chore(user/mw_get_audiobook_chapters.sh):Clean up desc

[BK-2020-03.git] / user / mw_create_subpage_navlinks.sh

#!/bin/bash
# Desc: Generates Mediawiki subpage navigation links
# Input: file   text file with list of chapters
#        stdin  text with list of chapters
# Output: [[../Chapter 4|Next]], [[../Chapter 2|Previous]], [[../|Up]]
# Version: 0.0.1
# Attrib: Steven Baltakatei Sandoval. (2024-01-29). reboil.com
# License: GPLv3+

yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
read_input() {
    # Note: May accept specified file or stdin, but not both
    # Input:  arg     input text (newline delimited)
    #         stdin   input text (newline delimited)
    # Output: stdout  output text (newline delimited)
    # Depends: BK-2020-03 read_stdin (v0.1.1), yell(), die()

    # Parse args
    ## Only 1 argument.
    if [[ "$#" -gt 1 ]]; then die "FATAL:Too many arguments ($#):$*"; fi;
    ## File specified.
    if [[ "$#" -eq 1 ]] && [[ -f "$1" ]] && [[ ! -p /dev/stdin ]]; then
        while read -r line; do
            printf "%s\n" "$line";
        done < "$1" && return 0; fi;
    if [[ "$#" -eq 0 ]] && [[ -p /dev/stdin ]]; then
        read_stdin && return 0; fi;
    die "FATAL:Unknown error.";
};
read_stdin() {
    # Desc: Consumes stdin; outputs as stdout lines
    # Input: stdin (consumes)
    # Output: stdout  (newline delimited)
    #         return  0  stdin read
    #         return  1  stdin not present
    # Example: printf "foo\nbar\n" | read_stdin
    # Depends: GNU bash (version 5.1.16), GNU Coreutils 8.32 (cat)
    # Version: 0.1.1
    # Attrib: Steven Baltakatei Sandoval (2024-01-29). reboil.com
    local input_stdin output;

    # Store stdin
    if [[ -p /dev/stdin ]]; then
        input_stdin="$(cat -)" || {
            echo "FATAL:Error reading stdin." 1>&2; return 1; };
    else
        return 1;
    fi;

    # Store as output array elements
    ## Read in stdin
    if [[ -n $input_stdin ]]; then
        while read -r line; do
            output+=("$line");
        done < <(printf "%s\n" "$input_stdin") || {
            echo "FATAL:Error parsing stdin."; return 1; };
    fi;

    # Print to stdout
    printf "%s\n" "${output[@]}";

    return 0;
}; # read stdin to stdout lines
validate_subpage_list() {
    # Desc: Check for illegal characters in subpage titles
    # Input:  stdin   unvalidated subpage list
    # Output: stdout  validated subpage list
    # Depends: BK-2020-03 read_stdin(), yell(), die()
    #          GNU sed v4.8
    while read -r line; do

        # Reject chars illegal in Mediawiki page titles.
        re_illegal='[][><|}{#_]'; #  match illegal page names chars #, <, >, [, ], _, {, |, }
        if [[ "$line" =~ $re_illegal ]]; then
            die "FATAL:Illegal char. Not allowed: #, <, >, [, ], _, {, |, }:$line";
        fi;

        # Reject trailing spaces.
        re_ts=' $';  # match trailing space
        if [[ "$line" =~ $re_ts ]]; then
            die "FATAL:Trailing spaces not allowed:$line";
        fi;

        # Replace some chars with HTML-style codes
        ## replace ampersand    & with &#38  # must be first
        ## replace double quote " with &#34
        ## replace single quote ' with &#39
        line="$(sed \
                  -e 's/&/\&#38;/g' \
                  -e 's/"/\&#34;/g' \
                  -e "s/'/\&#39;/g" \
                  <<< "$line" )" || { echo "FATAL:Error running sed."; };
        printf "%s\n" "$line";
    done || {
        echo "FATAL:Error reading stdin." 1>&2; return 1; };
};
generate_wikicode() {
    # Input:  stdin   validated subpage list
    # Output: stdout  wikicode
    local lprev lnext;

    n=0;
    while read -r line; do
        #yell "$n:Processing line:$line";  # debug
        lprev="$lcurr";
        lcurr="$lnext";
        lnext="$line";
        #declare -p lprev lcurr lnext;  # debug

        # Skip first iteration
        if [[ "$n" -eq 0 ]]; then
            # yell "$n:DEBUG:Skipping first iteration.";  # debug
            ((n++));
            #printf -- "----\n" 1>&2;  # debug
            continue; fi;

        # Handle first valid input set
        # yell "$n:DEBUG:Handling first valid input set.";  # debug
        if [[ "$n" -eq 1 ]]; then
            printf "[[../%s|Next]], [[../|Up]]\n" \
                   "$lnext";
            #printf -- "----\n" 1>&2; # debug
            ((n++)); continue; fi;

        # Handle middle lines
        # yell "$n:DEBUG:Handling middle lines.";  # debug
        printf "[[../%s|Next]], [[../%s|Previous]], [[../|Up]]\n" \
               "$lnext" "$lprev";
        ((n++));
        #printf -- "----\n" 1>&2; # debug
    done;

    # Handle last line
    lprev="$lcurr";
    lcurr="$lnext";
    lnext="$line";
    printf "[[../%s|Previous]], [[../|Up]]\n" \
           "$lprev";
    ((n++));
};
main() {
    read_input "$@" | validate_subpage_list | generate_wikicode;
}; # main program

main "$@";