function Get-SemverHistory {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $false)]
        [string]$Path = (Get-Location).Path
    )

    if ((Split-Path -Path $Path -Leaf) -eq 'sem.ver') {
        # We have a semver file already
    } else {
        if (-not (Get-Item -Path $Path).PSIsContainer) {
            throw "The Path argument should be a folder or a sem.ver specific file"
        }

        $Path = Join-Path -Path $Path -ChildPath "sem.ver"
        $Path = (Get-ChildItem -Path $Path -Recurse | Select-Object -First 1).FullName
    }

    if (-not (Test-Path -Path $Path)) {
        throw "Could not find the requested path [$Path]"
    }

    $semverLog = git log -c -- $Path

    $commits = @()
    $commit = $null
    $inSemverLines = $false
    foreach ($line in $semverLog) {
        if ([string]::IsNullOrWhiteSpace($line)) {
            continue
        }
        # This breaks if the comment starts with the word 'commit' on the left margin
        if ($line.StartsWith("commit") -and [string]::IsNullOrWhiteSpace($Commit.SemverValue)) {
            if ($null -ne $commit) {
                $commits += $commit
            }
            $commit = @{
                Hash           = ($line -split 'commit ')[1].Trim()
                Author         = ""
                Date           = ""
                SemverValue    = ""
                SemverContents = @()
                Comment        = @()
            }
            $inSemverLines = $false
        } elseif ($line.StartsWith("Author:")) {
            $commit.Author = ($line -split 'Author:')[1].Trim()
        } elseif ($line.StartsWith("Date:")) {
            $commit.Date = ($line -split 'Date:')[1].Trim()
        } else {
            if ($line.StartsWith("diff --git")) {
                # We don't care about [diff --git a/sem.ver b/sem.ver] type lines
                continue
            } elseif ($line.StartsWith("index") -and ($line -split ' ').Count -eq 3) {
                # we don't care about [index 7c4d2b4..e1de4ac 100644] type lines
                continue
            } elseif ($line.StartsWith("---") -or $line.StartsWith("+++")) {
                # we don't care about the diff filenames
                continue
            } elseif ($line.StartsWith("@@") -and $line.EndsWith("@@")) {
                $inSemverLines = $true
                continue
            } elseif ($inSemverLines) {
                if ($line.Trim().StartsWith("-") -or $line.StartsWith("\")) {
                    # ignore remove lines
                    continue
                } elseif ($line.Trim().StartsWith("+")) {
                    # skip the first two characters
                    $line = $line.Substring(2)
                }

                $commit.SemverContents += $line
            } else {
                $commit.Comment += $line.Trim()
            }
        }
    }
    # Save the last one too!
    if ($null -ne $commit) {
        $commits += $commit
    }

    foreach ($commit in $commits) {
        # Yes, it's a hack. It's cheaper than retrieving the file _at_ the hash tho
        $jsonString = "$($commit.SemverContents -join '')".Trim()
        $jsonString = $jsonString.Replace(' ', '').Replace("`t", "")
        if ([string]::IsNullOrWhiteSpace($jsonString)) {
            continue
        }
        if (($jsonString.IndexOf("Version") -eq -1) -or ($jsonString.StartsWith('{"Major"'))) {
            $jsonString = "`"Version`": {$jsonString"
        }
        if (-not $jsonString.StartsWith("{")) {
            $jsonString = "{$jsonString"
        }
        if ($jsonString.StartsWith("{{")) {
            $jsonString = $jsonString.Substring(1)
            $jsonString = "{`"Version`":$jsonString"
        }
        if (-not $jsonString.EndsWith("}")) {
            $jsonString = "$jsonString}"
        }
        if (-not $jsonString.EndsWith("}}")) {
            $jsonString = "$jsonString}"
        }
        $jsonString = $jsonString.Replace(' {{', '{')
        $json = ConvertFrom-Json $jsonString
        $commit.SemverValue = "$($json.Version.Major).$($json.Version.Minor).$($json.Version.Patch)"
        $commit.SemverContents = $null
    }

    return $commits
}

function Get-GitHistory {
    [CmdletBinding()]
    [OutputType([object[]])]
    param (
        [Parameter(Mandatory = $true, ParameterSetName = 'ByHash')]
        [ValidateNotNullOrEmpty()]
        [Alias('From')]
        [string]$HashStart,

        [Parameter(Mandatory = $true, ParameterSetName = 'ByHash')]
        [ValidateNotNullOrEmpty()]
        [Alias('To')]
        [string]$HashEnd,

        [Parameter(Mandatory = $true, ParameterSetName = 'ByObject')]
        [Alias('FromEntry')]
        [object]$StartEntry,

        [Parameter(Mandatory = $true, ParameterSetName = 'ByObject')]
        [Alias('ToEntry')]
        [object]$EndEntry
    )

    $logLead = Get-LogLeadName

    if ($PSCmdlet.ParameterSetName -eq 'ByHash') {
        if ($HashStart -eq $HashEnd) {
            Write-Error "$logLead : You must supply two different hashes. These hashes were the same."
            return
        }

        $dateStart = Invoke-CallOperatorWithPathAndParameters git @('log', '--no-walk', '--format="%ai"', $HashStart)
        $dateEnd = Invoke-CallOperatorWithPathAndParameters git @('log', '--no-walk', '--format="%ai"', $HashEnd)

        # Put them in the right order
        if ($dateStart -lt $dateEnd) {
            $HashStart, $HashEnd = $HashEnd, $HashStart
        }
    } else {
        if ($StartEntry.Date -lt $EndEntry.Date) {
            $StartEntry, $EndEntry = $EndEntry, $StartEntry
        }

        $HashEnd = $EndEntry.Hash
        $HashStart = $StartEntry.Hash
    }

    $lines = Invoke-CallOperatorWithPathAndParameters git @('log', "$HashEnd...$HashStart", '--format="Author: %aN%nDate: %ai%n%B%n-="', '--notes')

    $results = @()
    $result = $null
    $skipAdd = $false
    foreach ($line in $lines) {
        if ($line.StartsWith("Author: ")) {
            if ($null -ne $result) {
                $results += $result
                $skipAdd = $false
            }
            $result = @{
                Author      = $line.Substring(8)
                Date        = $null
                Comments    = @()
                JiraTickets = @()
            }
        } elseif ($line.Trim() -eq '-=') {
            if ($skipAdd -eq $false) {
                $results += $result
            }
            $skipAdd = $false
            $result = $null
        } elseif ($line.StartsWith("Date: ")) {
            $result.Date = [DateTime]($line.Substring(6))
        } else {
            $result.Comments += $line.Trim()
            if ($line.StartsWith('Merge')) {
                $skipAdd = $true
            }
        }
    }

    foreach ($result in $results) {
        $result.JiraTickets = (Select-String '[A-Z]+-[0-9]+' -InputObject $result.Comments -AllMatches -CaseSensitive).Matches.Value
    }

    return $results
}

function Get-RepoHistoryBySemver {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $false)]
        [string]$Path = (Get-Location).Path
    )

    $results = @()

    Write-Progress -Activity "Getting history for semver" -PercentComplete 1
    $semverHistory = Get-SemverHistory -Path $Path

    for ($i = 0; $i -lt ($semverHistory.Count - 1); $i++) {
        $from = $semverHistory[$i]
        $to = $semverHistory[$i + 1]
        Write-Progress -Activity "Getting history by semver" -PercentComplete ((100 * $i) / ($semverHistory.Count - 1)) -Status "Checking for data between $($from.Hash) and $($to.Hash)"
        $commitHistory = Get-GitHistory -StartEntry $from -EndEntry $to

        $results += @{
            Version       = $from.SemverValue
            JiraTickets   = ($commitHistory.JiraTickets | Sort-Object -Unique)
            CommitHistory = $commitHistory
            CommitCount   = $commitHistory.Count
            SemverData    = $from
        }
    }
    Write-Progress -Completed -Activity "Getting history by semver"

    return $results
}