#!powershell

# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)

#Requires -Module Ansible.ModuleUtils.Legacy
#Requires -Module Ansible.ModuleUtils.Backup

function WriteLines($outlines, $path, $linesep, $encodingobj, $validate, $check_mode) {
    Try {
        $temppath = [System.IO.Path]::GetTempFileName();
    }
    Catch {
        Fail-Json @{} "Cannot create temporary file! ($($_.Exception.Message))";
    }
    $joined = $outlines -join $linesep;
    [System.IO.File]::WriteAllText($temppath, $joined, $encodingobj);

    If ($validate) {

        If (-not ($validate -like "*%s*")) {
            Fail-Json @{} "validate must contain %s: $validate";
        }

        $validate = $validate.Replace("%s", $temppath);

        $parts = [System.Collections.ArrayList] $validate.Split(" ");
        $cmdname = $parts[0];

        $cmdargs = $validate.Substring($cmdname.Length + 1);

        $process = [Diagnostics.Process]::Start($cmdname, $cmdargs);
        $process.WaitForExit();

        If ($process.ExitCode -ne 0) {
            [string] $output = $process.StandardOutput.ReadToEnd();
            [string] $error = $process.StandardError.ReadToEnd();
            Remove-Item -LiteralPath $temppath -force;
            Fail-Json @{} "failed to validate $cmdname $cmdargs with error: $output $error";
        }

    }

    # Commit changes to the path
    $cleanpath = $path.Replace("/", "\");
    Try {
        Copy-Item -LiteralPath $temppath -Destination $cleanpath -Force -WhatIf:$check_mode;
    }
    Catch {
        Fail-Json @{} "Cannot write to: $cleanpath ($($_.Exception.Message))";
    }

    Try {
        Remove-Item -LiteralPath $temppath -Force -WhatIf:$check_mode;
    }
    Catch {
        Fail-Json @{} "Cannot remove temporary file: $temppath ($($_.Exception.Message))";
    }

    return $joined;

}


# Implement the functionality for state == 'present'
function Present {
    param (
        $path,
        $regex,
        $line,
        $insertafter,
        $insertbefore,
        $create,
        $backup,
        $backrefs,
        $validate,
        $encodingobj,
        $linesep,
        $check_mode,
        $diff_support
    )

    # Note that we have to clean up the path because ansible wants to treat / and \ as
    # interchangeable in windows pathnames, but .NET framework internals do not support that.
    $cleanpath = $path.Replace("/", "\");
    $endswithnewline = $null

    # Check if path exists. If it does not exist, either create it if create == "yes"
    # was specified or fail with a reasonable error message.
    If (-not (Test-Path -LiteralPath $path)) {
        If (-not $create) {
            Fail-Json @{} "Path $path does not exist !";
        }
        # Create new empty file, using the specified encoding to write correct BOM
        [System.IO.File]::WriteAllLines($cleanpath, "", $encodingobj);
        $endswithnewline = $false
    }

    # Initialize result information
    $result = @{
        backup = "";
        changed = $false;
        msg = "";
    }

    If ($insertbefore -and $insertafter) {
        Add-Warning $result "Both insertbefore and insertafter parameters found, ignoring `"insertafter=$insertafter`""
    }

    # Read the dest file lines using the indicated encoding into a mutable ArrayList.
    $before = [System.IO.File]::ReadAllLines($cleanpath, $encodingobj)
    If ($null -eq $before) {
        $lines = New-Object System.Collections.ArrayList;
    }
    Else {
        $lines = [System.Collections.ArrayList] $before;
        If ($null -eq $endswithnewline ) {
            $alltext = [System.IO.File]::ReadAllText($cleanpath, $encodingobj);
            $endswithnewline = (($alltext[-1] -eq "`n") -or ($alltext[-1] -eq "`r"))
        }
    }

    if ($diff_support) {
        if ($endswithnewline) {
            $before += ""
        }
        $result.diff = @{
            before = $before -join $linesep;
        }
    }

    # Compile the regex specified, if provided
    $mre = $null;
    If ($regex) {
        $mre = New-Object Regex $regex, 'Compiled';
    }

    # Compile the regex for insertafter or insertbefore, if provided
    $insre = $null;
    If ($insertafter -and $insertafter -ne "BOF" -and $insertafter -ne "EOF") {
        $insre = New-Object Regex $insertafter, 'Compiled';
    }
    ElseIf ($insertbefore -and $insertbefore -ne "BOF") {
        $insre = New-Object Regex $insertbefore, 'Compiled';
    }

    # index[0] is the line num where regex has been found
    # index[1] is the line num where insertafter/insertbefore has been found
    $index = -1, -1;
    $lineno = 0;

    # The latest match object and matched line
    $matched_line = "";

    # Iterate through the lines in the file looking for matches
    Foreach ($cur_line in $lines) {
        If ($regex) {
            $m = $mre.Match($cur_line);
            $match_found = $m.Success;
            If ($match_found) {
                $matched_line = $cur_line;
            }
        }
        Else {
            $match_found = $line -ceq $cur_line;
        }
        If ($match_found) {
            $index[0] = $lineno;
        }
        ElseIf ($insre -and $insre.Match($cur_line).Success) {
            If ($insertafter) {
                $index[1] = $lineno + 1;
            }
            If ($insertbefore) {
                $index[1] = $lineno;
            }
        }
        $lineno = $lineno + 1;
    }

    If ($index[0] -ne -1) {
        If ($backrefs) {
            $new_line = [regex]::Replace($matched_line, $regex, $line);
        }
        Else {
            $new_line = $line;
        }
        If ($lines[$index[0]] -cne $new_line) {
            $lines[$index[0]] = $new_line;
            $result.changed = $true;
            $result.msg = "line replaced";
        }
    }
    ElseIf ($backrefs) {
        # No matches - no-op
    }
    ElseIf ($insertbefore -eq "BOF" -or $insertafter -eq "BOF") {
        $lines.Insert(0, $line);
        $result.changed = $true;
        $result.msg = "line added";
    }
    ElseIf ($insertafter -eq "EOF" -or $index[1] -eq -1) {
        $lines.Add($line) > $null;
        $result.changed = $true;
        $result.msg = "line added";
    }
    Else {
        $lines.Insert($index[1], $line);
        $result.changed = $true;
        $result.msg = "line added";
    }

    # Write changes to the path if changes were made
    If ($result.changed) {

        # Write backup file if backup == "yes"
        If ($backup) {
            $result.backup_file = Backup-File -path $path -WhatIf:$check_mode
            # Ensure backward compatibility (deprecate in future)
            $result.backup = $result.backup_file
        }

        if ($endswithnewline) {
            $lines.Add("")
        }

        $writelines_params = @{
            outlines = $lines
            path = $path
            linesep = $linesep
            encodingobj = $encodingobj
            validate = $validate
            check_mode = $check_mode
        }
        $after = WriteLines @writelines_params;

        if ($diff_support) {
            $result.diff.after = $after;
        }
    }

    $result.encoding = $encodingobj.WebName;

    Exit-Json $result;
}


# Implement the functionality for state == 'absent'
function Absent($path, $regex, $line, $backup, $validate, $encodingobj, $linesep, $check_mode, $diff_support) {

    # Check if path exists. If it does not exist, fail with a reasonable error message.
    If (-not (Test-Path -LiteralPath $path)) {
        Fail-Json @{} "Path $path does not exist !";
    }

    # Initialize result information
    $result = @{
        backup = "";
        changed = $false;
        msg = "";
    }

    # Read the dest file lines using the indicated encoding into a mutable ArrayList. Note
    # that we have to clean up the path because ansible wants to treat / and \ as
    # interchangeable in windows pathnames, but .NET framework internals do not support that.
    $cleanpath = $path.Replace("/", "\");
    $before = [System.IO.File]::ReadAllLines($cleanpath, $encodingobj);
    If ($null -eq $before) {
        $lines = New-Object System.Collections.ArrayList;
    }
    Else {
        $lines = [System.Collections.ArrayList] $before;
        $alltext = [System.IO.File]::ReadAllText($cleanpath, $encodingobj);
        If (($alltext[-1] -eq "`n") -or ($alltext[-1] -eq "`r")) {
            $lines.Add("")
            $before += ""
        }
    }

    if ($diff_support) {
        $result.diff = @{
            before = $before -join $linesep;
        }
    }

    # Compile the regex specified, if provided
    $cre = $null;
    If ($regex) {
        $cre = New-Object Regex $regex, 'Compiled';
    }

    $found = New-Object System.Collections.ArrayList;
    $left = New-Object System.Collections.ArrayList;

    Foreach ($cur_line in $lines) {
        If ($regex) {
            $m = $cre.Match($cur_line);
            $match_found = $m.Success;
        }
        Else {
            $match_found = $line -ceq $cur_line;
        }
        If ($match_found) {
            $found.Add($cur_line) > $null;
            $result.changed = $true;
        }
        Else {
            $left.Add($cur_line) > $null;
        }
    }

    # Write changes to the path if changes were made
    If ($result.changed) {

        # Write backup file if backup == "yes"
        If ($backup) {
            $result.backup_file = Backup-File -path $path -WhatIf:$check_mode
            # Ensure backward compatibility (deprecate in future)
            $result.backup = $result.backup_file
        }

        $writelines_params = @{
            outlines = $left
            path = $path
            linesep = $linesep
            encodingobj = $encodingobj
            validate = $validate
            check_mode = $check_mode
        }
        $after = WriteLines @writelines_params;

        if ($diff_support) {
            $result.diff.after = $after;
        }
    }

    $result.encoding = $encodingobj.WebName;
    $result.found = $found.Count;
    $result.msg = "$($found.Count) line(s) removed";

    Exit-Json $result;
}


# Parse the parameters file dropped by the Ansible machinery
$params = Parse-Args $args -supports_check_mode $true;
$check_mode = Get-AnsibleParam -obj $params -name "_ansible_check_mode" -type "bool" -default $false;
$diff_support = Get-AnsibleParam -obj $params -name "_ansible_diff" -type "bool" -default $false;

# Initialize defaults for input parameters.
$path = Get-AnsibleParam -obj $params -name "path" -type "path" -failifempty $true -aliases "dest", "destfile", "name";
$regex = Get-AnsibleParam -obj $params -name "regex" -type "str" -aliases "regexp";
$state = Get-AnsibleParam -obj $params -name "state" -type "str" -default "present" -validateset "present", "absent";
$line = Get-AnsibleParam -obj $params -name "line" -type "str";
$backrefs = Get-AnsibleParam -obj $params -name "backrefs" -type "bool" -default $false;
$insertafter = Get-AnsibleParam -obj $params -name "insertafter" -type "str";
$insertbefore = Get-AnsibleParam -obj $params -name "insertbefore" -type "str";
$create = Get-AnsibleParam -obj $params -name "create" -type "bool" -default $false;
$backup = Get-AnsibleParam -obj $params -name "backup" -type "bool" -default $false;
$validate = Get-AnsibleParam -obj $params -name "validate" -type "str";
$encoding = Get-AnsibleParam -obj $params -name "encoding" -type "str" -default "auto";
$newline = Get-AnsibleParam -obj $params -name "newline" -type "str" -default "windows" -validateset "unix", "windows";

# Fail if the path is not a file
If (Test-Path -LiteralPath $path -PathType "container") {
    Fail-Json @{} "Path $path is a directory";
}

# Default to windows line separator - probably most common
$linesep = "`r`n"
If ($newline -eq "unix") {
    $linesep = "`n";
}

# Figure out the proper encoding to use for reading / writing the target file.

# The default encoding is UTF-8 without BOM
$encodingobj = [System.Text.UTF8Encoding] $false;

# If an explicit encoding is specified, use that instead
If ($encoding -ne "auto") {
    $encodingobj = [System.Text.Encoding]::GetEncoding($encoding);
}

# Otherwise see if we can determine the current encoding of the target file.
# If the file doesn't exist yet (create == 'yes') we use the default or
# explicitly specified encoding set above.
ElseIf (Test-Path -LiteralPath $path) {

    # Get a sorted list of encodings with preambles, longest first
    $max_preamble_len = 0;
    $sortedlist = New-Object System.Collections.SortedList;
    Foreach ($encodinginfo in [System.Text.Encoding]::GetEncodings()) {
        $encoding = $encodinginfo.GetEncoding();
        $plen = $encoding.GetPreamble().Length;
        If ($plen -gt $max_preamble_len) {
            $max_preamble_len = $plen;
        }
        If ($plen -gt 0) {
            $sortedlist.Add( - ($plen * 1000000 + $encoding.CodePage), $encoding) > $null;
        }
    }

    # Get the first N bytes from the file, where N is the max preamble length we saw
    [Byte[]]$bom = Get-Content -Encoding Byte -ReadCount $max_preamble_len -TotalCount $max_preamble_len -LiteralPath $path;

    # Iterate through the sorted encodings, looking for a full match.
    $found = $false;
    Foreach ($encoding in $sortedlist.GetValueList()) {
        $preamble = $encoding.GetPreamble();
        If ($preamble -and $bom) {
            Foreach ($i in 0..($preamble.Length - 1)) {
                If ($i -ge $bom.Length) {
                    break;
                }
                If ($preamble[$i] -ne $bom[$i]) {
                    break;
                }
                ElseIf ($i + 1 -eq $preamble.Length) {
                    $encodingobj = $encoding;
                    $found = $true;
                }
            }
            If ($found) {
                break;
            }
        }
    }
}


# Main dispatch - based on the value of 'state', perform argument validation and
# call the appropriate handler function.
If ($state -eq "present") {

    If ($backrefs -and -not $regex) {
        Fail-Json @{} "regexp= is required with backrefs=true";
    }

    If (-not $line) {
        Fail-Json @{} "line= is required with state=present";
    }

    If (-not $insertbefore -and -not $insertafter) {
        $insertafter = "EOF";
    }

    $present_params = @{
        path = $path
        regex = $regex
        line = $line
        insertafter = $insertafter
        insertbefore = $insertbefore
        create = $create
        backup = $backup
        backrefs = $backrefs
        validate = $validate
        encodingobj = $encodingobj
        linesep = $linesep
        check_mode = $check_mode
        diff_support = $diff_support
    }
    Present @present_params;

}
ElseIf ($state -eq "absent") {

    If (-not $regex -and -not $line) {
        Fail-Json @{} "one of line= or regexp= is required with state=absent";
    }

    $absent_params = @{
        path = $path
        regex = $regex
        line = $line
        backup = $backup
        validate = $validate
        encodingobj = $encodingobj
        linesep = $linesep
        check_mode = $check_mode
        diff_support = $diff_support
    }
    Absent @absent_params;
}