#!/usr/bin/env bash

# This script is used to generate a gconv-modules file that takes into
# account only the gconv modules installed by Buildroot, and generates
# a stripped-down gconv-moduels file on its stdout.
# It takes two arguments:
#   $1: the directory where to look for gconv modules definitions
#   $2: a space-separated list of gconv modules that were actually
#       installed

# Starting with glibc-2.34, modules definitions are located in multiple
# files:
#   ${1}/gconv-modules
#   ${1}/gconv-modules.d/*.conf

# The format of gconv-modules is precisely documented in the
# file itself. It consists of two different directives:
#   module  FROMSET  TOSET  FILENAME  COST
#   alias   ALIAS  REALNAME
# and that's what this script parses and generates.
#
# There are two kinds of 'module' directives:
#   - the first defines conversion of a charset to/from INTERNAL representation
#   - the second defines conversion of a charset to/from another charset
# we handle each with slightly different code, since the second never has
# associated aliases.

for f in ${1}/gconv-modules ${1}/gconv-modules.d/*.conf; do
    [ -e "${f}" ] || continue
    cat "${f}"
done \
|awk -v files="${2}" '
$1 == "alias" {
    aliases[$3] = aliases[$3] " " $2;
}
$1 == "module" && $2 != "INTERNAL" && $3 == "INTERNAL" {
    file2internals[$4] = file2internals[$4] " " $2;
    mod2cost[$2] = $5;
}
$1 == "module" && $2 != "INTERNAL" && $3 != "INTERNAL" {
    file2cset[$4] = file2cset[$4] " " $2 ":" $3;
    mod2cost[$2] = $5;
}

END {
    nb_files = split(files, all_files);
    for(f = 1; f <= nb_files; f++) {
        file = all_files[f];
        printf("# Modules and aliases for: %s\n", file);
        nb_mods = split(file2internals[file], mods);
        for(i = 1; i <= nb_mods; i++) {
            nb_aliases = split(aliases[mods[i]], mod_aliases);
            for(j = 1; j <= nb_aliases; j++) {
                printf("alias\t%s\t%s\n", mod_aliases[j], mods[i]);
            }
            printf("module\t%s\t%s\t%s\t%d\n", mods[i], "INTERNAL", file, mod2cost[mods[i]]);
            printf("module\t%s\t%s\t%s\t%d\n", "INTERNAL", mods[i], file, mod2cost[mods[i]]);
            printf("\n" );
        }
        printf("%s", nb_mods != 0 ? "\n" : "");
        nb_csets = split(file2cset[file], csets);
        for(i = 1; i <= nb_csets; i++) {
            split(csets[i], cs, ":");
            printf("module\t%s\t%s\t%s\t%d\n", cs[1], cs[2], file, mod2cost[cs[1]]);
        }
        printf("%s", nb_csets != 0 ? "\n\n" : "");
    }
}
'