#!/usr/bin/env fish

# Updates the files used for gettext translations.
# By default, the whole xgettext + msgmerge pipeline runs,
# which extracts the messages from the source files into $template_file,
# and updates the PO files for each language from that.
#
# Use cases:
# For developers:
#   - Run with no args to update all PO files after making changes to Rust/fish sources.
# For translators:
#   - Specify the language you want to work on as an argument, which must be a file in the po/
#     directory. You can specify a language which does not have translations yet by specifying the
#     name of a file which does not yet exist. Make sure to follow the naming convention.
# For testing:
#   - Specify `--dry-run` to see if any updates to the PO files would by applied by this script.
#     If this flag is specified, the script will exit with an error if there are outstanding
#     changes, and will display the diff. Do not specify other flags if `--dry-run` is specified.
#
# Specify `--use-existing-template=DIR` to prevent running cargo for extracting an up-to-date
# version of the localized strings. This flag is intended for testing setups which make it
# inconvenient to run cargo here, but run it in an earlier step to ensure up-to-date values.
# This argument is passed on to the `fish_xgettext.fish` script and has no other uses.
# `DIR` must be the path to a gettext template file generated from our compilation process.
# It can be obtained by running:
#   set -l DIR (mktemp -d)
#   FISH_GETTEXT_EXTRACTION_DIR=$DIR cargo check --features=gettext-extract

# The sort utility is locale-sensitive.
# Ensure that sorting output is consistent by setting LC_ALL here.
set -gx LC_ALL C.UTF-8

set -l build_tools (status dirname)
set -l po_dir $build_tools/../po

set -l extract

argparse dry-run use-existing-template= -- $argv
or exit $status

if test -z $argv[1]
    # Update everything if not specified otherwise.
    set -g po_files $po_dir/*.po
else
    set -l po_dir_id (stat --format='%d:%i' -- $po_dir)
    for arg in $argv
        set -l arg_dir_id (stat --format='%d:%i' -- (dirname $arg) 2>/dev/null)
        if test $po_dir_id != "$arg_dir_id"
            echo "Argument $arg is not a file in the directory $(realpath $po_dir)."
            echo "Non-option arguments must specify paths to files in this directory."
            echo ""
            echo "If you want to add a new language to the translations not the following:"
            echo "The filename must identify a language, with a two letter ISO 639-1 language code of the target language (e.g. 'pt' for Portuguese), and use the file extension '.po'."
            echo "Optionally, you can specify a regional variant (e.g. 'pt_BR')."
            echo "So valid filenames are of the shape 'll.po' or 'll_CC.po'."
            exit 1
        end
        if not basename $arg | grep -qE '^[a-z]{2,3}(_[A-Z]{2})?\.po$'
            echo "Filename does not match the expected format ('ll.po' or 'll_CC.po')."
            exit 1
        end
    end
    set -g po_files $argv
end

set -g template_file (mktemp)
# Protect from externally set $tmpdir leaking into this script.
set -g tmpdir

function cleanup_exit
    set -l exit_status $status

    rm $template_file

    if set -g --query tmpdir[1]
        rm -r $tmpdir
    end

    exit $exit_status
end

if set -l --query extract
    set -l xgettext_args
    if set -l --query _flag_use_existing_template
        set xgettext_args --use-existing-template=$_flag_use_existing_template
    end
    $build_tools/fish_xgettext.fish $xgettext_args >$template_file
    or cleanup_exit
end

if set -l --query _flag_dry_run
    # On a dry run, we do not modify po/ but write to a temporary directory instead and check if
    # there is a difference between po/ and the tmpdir after re-generating the PO files.
    set -g tmpdir (mktemp -d)

    # Ensure tmpdir has the same initial state as the po dir.
    cp -r $po_dir/* $tmpdir
end

# This is used to identify lines which should be set here via $header_lines.
# Make sure that this prefix does not appear elsewhere in the file and only contains characters
# without special meaning in a sed pattern.
set -g header_prefix "# fish-note-sections: "

function print_header
    set -l header_lines \
        "Translations are divided into sections, each starting with a fish-section-* pseudo-message." \
        "The first few sections are more important." \
        "Ignore the tier3 sections unless you have a lot of time."
    for line in $header_lines
        printf '%s%s\n' $header_prefix $line
    end
end

function merge_po_files --argument-names template_file po_file
    msgmerge --no-wrap --update --no-fuzzy-matching --backup=none --quiet \
        $po_file $template_file
    or cleanup_exit
    set -l new_po_file (mktemp) # TODO Remove on failure.
    # Remove obsolete messages instead of keeping them as #~ entries.
    and msgattrib --no-wrap --no-obsolete -o $new_po_file $po_file
    or cleanup_exit

    begin
        print_header
        # Paste PO file without old header lines.
        sed '/^'$header_prefix'/d' $new_po_file
    end >$po_file
    rm $new_po_file
end

for po_file in $po_files
    if set --query tmpdir[1]
        set po_file $tmpdir/(basename $po_file)
    end
    if test -e $po_file
        merge_po_files $template_file $po_file
    else
        begin
            print_header
            cat $template_file
        end >$po_file
    end
end

if set -g --query tmpdir[1]
    diff -ur $po_dir $tmpdir
    or begin
        echo ERROR: translations in ./po/ are stale. Try running build_tools/update_translations.fish
        cleanup_exit
    end
end

cleanup_exit