#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
#
# Treewide grep for references to files under Documentation, and report
# non-existing files in stderr.

use warnings;
use strict;
use Getopt::Long qw(:config no_auto_abbrev);

# NOTE: only add things here when the file was gone, but the text wants
# to mention a past documentation file, for example, to give credits for
# the original work.
my %false_positives = (
        "Documentation/scsi/scsi_mid_low_api.txt" => "Documentation/Configure.help",
        "drivers/vhost/vhost.c" => "Documentation/virtual/lguest/lguest.c",
);

my $scriptname = $0;
$scriptname =~ s,.*/([^/]+/),$1,;

# Parse arguments
my $help = 0;
my $fix = 0;
my $warn = 0;

if (! -d ".git") {
        printf "Warning: can't check if file exists, as this is not a git tree";
        exit 0;
}

GetOptions(
        'fix' => \$fix,
        'warn' => \$warn,
        'h|help|usage' => \$help,
);

if ($help != 0) {
    print "$scriptname [--help] [--fix]\n";
    exit -1;
}

# Step 1: find broken references
print "Finding broken references. This may take a while...  " if ($fix);

my %broken_ref;

my $doc_fix = 0;

open IN, "git grep ':doc:\`' Documentation/|"
     or die "Failed to run git grep";
while (<IN>) {
        next if (!m,^([^:]+):.*\:doc\:\`([^\`]+)\`,);

        my $d = $1;
        my $doc_ref = $2;

        my $f = $doc_ref;

        $d =~ s,(.*/).*,$1,;
        $f =~ s,.*\<([^\>]+)\>,$1,;

        $f ="$d$f.rst";

        next if (grep -e, glob("$f"));

        if ($fix && !$doc_fix) {
                print STDERR "\nWARNING: Currently, can't fix broken :doc:`` fields\n";
        }
        $doc_fix++;

        print STDERR "$f: :doc:`$doc_ref`\n";
}
close IN;

open IN, "git grep 'Documentation/'|"
     or die "Failed to run git grep";
while (<IN>) {
        next if (!m/^([^:]+):(.*)/);

        my $f = $1;
        my $ln = $2;

        # On linux-next, discard the Next/ directory
        next if ($f =~ m,^Next/,);

        # Makefiles and scripts contain nasty expressions to parse docs
        next if ($f =~ m/Makefile/ || $f =~ m/\.sh$/);

        # Skip this script
        next if ($f eq $scriptname);

        # Ignore the dir where documentation will be built
        next if ($ln =~ m,\b(\S*)Documentation/output,);

        if ($ln =~ m,\b(\S*)(Documentation/[A-Za-z0-9\_\.\,\~/\*\[\]\?+-]*)(.*),) {
                my $prefix = $1;
                my $ref = $2;
                my $base = $2;
                my $extra = $3;

                # some file references are like:
                # /usr/src/linux/Documentation/DMA-{API,mapping}.txt
                # For now, ignore them
                next if ($extra =~ m/^{/);

                # Remove footnotes at the end like:
                # Documentation/devicetree/dt-object-internal.txt[1]
                $ref =~ s/(txt|rst)\[\d+]$/$1/;

                # Remove ending ']' without any '['
                $ref =~ s/\].*// if (!($ref =~ m/\[/));

                # Remove puntuation marks at the end
                $ref =~ s/[\,\.]+$//;

                my $fulref = "$prefix$ref";

                $fulref =~ s/^(\<file|ref)://;
                $fulref =~ s/^[\'\`]+//;
                $fulref =~ s,^\$\(.*\)/,,;
                $base =~ s,.*/,,;

                # Remove URL false-positives
                next if ($fulref =~ m/^http/);

                # Remove sched-pelt false-positive
                next if ($fulref =~ m,^Documentation/scheduler/sched-pelt$,);

                # Discard some build examples from Documentation/target/tcm_mod_builder.rst
                next if ($fulref =~ m,mnt/sdb/lio-core-2.6.git/Documentation/target,);

                # Check if exists, evaluating wildcards
                next if (grep -e, glob("$ref $fulref"));

                # Accept relative Documentation patches for tools/
                if ($f =~ m/tools/) {
                        my $path = $f;
                        $path =~ s,(.*)/.*,$1,;
                        next if (grep -e, glob("$path/$ref $path/../$ref $path/$fulref"));
                }

                # Discard known false-positives
                if (defined($false_positives{$f})) {
                        next if ($false_positives{$f} eq $fulref);
                }

                if ($fix) {
                        if (!($ref =~ m/(scripts|Kconfig|Kbuild)/)) {
                                $broken_ref{$ref}++;
                        }
                } elsif ($warn) {
                        print STDERR "Warning: $f references a file that doesn't exist: $fulref\n";
                } else {
                        print STDERR "$f: $fulref\n";
                }
        }
}
close IN;

exit 0 if (!$fix);

# Step 2: Seek for file name alternatives
print "Auto-fixing broken references. Please double-check the results\n";

foreach my $ref (keys %broken_ref) {
        my $new =$ref;

        my $basedir = ".";
        # On translations, only seek inside the translations directory
        $basedir  = $1 if ($ref =~ m,(Documentation/translations/[^/]+),);

        # get just the basename
        $new =~ s,.*/,,;

        my $f="";

        # usual reason for breakage: DT file moved around
        if ($ref =~ /devicetree/) {
                # usual reason for breakage: DT file renamed to .yaml
                if (!$f) {
                        my $new_ref = $ref;
                        $new_ref =~ s/\.txt$/.yaml/;
                        $f=$new_ref if (-f $new_ref);
                }

                if (!$f) {
                        my $search = $new;
                        $search =~ s,^.*/,,;
                        $f = qx(find Documentation/devicetree/ -iname "*$search*") if ($search);
                        if (!$f) {
                                # Manufacturer name may have changed
                                $search =~ s/^.*,//;
                                $f = qx(find Documentation/devicetree/ -iname "*$search*") if ($search);
                        }
                }
        }

        # usual reason for breakage: file renamed to .rst
        if (!$f) {
                $new =~ s/\.txt$/.rst/;
                $f=qx(find $basedir -iname $new) if ($new);
        }

        # usual reason for breakage: use dash or underline
        if (!$f) {
                $new =~ s/[-_]/[-_]/g;
                $f=qx(find $basedir -iname $new) if ($new);
        }

        # Wild guess: seek for the same name on another place
        if (!$f) {
                $f = qx(find $basedir -iname $new) if ($new);
        }

        my @find = split /\s+/, $f;

        if (!$f) {
                print STDERR "ERROR: Didn't find a replacement for $ref\n";
        } elsif (scalar(@find) > 1) {
                print STDERR "WARNING: Won't auto-replace, as found multiple files close to $ref:\n";
                foreach my $j (@find) {
                        $j =~ s,^./,,;
                        print STDERR "    $j\n";
                }
        } else {
                $f = $find[0];
                $f =~ s,^./,,;
                print "INFO: Replacing $ref to $f\n";
                foreach my $j (qx(git grep -l $ref)) {
                        qx(sed "s\@$ref\@$f\@g" -i $j);
                }
        }
}