# Copyright (c) Microsoft Corporation.
# Licensed under the MIT license.

#################################
# New-TerminalStackedChangelog generates a markdown file with attribution
# over a set of revision ranges.
# Dustin uses it when he's writing the changelog.
# 
## For example, generating the changelog for both 1.9 and 1.10 might look like this:
# $ New-TerminalStackedChangelog 1.9..release-1.9, 1.10..release-1.10
## The output will be a markdown-like document. Each commit will be converted into a
## single-line entry with attribution and an optional count:
#
# * Foo the bar (thanks @PanosP!)
# * [2] Fix the bug
#
# Entries with a count were present in both changelists.
#
# If you don't have the release tags/branches checked out locally, you might
# need to do something like:
#
# $ New-TerminalStackedChangelog origin/release-1.8..origin/release-1.9

#Requires -Version 7.0

[CmdletBinding()]
Param(
    [string[]]$RevisionRanges
)

Function Test-MicrosoftPerson($email) {
    Return $email -like "*@microsoft.com" -Or $email -like "pankaj.d*"
}

Function Generate-Thanks($Entry) {
    # We don't need to thank ourselves for doing our jobs
    If ($_.Microsoft) {
        ""
    } ElseIf (-Not [string]::IsNullOrEmpty($_.PossibleUsername)) {
        " (thanks @{0}!)" -f $_.PossibleUsername
    } Else {
        " (thanks @<{0}>!)" -f $_.Email
    }
}

$usernameRegex = [regex]::new("(?:\d+\+)?(?<name>[^@]+)@users.noreply.github.com")
Function Get-PossibleUserName($email) {
    $match = $usernameRegex.Match($email)
    if ($null -Ne $match) {
        return $match.Groups["name"].Value
    }
    return $null
}

$Entries = @()

ForEach ($RevisionRange in $RevisionRanges) {
    # --pretty=format notes:
    #   - %an: author name
    #   - %x1C: print a literal FS (0x1C), which will be used as a delimiter
    #   - %ae: author email
    #   - %x1C: another FS
    #   - %s: subject, the title of the commit
    $NewEntries = & git log $RevisionRange "--pretty=format:%an%x1C%ae%x1C%s" |
        ConvertFrom-CSV -Delimiter "`u{001C}" -Header Author,Email,Subject

    $Entries += $NewEntries | % { [PSCustomObject]@{
        Author = $_.Author;
        Email = $_.Email;
        Subject = $_.Subject;
        Microsoft = (Test-MicrosoftPerson $_.Email);
        PossibleUsername = (Get-PossibleUserName $_.Email);
    } }
}

$Unique = $Entries | Group-Object Subject | %{ $_.Group[0] | Add-Member Count $_.Count -Force -PassThru }

$Unique | % {
    $c = ""
    If ($_.Count -Gt 1) {
        $c = "[{0}] " -f $_.Count
    }
    "* {0}{1}{2}" -f ($c, $_.Subject, (Generate-Thanks $_))
}