#!/bin/bash

# vars
SELF="${BASH_SOURCE[0]}"
BASE_DIR=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd -P)
BASE_DIR="${BASE_DIR:-$(pwd)}"
CONFIG="${BASE_DIR}/config.yaml"
DOCS_DIR="${BASE_DIR}/docs"
SOURCE_DIR="${BASE_DIR}/source"
TEMPLATE_DIR="${BASE_DIR}/templates"
TOOLS_DIR="${BASE_DIR}/tools"

# dependencies
MARKDOWN="${BASE_DIR}/tools/discount/markdown"
DEPS=("${MARKDOWN}")

# creates bash variables from yaml records
# https://gist.github.com/pkuczynski/8665367
function parse_yaml {
   local prefix=$2
   local s='[[:space:]]*' w='[a-zA-Z0-9_]*' fs=$(echo @|tr @ '\034')
   sed -ne "s|^\($s\)\($w\)$s:$s\"\(.*\)\"$s\$|\1$fs\2$fs\3|p" \
        -e "s|^\($s\)\($w\)$s:$s\(.*\)$s\$|\1$fs\2$fs\3|p"  $1 |
   awk -F$fs '{
      indent = length($1)/2;
      vname[indent] = $2;
      for (i in vname) {if (i > indent) {delete vname[i]}}
      if (length($3) > 0) {
         vn=""; for (i=0; i<indent; i++) {vn=(vn)(vname[i])("_")}
         printf("%s%s%s=\"%s\"\n", "'$prefix'",vn, $2, $3);
      }
   }'
}

# checks for required external tools
function check_dependencies {  # takes 1 argument
    local DEPS ERROR
    DEPS=("${1}");
    ERROR=false
    for DEP in ${DEPS[@]}; do
        if echo "${DEP}" | grep '/' >/dev/null 2>&1 && [[ ! -x "${DEP}" ]]; then
            ERROR=true
        elif ! hash "${DEP}" >/dev/null 2>&1; then
            ERROR=true
        fi
    done
    if [[ "${ERROR}" == true ]]; then
        echo "Error: Unable to find command '${DEP#$BASE_DIR/}'." >&2
        return 1
    fi
}

# builds document(s) from a single source file
function build_source {

    local SOURCE DEST DEST_NAME YAML DOCUMENT_Title DOCUMENT_Project DOCUMENT_Project_URL DOCUMENT_Project_Version DOCUMENT_Language DOCUMENT_Language_Code DOCUMENT_Text_Encoding DOCUMENT_Authors DOCUMENT_Copyright DOCUMENT_License DOCUMENT_License_URL DOCUMENT_Redirect_URL DOCUMENT_Content
    SOURCE="${1}"
    DEST="${SOURCE%.markdown}"
    DEST_NAME="${DEST##*/}"
    DOCUMENT_Content="${DEST}.html.temp"

    # check for yaml header
    YAML=false
    if head -n 1 "${SOURCE}" | grep '^---$' >/dev/null 2>&1; then
        YAML=true
    fi
    if [[ "${YAML}" == true ]]; then
        # split yaml and markdown
        awk '{ drop = 0; } /^---$/ { if (NR==1) { drop = 1 } else if (NR>1) { exit } else { drop = 0; next } } drop == 0 { print }' "${SOURCE}" > "${DEST}.yaml"
        mv "${SOURCE}" "${DEST}.markdown.temp"
        tail -n +$(wc -l "${DEST}.yaml" | awk '{ print $1+3 }') "${DEST}.markdown.temp" > "${SOURCE}"
        rm -f "${DEST}.markdown.temp"
        # parse yaml
        eval $(parse_yaml "${DEST}.yaml" "DOCUMENT_")
    fi

    # preprocess markdown to add implicit figures
    sed -E \
    -e 's|^!\[(.+)]\([ ]*(.+)[ ]*"(.+)"[ ]*\)$|<figure><a href="\2"><img src="\2" alt="\1" /></a><figcaption>\3</figcaption></figure>|' \
    -i.sedbak "${SOURCE}"
    # convert preprocessed markdown document to html
    "${MARKDOWN}" -fdlextra -ffencedcode -ffootnote -fgithubtags "${SOURCE}" > "${DOCUMENT_Content}"
    # copy main template
    if [[ "${DOCUMENT_Redirect_URL:-}" != "" ]]; then
        cp "${TEMPLATE_Redirect}" "${DEST}.html"
    else
        cp "${TEMPLATE_Document}" "${DEST}.html"
    fi
    # omit header and footer templates from license documents
    if [[ "${DEST_NAME}" == "license" ]] || [[ "${DEST_NAME}" == "license-summary" ]]; then
        sed -E \
        -e 's|\{\{[ ]*template\.header[ ]*\}\}||g' \
        -e 's|\{\{[ ]*template\.footer[ ]*\}\}||g' \
        -i.sedbak "${DEST}.html"
    fi
    # inject header, content, footer
    sed -E \
    -e '/\{\{[ ]*template\.header[ ]*\}\}/{r '"${TEMPLATE_Header}" -e 'd;}' \
    -e '/\{\{[ ]*document\.content[ ]*\}\}/{r '"${DOCUMENT_Content}" -e 'd;}' \
    -e '/\{\{[ ]*template\.footer[ ]*\}\}/{r '"${TEMPLATE_Footer}" -e 'd;}' \
    -i.sedbak "${DEST}.html"
    # process custom tags
    sed -E \
    -e 's|\{\{[ ]*document\.title[ ]*\}\}|'"${DOCUMENT_Title:-}"'|g' \
    -e 's|\{\{[ ]*document\.project[ ]*\}\}|'"${DOCUMENT_Project:-}"'|g' \
    -e 's|\{\{[ ]*document\.project-url[ ]*\}\}|'"${DOCUMENT_Project_URL:-}"'|g' \
    -e 's|\{\{[ ]*document\.project-version[ ]*\}\}|'"${DOCUMENT_Project_Version:-}"'|g' \
    -e 's|\{\{[ ]*document\.language[ ]*\}\}|'"${DOCUMENT_Language:-}"'|g' \
    -e 's|\{\{[ ]*document\.language-code[ ]*\}\}|'"${DOCUMENT_Language_Code:-}"'|g' \
    -e 's|\{\{[ ]*document\.text-encoding[ ]*\}\}|'"${DOCUMENT_Text_Encoding:-}"'|g' \
    -e 's|\{\{[ ]*document\.authors[ ]*\}\}|'"${DOCUMENT_Authors:-}"'|g' \
    -e 's|\{\{[ ]*document\.copyright[ ]*\}\}|'"${DOCUMENT_Copyright:-}"'|g' \
    -e 's|\{\{[ ]*document\.license[ ]*\}\}|'"${DOCUMENT_License:-}"'|g' \
    -e 's|\{\{[ ]*document\.license-abbr[ ]*\}\}|'"${DOCUMENT_License_Abbr:-}"'|g' \
    -e 's|\{\{[ ]*document\.license-url[ ]*\}\}|'"${DOCUMENT_License_URL:-}"'|g' \
    -e 's|\{\{[ ]*document\.redirect-url[ ]*\}\}|'"${DOCUMENT_Redirect_URL:-}"'|g' \
    -e 's|\{\{[ ]*base\.relpath[ ]*\}\}|'"${BASE_RELPATH:-}"'|g' \
    -i.sedbak "${DEST}.html"
    # postprocess
    sed -E \
    -e 's|<p><figure>|<figure>|' \
    -e 's|</figure></p>|</figure>|' \
    -i.sedbak "${DEST}.html"

    # clean up
    rm -f "${DEST}.yaml"
    rm -f "${DEST}.markdown"
    rm -f "${DEST}.markdown.sedbak"
    rm -f "${DEST}.html.temp"
    rm -f "${DEST}.html.sedbak"

}

# base directory (absolute)
cd "${BASE_DIR}"

# check deps
check_dependencies "${DEPS[@]}" || exit 1

# parse config
if [[ -e "${CONFIG}" ]]; then
    eval $(parse_yaml "${CONFIG}" "CONFIG_")
else
    echo "Configuration file not found." >&2
    exit 1
fi

# check template
TEMPLATE_DIR+="/${CONFIG_Template}"
if [[ ! -d "${TEMPLATE_DIR}" ]] || [[ ! -e "${TEMPLATE_DIR}/document.html" ]]; then
    echo "Template '${CONFIG_Template}' not found." >&2
    exit 1
fi

# template vars
TEMPLATE_Document="${TEMPLATE_DIR}/document.html"
TEMPLATE_Header="${TEMPLATE_DIR}/header.html"
TEMPLATE_Footer="${TEMPLATE_DIR}/footer.html"
TEMPLATE_Redirect="${TEMPLATE_DIR}/redirect.html"

# clean docs dir
mkdir -p "${DOCS_DIR}"
$(GLOBIGNORE='*.gitkeep'; rm -rf "${DOCS_DIR}"/*)

# build
cp -R "${TEMPLATE_DIR}"/css "${TEMPLATE_DIR}"/fonts "${TEMPLATE_DIR}"/js "${SOURCE_DIR}"/* "${DOCS_DIR}"/
SOURCES=($(find "${DOCS_DIR}" | sed 's/^\.\///' | grep -i '.markdown'))
for SOURCE in ${SOURCES[@]}; do
    BASE_RELPATH="${SOURCE#$DOCS_DIR/}"       # strip abs prefix
    BASE_RELPATH="${BASE_RELPATH//[^\/]}"     # leave only slashes
    BASE_RELPATH="${BASE_RELPATH//[\/]/../}"  # slashes to dirs
    build_source "${SOURCE}"
done

# done
exit 0