#!/bin/bash
set +vx -o pipefail
[[ $- = *i* ]] && echo "Don't source this script!" && return 1
VERSION='0.1a'
# tldr-bash-client version 0.1a
# Bash client for tldr: community driven man-by-example
# - 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 Space Bold Green }
: ${TLDR_CODE_STYLE:= Space Bold Blue }
: ${TLDR_VALUE_STYLE:= Space Bold Cyan }
# Color and/or background (Newline and Space also allowed) for error messages
: ${TLDR_ERROR_COLOR:= Space 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
		$version

		 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-v$DEF,$YEL --version$DEF$XB:              Version number and repo location
		  [$B$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: keep error messages

Out(){ STDOUT+=$1$N;}  # $1: keep output

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...)
			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)
		}
	}

	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 5 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(){  # Download index.json
	$DL "$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, check the environment
	PLATFORM=common STDOUT='' STDERR='' Q='"' N=$'\n'
	case "$(uname -s)" in
		Darwin) PLATFORM='osx' ;;
		Linux) PLATFORM='linux' ;;
		SunOS) PLATFORM='sunos' ;;
	esac
	Init_term
	trap 'less -RXQFP"Press Q to exit " <<<"$STDOUT$STDERR"' EXIT

	version="$GRE$B tldr-bash-client version $VERSION$XB $YEL http://github.com/pepa65/tldr-bash-client$DEF"

	# 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='http://tldr-pages.github.io/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
	# update if the file doesn't exists, or if it's older than $TLDR_EXPIRY
	[[ -f $index ]] && Recent "$index" || Update_index
}

Unlinted(){  # $1: error message
	Err "Page $I$PAGE$XI not properly linted!\nLine $I$L$XI:[$U$REPLY$XU]$N$ERR$B$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  # just not found

	local err=0
	if [[ $platform ]]
	then  # platform given on commandline
		[[ ! $desc =~ \"$platform\" ]] && notfound=$I$platform$XI && err=1 || PAGE=$platform/$1.md
	else  # check common
		[[ $desc =~ \"common\" ]] && PAGE=common/$1.md || {  # not in common either
			[[ $notfound ]] && notfound+=" or "
			notfound+=${I}common$XI
		}
	fi
	# if no page found yet, try the system platform
	[[ $PAGE ]] || [[ $platform = "$PLATFORM" ]] || {
			[[ $desc =~ \"$PLATFORM\" ]] && PAGE=$PLATFORM/$1.md
	} || {
		notfound+=" or $I$PLATFORM$XI"
		err=1
	}
	# if still no page found, get the first entry in index
	[[ $PAGE ]] || PAGE=$(cut -d "$Q" -f 8 <<<"$desc")/"$1.md"
	((err)) && Err "tldr page $I$1$XI not found in $notfound, page from platform $U${PAGE%/*}$XU instead"

	# 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"
	}
}

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
	local newfmt len line
	while read -r || [[ $REPLY ]]
	do
		((++L))
		((L==1)) && {
			[[ ${REPLY:0:1} = '#' ]] && newfmt=0 || newfmt=1
			((newfmt)) && {
				[[ $REPLY ]] || Unlinted "No title"
				Out "$TNL$TSP$T$REPLY$XT"
				len=${#REPLY}
				read -r; ((++L))
				[[ $REPLY =~ [^=] ]] && Unlinted "Title underline must be equal signs"
				((len!=${#REPLY})) && Unlinted "Underline length not equal to title's"
				read -r; ((++L))
			}
		}
		case "${REPLY:0:1}" in  # first character
			'#') ((newfmt)) && Unlinted "Bad first character"
				((${#REPLY} <= 2)) && Unlinted "No title"
				[[ ! ${REPLY:1:1} = ' ' ]] && Unlinted "2nd character no space"
				Out "$TNL$TSP$T${REPLY:2}$XT" ;;
			'>') ((${#REPLY} <= 3)) && Unlinted "No valid desciption"
				[[ ! ${REPLY:1:1} = ' ' ]] && Unlinted "2nd character no space"
				[[ ! ${REPLY: -1} = '.' ]] && Unlinted "Description doesn't end in full stop"
				Out "$DNL$DSP$D${REPLY:2}$XD"
				DNL='' ;;
			'-') ((newfmt)) && Unlinted "Bad first character"
				((${#REPLY} <= 2)) && Unlinted "No example content"
				[[ ! ${REPLY:1:1} = ' ' ]] && Unlinted "2nd character no space"
				Out "$ENL$ESP$E${REPLY:2}$XE" ;;
			' ') ((newfmt)) || Unlinted "Bad first character"
				((${#REPLY} <= 4)) && Unlinted "No valid code content"
				[[ ${REPLY:0:4} = '    ' ]] || Unlinted "No four spaces before code"
				line=${REPLY:4}
				# Value: convert {{value}}
				line=${line//\{\{/$CX$V}
				line=${line//\}\}/$XV$C}
				Out "$CNL$CSP$C$line$XC" ;;
			'`') ((newfmt)) && Unlinted "Bad first character"
				((${#REPLY} <= 2)) && Unlinted "No valid code content"
				[[ ! ${REPLY: -1} = '`' ]] && Unlinted "Code doesn't end in backtick"
				line=${REPLY:1:-1}
				# Value: convert {{value}}
				line=${line//\{\{/$CX$V}
				line=${line//\}\}/$XV$C}
				Out "$CNL$CSP$C$line$XC" ;;
			'') continue ;;
			*) ((newfmt)) || Unlinted "Bad first character"
				[[ -z $REPLY ]] && Unlinted "No example content"
				Out "$ENL$EPS$E$REPLY$XE" ;;
		esac
	done
	trap 'less +Gg -RXQFP"%pB\% tldr $I$page$XI - press Q to exit" <<<"$STDOUT$STDERR"' EXIT
}

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

Cache_fill(){  # $1: exit code
	local tmp=$(mktemp -d)
	$DL "$tmp/pages.zip" "$zip_url" || {
		rm -- "$tmp"
		Err "Could not download pages archive from $U$zip_url$XU"
		exit 6
	}
	unzip="$(type -p unzip) -q" || {
		rm -- "$tmp"
		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" ;;
	-v|--version) [[ $2 ]] && Err "No more command line arguments allowed" && err=11
		Out "$version"
		exit "$err" ;;
	-u|--update) [[ $2 ]] && Err "No more command line arguments allowed" && err=12
		Update_index
		exit "$err" ;;
	-r|--render) [[ -z $2 ]] && Err "Specify a file to render" && Usage 13
		[[ $3 ]] && Err "No more command line arguments allowed" && err=14
		[[ -f "$2" ]] && {
			Display_tldr <"$2" && exit "$err"
			Err "A file error occured"
			exit 15
		} || Err "No file:$I $2$XI" && exit 16 ;;
	-m|--markdown) shift
		page=$*
		[[ -z $page ]] && Err "Specify a page to display" && Usage 17
		[[ -f "$page" && ${page: -3:3} = .md ]] && Out "$(cat "$page")" && exit 0
		markdown=1 ;;
	''|-h|-\?|--help) [[ $2 ]] && Err "No more command line arguments allowed" && err=18
		Usage "$err" ;;
	-*) Err "Unrecognized option $I$1$XI"; Usage 19 ;;
	*) page=$* ;;
esac

[[ -z $page ]] && Err "No command specified" && Usage 20
[[ $page =~ ' -' || ${page:0:1} = '-' ]] && Err "Only one option allowed" && Usage 21
[[ $page = */* ]] && platform=${page%/*} && page=${page##*/}
[[ $platform && ,common,linux,osx,sunos, != *,$platform,* ]] && {
	Err "Unknown platform $I$platform$XI"
	Usage 22
}

Get_tldr "${page// /-}"
[[ ! -s $CACHED ]] && Err "tldr page for command $I$page$XI not found" && exit 23

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