#!/usr/bin/perl
#############################################################################
##
## Copyright (C) 2013 Intel Corporation.
## Contact: http://www.qt-project.org/legal
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## $QT_BEGIN_LICENSE:BSD$
## You may use this file under the terms of the BSD license as follows:
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##   * Redistributions of source code must retain the above copyright
##     notice, this list of conditions and the following disclaimer.
##   * Redistributions in binary form must reproduce the above copyright
##     notice, this list of conditions and the following disclaimer in
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##     of its contributors may be used to endorse or promote products derived
##     from this software without specific prior written permission.
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#############################################################################

use strict;
use warnings;
use Text::Wrap;
my %log;

sub help {
    print "Usage: create-changelog <srcdir> <revision-range>\n" .
        "\n" .
        "srcdir                  the qt source directory\n" .
        "revision-range          arguments to git log, like v5.0.0..v5.1.0-rc1\n";
    exit 0;
}

sub collect_entries {
    # Run git submodule foreach
    chdir(shift @ARGV) if (scalar @ARGV);
    open FOREACH, "-|", "git", "submodule", "foreach", "--quiet",
    "git rev-list --reverse --grep '^\\[ChangeLog\\]' " . $ARGV[0] .
        " 2> /dev/null | git cat-file --batch || true";

    # Collect all entries
    while (<FOREACH>) {
        /(^[0-9a-f]{40}) commit (\d+)/
            or die("Could not parse header line: $_");
        my %entry;
        $entry{commit} = $1;

        my $msg;
        die("Could not read log message")
            unless read(FOREACH, $msg, $2 + 1) == $2 + 1;

        # is there a task number?
        # Extract each argument after Task-number: to an array
        my @tasks = ( $msg =~ /^Task-number:\s*(.*)\s*$/mixg );
        $entry{tasks} = \@tasks;

        # Extract the changelogs from $msg
        my @texts = ( $msg =~ /\[ChangeLog\](.*?)\n(?=\n)/sixg );
        foreach (@texts) {
            /\[((?:[^]]|\]\[)+)\]\s*(.*)\z/si;
            my @groups = split(/\]\[/, $1);
            $entry{text} = $2 =~ s/\s+/ /gr;
            $entry{text} =~ s/\s+$//;

            # Store this entry
            # Each entry in %log is a hash
            my $topgroup = shift @groups;
            my $logentry = \$log{$topgroup};
            $$logentry = {} unless defined($$logentry);

            my $subentry;
            if (scalar @groups) {
                # Two-level entry
                $subentry = join(' / ', @groups);
            } else {
                # One-level entry
                $subentry = 0;
            }
            my $array = \$$$logentry{$subentry};
            $$array = [] unless defined($$array);
            push $$array, { %entry };
        }
    }
    close FOREACH or die("git submodule foreach died: $!");
}

sub print_entry($%) {
    my $level = $_[0];
    my %entry = %{$_[1]};
    die if $level > 1;

    my $line;
    #$line = $entry{commit};
    $line .= join('', map { "[$_]" } @{$entry{tasks}});
    $line .= ' ' if scalar @{$entry{tasks}};
    $line .= $entry{text};
    if ($level == 0) {
        print wrap(" - ", "   ", $line);
    } else {
        print wrap("   * ", "     ", $line);
    }
    print "\n";
}

help() unless scalar @ARGV;

# Now print the output
collect_entries();
for my $toplevel (sort keys %log) {
    print "\n$toplevel\n";
    print '-' x (length $toplevel) . "\n";

    my $value = \$log{$toplevel};

    # Print one-level entries first
    my $entry = \$$$value{0};
    if (defined($$entry)) {
        print "\n";
        foreach my $subentry (@$$entry) {
            print_entry(0, $subentry);
        }
    }

    # Print two-level entries now
    foreach my $sublevel (sort keys $$value) {
        next if $sublevel eq "0";
        print "\n - $sublevel:\n";
        $entry = \$$$value{$sublevel};
        foreach my $subentry (@$$entry) {
            print_entry(1, $subentry);
        }
    }
}