#!/usr/bin/env bash
#
# Author: Hsieh Chin Fan (typebrook) <typebrook@gmail.com>
# License: MIT
# https://gist.github.com/typebrook/b0d2e7e67aa50298fdf8111ae7466b56
#
#
# This script host your gists as local cloned git repo
# It works under GNU curl, which is easy to get in most cases
#
# Use the following commands to manage your gists:
# 
# * update the local list of your gists, star for your starred gists
# gist (update | u) [star | s] 
# 
# * list your gists with format: [number] [url] [file_num] [comment_num] [short description]
# gist [star | s]
# 
# * clone gist repos which are not in local
# * pull master branch if a local repo is behind its remote
# gist (sync | S) 
#
# * Go to local gist repo
# . gist <number_of_gist_in_list> 
#
# * create a new gist with files
# gist (new | n) [-d | --desc "<gist-description>"] <files>...
#
# * create a new gist with STDIN
# gist (new | n) [-d | --desc "<gist-description>"] [-f | --file <file>] < <file-with-content>
#
# * show the detail of a gist
# gist (detail | d) <gist_index>
#
# * edit a gist description
# gist (edit | e) <gist_index>
#
# * delete a gist
# gist (delete | D) <gist_index>...
#
# * clean removed gists in local
# gist (clean | C)
# 
# * update a gist 
# Since now a gist is a local cloned repo
# It is your business to do git commit and git push
#
# * configuration
# gist (config | c) [token <value>] [user <value>] [folder <value>] [auto-sync false]
#
# * show this help message
# gist (help | h)

# TODO parallel branch works with wget and other stuff
# TODO unify indent
# TODO grep mode for description, file content
# TODO description for current directory
# TODO error handling, unit test
# TODO completion

# Validate configuration
set -eo pipefail
[ "$TRACE" ] && set -x

GITHUB_API=https://api.github.com
CONFIG=~/.config/gistrc
mkdir -p ~/.config && umask 0077
configuredClient=""

_config_cases() {
    if [[ $1 == 'token' ]]; then
        [[ ${#2} -eq 40 ]] && echo $1=$2 \
        || echo -e Invalid token format, it is not 40 chars '\n' > /dev/tty
    elif [[ $1 == 'auto_sync' ]]; then
        [[ $2 == 'false' ]] && echo $1=$2 \
        || echo $1=true
    elif [[ $1 == 'folder' ]]; then
        [[ -n "$2" ]] && echo $1=$2 \
        || echo $1=~/gist
    elif [[ $1 == 'user' ]]; then
        echo $1=$2
    fi
}

_configure() {
    [[ -z "$@" ]] && (${EDITOR:-vi} $CONFIG) && return 0
    target=$(_config_cases "$@")

    touch $CONFIG
    [[ "$target" =~ [^=]$ ]] && sed -i "/^$1=/ d" $CONFIG && echo $target >> $CONFIG
    cat $CONFIG
}

_ask_username() {
    while [[ ! $user =~ ^[[:alnum:]]+$ ]]; do
      [[ ! -z $user ]] && echo "Not a valid username"
      read -p "Github username: " user < /dev/tty
    done
    _configure user $user
}

_ask_token() {
    echo -n "Create a new token from web browser? [Y/n] "
    read answer < /dev/tty
    if [[ ! $answer =~ ^(N|n|No|NO|no)$ ]]; then
        python -mwebbrowser https://github.com/settings/tokens/new\?scopes\=gist; 
    fi

    while [[ ! $token =~ ^[[:alnum:]]{40}$ ]]; do
        [[ ! -z $token ]] && echo "Not a valid token"
        read -p "Paste your token here (Ctrl-C to skip): " token < /dev/tty
    done
    _configure token $token
}

_apply_config() {
    source $CONFIG
    if [[ ! -e $CONFIG ]] || [[ -z $user ]]; then
        echo -n 'Hi fellow! To access your gists, I need your Github username, '
        echo -n "also a personal token with scope which allows "gist"!'"
        _ask_username
        _ask_token
    elif [[ -z $token ]] && [[ $1 =~ ^(n|new|e|edit|D|delete)$ ]]; then
        _ask_token
    fi

    source $CONFIG
}

_apply_config "$@"

auth_header="Authorization: token $token"

[[ -z "$folder" ]] && folder=~/gist && mkdir -p $folder
INDEX=$folder/index
STARRED=$folder/starred

## This function determines which http get tool the system has installed and returns an error if there isnt one
getConfiguredClient()
{
  if  command -v curl &>/dev/null; then
    configuredClient="curl"
  elif command -v wget &>/dev/null; then
    configuredClient="wget"
  elif command -v http &>/dev/null; then
    configuredClient="httpie"
  elif command -v fetch &>/dev/null; then
    configuredClient="fetch"
  else
    echo "Error: This tool requires either curl, wget, httpie or fetch to be installed." >&2
    return 1
  fi
}

## Allows to call the users configured client without if statements everywhere
httpGet()
{
  case "$configuredClient" in
    curl)   curl -A curl -s "$@" ;;
    wget)   wget -qO- "$@" ;;
    httpie) http -b GET "$@" ;;
    fetch)  fetch -q "$@" ;;
  esac
}

# Show the list of gist, but not updated time
# TODO a way to show files
# TODO show git status outdated
_show_list() {
    if [[ ! -e "$1" ]]; then 
        echo 'No local file found for last update, please run command:'
        echo "    gist update $([[ $1 == $STARRED ]] && echo 'star')"
        return 0
    fi
    cat $1 \
    | while read line_num link file_url_array file_num extra description; do
        local repo=$folder/$(echo $link | sed 's#.*/##')
        local occupy=0

        # if repo is not yet cloned, show green message "Not cloned yet"
        [[ ! -d $repo ]] && extra="\e[32m[Not cloned yet]\e[0m" && occupy=16
        # if there are some changes in git index or working directory, show blue message "working"
        [[ -n $(cd $repo && git status --short) ]] 2>/dev/null && extra="\e[36m[working]\e[0m" && occupy=9
        # if there is a commit not yet push, show red message "ahead"
        [[ -n $(cd $repo && git cherry) ]] 2>/dev/null && extra="\e[31m[ahead]\e[0m" && occupy=7

        echo -e $line_num $link $file_num $extra $(echo $description | cut -c -$(( 60 -$occupy -1 )) )
    done
}

# get the list of gists
_update() {
    echo "fetching $user's gists from $GITHUB_API..."
    echo
    local list_file=$INDEX
    local route="users/$user/gists"
    local mark=""
    [[ "$1" =~ ^(star|s)$ ]] && list_file=$STARRED && route="gists/starred" && mark="s"

    httpGet $GITHUB_API/$route \
    | _parse_response | nl -s' ' | sed -E "s/^ */$mark/" > $list_file \
    && _show_list $list_file \
    || echo Fail to update gists

    if [[ $auto_sync != "false" ]]; then (_sync_repos $1 > /dev/null 2>&1 &); fi
}

## parse JSON from STDIN with string of commands
AccessJsonElement() {
    PYTHONIOENCODING=utf-8 \
    python -c "from __future__ import print_function; import sys, json; raw = json.load(sys.stdin); $1"
    return "$?"
}

# equal to: jq '.[] | "\(.html_url) \([.files[] | .raw_url]) \(.files | keys | length) \(.comments) \(.description)"'
_handle_gists() {
    echo '
for gist in raw:
    print(gist["html_url"], end=" ")
    print([file["raw_url"] for file in gist["files"].values()], end=" ")
    print(len(gist["files"]), end=" ")
    print(gist["comments"], end=" ")
    print(gist["description"])
    ' 
}

# TODO check if a user create a very first gist
_parse_response() {
    AccessJsonElement "$(_handle_gists)" \
    | tac | sed 's/, /,/g'\
    | while read link file_url_array file_num comment_num description; do
        local blob_code=$(echo $file_url_array | tr ',' '\n' | sed -E 's#.*raw/(.*)/.*#\1#' | sort | cut -c -7 | paste -sd '-')
        echo $link $blob_code $file_num $comment_num $description | tr -d '"'
    done
}

_sync_repos() {
    local list_file=$INDEX
    [[ "$1" =~ ^(star|s)$ ]] && list_file=$STARRED && route="gists/starred"

    # clone repos which are not in the local
    comm -13 <(find $folder -maxdepth 1 -type d | sed '1d; s#.*/##' | sort) \
             <(cat $list_file | cut -d' ' -f2 | sed 's#.*/##' | sort) \
    | xargs -I{} --max-procs 8 git clone git@github.com:{}.git $folder/{}

    # pull if remote repo has different blob objects
    cat $INDEX | cut -d' ' -f2,3 \
    | while read url blob_code_remote; do
        local repo=$folder/$(echo $url | sed 's#.*/##')
        local blob_code_local=$(cd $repo && git ls-tree master | cut -d' ' -f3 | cut -c-7 | sort | paste -sd '-')
        cd $repo \
        && [[ $blob_code_local != $blob_code_remote ]] \
        && [[ $(git rev-parse origin/master) == $(git rev-parse master) ]] \
        && git pull
    done
    echo Everything is fine!
}

# get gist id from index files
_gist_id() {
    GIST_ID=$( (grep -hs '' $INDEX $STARRED || true) | sed -n "/^$1 / p" | cut -d' ' -f2 | sed -E 's#.*/##')
    if [[ -z "$GIST_ID" ]]; then
        echo -e "Not a valid index: \e[31m$1\e[0m"
        echo Use the index in the first column instead:
        echo
        _show_list "$INDEX"
        return 1
    fi
}

# TODO a better way without source
_goto_gist() {
    _gist_id $1

    if [[ ! -d $folder/$GIST_ID  ]]; then
        echo 'Cloning gist as repo...'
        git clone git@github.com:$GIST_ID.git $folder/$GIST_ID \
        && echo 'Repo is cloned' \
        || echo 'Failed to clone the gist' \
        && return 1
    fi

    echo This gist is at $folder/$GIST_ID
    echo -e "You can run the following command to jump to this directory: \n"
    echo -e "    \e[32m. gist $1\e[0m\n"
    echo -n 'files: ' && cd $folder/$GIST_ID && ls
    tig --all 2> /dev/null || true
}

_delete_gist() {
    for i in "$@"; do
        _gist_id "$i"
        curl -X DELETE -s -H "$auth_header" $GITHUB_API/gists/$GIST_ID \
        && echo "$i" deleted \
        && sed -i -E "/^$i / d" $INDEX
    done
}

# remove repos which are not in user gists anymore
_clean_repos() {
    comm -23 <(find $folder -maxdepth 1 -type d | sed '1d; s#.*/##' | sort) \
             <(cat $INDEX $STARRED 2> /dev/null | cut -d' ' -f2 | sed 's#.*/##' | sort) \
    | while read dir; do
        mv $folder/$dir /tmp && echo move $folder/$dir to /tmp
    done
}

_handle_gist() {
    echo '
print("site:", raw["html_url"])
print("description:", raw["description"])
print("public:", raw["public"])
print("API:", raw["url"])
print("created_at:", raw["created_at"])
print("updated_at:", raw["updated_at"])
print("files:")
for file in raw["files"].keys():
    print("   ", file)
    ' 
}

# equal to jq '.[] | {user: .user.login, created_at: .created_at, updated_at: .updated_at, body: .body}'
_handle_comment() {
    echo '
for comment in raw:
    print()
    print("|", "user:", comment["user"]["login"])
    print("|", "created_at:", comment["created_at"])
    print("|", "updated_at:", comment["updated_at"])
    print("|", comment["body"])
    ' 
}

# TODO format with simple text
_show_detail() {
    _gist_id $1
    httpGet $GITHUB_API/gists/$GIST_ID \
    | AccessJsonElement "$(_handle_gist)"

    httpGet $GITHUB_API/gists/$GIST_ID/comments \
    | AccessJsonElement "$(_handle_comment)"
}

_set_gist() {
    while [[ -n "$@" ]]; do case $1 in
        -d | --desc)
          description="$2"
          shift; shift;;
        -f | --file)
          filename="$2"
          shift; shift;;
        *)
          files="$1 $files"
          shift;;
      esac
    done
    ls $files > /dev/null || return 1
}

_new_file() {
    [[ -t 0 ]] && echo "Type a gist. <Ctrl-C> to cancel, <Ctrl-D> when done" > /dev/tty
    tmp_file=$(mktemp)
    cat > $tmp_file
    echo -e '\n' > /dev/tty
    [[ -z "$1" ]] && read -p 'Type file name: ' filename < /dev/tty
    mv $tmp_file /tmp/$filename
    echo /tmp/$filename
}

# create a new gist with files
# TODO support secret gist
# FIXME catch status code from curl if it fails
_create_gist() {
    _set_gist "$@" || return 1
    [[ -z "$files" ]] && files=$(_new_file $filename)
    [[ -z "$description" ]] && read -p 'Type description: ' description < /dev/tty

    for file in $files; do
        echo "\"$(basename $file)\": {\"content\": \"$(sed '$ !s/$/\\n/' $file)\"},"
    done | tr -d '\n' | sed 's/^/{/; s/,$/}/' \
    | echo "{ \"public\": true, \"files\": $(cat -), \"description\": \"$description\"}" \
    | curl -s -H "$auth_header" --data @- $GITHUB_API/gists \
    | sed '1 s/^/[/; $ s/$/]/' \
    | _parse_response \
    | sed -E "s/^/$(( $(wc -l $INDEX | cut -d' ' -f1) + 1 )) /" >> $INDEX \
    && echo -e '\nGist created' \
    || echo 'Fail to create gist'

    _show_list $INDEX | tail -1
}

# update description of a gist
_edit_gist() {
    _gist_id $1

    echo -n 'Type new description: '
    read DESC < /dev/tty
    echo "{ \"description\": \"$DESC\" }" \
    | curl -X PATCH -H "$auth_header" --data @- $GITHUB_API/gists/$GIST_ID > /dev/null \
    && _update
}

_help_message() {
    sed -E -n ' /^$/ q; 8,$ s/^#//p' $0
}

getConfiguredClient
case "$1" in
  "")
    _show_list $INDEX ;;
  star | s)
    _show_list $STARRED ;;
  update | u)
    _update "$2" ;;
  new | n)
    shift
    _create_gist "$@" ;;
  edit | e)
    _edit_gist "$2" ;;
  sync | S)
    _sync_repos ;;
  detail | d)
    shift
    _show_detail "$@" ;;
  delete | D)
    shift
    _delete_gist "$@" ;;
  clean | C)
    _clean_repos ;;
  config | c)
    shift
    _configure "$@" ;;
  help | h)
    _help_message ;;
  *)
    _goto_gist "$1" ;;
esac