#!/usr/bin/env bash
#
# Author: Hsieh Chin Fan (typebrook) <typebrook@gmail.com>
# License: MIT
# https://gist.github.com/typebrook/b0d2e7e67aa50298fdf8111ae7466b56
#
# gist
# Description: Manage your gists with git and Github API v3
# Usage: gist [command] [<args>]
#
#   [star | s]                    List your gists with format below, star for your starred gists: 
#                                 [index_of_gist] [url] [file_num] [comment_num] [short description]
#   fetch, f [star | s]           Update the local list of your gists, star for your starred gists
#   <index_of_gist> [--no-action] Show the path of local gist repo and do custom actions
#   new, n [-d | --desc <description>] [-p] <files>... create a new gist with files
#   new, n [-d | --desc <description>] [-p] [-f | --file <file_name>] create a new gist from STDIN
#   detail, d <index_of_gist>     Show the detail of a gist
#   edit, e   <index_of_gist>     Edit a gist's description
#   delete, D <index_of_gist>...  Delete a gist
#   clean, C                      Clean removed gists in local
#   config, c [token | user | folder | auto_sync | EDITOR | action [value] ] Do configuration
#   user, U   <user>              Get gists from a given Github user
#   grep, g   <pattern>           Grep gists by a given pattern
#   push, p   <index_of_gist>     Push changes by git (well, better to make commit by youself)
#   github, G <index_of_gist>     Import selected gist as a new Github repo
#   help, h                       Show this help message
#   version                       Get the tool version
#   update                        Update Bash-Snippet Tools
# 
# Example:
#   gist (Show your gists)
#   gist update (update the list of gists from github.com)
#   gist 3 (show the repo path of your 3rd gist, and do custom actions)
#   gist 3 --no-action (show the repo path of your 3rd gist, and do not perform actions)
#   gist new --desc bar foo (create a new gist with file and description)
# 
# Since now a gist is a local cloned repo
# It is your business to do git commit and git push

currentVersion="1.23.0"
configuredClient=""

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

folder=~/gist && mkdir -p $folder
action="${EDITOR:-vi} ."
auto_sync=true # automatically clone the gist repo
[[ -z $hint ]] && hint=true # default to show hint with list of gist

# Shell configuration
set -o pipefail
[[ $TRACE == 'true' ]] && set -x
[[ $(uname) == 'Darwin' ]] && alias tac='tail -r'
trap 'rm -f "$http_data" "$tmp_file"' EXIT

# 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"
  else
    echo "Error: This tool requires either curl, wget, or httpie to be installed." >&2
    return 1
  fi
}

# Allows to call the users configured client without if statements everywhere
# TODO return false if code is not 20x
http_method() {
  local METHOD=$1; shift
  local header_opt; local header; local data_opt
  case "$configuredClient" in
    curl)   [[ -n $token ]] && header_opt="--header" header="Authorization: token $token"
      [[ $METHOD =~ (POST|PATCH) ]] && data_opt='--data'
      curl -X "$METHOD" -A curl -s $header_opt "$header" $data_opt "@$http_data" "$@" ;;
    wget)   [[ -n $token ]] && header_opt="--header" header="Authorization: token $token"
      [[ $METHOD =~ (POST|PATCH) ]] && data_opt='--body-file'
      wget --method="$METHOD" -qO- $header_opt "$header" $data_opt "$http_data" "$@" ;;
    httpie) [[ -n $token ]] && header="Authorization:token $token"
      [[ $METHOD =~ (POST|PATCH) ]] && data_opt="@$http_data"
      http -b "$METHOD" "$@" "$header" "$data_opt" ;;
  esac
}

httpGet(){
  http_method GET "$@"
}

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

checkInternet() {
  httpGet github.com 2>&1 || { echo "Error: no active internet connection" >&2; return 1; } # query github with a get request
}

update() {
  # Author: Alexander Epstein https://github.com/alexanderepstein
  # Update utility version 2.2.0
  # To test the tool enter in the defualt values that are in the examples for each variable
  repositoryName="Bash-Snippets" #Name of repostiory to be updated ex. Sandman-Lite
  githubUserName="alexanderepstein" #username that hosts the repostiory ex. alexanderepstein
  nameOfInstallFile="install.sh" # change this if the installer file has a different name be sure to include file extension if there is one
  latestVersion=$(httpGet https://api.github.com/repos/$githubUserName/$repositoryName/tags | grep -Eo '"name":.*?[^\\]",'| head -1 | grep -Eo "[0-9.]+" ) #always grabs the tag without the v option

  if [[ $currentVersion == "" || $repositoryName == "" || $githubUserName == "" || $nameOfInstallFile == "" ]]; then
    echo "Error: update utility has not been configured correctly." >&2
    exit 1
  elif [[ $latestVersion == "" ]]; then
    echo "Error: no active internet connection" >&2
    exit 1
  else
    if [[ $latestVersion != "$currentVersion" ]]; then
      echo "Version $latestVersion available"
      echo -n "Do you wish to update $repositoryName [Y/n]: "
      read -r answer
      if [[ $answer == [Yy] ]]; then
        cd ~ || { echo 'Update Failed'; exit 1; }
        if [[ -d  ~/$repositoryName ]]; then rm -r -f $repositoryName || { echo "Permissions Error: try running the update as sudo"; exit 1; } ; fi
        echo -n "Downloading latest version of: $repositoryName." 
        # shellcheck disable=SC2015
        git clone -q "https://github.com/$githubUserName/$repositoryName" && touch .BSnippetsHiddenFile || { echo "Failure!"; exit 1; } &
        while [ ! -f .BSnippetsHiddenFile ]; do { echo -n "."; sleep 2; };done
        rm -f .BSnippetsHiddenFile
        echo "Success!"
        cd $repositoryName || { echo 'Update Failed'; exit 1; }
        git checkout "v$latestVersion" 2> /dev/null || git checkout "$latestVersion" 2> /dev/null || echo "Couldn't git checkout to stable release, updating to latest commit."
        chmod a+x install.sh #this might be necessary in your case but wasnt in mine.
        ./$nameOfInstallFile "update" || exit 1
        cd ..
        rm -r -f $repositoryName || { echo "Permissions Error: update succesfull but cannot delete temp files located at ~/$repositoryName delete this directory with sudo"; exit 1; }
      else
        exit 1
      fi
    else
      echo "$repositoryName is already the latest version"
    fi
  fi
}

# handle configuration cases
_configure() {
  [[ $# == 0 ]] && (${EDITOR:-vi} "$CONFIG") && return 0

  local valid_keys='user|token|folder|auto_sync|EDITOR|action'
  if [[ $1 =~ ^($valid_keys)$ ]]; then
    if [[ $1 == 'user' ]]; then
      [[ -z $2 ]] && echo "Must specify username" >&2 && return 1
    elif [[ $1 == 'token' ]]; then
      [[ ${#2} -ne 40 ]] && echo 'Invalid token format, it is not 40 chars' >&2 \
      && return 1
    elif [[ $1 == 'auto_sync' ]]; then
      [[ ! $2 =~ ^(true|false)$ ]] && return 1
    fi
    local key=$1 && shift && local target=$key="'$*'"
  else 
    echo "Not a valid key for configuration, use <$valid_keys> instead."
    return 1
  fi

  umask 0077 && touch "$CONFIG"
  sed -i'' -e "/^$key=/ d" "$CONFIG" && [[ -n $target ]] && echo "$target" >> "$CONFIG"
  cat "$CONFIG"
}

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

# prompt for token
# TODO check token scope contains gist, 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 -r 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 $token ]] && echo "Not a valid token"
    read -r -p "Paste your token here (Ctrl-C to skip): " token < /dev/tty
  done
  _configure token "$token"
}

# check configuration is fine with user setting
_validate_config(){
  # shellcheck source=/dev/null
  source "$CONFIG" 2> /dev/null
  [[ $1 =~ ^(c|config|h|help|u|user|update|version) ]] && return 0
  if [[ -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 && init=true
  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 && $1 =~ ^(f|fetch)$ && $2 =~ ^(s|star) ]]; then
    if ! (_ask_token); then
        echo 'To get user starred gists, a token is needed'
        return 1
    fi
  fi
}

# load configuration
_apply_config() {
  _validate_config "$@" || return 1
  INDEX=$folder/index; [[ -e $INDEX ]] || touch $INDEX
}

_check_repo_status() {
    if [[ ! -d $1 ]]; then
      if [[ $auto_sync == 'true' ]]; then 
        echo "\e[32m[cloning]\e[0m"; 
      else
        echo "\e[32m[Not cloned yet]\e[0m"; 
      fi
    else
      cd "$1" || exit
      if [[ -n $(git status --short) ]] &>/dev/null; then 
        echo "\e[36m[working]\e[0m"
      else 
        [[ $(_blob_code "$1") != "$2" ]] 2>/dev/null && echo "\e[31m[outdated]\e[0m"
        [[ -n $(git cherry) ]] 2>/dev/null && echo "\e[31m[ahead]\e[0m"
      fi
    fi
}

# Show the list of gist, but not updated time
# show username for starred gist
_show_list() {
  if [[ ! -e $INDEX ]]; then 
    echo 'No local file found for last update, please run command:'
    echo '    gist update'
    return 0
  fi
  local filter='/^ *s/ d; /^$/ d'
  [[ $mark == 's' ]] && filter='/^ *[^ s]/ d; /^$/ d'

  sed -e "$filter" $INDEX \
  | while read -r index link blob_code file_num comment_num author description; do
    [[ $mark == 's' ]] && local name=$author
    #local repo; repo=$folder/$(echo $link | sed 's#.*/##')
    local repo; repo=$folder/${link##*/}
    local extra; extra=$(_check_repo_status "$repo" "$blob_code")
    [[ -z $extra ]] && extra="$file_num $comment_num"

    echo -e "$(printf "% 3s" "$index") $link $name $extra $description" \
    | cut -c -"$(tput cols)"
  done

  [[ $hint == 'true' ]] && echo -e '\nrun "gist fetch" to update gists or "gist help" for more details' > /dev/tty \
  || return 0
}

# TODO support filenames, file contents
_grep_content() {
  _show_list | grep -i "$1"
}

# Open Github repository import page
_import_to_github() {
  _gist_id "$1"
  echo put the folowing URL into web page:
  echo -n "git@github.com:$GIST_ID.git"
  python -mwebbrowser https://github.com/new/import
}

_push_to_remote() {
  _gist_id "$1"
  cd "$folder/$GIST_ID" && git add . \
  && git commit --allow-empty-message -m '' && git push origin master
}

_parse_gists() {
    _process_json '
raw = json.load(sys.stdin)
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["owner"]["login"], end=" ")
    print(gist["description"])
    ' 
}

# TODO check if a user has no gist
# parse response from gists require
_parse_response() {
  _parse_gists \
  | tac | sed -e 's/, /,/g' | nl -s' ' \
  | while read -r index link file_url_array public file_num comment_num author description; do
    local blob_code; blob_code=$(echo "$file_url_array" | tr ',' '\n' | sed -E -e 's#.*raw/(.*)/.*#\1#' | sort | cut -c -7 | paste -s -d '-' -)
    [[ $public == 'False' ]] && local mark=p
    [[ -n $1 ]] && local index=$1
    echo "$mark$index $link $blob_code $file_num $comment_num $author $description" | tr -d '"'
  done
}

# TODO pagnation for more than 30 gists
# TODO add files and date of a gist 
# get latest list of gists from Github API
_fetch_gists() {
  echo "fetching $user's gists from $GITHUB_API..."
  echo
  local route="users/$user/gists"
  local filter='/^[^s]/ d; /^$/ d'
  if [[ $1 =~ ^(star|s)$ ]];then
    route="gists/starred"
    local mark="s"
    filter='/^[s]/ d; /^$/ d'
  fi

  result=$(http_method GET $GITHUB_API/$route | mark=$mark _parse_response)
  [[ -z $result ]] && echo Failed to update gists && return 1

  sed -i'' -e "$filter" $INDEX && echo "$result" >> $INDEX
  mark=$mark _show_list

  [[ $auto_sync == 'true' ]] && (_sync_repos "$1" > /dev/null 2>&1 &)
}

_query_user() {
  local route="users/$1/gists"
  result=$(http_method GET $GITHUB_API/"$route" | _parse_response)
  [[ -z $result ]] && echo "Failed to query $1's gists" && return 1

  echo "$result" \
  | while read -r index link blob_code file_num extra description; do
    echo "$link $file_num $extra $description" | cut -c -"$(tput cols)"
  done
}

_blob_code() {
  cd "$1" && git ls-tree master | cut -d' ' -f3 | cut -c-7 | sort | paste -sd '-'
}

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

  # pull if remote repo has different blob objects
  cut -d' ' -f2,3 < "$INDEX" \
  | while read -r url blob_code_remote; do
    local repo; repo=$folder/${url##*/}
    local blob_code_local; blob_code_local=$(_blob_code "$repo")
    cd "$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 -e "/^$1 / p" | cut -d' ' -f2 | sed -E -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 (like 1 or s1):'
    echo
    _show_list
    return 1
  fi
}

_goto_gist() {
  _gist_id "$1" || return 1

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

  [[ $2 != '--no-action' ]] && cd "$folder/$GIST_ID" && eval "$action"
  echo "$folder/$GIST_ID"
}

_delete_gist() {
  read -r -p "Delete gists above? [y/N] " response
  response=${response,,}
  [[ ! $response =~ ^(yes|y)$ ]] && return 0

  for i in "$@"; do
    _gist_id "$i"
    http_method DELETE "$GITHUB_API/gists/$GIST_ID" \
    && echo "$i" deleted \
    && sed -E -i'' -e "/^$i / d" $INDEX
  done
}

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

# parse JSON from gist detail
_parse_gist() {
  _process_json '
raw = json.load(sys.stdin)
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}'
_parse_comment() {
  _process_json '
raw = json.load(sys.stdin);
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"])
  ' 
}

_show_detail() {
  _gist_id "$1"
  http_method GET "$GITHUB_API/gists/$GIST_ID" \
  | _parse_gist

  http_method GET "$GITHUB_API/gists/$GIST_ID"/comments \
  | _parse_comment
}

# set filename/description/permission for a new gist
_set_gist() {
  files=()
  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+=($1)
      shift;;
    esac
  done
  ls "${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
  tmp_file=$(mktemp)
  cat > "$tmp_file"
  echo -e '\n' > /dev/tty
  [[ -z $1 ]] && read -r -p 'Type file name: ' filename < /dev/tty
  mv "$tmp_file" /tmp/"$filename"
  echo /tmp/"$filename"
}

_gist_body(){
  _process_json "
import os.path
files_json = {}
files = sys.stdin.readline().split()
description = sys.stdin.readline().replace('\n','')
for file in files:
    with open(file, 'r') as f:
        files_json[os.path.basename(file)] = {'content': f.read()}
print(json.dumps({'public': $public, 'files': files_json, 'description': description}))
  "
}

# create a new gist with files
_create_gist() {
  _set_gist "$@" || return 1
  [[ -z $files ]] && files=(_new_file "$filename")
  [[ -z $description ]] && read -r -p 'Type description: ' description < /dev/tty

  echo 'Creating a new gist...'
  http_data=$(mktemp)

  echo -e "${files[*]}\n$description" \
  | _gist_body > "$http_data" \
  && http_method POST $GITHUB_API/gists \
  | sed -e '1 s/^/[/; $ s/$/]/' \
  | _parse_response $(( $(sed -e '/^s/ d' $INDEX | wc -l) +1 )) \
  | tee -a $INDEX \
  | cut -d' ' -f2 | sed -E -e 's#.*/##' \
  | (xargs -I{} git clone git@github.com:{}.git $folder/{} &> /dev/null &)

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

# update description of a gist
# TODO use response to modify index file, do not fetch gists again
_edit_gist() {
  _gist_id "$1"

  echo -n 'Type new description: '
  read -r DESC < /dev/tty
  
  http_data=$(mktemp)
  echo '{' \"description\": \"${$DESC//\"/\\\"}\" '}' > "$http_data"
  http_method PATCH "$http_data $GITHUB_API/gists/$GIST_ID" > /dev/null \
  && hint=false _fetch_gists | grep -E "^[ ]+$1"
}

usage() {
  sed -E -n -e ' /^$/ q; 7,$ s/^# //p' "$0"
}

_apply_config "$@" || exit 1
getConfiguredClient || exit 1
if [[ $init ]]; then _fetch_gists; exit 0; fi
case "$1" in
  "")
    _show_list ;;
  star | s)
    mark=s _show_list ;;
  fetch | f)
    _fetch_gists "$2" ;;
  new | n)
    shift
    _create_gist "$@" ;;
  edit | e)
    _edit_gist "$2" ;;
  sync | S)
    _sync_repos ;;
  detail | d)
    shift
    _show_detail "$@" ;;
  delete | D)
    shift
    _delete_gist "$@" ;;
  clean | C)
    _clean_repos ;;
  config | c)
    shift
    _configure "$@" ;;
  user | U)
    shift
    _query_user "$@" ;;
  grep | g)
    shift
    _grep_content "$@" ;;
  github | G)
    shift
    _import_to_github "$1" ;;
  push | p)
    shift
    _push_to_remote "$1" ;;
  version)
    echo "Version $currentVersion"
    exit 0 ;;
  update)  
    checkInternet || exit 1
    update
    exit 0
    ;;
  help | h)
    usage ;;
  *)
    _goto_gist "$@" ;;
esac