#!/bin/bash
set +x -o pipefail
[[ $- == *i* ]] && echo "Don't source this script!" && return 1
# Bash tldr client
#  forked from Ray Lee, http://github.com/raylee/tldr
#  modified and expanded by pepa65: http://github.com/pepa65/tldr-bash-client
# Requiring: coreutils, less, grep, unzip, curl/wget

# The 5 elements in TLDR markup that can be styled with these colors and
# backgrounds (last one specified will be used) and modes (more can apply):
#  Colors: Black, Red, Green, Yellow, Blue, Magenta, Cyan, White
#  BG: BlackBG, RedBG, GreenBG, YellowBG, BlueBG, MagentaBG, CyanBG, WhiteBG
#  Modes: Bold, Underline, Italic, Inverse
# 'Newline' can be added to the Style list to add a newline before the element
# and 'Space' to add a space at the start of the line (not for Value element)
# (The style items are separated by space, lower or uppercase mixed allowed.)
: ${TLDR_TITLE_STYLE:= Newline Space Bold Yellow }
: ${TLDR_DESCRIPTION_STYLE:= Space Yellow }
: ${TLDR_EXAMPLE_STYLE:= Newline Bold Green }
: ${TLDR_CODE_STYLE:= Space Bold Blue }
: ${TLDR_VALUE_STYLE:= Bold Cyan }
# Color and/or background (Newline and Space also allowed) for error messages
: ${TLDR_ERROR_COLOR= Red }

# How long before an attempt will be made to re-download a page
: ${TLDR_EXPIRY:= 60 }

Usage(){  # $1: optional exit code
	self=$(basename $0)
	local exit=${1:-0}
	Out "$(cat <<-EOF

		 USAGE: $GRE$B$self$XB$DEF [$YEL${B}option$XB$DEF] [$BLU${B}platform$XB/$DEF]$CYA$B<command>$XB$DEF

		$BLU$B platform$XB/$CYA${B}command$XB$DEF:           Show page for$CYA$B command$XB$DEF (from$BLU$B platform$XB$DEF)

		$BLU$B platform$XB$DEF is optionally one of:$YEL common$DEF,$YEL linux$DEF,$YEL osx$DEF,$YEL sunos$DEF

		$YEL$B option$XB$DEF is optionally one of:
		  $B$YEL-l$DEF,$YEL --list$DEF $BLU[platform]$DEF$XB:      Show all available pages (from$BLU$B platform$XB$DEF)
		  $B$YEL-r$DEF,$YEL --render$DEF$XB $MAG$B<file>$XB$DEF:        Render a local$B$MAG file$DEF$XB as tldr markdown
		  $B$YEL-m$DEF,$YEL --markdown$DEF$XB $CYA$B<command>$XB$DEF:   Show the markdown source for$B$CYA command$DEF$XB
		  $B$YEL-c$DEF,$YEL --cache$DEF$XB:                Cache all pages by downloading archive from repo
		  $B$YEL-u$DEF,$YEL --update$DEF$XB:               Re-download index file from repo
		  [$B$YEL-h$DEF,$YEL -?$DEF,$YEL --help$DEF$XB]:           This help overview

		 Element styling:$T Title$XT$D Description$XD$E Example$XD$C Code$XC$V Value$XV
		 All pages and the index are cached locally under $YEL$configdir$DEF.
		 By default, the cached copies will be re-downloaded after $YEL${TLDR_EXPIRY// /}$DEF days.
		EOF
	)"
	exit $exit
}

Err(){ STDERR+=$ERRNL$ERRSP$ERR$B$1$XB$XERR$N;}  # $1: error message for later

Out(){ STDOUT+=$1$N;}  # $1: message for later

Style(){  # $1: Style specification
	local style
	STYLES= XSTYLES= COLOR= XCOLOR= NL= SP=
	for style in $1
	do
		[[ ${style,,} = newline ]] && NL=$N
		[[ ${style,,} = space ]] && SP=' '
		COLOR+=${color[${style,,}]:-}${bg[${style,,}]:-}
		XCOLOR=${xbg[${style,,}]:-}${xcolor[${style,,}]:-}$XCOLOR
		STYLES+=${color[${style,,}]:-}${bg[${style,,}]:-}${mode[${style,,}]:-}
		XSTYLES=${xmode[${style,,}]:-}${xbg[${style,,}]:-}${xcolor[${style,,}]:-}$XSTYLES
	done
}	

Init_term(){
	[[ -t 2 ]] && {  # only if interactive session (stderr open)
			B=$'\e[1m' # $(tput bold || tput md)  # Start bold
			XB=$'\e[0m'  # End bold (no tput code...) -- needs echo -e
			U=$'\e[4m' # $(tput smul || tput us)  # Start underline
			XU=$'\e[24m' # $(tput rmul || tput ue)  # End underline
			I=$'\e[3m' # $(tput sitm || tput ZH)  # Start italic
			XI=$'\e[23m' # $(tput ritm || tput ZR)  # End italic
			R=$'\e[7m' # $(tput smso || tput so)  # Start reverse
			XR=$'\e[27m' # $(tput rmso || tput se)  # End reverse
			X=$'\e[0m' # $(tput sgr0 || tput me)  # End all

		[[ $TERM != *-m ]] && {
				BLA=$'\e[30m' # $(tput setaf 0 || tput AF 0)
				RED=$'\e[31m' # $(tput setaf 1 || tput AF 1)
				GRE=$'\e[32m' # $(tput setaf 2 || tput AF 2)
				YEL=$'\e[33m' # $(tput setaf 3 || tput AF 3)
				BLU=$'\e[34m' # $(tput setaf 4 || tput AF 4)
				MAG=$'\e[35m' # $(tput setaf 5 || tput AF 5)
				CYA=$'\e[36m' # $(tput setaf 6 || tput AF 6)
				WHI=$'\e[37m' # $(tput setaf 7 || tput AF 7)
				DEF=$'\e[39m' # $(tput op)
				BLAB=$'\e[40m' # $(tput setab 0 || tput AB 0)
				REDB=$'\e[41m' # $(tput setab 1 || tput AB 1)
				GREB=$'\e[42m' # $(tput setab 2 || tput AB 2)
				YELB=$'\e[43m' # $(tput setab 3 || tput AB 3)
				BLUB=$'\e[44m' # $(tput setab 4 || tput AB 4)
				MAGB=$'\e[45m' # $(tput setab 5 || tput AB 5)
				CYAB=$'\e[46m' # $(tput setab 6 || tput AB 6)
				WHIB=$'\e[47m' # $(tput setab 7 || tput AB 7)
				DEFB=$'\e[49m' # $(tput op)
		}
		# osx's termcap doesn't have italics. The below adds support for iTerm2
		# and is harmless on Terminal.app
		#[[ $(uname -s) = Darwin ]] && {
		#		I=$(echo -e "\e[3m")
		#		XI=$(echo -e "\e[23m")
		#}
	}

	declare -A color=(['black']=$BLA ['red']=$RED ['green']=$GRE ['yellow']=$YEL \
			['blue']=$BLU ['magenta']=$MAG ['cyan']=$CYA ['white']=$WHI)
	declare -A xcolor=(['black']=$DEF ['red']=$DEF ['green']=$DEF ['yellow']=$DEF \
			['blue']=$DEF ['magenta']=$DEF ['cyan']=$DEF ['white']=$DEF)
	declare -A bg=(['blackbg']=$BLAB ['redbg']=$REDB ['greenbg']=$GREB ['yellowbg']=$YELB \
			['bluebg']=$BLUB ['magentabg']=$MAGB ['cyanbg']=$CYAB ['whitebg']=$WHIB)
	declare -A xbg=(['blackbg']=$DEFB ['redbg']=$DEFB ['greenbg']=$DEFB ['yellowbg']=$DEFB \
			['bluebg']=$DEFB ['magentabg']=$DEFB ['cyanbg']=$DEFB ['whitebg']=$DEFB)
	declare -A mode=(['bold']=$B ['underline']=$U ['italic']=$I ['inverse']=$R)
	declare -A xmode=(['bold']=$XB ['underline']=$XU ['italic']=$XI ['inverse']=$XR)

	# the five main tldr page styles and error message colors
	Style "$TLDR_TITLE_STYLE"
	T=$STYLES XT=$XSTYLES TNL=$NL TSP=$SP
	Style "$TLDR_DESCRIPTION_STYLE"
	D=$STYLES XD=$XSTYLES DNL=$NL DSP=$SP
	Style "$TLDR_EXAMPLE_STYLE"
	E=$STYLES XE=$XSTYLES ENL=$NL ESP=$SP
	Style "$TLDR_CODE_STYLE"
	C=$STYLES XC=$XSTYLES CNL=$NL CSP=$SP
	Style "$TLDR_VALUE_STYLE"
	V=$STYLES XV=$XSTYLES
	Style "$TLDR_ERROR_COLOR"
	ERR=$COLOR XERR=$XCOLOR ERRNL=$NL ERRSP=$SP
}

Recent(){ find "$1" -mtime -${TLDR_EXPIRY// /} &>/dev/null;}  # $1: page

Update_index(){
	$DL "$index" "$index_url" && Out "${GRE}Index file $I$index$XI re-downloaded$DEF" || {
		Err "Could not download index from $I$index_url$XI"
		exit 2
	}
}

Config(){  # initialize globals, sanity check the environment, etc.
	PLATFORM=common STDOUT= STDERR= Q='"' N=$'\n'
	case $(uname -s) in
		Darwin) PLATFORM='osx' ;;
		Linux) PLATFORM='linux' ;;
		SunOS) PLATFORM='sunos' ;;
	esac
	Init_term
	trap 'echo -ne "$STDOUT$N$STDERR" |less -RXMQF' EXIT

	# Select download method
	DL="$(type -p curl) -sfo" || {
		DL="$(type -p wget) -qNO" || {
			Err "tldr requires$I curl$XI or$I wget $XI installed in your path"
			exit 3
		}
	}

	base_url='https://raw.githubusercontent.com/tldr-pages/tldr/master/pages'
	zip_url='https://raw.githubusercontent.com/tldr-pages/tldr-pages.github.io/master/assets/tldr.zip'
	index_url='http://tldr-pages.github.io/assets/index.json'

	[[ -d ~/.config ]] && configdir=~/.config/tldr || configdir=~/.tldr
	[[ -d "$configdir" ]] || mkdir -p "$configdir"
	index=$configdir/index.json
	# if the file doesn't exists, or if it's younger than $TLDR_EXPIRY
	[[ -f $index ]] && Recent "$index" || Update_index
}

Unlinted(){  # $1: error message
	Err "Page $I$PAGE$XI not properly linted!${N}Line $I$L$XI:[$U$line$XU]$N$1"
	exit 4
}

Get_tldr(){  # $1: page
	# convert the local platform name to tldr's version
	# extract the platform key from index.json, return preferred subpath to page
	local desc=$(tr '{' '\n' <$index |grep "\"name\":\"$1\"")
	# results in, eg, "name":"netstat","platform":["linux","osx"]},

	[[ $desc ]] || return  # not found
	if [[ $desc =~ \"$platform\" ]]
	then  # user specified platform first
		PAGE=$platform/$1.md
	elif [[ $desc =~ \"common\" ]]
	then  # common platform?
		PAGE=common/$1.md
	else  # give warning for sure now
		# system platform, or first one listed in index
		[[ $desc =~ \"$PLATFORM\" ]] && PAGE=$PLATFORM/$1.md \
				|| PAGE=$(cut -d $Q -f 8 <<<"$desc")/"$1.md"
		Err "tldr page $I$1$XI not found in $I$platform$XI or$I common$XI, page from platform $U${PAGE%/*}$XU instead"
	fi

	# return the local cached copy of the tldrpage, or retrieve and cache from github
	CACHED=$configdir/$PAGE
	Recent "$CACHED" || {
		mkdir -p "${CACHED%/*}"
		$DL "$CACHED" "$base_url/$PAGE" || {
			Err "Could not download page $I$CACHED$XI from index $U$index_url$XU"
			exit 5
		}
	}
}

Title(){  # $1: line
	line=$1
	((${#line} <= 2)) && Unlinted "No title"
	[[ ! ${line:1:1} = ' ' ]] && Unlinted "2nd character no space"
	Out "$TNL$TSP$T${line:2}$XT";
}

Description(){  # $1: line
	line=$1
	((${#line} <= 3)) && Unlinted "No valid desciption"
	[[ ! ${line:1:1} = ' ' ]] && Unlinted "2nd character no space"
	[[ ! ${line: -1} = '.' ]] && Unlinted "Description doesn't end in full stop"
	Out "$DNL$DSP$D${line:2}$XD";
	DNL=
}

Example(){  # $1: line
	line=$1
	((${#line} <= 2)) && Unlinted "No example content"
	[[ ! ${line:1:1} = ' ' ]] && Unlinted "2nd character no space"
	Out "$ENL$EPS$E$line$XE"
}

Code(){  # $1: line
	line=$1
	((${#1} <= 2)) && Unlinted "No valid code content"
	[[ ! ${line: -1} = '`' ]] && Unlinted "Code doesn't end in backtick"
	line=${line:1:-1}
	# Value: convert {{value}}
	line=${line//\{\{/$CX$V}
	line=${line//\}\}/$XV$C}
	Out "$CNL$CSP$C$line$XC"
}

Display_tldr(){
	# read one line at a time, don't strip whitespace ('IFS='), and
	# process last line even if it doesn't have a newline at the end
	L=0
	while IFS= read -r line || [[ $line ]]
	do
		((++L))
		case ${line:0:1} in  # first character
			'#') Title "$line" ;;
			'>') Description "$line" ;;
			'-') Example "$line" ;;
			'`') Code "$line" ;;
			'') continue ;;
			*) Unlinted "Bad first character" ;;
		esac
	done
}

List_pages(){  # $1: exit code
	[[ $platform ]] && platf=" from platform $I$platform$XI"
	Out "${GRE}Known tldr pages$platf:"
	Out "$(while read c1 c2 c3; do printf "%-19s %-19s %-19s %-19s$N" $c1 $c2 $c3; done \
			<<<$(tr '{' '\n' <"$configdir/index.json" |grep "$platform" |cut -d $Q -f4))"
	exit $1
}

Cache_fill(){  # $1: exit code
	tmp=$(mktemp -d)
	$DL "$tmp/pages.zip" "$zip_url" || {
		Err "Could not download pages archive from $U$zip_url$XU"
		exit 6
	}
	unzip="$(type -p unzip) -q" || {
		Err "Unzip is necessary to fill the cache"
		exit 7
	}
	$unzip "$tmp/pages.zip" -d "$tmp" 'pages/*'
	rm -rf -- "$configdir/"*
	mv -- "$tmp/pages/"* "$configdir/"
	rm -rf -- "$tmp"
	Out "${GRE}Pages cached in $U$configdir$XU$DEF"
	exit $1
}

Config
markdown=0 err=0
arg=$1
case "$arg" in
	-l|--list) [[ $2 ]] && {
			platform=$2
			[[ ,common,linux,osx,sunos, == *,$platform,* ]] || {
				Err "Unknown platform $I$platform$XI"
				Usage 8
			}
			[[ $3 ]] && Err "No more command line arguments allowed" && err=9
		}
		List_pages $err ;;
	-c|--cache) [[ $2 ]] && Err "No more command line arguments allowed" && err=10
		Cache_fill $err ;;
	-u|--update) [[ $2 ]] && Err "No more command line arguments allowed" && err=11
		Update_index
		exit $err ;;
	-r|--render) [[ -z $2 ]] && Err "Specify a file to render" && Usage 12
		file=$2
		[[ $3 ]] && Err "No more command line arguments allowed" && err=13 ;;
	''|-h|-\?|--help) [[ $2 ]] && Err "No more command line arguments allowed" && err=14
		Usage $err ;;
	-m|--markdown) markdown=1; shift; page=$@ ;;
	''|-h|-\?|--help) [[ $2 ]] && Err "No more command line arguments allowed" && err=15
		Usage $err ;;
	-*) Err "Unrecognized option $I$1$XI"; Usage 16 ;;
	*) page=$@ ;;
esac

[[ -f $file ]] && {
	Display_tldr <"$file" && exit 0
	Err "A file error occured"
	exit 17
}
[[ $file ]] && Err "No file:$I $file$XI" && exit 18
[[ -z $page ]] && Err "No command specified" && Usage 19
[[ $page =~ ' -' || ${page:0:1} = '-' ]] && Err "Only one option allowed" && Usage 20
[[ $page == */* ]] && platform=${page%/*} && page=${page##*/}
[[ $platform && ,common,linux,osx,sunos, != *,$platform,* ]] && {
	Err "Unknown platform $I$platform$XI"
	Usage 21
}

Get_tldr ${page// /-}
[[ ! -s $CACHED ]] && Err "tldr page for command $I$page$XI not found" && exit 22

((markdown)) && Out "$(cat "$CACHED")" || Display_tldr <"$CACHED"
# The error trap will output the accumulated stdout and stderr
exit 0