startDate,
            'endDate'   => $endDate,
        ]);
    }

    // ──────────────────────────────────────────────
    //  Internal helpers
    // ──────────────────────────────────────────────

    /**
     * Send a GET request to the API.
     *
     * @param string $endpoint API endpoint path (e.g. "/getData")
     * @param array  $params   Query parameters (null values are filtered out)
     * @return array Decoded JSON response
     * @throws FreeCryptoAPIException
     */
    private function request(string $endpoint, array $params = []): array
    {
        // Remove null values from parameters
        $params = array_filter($params, function ($value) {
            return $value !== null;
        });

        $url = self::BASE_URL . $endpoint;

        if (!empty($params)) {
            $url .= '?' . http_build_query($params);
        }

        $ch = curl_init();

        if ($ch === false) {
            throw new FreeCryptoAPIException('Failed to initialise cURL', 0);
        }

        curl_setopt_array($ch, [
            CURLOPT_URL            => $url,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => $this->timeout,
            CURLOPT_HTTPHEADER     => [
                'Authorization: Bearer ' . $this->apiKey,
                'Accept: application/json',
            ],
        ]);

        $response   = curl_exec($ch);
        $statusCode = (int) curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $curlError  = curl_error($ch);

        curl_close($ch);

        if ($response === false) {
            throw new FreeCryptoAPIException(
                'cURL request failed: ' . $curlError,
                0
            );
        }

        $decoded = json_decode($response, true);

        if (json_last_error() !== JSON_ERROR_NONE) {
            throw new FreeCryptoAPIException(
                'Failed to decode JSON response: ' . json_last_error_msg(),
                $statusCode
            );
        }

        if ($statusCode < 200 || $statusCode >= 300) {
            $message = isset($decoded['message'])
                ? $decoded['message']
                : 'API request failed';

            throw new FreeCryptoAPIException($message, $statusCode);
        }

        return $decoded;
    }
}