<?php

namespace App\Services;

class DataSetReader {
    public array $lines = [];
    private array $currentLines = [];

    private int $lastReadLineIndex = -1;

    public function __construct(
        public string $filename,
    ) {
        // For now, we only support CSV files, so we can delegate to CsvReader
        $csvReader = new CsvReader($filename);
        $this->readEntireFile($csvReader);
        $this->reset();
    }

    private function readEntireFile(CsvReader $reader): void
    {
        while ($line = $reader->readNextLine()) {
            $newLine = [];
            foreach ($line as $value) { // Transform to float
                $newLine[] = (float) $value;
            }

            // if the dataset is for regression, we add a fake label of 0
            if (count($newLine) === 2) {
                $newLine[] = 0.0;
            }

            $this->lines[] = $newLine;
        }
    }

    public function getRandomLine(): array | null
    {
        if (empty($this->currentLines)) {
            return null; // No more lines to read
        }
        $randomNumber = array_rand($this->currentLines);
        $randomLine = $this->currentLines[$randomNumber];

        // Remove the line from the current lines to avoid repetition
        unset($this->currentLines[$randomNumber]);

        // Remember the index of the last read line in the full list
        $this->lastReadLineIndex = array_search($randomLine, $this->lines, true);

        return $randomLine;
    }

    public function getNextLine(): array | null {
        if (!isset($this->currentLines[0])) {
            return null; // No more lines to read
        }

        $this->lastReadLineIndex = array_search($this->currentLines[0], $this->lines, true);
        
        return array_shift($this->currentLines);
    }

    public function getInputSize(): int
    {
        return count($this->lines[0]) - 1; // Don't count the label
    }

    public function reset(): void
    {
        $this->currentLines = $this->lines;
    }

    public function getLastReadLineIndex(): int
    {
        return $this->lastReadLineIndex;
    }
}