wiki2html_pandoc

#!/bin/bash
# Vimwiki (markdown style) conversion script using pandoc.
# This script shall be used as the source for vimwiki's custom wiki2html
# conversion binary.
#
# Usage: cf https://github.com/vimwiki/vimwiki/blob/master/doc/vimwiki.txt#L2216
# Requirements: pandoc (https://pandoc.org/)

# check that pandoc is available
if ! command -v pandoc >/dev/null; then
    echo -e "pandoc cannot be found! Please install it first from https://pandoc.org"
    exit 1
fi

# parse `force` argument: assert that it is either 0 or 1
force=$1
if [[ ${force} -ne 0 ]] && [[ ${force} -ne 1 ]]; then
    echo -e "Invalid 'force' argument! It should be either 0 or 1."
    exit 1
fi
# parse `syntax` argument: map vimwiki namings and assert it is supported by pandoc
syntax=$2
if [[ "${syntax}" == "default" ]]; then
    syntax="vimwiki"
elif [[ "${syntax}" == "media" ]]; then
    syntax="mediawiki"
fi
# shellcheck disable=SC2207
syntaxes=($(awk '{print}' <(pandoc --list-input-formats)))
if ! [[ ${syntaxes[*]} =~ (^|[[:space:]])$syntax($|[[:space:]]) ]]; then
    echo -e "Unsupported input format '${syntax}' for pandoc!"
    exit 1
fi
# parse `extension` argument
extension=$3
# parse `output_dir` argument: assert directory exists
output_dir=$4
if [[ ! -d "${output_dir}" ]]; then
    echo -e "The output directory '${output_dir}' does not exist or is not a directory!"
    exit 1
fi
# parse `input_file` argument: assert file exists
input_file=$5
if [[ ! -f "${input_file}" ]]; then
    echo -e "The input file '${input_file}' does not exist or is not a regular file!"
    exit 1
fi
# parse `css_file` argument: assert file exists
css_file=$6
if [[ "${css_file}" != "" ]] && [[ ! -f "${css_file}" ]]; then
    echo -e "The css file '${css_file}' does not exist or is not a regular file!"
    exit 1
fi
# NOTE: the remaning arguments are optional! If unspecified, they default to '-'
# parse `template_path` argument: assert directory exists
template_path=$7
if [[ "${template_path}" != -* ]] && [[ ! -d "${template_path}" ]]; then
    echo -e "The template path '${template_path}' does not exist or is not a directory!"
    exit 1
fi
# parse `template_default` argument
template_default=$8
# parse `template_ext` argument
template_ext=$9
# assert template `template_path/template_default.templat_ext` exists
template_file="${template_path}/${template_default}.${template_ext}"
if [[ "${template_file}" != -* ]] && [[ ! -f "${template_file}" ]]; then
    echo -e "The template file '${template_file}' does not exist or is not a regular file!"
    exit 1
fi
# NOTE: the remaining optional arguments (`root_path` and `custom_args`) are ignored!

output_file=${input_file##*/}
output_file=${output_file%.${extension}}

if [[ -f "${output_dir}/${output_file}.html" ]] && [[ ${force} -ne 1 ]]; then
    echo -e "File ${output_file}.html already exists! Specify force = 1 to overwrite."
    exit 1
fi

# preprocess the input_file
contents=$(cat "${input_file}")

# Links to specific sections [desc](#section) need to have spaces replaced by hyphens
contents=$(sed -E ":a;s/\[([^]]+)\]\(\#([^\)]+)\ ([^\)]+)\)/\[\1\]\(\#\2-\3\)/;ta;" <<< "${contents}")
# Links to specific sections [desc](#section) need to be all lowercase
contents=$(sed -E "s/\[([^]]+)\]\(\#([^\)]+)\)/\[\1\]\(\#\L\2\)/g" <<< "${contents}")
# Links of other files [desc](file) need to have .html appended to them [desc](file.html)
contents=$(sed -E "/(!\[.*|.*http.*)/b; s/\[([^]]+)\]\(([^\#\)]+)\)/\[\1\]\(\2.html\)/g" <<< "${contents}")

# perform actual conversion with pandoc
if [[ "${template_file}" != -* ]]; then
    pandoc -f "${syntax}" -t html5 -o "${output_dir}"/"${output_file}".html \
        --self-contained --css="${css_file}" --template="${template_file}" \
        < "${contents}"
else
    pandoc -f "${syntax}" -t html5 -o "${output_dir}"/"${output_file}".html \
        --self-contained --css="${css_file}" \
        <<< "${contents}"
fi