#!/bin/bash

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

# dependencies
MARKDOWN="${TOOLS_BIN}/markdown"
DEPS=("${MARKDOWN}")

# optional dependencies
PARALLEL=$(which parallel)

# 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 {  # check_dependencies $DEP1 $DEP2 ...
    local DEPS ERRORS
    DEPS=("${@}");
    ERRORS=()
    for DEP in ${DEPS[@]}; do
        if echo "${DEP}" | grep '/' >/dev/null 2>&1 && [[ ! -x "${DEP}" ]]; then
            ERRORS+=("${DEP}")
        elif ! hash "${DEP}" >/dev/null 2>&1; then
            ERRORS+=("${DEP}")
        fi
    done
    if [[ "${#ERRORS[@]}" -ne 0 ]]; then
        echo "dependencies: ${DEPS[@]}"
        echo "unable to find command(s): ${ERRORS[*]}" >&2
        return 1
    fi
}

# transforms a string
function string_filter {
    local STRING FILTERS
    STRING=("${1}");
    shift 1
    FILTERS=("${@}")
    for FILTER in ${FILTERS[@]}; do
        case "${FILTER}" in
            'slug')
                STRING=$(echo "${STRING}" | sed -E -e 's/[ _]+/-/g' -e 's/[^-a-zA-Z0-9.]//g' -e 's/(^-+)|(-+$)//' | awk '{ print tolower($0) }')
                ;;
        esac
    done
    echo -n "${STRING}"
}

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

    local SOURCE BASE_RELPATH 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 NAVIGATION_PARTIAL NAVIGATION_RELPATH TEMPLATE_Scripts TEMPLATE_Styles
    SOURCE="${1}"
    BASE_RELPATH="${SOURCE#$DOCS_DIR/}"       # strip abs prefix
    BASE_RELPATH="${BASE_RELPATH//[^\/]}"     # leave only slashes
    BASE_RELPATH="${BASE_RELPATH//[\/]/../}"  # slashes to dirs
    BASE_RELPATH="${BASE_RELPATH:-./}"        # empty to current dir
    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

    # process authors
    DOCUMENT_Authors=$(echo "${DOCUMENT_Authors}" | sed -e 's/,[^ ]/, /g' -e 's/[ ]*<[^,]*>//g' -e 's/\(.*\), /\1, and /' -e 's/\([^,]\) /\1\\\&nbsp;/g')
    DELIM_NUM=$(grep -o ',' <<< "${DOCUMENT_Authors}" | wc -l)
    if [[ "${DELIM_NUM}" -eq 1 ]]; then
        DOCUMENT_Authors=$(echo "${DOCUMENT_Authors}" | sed -e  's/,//')
    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}" > "${DOCUMENT_Content}"
    # select output type
    if [[ "${CONFIG_Embeddable:-}" != true ]]; then
        if [[ "${DOCUMENT_Redirect_URL:-}" != "" ]]; then
            # full html redirect only
            cp "${TEMPLATE_Redirect}" "${DEST}.html"
        else
            # full html content
            cp "${TEMPLATE_Base}" "${DEST}.html"
        fi
    else
        # partial html
        cp "${TEMPLATE_Document}" "${DEST}.html"
    fi
    # inject meta, title, styles, document, scripts
    sed -E \
    -e '/\{\{[ ]*template\.meta[ ]*\}\}/{r '"${TEMPLATE_Meta:-}" -e 'd;}' \
    -e '/\{\{[ ]*template\.title[ ]*\}\}/{r '"${TEMPLATE_Title:-}" -e 'd;}' \
    -e '/\{\{[ ]*template\.document[ ]*\}\}/{r '"${TEMPLATE_Document:-}" -e 'd;}' \
    -i.sedbak "${DEST}.html"
    # inject header, content, footer
    sed -E \
    -e '/\{\{[ ]*template\.header[ ]*\}\}/{r '"${TEMPLATE_Header:-}" -e 'd;}' \
    -e '/\{\{[ ]*document\.content[ ]*\}\}/{r '"${DOCUMENT_Content:-}" -e 'd;}' \
    -e '/\{\{[ ]*template\.footer[ ]*\}\}/{r '"${TEMPLATE_Footer:-}" -e 'd;}' \
    -i.sedbak "${DEST}.html"
    # inject nav
    sed -E \
    -e '/\{\{[ ]*template\.nav[ ]*\}\}/{r '"${TEMPLATE_Nav:-}" -e 'd;}' \
    -i.sedbak "${DEST}.html"
    # process includes
    NAVIGATION_PARTIAL="${DOCS_DIR}/$(string_filter \"${DOCUMENT_Language_Code:-.}\" slug)/$(string_filter \"${DOCUMENT_Project_Version:-.}\" slug)/${CONFIG_Navigation%.markdown}.partial.html"
    NAVIGATION_RELPATH="${BASE_RELPATH#../../}"
    if [[ -e "${NAVIGATION_PARTIAL}" ]] && [[ "${DOCUMENT_Type}" == "article" ]]; then
        sed -E \
        -e 's|<h1>([^<]+)</h1>|<h1><a href="'"${NAVIGATION_RELPATH}${CONFIG_Navigation%.markdown}.html"'">\1</a></h1>|' \
        -e 's|(<a href=")([^.])|\1'"${NAVIGATION_RELPATH}"'\2|g' \
        -e 's|<a (href="[^"]*'"${DEST_NAME}.html"'"[^>]*)>([^<>]+)</a>|<a \1 class="selected">\2</a>|g' \
        "${NAVIGATION_PARTIAL}" > "${DEST}.nav.partial.html"
        sed -E \
        -e '/\{\{[ ]*include\.navigation[ ]*\}\}/{r '"${DEST}.nav.partial.html" -e 'd;}' \
        -i.sedbak "${DEST}.html"
    else
        sed -E \
        -e '/\{\{[ ]*include\.navigation[ ]*\}\}/d' \
        -i.sedbak "${DEST}.html"
    fi
    # process template tags
    TEMPLATE_Scripts=""
    for SCRIPT in ${TEMPLATE_Scripts_array[@]}; do
        TEMPLATE_Scripts+="<script src=\"${BASE_RELPATH}${SCRIPT}\" charset=\"utf-8\"></script>"
    done
    TEMPLATE_Styles=""
    for STYLE in ${TEMPLATE_Styles_array[@]}; do
        TEMPLATE_Styles+="<link rel=\"stylesheet\" href=\"${BASE_RELPATH}${STYLE}\" />"
    done
    sed -E \
    -e 's|\{\{[ ]*template\.scripts[ ]*\}\}|'"${TEMPLATE_Scripts:-}"'|g' \
    -e 's|\{\{[ ]*template\.styles[ ]*\}\}|'"${TEMPLATE_Styles:-}"'|g' \
    -e 's|\{\{[ ]*document\.title[ ]*\}\}|'"${DOCUMENT_Title:-}"'|g' \
    -e 's|\{\{[ ]*document\.type[ ]*\}\}|'"${DOCUMENT_Type:-}"'|g' \
    -e 's|\{\{[ ]*document\.project[ ]*\}\}|'"${DOCUMENT_Project:-}"'|g' \
    -e 's|\{\{[ ]*document\.project slug[ ]*\}\}|'$(string_filter "${DOCUMENT_Project:-}" slug)'|g' \
    -e 's|\{\{[ ]*document\.project-url[ ]*\}\}|'"${DOCUMENT_Project_URL:-}"'|g' \
    -e 's|\{\{[ ]*document\.project-version[ ]*\}\}|'"${DOCUMENT_Project_Version:-}"'|g' \
    -e 's|\{\{[ ]*document\.project-version slug[ ]*\}\}|'$(string_filter "${DOCUMENT_Project_Version:-}" slug)'|g' \
    -e 's|\{\{[ ]*document\.language[ ]*\}\}|'"${DOCUMENT_Language:-}"'|g' \
    -e 's|\{\{[ ]*document\.language slug[ ]*\}\}|'$(string_filter "${DOCUMENT_Language:-}" slug)'|g' \
    -e 's|\{\{[ ]*document\.language-code[ ]*\}\}|'"${DOCUMENT_Language_Code:-}"'|g' \
    -e 's|\{\{[ ]*document\.language-code slug[ ]*\}\}|'$(string_filter "${DOCUMENT_Language_Code:-}" slug)'|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\.license-url rel[ ]*\}\}|'"${BASE_RELPATH}${CONFIG_License%.markdown}.html"'|g' \
    -e 's|\{\{[ ]*document\.redirect-url[ ]*\}\}|'"${DOCUMENT_Redirect_URL:-}"'|g' \
    -e 's|\{\{[ ]*base\.relpath[ ]*\}\}|'"${BASE_RELPATH:-}"'|g' \
    -i.sedbak "${DEST}.html"
    # process comment tags
    sed -E \
    -e 's|<!--[ ]*\.([^ ]*)[ ]*-->|<div class="\1">|g' \
    -e 's|<!--[ ]*\#([^ ]*)[ ]*-->|<div id="\1">|g' \
    -e 's|<!--[ ]*\/([.#])([^ ]*)[ ]*-->|</div><!-- /\1\2 -->|g' \
    -i.sedbak "${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}.nav.partial.html"
    rm -f "${DEST}.html.temp"
    rm -f "${DEST}.html.sedbak"

}

# base directory (absolute)
cd "${SELF_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

# parse template config
TEMPLATE_DIR+="/${CONFIG_Template}"
TEMPLATE_CONFIG="${TEMPLATE_DIR}/template.yaml"
if [[ -e "${TEMPLATE_CONFIG}" ]]; then
    eval $(parse_yaml "${TEMPLATE_CONFIG}" "TEMPLATE_")
    TEMPLATE_Base="${TEMPLATE_DIR}/${TEMPLATE_Base}"
    TEMPLATE_Meta="${TEMPLATE_DIR}/${TEMPLATE_Meta}"
    TEMPLATE_Title="${TEMPLATE_DIR}/${TEMPLATE_Title}"
    TEMPLATE_Document="${TEMPLATE_DIR}/${TEMPLATE_Document}"
    TEMPLATE_Header="${TEMPLATE_DIR}/${TEMPLATE_Header}"
    TEMPLATE_Footer="${TEMPLATE_DIR}/${TEMPLATE_Footer}"
    TEMPLATE_Nav="${TEMPLATE_DIR}/${TEMPLATE_Nav}"
    TEMPLATE_Redirect="${TEMPLATE_DIR}/${TEMPLATE_Redirect}"
    TEMPLATE_Fonts_array=($(echo "${TEMPLATE_Fonts}" | sed -e "s/,[ ]*/ /g"))
    TEMPLATE_Scripts_array=($(echo "${TEMPLATE_Scripts}" | sed -e "s/,[ ]*/ /g"))
    TEMPLATE_Styles_array=($(echo "${TEMPLATE_Styles}" | sed -e "s/,[ ]*/ /g"))
else
    echo "Template configuration file not found." >&2
    exit 1
fi

# build
if [[ "${1:-}" != "" ]]; then
    # single source
    build_source "${1}"
else
    # everything
    # assets
    mkdir -p "${DOCS_DIR}"
    $(GLOBIGNORE='*.gitkeep'; rm -rf "${DOCS_DIR}"/*)
    cp -R "${SOURCE_DIR}"/* "${DOCS_DIR}"/
    for REF in ${TEMPLATE_Fonts_array[@]} ${TEMPLATE_Scripts_array[@]} ${TEMPLATE_Styles_array[@]}; do
        FILE="${REF%\?*}"
        mkdir -p "${DOCS_DIR}/${FILE%/*}"
        cp "${TEMPLATE_DIR}/${FILE}" "${DOCS_DIR}/${FILE}"
    done

    # navigation
    cd "${SOURCE_DIR}"
    LANGUAGES=()
    while IFS= read -r -d '' x; do
      LANGUAGES+=("$(basename "${x}")")
    done < <(find . -maxdepth 1 -type d -not -name '.*' -print0)
    for LANGUAGE in "${LANGUAGES[@]}"; do
        cd "${LANGUAGE}"
        VERSIONS=()
        while IFS= read -r -d '' x; do
          VERSIONS+=("$(basename "${x}")")
        done < <(find . -maxdepth 1 -type d -not -name '.*' -print0)
        for VERSION in "${VERSIONS[@]}"; do
            cd "${VERSION}"
            if [[ -e "${CONFIG_Navigation}" ]]; then
                NAVIGATION_PARTIAL="${DOCS_DIR}/${LANGUAGE}/${VERSION}/${CONFIG_Navigation%.markdown}.partial.html"
                cp "${CONFIG_Navigation}" "${NAVIGATION_PARTIAL}"
                if head -n 1 "${NAVIGATION_PARTIAL}" | grep '^---$' >/dev/null 2>&1; then
                    # remove yaml
                    tail -n +$(awk '{ drop = 0; } /^---$/ { if (NR==1) { drop = 1 } else if (NR>1) { exit } else { drop = 0; next } } drop == 0 { print }' "${NAVIGATION_PARTIAL}" | wc -l | awk '{ print $1+3 }') "${NAVIGATION_PARTIAL}" > "${NAVIGATION_PARTIAL}.temp"
                else
                    cp "${NAVIGATION_PARTIAL}" "${NAVIGATION_PARTIAL}.temp"
                fi
                "${MARKDOWN}" -fdlextra -ffencedcode -ffootnote -fgithubtags "${NAVIGATION_PARTIAL}.temp" > "${NAVIGATION_PARTIAL}"
                rm -f "${NAVIGATION_PARTIAL}.temp"
            fi
            cd "${SOURCE_DIR}/${LANGUAGE}"
        done
        cd "${SOURCE_DIR}"
    done
    cd "${SELF_DIR}"

    # sources
    SOURCES=($(find "${DOCS_DIR}" | sed 's/^\.\///' | grep -i '.markdown'))
    if [[ "${PARALLEL:-}" != "" ]]; then
        export -f build_source
        "${PARALLEL}" "${SELF}" ::: "${SOURCES[@]}"
    else
        for SOURCE in ${SOURCES[@]}; do
            build_source "${SOURCE}"
        done
    fi

    # clean up
    find "${DOCS_DIR}" -name '*.partial.html' -exec rm -f {} \;
fi

# done
exit 0