Find and print the changelog of a python package

changelog

#!/usr/bin/env bash

#   Try finding the changelog of a Python package and render it with glow (markdown) or
#   pygments (md and rst), if they are installed.
#
#   Tested with bash and zsh. It isn't POSIX-compatible however.
#
#   ### clone the gist
#   $ chmod a+x changelog
#   $ ln -is `realpath changelog` ~/.local/bin/changelog
#
#   USAGE:
#
#       $ changelog <package-name> [-p|--pager] [-P|--plain] [-s|--silent] [-h|--help]
#
#   (or just source the functions to your environment)
#
#   It depends on libraries providing links to their *github* repos in the 'Home-page'
#   field on PyPI. For those which don't, there's a CHANGELOGS variable that allows to
#   hard-code the mappings.
#
#   It tries using Dephell to find the package details (since it doesn't need the package
#   installed in order to `dephell show <pkg>`, unlike pip). If Dephell isn't available, it
#   uses pip.
#
#   If the changelog isn't found in the repo, it prints out the README, given it exists.
#
#   If you want to access private repos and increase the Github API's rate limits,
#
#       $ export GITHUB_TOKEN=<your github token>
#
declare -A CHANGELOGS
CHANGELOGS[attrs]="python-attrs/attrs/master/CHANGELOG.rst"
CHANGELOGS[isort]="PyCQA/isort/develop/CHANGELOG.md"
CHANGELOGS[pip]="pypa/pip/master/NEWS.rst"
CHANGELOGS[poetry]="python-poetry/poetry/master/CHANGELOG.md"
CHANGELOGS[psycopg2]="psycopg/psycopg2/master/NEWS"
CHANGELOGS[psycopg2-binary]="psycopg/psycopg2/master/NEWS"

good() {
    printf "\e[1;3;32m$1\e[0m"
}

okay() {
    printf "\e[1;33m$1\e[0m"
}

oh() {
    printf "\e[1;31m$1\e[0m"
}

happy() {
    printf "$(good "$1")"
    [[ -n $2 ]] && printf " $2\n" || printf "\n"
}

hmmm() {
    printf >&2 "$(okay WARNING:) $1\n"
}

uhoh() {
    printf >&2 "$(oh ERROR:) $1\n"
}

parse_homepage() {
    sed -n 's/.*\"\?Home-\?page\"\?: //pI' | tr -d '",'
}

get_homepage() {
    pkg=$1
    if which dephell &> /dev/null; then
        details=$(dephell package show "$pkg" 2> /dev/null)
        [[ -n $details ]] && echo "$details" | parse_homepage && return
        hmmm "Dephell didn't find the package: Using pip"
    else
        hmmm "Dephell executable not found: Using pip"
    fi

    details=$(pip show "$pkg" 2> /dev/null)
    [[ -n $details ]] && echo "$details" | parse_homepage
}

get() {
    curl -s -u "username:$GITHUB_TOKEN" "$(echo "$1" | tr -d ' "')"
}

show() {
# Markdown: glow -> pygments -> plain
# Restructured text: pygments -> plain
    url="$1"
    plain=$2
    [[ $plain -eq 1 ]] && get "$url" && return

    format="rst"
    echo "$url" | grep -vq ".rst" && format="md"
    if [[ $format == "md" ]] && which glow &> /dev/null; then
        get "$url" | glow -s dark - && return 0
    fi

    if which pygmentize &> /dev/null; then
        get "$url" | pygmentize -l "$format" -O style=monokai
    else
        get "$url"
    fi
}

render() {
    url=$1
    pager=$2
    plain=$3

    if [[ $pager -eq 0 ]]; then
        show "$url" $plain 1>&2
    else
        printf "$(show "$url" $plain)" | less 1>&2
    fi
}

changelog() {
    pkg=$1
    pager=$2
    plain=$3

    printf "Looking for $(good "$pkg") changelog\n"

    [[ -z $GITHUB_TOKEN ]] && hmmm "GITHUB_TOKEN is not found in the environment"
    if [ ${CHANGELOGS[$pkg]} ]; then
        happy "Found it in the pre-defined changelogs list"
        render "https://raw.githubusercontent.com/${CHANGELOGS[$pkg]}" $pager $plain
        exit 0
    fi

    pat_projectname='s/^.*hub\.com\/\(.*\/\?\$\?\)/\1/pI'
    pat_changelogurl='s/download_url.*\(https.*change.*\),/\1/pI'
    pat_downloadurl='s/download_url.*\(https.*\),/\1/pI'

    homepage="$(get_homepage $pkg)"
    [[ -z $homepage ]] && uhoh "Pip failed to find the package" && exit 1
    happy "Home-page:" "$homepage"

    projectname=$(echo "$homepage" | sed -n "$pat_projectname")
    [[ -z $projectname ]] && \
        uhoh "Could not find $pkg github repository. Check out its home page instead: $homepage" && \
        exit 1
    happy "Github project:" "$projectname"

    changelogurl=$(get "https://api.github.com/repos/$projectname/contents" | sed -n "$pat_changelogurl")
    if [[ -n $changelogurl ]]; then
        happy "Found the changelog"
        url="$changelogurl"
    else
        hmmm "Failed to find the changelog in the repository root. Looking for a readme instead."
        readmeurl=$(get "https://api.github.com/repos/$projectname/readme" | sed -n "$pat_downloadurl")
        [[ -z $readmeurl ]] && uhoh "❓ $pkg doesn't have a readme❓" && exit 1
        happy 'Found the readme'
        url="$readmeurl"
    fi
    render "$url" $pager $plain
    exit 0
}

chill() {
    printf "\e[1;34m$1\e[0m"
}

comment() {
    printf "\e[1;3;90m$1\e[0m"
}

show_help() {
    cat <<-EOF

  » $(chill "changelog") $(okay "[options]") $(good "package") $(okay "[options]")

  ┌ $(okay "-p, --pager")       $(comment "# page the output")
  ├ $(okay "-P, --plain")       $(comment "# do not apply post-processing")
  ├ $(okay "-s, --silent")      $(comment "# only print errors and the output")
  └ $(okay "-h, --help")        $(comment "# display help")

EOF
    exit 0
}

unhappy_input() {
    uhoh "$1\n"
    chill "    changelog"
    oh " package\n\n"
}

if test $# -eq 0; then
    show_help
else
    pager=0
    plain=0
    silent=0
    pkg=""
    while test $# -ne 0; do
        case $1 in
            -p|--pager) pager=1 ;;
            -P|--plain) plain=1 ;;
            -s|--silent) silent=1 ;;
            -h|--help) show_help; exit ;;
            *)
            if [[ -z $pkg ]]; then
                pkg="$1"
            else
                unhappy_input "Please provide a single package name"
                exit 1
            fi; ;;
        esac
        shift
    done
    [[ -z $pkg ]] && unhappy_input "Please provide a package name"  && exit 1
    if [[ $silent -eq 1 ]]; then
        changelog $pkg $pager $plain 1> /dev/null
    else
        changelog $pkg $pager $plain
    fi
fi
# vim:ft=bash