#!/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]
#
# * show the path of local gist repo and files
# gist <index_of_gist> 
#
# * 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) <index_of_gist>
#
# * edit a gist description
# gist (edit | e) <index_of_gist>
#
# * delete a gist
# gist (delete | D) <index_of_gist>...
#
# * 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 grep mode for description, file content
# TODO push github.com (may need new token)
# TODO description for current directory
# TODO error handling, unit test
# TODO test on mac and remote machine
# TODO completion

# Shell configuration
[ "$TRACE" ] && set -x

GITHUB_API=https://api.github.com
CONFIG=~/.config/gist.conf; mkdir -p ~/.config
configuredClient=""

# handle configuration cases
_configure() {
  local target=""
  [[ -z "$@" ]] && (${EDITOR:-vi} $CONFIG) && return 0
  if [[ $1 == 'token' ]]; then
    [[ ${#2} -eq 40 ]] && target=$1=$2 \
    || echo -e Invalid token format, it is not 40 chars '\n' > /dev/tty
  elif [[ $1 == 'auto_sync' ]]; then
    [[ $2 == 'false' ]] && target=$1=$2 \
    || target=$1=true
  elif [[ $1 == 'folder' ]]; then
    [[ -n "$2" ]] && target=$1=$2 \
    || target=$1=~/gist
  elif [[ $1 == 'user' ]]; then
    target=$1=$2
  fi

  umask 0077 && touch $CONFIG
  [[ "$target" =~ [^=]$ ]] && sed -i "/^$1=/ d" $CONFIG && echo $target >> $CONFIG
  cat $CONFIG
}

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

# prompt for toekn
# TODO token check, ref: https://developer.github.com/v3/apps/oauth_applications/#check-a-token
_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
    [[ -n $token ]] && echo "Not a valid token"
    trap 'echo; return 1' INT
    read -p "Paste your token here (Ctrl-C to skip): " token < /dev/tty
  done
  _configure token $token
}

# load configuration
_apply_config() {
  source $CONFIG 2> /dev/null || true
  if [[ ! -e $CONFIG || -z $user ]]; then
    echo 'Hi fellow! To access your gists, I need your Github username'
    echo "Also a personal token with scope which allows "gist"!'"
    echo
    _ask_username
    _ask_token
  elif [[ -z $token && $1 =~ ^(n|new|e|edit|D|delete)$ ]]; then
    if ! (_ask_token); then
        echo 'To create/edit/delete a gist, a token is needed'
        return 1
    fi
  elif [[ -z $token && $1 =~ ^(u|update)$ && $2 =~ ^(s|star) ]]; then
    if ! (_ask_token); then
        echo 'To get user starred gists, a token is needed'
        return 1
    fi
  fi

  source $CONFIG
}

_apply_config "$@" || exit 1

AUTH_HEADER="Authorization: token $token"

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

## 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 $INDEX ]]; then 
    echo 'No local file found for last update, please run command:'
    echo '    gist update'
    return 0
  fi
  local filter=""
  if [[ $1 == "s" ]]; then
    filter='/^[^s]/ d'
  else
    filter='/^s/ d'
  fi
  cat $INDEX \
  | while read index link blob_code file_num extra description; do
    local repo=$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 $index $link $file_num $extra $(echo $description | cut -c -$(( 60 -$occupy -1 )) )
  done \
  | sed "$filter"
}

# 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); $1" 2> /dev/null
    return "$?"
}

# 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(gist["public"], 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 from gists require
_parse_response() {
  AccessJsonElement "$(_handle_gists)" \
  | tac | sed 's/, /,/g' | nl -s' ' \
  | while read index link file_url_array public file_num comment_num description; do
    local blob_code=$(echo $file_url_array | tr ',' '\n' | sed -E 's#.*raw/(.*)/.*#\1#' | sort | cut -c -7 | paste -sd '-')
    [[ $public == 'False' ]] && local mark=p
    [[ -n $1 ]] && local index=$1
    echo $mark$index $link $blob_code $file_num $comment_num $description | tr -d '"'
  done
}

# get latest list of gists from Github API
_update() {
  echo "fetching $user's gists from $GITHUB_API..."
  echo
  local route="users/$user/gists"
  local mark=""
  local filter='/^[^s]/ d'
  if [[ "$1" =~ ^(star|s)$ ]];then
    route="gists/starred"
    mark="s"
    filter='/^[s]/ d'
  fi

  local response=$(curl -s -H "$AUTH_HEADER" $GITHUB_API/$route)
  false && echo Failed to update gists && return 1
  sed -i "$filter" $INDEX
  echo $response | _parse_response >> $INDEX
  _show_list $mark

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

# update local git repos
_sync_repos() {
  # clone repos which are not in the local
  comm -13 <(find $folder -maxdepth 1 -type d | sed '1d; s#.*/##' | sort) \
           <(cat $INDEX | 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 || 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
    return 1
  fi
}

_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
    if [[ "$?" -ne 0 ]]; then
        echo 'Repo is cloned' > /dev/tty
    else
        echo 'Failed to clone the gist' > /dev/tty
    fi
  fi

  echo $folder/$GIST_ID
  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 2> /dev/null | cut -d' ' -f2 | sed 's#.*/##' | sort) \
  | while read dir; do
    mv $folder/$dir /tmp && echo move $folder/$dir to /tmp
  done
}

# parse JSON from gist detail
_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 filename/description/permission for a new gist
_set_gist() {
  public=true
  while [[ -n "$@" ]]; do case $1 in
    -d | --desc)
      description="$2"
      shift; shift;;
    -f | --file)
      filename="$2"
      shift; shift;;
    -p)
      public=false
      shift;;
    *)
      files="$1 $files"
      shift;;
    esac
  done
  ls $files > /dev/null || return 1
}

# Let user type the content of gist before setting filename
_new_file() {
  [[ -t 0 ]] && echo "Type a gist. <Ctrl-C> to cancel, <Ctrl-D> when done" > /dev/tty
  local 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
_create_gist() {
  _set_gist "$@" || return 1
  [[ -z "$files" ]] && files=$(_new_file $filename)
  [[ -z "$description" ]] && read -p 'Type description: ' description < /dev/tty

  local index=$(( $(sed '/^s/ d' $INDEX | wc -l) +1 ))
  echo 'Creating a new gist'
  for file in $files; do
    echo "\"$(basename $file)\": {\"content\": \"$(sed '$ !s/$/\\n/' $file)\"},"
  done | tr -d '\n' | sed 's/^/{/; s/,$/}/' \
  | echo "{ \"public\": $public, \"files\": $(cat -), \"description\": \"$description\"}" \
  | curl -s -H "$AUTH_HEADER" --data @- $GITHUB_API/gists \
  | sed '1 s/^/[/; $ s/$/]/' \
  | _parse_response $index >> $INDEX

  if [[ "$?" -ne 0 ]]; then
    echo 'Gist is created'
    _show_list | tail -1
  else
    echo 'Failed to create gist'
  fi
}

# 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
}

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

getConfiguredClient
case "$1" in
  "")
    _show_list ;;
  star | s)
    _show_list s ;;
  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)
    usage ;;
  *)
    _goto_gist "$1" ;;
esac