<#
.SYNOPSIS
    Creates a line chart from cvs data
.DESCRIPTION
    Creates a fancy (more or less...) line chart reading a csv file
    (a _real_ 'comma separated values'-file, not the thing which is
    generated  by excel. The chart is written to a png file.

    This thing has been created to automaticly report the utilization
    of our horizon view pools to my boss.
.PARAMETER CsvPath
    Specifies full path to the csv file.
.PARAMETER Caption
    Specifies the chart's caption.
.PARAMETER MetricFields
    Specifies the fields within the csv file which contain the y-axis
    data
.PARAMETER DateField
    Specifies the name of the field containing date
.PARAMETER DateFieldFormat
    Specifies the input format for parsing the dare file. For a list 
    of available format specifiers, see DateTimeFormatInfo Class
.PARAMETER ImagePath
    Specifies the path where the image file is written. If the file
    exists, it will be overwritten.
.PARAMETER ImageHeight
    Specifies the desired height of the image
.PARAMETER ImageWidth
    Specifies the desired width of the image
.PARAMETER AxisXIsLogarithmic
    If Present, the y-axis will be drawn logarithmic
.NOTES
    Author: kurator | lagerhaus128.ch
    Changelog:
    Revision 0:
        Initial revision
.EXAMPLE
    Convert-CsvToChart.ps1 -CsvPath "c:\temp\20160503_poolusage.csv" -Caption "VDI pool statistics 20160403-20160503" -MetricFields @("POOL01","POOL02","POOL03","POOL04","POOL05","POOL06") -DateField "Date" -DateFieldFormat "yyyyMMdd" -ImagePath "c:\temp\out.png"
 .COMPONENT
#>

#Requires -Version 4.0

param(
    [Parameter(Mandatory=$true)][string]$CsvPath,
    [Parameter(Mandatory=$true)][string]$Caption,
    [Parameter(Mandatory=$true)][array]$MetricFields,
    [Parameter(Mandatory=$true)][string]$DateField,
    [Parameter(Mandatory=$false)][string]$DateFieldFormat = "dd.MM.yyyy hh:mm",
    [Parameter(Mandatory=$true)][string]$ImagePath,
    [Parameter(Mandatory=$false)][int]$ImageHeight = 1500,
    [Parameter(Mandatory=$false)][int]$ImageWidth = 1000,
    [switch]$AxisYIsLogarithmic
)

Try{
    [void][Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms.DataVisualization")
} catch {
    Write-Error "The assembly System.Windows.Forms.DataVisualization Assembly is not available."
    exit 1
}
Try{
    $data = Import-Csv $CsvPath
    $chart = New-Object System.Windows.Forms.DataVisualization.Charting.Chart
    $chart.width = $ImageHeight
    $chart.Height = $ImageWidth
    $chart.Left = 40
    $chart.top = 30
    $chart.Name = $Caption
    [void]$chart.Titles.Add($Caption) 
    [void]$chart.ChartAreas.Add((New-Object System.Windows.Forms.DataVisualization.Charting.ChartArea))
    [void]$chart.Legends.Add((New-Object System.Windows.Forms.DataVisualization.Charting.Legend))
    foreach ($Metric in $MetricFields)
    {
        [void]$chart.Series.Add($Metric)
        $chart.Series[$Metric].ChartType = [System.Windows.Forms.DataVisualization.Charting.SeriesChartType]::Line
        $chart.Series[$Metric].XValueType = [System.Windows.Forms.DataVisualization.Charting.ChartValueType]::DateTime
        $chart.ChartAreas[0].AxisY.IsLogarithmic = $AxisYIsLogarithmic
        foreach ($row in $data)
        {
            [void]$chart.Series[$Metric].Points.Add((New-Object System.Windows.Forms.DataVisualization.Charting.DataPoint(($([datetime]::ParseExact([string]$row.$DateField, $DateFieldFormat, $null)).ToOADate()), [double]$($row.$Metric).Replace(',','.'))))
        }
    }
    $chart.SaveImage($ImagePath, "PNG")
    Remove-Variable chart,data
} catch {
    Write-Error $_.Exception.Message
}