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# Determine input file
if ($args.Count -gt 0) {
    $inputFile = $args[0]
} else {
    # Search for CSV files in current directory (excluding already processed)
    $csvFiles = Get-ChildItem -Path . -Filter "*.csv" | Where-Object { $_.Name -notlike "*_shifted.csv" }
    if ($csvFiles.Count -eq 0) {
        Write-Host "Error: No CSV files found in current directory"
        exit 1
    } elseif ($csvFiles.Count -eq 1) {
        $inputFile = $csvFiles[0].Name
        Write-Host "Found file: $inputFile"
    } else {
        Write-Host "Multiple CSV files found. Please select a file:"
        $index = 1
        $csvFiles | ForEach-Object {
            Write-Host "  [$index] $($_.Name)"
            $index++
        }
        do {
            $selection = Read-Host "Enter number (1-$($csvFiles.Count))"
            $selectedIndex = [int]$selection - 1
            if ($selectedIndex -ge 0 -and $selectedIndex -lt $csvFiles.Count) {
                $inputFile = $csvFiles[$selectedIndex].Name
                Write-Host "Selected: $inputFile"
                break
            } else {
                Write-Host "Invalid selection. Please enter a number between 1 and $($csvFiles.Count)"
            }
        } while ($true)
    }
}

# Check if file exists
if (-not (Test-Path $inputFile)) {
    Write-Host "Error: File '$inputFile' not found"
    exit 1
}

# Request number of weeks to shift
$defaultWeeks = 52  # Approximately a year
Write-Host ""
Write-Host "How many weeks to shift dates? (default: $defaultWeeks)"
Write-Host "You can specify a negative value to shift backward (e.g., -52)"
do {
    $weeksInput = Read-Host "Enter number of weeks [$defaultWeeks]"
    if ([string]::IsNullOrWhiteSpace($weeksInput)) {
        $weeksShift = $defaultWeeks
        break
    }
    try {
        $weeksShift = [int]$weeksInput
        if ($weeksShift -eq 0) {
            Write-Host "Number of weeks cannot be zero"
            continue
        }
        break
    } catch {
        Write-Host "Please enter an integer"
    }
} while ($true)

$direction = if ($weeksShift -gt 0) { "forward" } else { "backward" }
Write-Host "Will shift $direction by $([math]::Abs($weeksShift)) weeks ($([math]::Abs($weeksShift) * 7) days)"

# Form output file name
$baseName = [System.IO.Path]::GetFileNameWithoutExtension($inputFile)
$outputFile = "${baseName}_shifted.csv"

# Get file size for progress
$fileInfo = Get-Item $inputFile
$fileSize = $fileInfo.Length
$fileSizeMB = [math]::Round($fileSize / 1MB, 2)

Write-Host "Input file: $inputFile"
Write-Host "File size: $fileSizeMB MB"
Write-Host "Output file: $outputFile"
Write-Host "Processing..."

# Use UTF-8 without BOM (like Python)
$utf8NoBom = New-Object System.Text.UTF8Encoding $false

# Determine line ending format from source file (read only first bytes via FileStream)
$sampleSize = 2048
$sampleBytes = New-Object byte[] $sampleSize
$fileStream = [System.IO.File]::OpenRead($inputFile)
try {
    $bytesRead = $fileStream.Read($sampleBytes, 0, $sampleSize)
    $fileStream.Close()
    
    if ($bytesRead -gt 0) {
        $actualBytes = $sampleBytes[0..($bytesRead - 1)]
        $sampleText = $utf8NoBom.GetString($actualBytes)
        if ($sampleText -match "`r`n") {
            $lineEnding = "`r`n"
        } elseif ($sampleText -match "`n") {
            $lineEnding = "`n"
        } else {
            $lineEnding = "`r`n"  # Default CRLF for Windows
        }
    } else {
        $lineEnding = "`r`n"  # Default CRLF for Windows
    }
} catch {
    $lineEnding = "`r`n"  # Default CRLF for Windows
} finally {
    if ($fileStream) { $fileStream.Close() }
}

$reader = [System.IO.StreamReader]::new($inputFile, $utf8NoBom, $true, 1024*1024)
$writer = [System.IO.StreamWriter]::new($outputFile, $false, $utf8NoBom, 1024*1024)

# Header
$header = $reader.ReadLine()
$writer.Write($header + $lineEnding)

# Determine file type by header
$headerUpper = $header.ToUpper()
if ($headerUpper -match '<OPEN>' -and $headerUpper -match '<HIGH>') {
    $fileType = "Bars"
} elseif ($headerUpper -match '<BID>' -and $headerUpper -match '<ASK>') {
    $fileType = "Ticks"
} else {
    $fileType = "Unknown"
}

Write-Host "File type: $fileType"

$processed = 0
$bytesRead = $utf8NoBom.GetByteCount($header + $lineEnding)

while ($null -ne ($line = $reader.ReadLine())) {
    # Quick check and process date
    # Date format is the same for both types: YYYY.MM.DD
    if ($line -and $line.Length -gt 0 -and $line[0] -match '\d') {
        # Find position of first tabulator
        $tabPos = $line.IndexOf("`t")
        if ($tabPos -ge 10) {  # Minimum YYYY.MM.DD (10 characters)
            try {
                # Parse date
                $dateStr = $line.Substring(0, $tabPos)
                $dt = [DateTime]::ParseExact($dateStr, "yyyy.MM.dd", $null)
                # Add weeks
                $dtNew = $dt.AddDays($weeksShift * 7)
                # Form new line with updated date
                $newDateStr = $dtNew.ToString("yyyy.MM.dd")
                $line = $newDateStr + $line.Substring($tabPos)
            } catch {
                # If failed to parse date, skip line without changes
            }
        }
    }
    
    # Write line with original ending
    $writer.Write($line + $lineEnding)
    
    $processed++
    $lineBytes = $utf8NoBom.GetByteCount($line + $lineEnding)
    $bytesRead += $lineBytes
    
    # Update progress every 10000 lines
    if ($processed % 10000 -eq 0) {
        $percent = [math]::Min(100, [int]($bytesRead / $fileSize * 100))
        $mbProcessed = [math]::Round($bytesRead / 1MB, 1)
        Write-Progress -Activity "Processing CSV" -Status "Processed $mbProcessed MB of $fileSizeMB MB ($processed lines)" -PercentComplete $percent
    }
}

$reader.Close()
$writer.Close()

Write-Progress -Activity "Processing CSV" -Completed
Write-Host "Done! Result saved to $outputFile"
Write-Host "Processed lines: $processed"

@echo off
chcp 65001 >nul
echo Processing file...

cd /d "%~dp0"
powershell.exe -NoProfile -ExecutionPolicy Bypass -File "shift_dates_en.ps1" %*

pause