#!/usr/bin/env bash

#
# Steps:
#
#  1. Download corresponding html file for some README.md:
#       curl -s $1
#
#  2. Discard rows where no substring 'user-content-' (github's markup):
#       awk '/user-content-/ { ...
#
#  3.1 Get last number in each row like ' ... </span></a>sitemap.js</h1'.
#      It's a level of the current header:
#       substr($0, length($0), 1)
#
#  3.2 Get level from 3.1 and insert corresponding number of spaces before '*':
#       sprintf("%*s", substr($0, length($0), 1)*3, " ")
#
#  4. Find head's text and insert it inside "* [ ... ]":
#       substr($0, match($0, /a>.*<\/h/)+2, RLENGTH-5)
#
#  5. Find anchor and insert it inside "(...)":
#       substr($0, match($0, "href=\"[^\"]+?\" ")+6, RLENGTH-8)
#

gh_toc_version="0.5.0"

gh_user_agent="gh-md-toc v$gh_toc_version"

#
# Download rendered into html README.md by its url.
#
#
gh_toc_load() {
    local gh_url=$1

    if type curl &>/dev/null; then
        curl --user-agent "$gh_user_agent" -s "$gh_url"
    elif type wget &>/dev/null; then
        wget --user-agent="$gh_user_agent" -qO- "$gh_url"
    else
        echo "Please, install 'curl' or 'wget' and try again."
        exit 1
    fi
}

#
# Converts local md file into html by GitHub
#
# ➥ curl -X POST --data '{"text": "Hello world github/linguist#1 **cool**, and #1!"}' https://api.github.com/markdown
# <p>Hello world github/linguist#1 <strong>cool</strong>, and #1!</p>'"
gh_toc_md2html() {
    local gh_file_md=$1
    URL=https://api.github.com/markdown/raw
    TOKEN="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/token.txt"
    if [ -f "$TOKEN" ]; then
        URL="$URL?access_token=$(cat $TOKEN)"
    fi
    curl -s --user-agent "$gh_user_agent" \
        --data-binary @"$gh_file_md" -H "Content-Type:text/plain" \
        $URL
}

#
# Is passed string url
#
gh_is_url() {
    case $1 in
        https* | http*)
            echo "yes";;
        *)
            echo "no";;
    esac
}

#
# TOC generator
#
gh_toc(){
    local gh_src=$1
    local gh_src_copy=$1
    local gh_ttl_docs=$2
    local need_replace=$3

    if [ "$gh_src" = "" ]; then
        echo "Please, enter URL or local path for a README.md"
        exit 1
    fi


    # Show "TOC" string only if working with one document
    if [ "$gh_ttl_docs" = "1" ]; then

        echo "Table of Contents"
        echo "================="
        echo ""
        gh_src_copy=""

    fi

    if [ "$(gh_is_url "$gh_src")" == "yes" ]; then
        gh_toc_load "$gh_src" | gh_toc_grab "$gh_src_copy"
        if [ "$need_replace" = "yes" ]; then
            echo
            echo "!! '$gh_src' is not a local file"
            echo "!! Can't insert the TOC into it."
            echo
        fi
    else
        local toc=`gh_toc_md2html "$gh_src" | gh_toc_grab "$gh_src_copy"`
        echo "$toc"
        if [ "$need_replace" = "yes" ]; then
            local ts="<\!--ts-->"
            local te="<\!--te-->"
            local dt=`date +'%F_%H%M%S'`
            local ext=".orig.${dt}"
            local toc_path="${gh_src}.toc.${dt}"
            local toc_footer="<!-- Added by: `whoami`, at: `date --iso-8601='minutes'` -->"
            # http://fahdshariff.blogspot.ru/2012/12/sed-mutli-line-replacement-between-two.html
            # clear old TOC
            sed -i${ext} "/${ts}/,/${te}/{//!d;}" "$gh_src"
            # create toc file
            echo "${toc}" > "${toc_path}"
            echo -e "\n${toc_footer}\n" >> "$toc_path"
            # insert toc file
            if [[ "`uname`" == "Darwin" ]]; then
                sed -i "" "/${ts}/r ${toc_path}" "$gh_src"
            else
                sed -i "/${ts}/r ${toc_path}" "$gh_src"
            fi
            echo
            echo "!! TOC was added into: '$gh_src'"
            echo "!! Origin version of the file: '${gh_src}${ext}'"
            echo "!! TOC added into a separate file: '${toc_path}'"
            echo
        fi
    fi
}

#
# Grabber of the TOC from rendered html
#
# $1 — a source url of document.
# It's need if TOC is generated for multiple documents.
#
gh_toc_grab() {
	# if closed <h[1-6]> is on the new line, then move it on the prev line
	# for example:
	# 	was: The command <code>foo1</code>
	# 		 </h1>
	# 	became: The command <code>foo1</code></h1>
    sed -e ':a' -e 'N' -e '$!ba' -e 's/\n<\/h/<\/h/g' |
    # find strings that corresponds to template
    grep -E -o '<a.*id="user-content-[^"]*".*</h[1-6]' |
    # remove code tags
    sed 's/<code>//' | sed 's/<\/code>//' |
    # now all rows are like:
    #   <a id="user-content-..." href="..."><span ...></span></a> ... </h1
    # format result line
    #   * $0 — whole string
    echo -e "$(awk -v "gh_url=$1" '{
    print sprintf("%*s", substr($0, length($0), 1)*3, " ") "* [" substr($0, match($0, /a>.*<\/h/)+2, RLENGTH-5)"](" gh_url substr($0, match($0, "href=\"[^\"]+?\" ")+6, RLENGTH-8) ")"}' | sed 'y/+/ /; s/%/\\x/g')"
}

#
# Returns filename only from full path or url
#
gh_toc_get_filename() {
    echo "${1##*/}"
}

#
# Options hendlers
#
gh_toc_app() {
    local app_name="gh-md-toc"
    local need_replace="no"

    if [ "$1" = '--help' ] || [ $# -eq 0 ] ; then
        echo "GitHub TOC generator ($app_name): $gh_toc_version"
        echo ""
        echo "Usage:"
        echo "  $app_name [--insert] src [src]  Create TOC for a README file (url or local path)"
        echo "  $app_name -                     Create TOC for markdown from STDIN"
        echo "  $app_name --help                Show help"
        echo "  $app_name --version             Show version"
        return
    fi

    if [ "$1" = '--version' ]; then
        echo "$gh_toc_version"
        return
    fi

    if [ "$1" = "-" ]; then
        if [ -z "$TMPDIR" ]; then
            TMPDIR="/tmp"
        elif [ -n "$TMPDIR" -a ! -d "$TMPDIR" ]; then
            mkdir -p "$TMPDIR"
        fi
        local gh_tmp_md
        gh_tmp_md=$(mktemp $TMPDIR/tmp.XXXXXX)
        while read input; do
            echo "$input" >> "$gh_tmp_md"
        done
        gh_toc_md2html "$gh_tmp_md" | gh_toc_grab ""
        return
    fi

    if [ "$1" = '--insert' ]; then
        need_replace="yes"
        shift
    fi

    for md in "$@"
    do
        echo ""
        gh_toc "$md" "$#" "$need_replace"
    done

    echo ""
    echo "Created by [gh-md-toc](https://github.com/ekalinin/github-markdown-toc)"
}

#
# Entry point
#
gh_toc_app "$@"