<?php

namespace ExpressionEngine\Dependency\Dotenv\Loader;

class Lines
{
    /**
     * Process the array of lines of environment variables.
     *
     * This will produce an array of entries, one per variable.
     *
     * @param string[] $lines
     *
     * @return string[]
     */
    public static function process(array $lines)
    {
        $output = [];
        $multiline = \false;
        $multilineBuffer = [];
        foreach ($lines as $line) {
            list($multiline, $line, $multilineBuffer) = self::multilineProcess($multiline, $line, $multilineBuffer);
            if (!$multiline && !self::isCommentOrWhitespace($line)) {
                $output[] = $line;
            }
        }
        return $output;
    }
    /**
     * Used to make all multiline variable process.
     *
     * @param bool     $multiline
     * @param string   $line
     * @param string[] $buffer
     *
     * @return array{bool,string,string[]}
     */
    private static function multilineProcess($multiline, $line, array $buffer)
    {
        $startsOnCurrentLine = $multiline ? \false : self::looksLikeMultilineStart($line);
        // check if $line can be multiline variable
        if ($startsOnCurrentLine) {
            $multiline = \true;
        }
        if ($multiline) {
            \array_push($buffer, $line);
            if (self::looksLikeMultilineStop($line, $startsOnCurrentLine)) {
                $multiline = \false;
                $line = \implode("\n", $buffer);
                $buffer = [];
            }
        }
        return [$multiline, $line, $buffer];
    }
    /**
     * Determine if the given line can be the start of a multiline variable.
     *
     * @param string $line
     *
     * @return bool
     */
    private static function looksLikeMultilineStart($line)
    {
        if (\strpos($line, '="') === \false) {
            return \false;
        }
        return self::looksLikeMultilineStop($line, \true) === \false;
    }
    /**
     * Determine if the given line can be the start of a multiline variable.
     *
     * @param string $line
     * @param bool   $started
     *
     * @return bool
     */
    private static function looksLikeMultilineStop($line, $started)
    {
        if ($line === '"') {
            return \true;
        }
        $seen = $started ? 0 : 1;
        foreach (self::getCharPairs(\str_replace('\\\\', '', $line)) as $pair) {
            if ($pair[0] !== '\\' && $pair[1] === '"') {
                $seen++;
            }
        }
        return $seen > 1;
    }
    /**
     * Get all pairs of adjacent characters within the line.
     *
     * @param string $line
     *
     * @return array{array{string,string|null}}
     */
    private static function getCharPairs($line)
    {
        $chars = \str_split($line);
        /** @var array{array{string,string|null}} */
        return \array_map(null, $chars, \array_slice($chars, 1));
    }
    /**
     * Determine if the line in the file is a comment or whitespace.
     *
     * @param string $line
     *
     * @return bool
     */
    private static function isCommentOrWhitespace($line)
    {
        if (\trim($line) === '') {
            return \true;
        }
        $line = \ltrim($line);
        return isset($line[0]) && $line[0] === '#';
    }
}
