#!/bin/sh

# - Usage: dv command [options] [args]
# -   dv is a dumb version management tool.
# - Options:
# -   -a num  set ancestor level (default 1)
# -   -n      dry-run mode, no changes are made
# -   -v      verbose mode
# - Commands:

unset CDPATH
export LC_ALL=C IFS=' 	
'
version=dv-0.2
dvlib=${DVLIB:-$HOME/dvlib}
script="$(cd "$(dirname "$0")" && pwd)/${0##*/}"
aopt=1

case $(uname -o) in
	(Android|Linux)
		diffopt='--color=always'
		lsopt='-v --color'
		;;
	(Darwin)
		diffopt='--color=always'
		lsopt='-G'
		;;
	(*BSD)
		;;
esac

# anc [-a num] [dir] - prints the current ancestor of dir or current.
anc() {
	set -- "$(dvdir "$1")"
	for _ in $(seq "$aopt"); do
		set -- "$1/.dv/anc"
	done
	[ -L "$1" ] && readlink -f "$1"
}

# clone [-nv] v1 [dir] - clones an iterm version into dir (default: item).
clone() {
	case $1 in
		('')      die 'missing argument' ;;
		(*[/.-]*) set -- "$(path "$1")" "$2" ;;
		(*)       set -- "$(head "$1")" "$2" ;;
	esac
	[ "$2" ] || { set -- "$1" "${1##*/}"; set -- "$1" "${2%%-*}"; } 
	[ -d "$1" ] || die "not found: $1"
	rsync ${vopt:+"$vopt"} ${nopt:+"$nopt"} -a "$1/" "$2/"
	rm -f "$2/.dv/anc" && ln -s "$1" "$2/.dv/anc"
}

# desc - prints the descendants of a version
desc() {
	set -- "$(path "$1")"
	set -- "$1" "${1%/*}"
	set -- "$1" "${2##*/}"
	for a in "$dvlib/$2"/*/.dv/anc*; do
		[ "$a" -ef "$1" ] && echo "${a%/*/*}"
	done
}

die() {
	echo "$@" >&2
	exit 1
}

# diff [-a num] [[v1] v2] - prints differences (default: current and ancestor).
diff() {
	if [ "$2" ]; then
		set -- "$(path "$2")" "$(path "$1")"
	elif [ "$1" ]; then
		set -- "$(path "$1")" "$(anc "$(path "$1")")"
	else
		set -- "$(dvdir)" "$(anc)"
	fi
	[ "$2" ] && command diff $diffopt -U 3 -x .dv "$2" "$1" | less -F
}

# dvdir prints the dir containing .dv.
dvdir() {
	set -- "$(realpath "${1:-.}")"
	while [ "$1" ]; do
		[ -d "$1/.dv" ] && echo "$1" && return
		set -- "${1%/*}"
	done
}

# head - prints the branch head versions.
head() {
	for v in "$dvlib/${1:-$(name)}/"*; do
		[ "$(desc "$v")" ] || echo "$v"
	done
}

# help - prints this help text.
help() {
	while read -r line; do
		case $line in
			(\#*\ -\ *) ;;
			(*) continue ;;
		esac
		set -- "${line% - *}" "${line#* - }" 
		[ "$1" = '#' ] || printf "  %-26s" "${1#\# }"
		echo "$2"
	done < "$script"
}

# incv increments version.
incv() {
	set -- "$1" "${1##*[-.a-z_A-Z]}"
	set -- "${1%"$2"}" "$2"
	echo "$1$(($2 + 1))"
}

# init - creates an initial clone in the current directory.
init() {
	[ "$(dvdir)" ] && die "already initialized: $(dvdir)"
	mkdir .dv
}

# ls [item] - lists dvlib.
ls() (
	cd "$dvlib" && command ls $lsopt "$@"
)

# name prints the item name.
name() {
	set -- "$(dvdir)"
	[ "$1" ] && echo "${1##*/}" || die "not a dv item, no .dv found"
}

# path prints the version path, if exist.
path() {
	case $1 in
		(*/*|.) dvdir "$1"; return ;;
		([0-9]*) set -- "$(name)-$1" ;;
	esac
	set -- "${1%%-*}" "${1#*-}"
	[ -d "$dvlib/$1/$1-$2" ] && echo "$dvlib/$1/$1-$2"
}

# save [-nv] [v1] - creates a new version from clone.
save() {
	[ "$1" ] && case $1 in (*[0-9]) ;; (*) die "invalid version: $1" ;; esac
	set -- "$(dvdir)" "$(aopt=1 anc)" "$(name)" "${1#[a-zA-Z_]*-}"
	set -- "$1" "$2" "$3" "${4:-$(incv "${2##*/[a-zA-Z_]*-}")}"
	echo "$dvlib/$3/$3-$4"
	command diff -q -x .dv "$2" "$1" >/dev/null 2>&1 && die 'no changes, abort'
	[ "$nopt" ] && return

	# Update ancestor in clone then copy in dvlib.
	rm -f "$1/.dv/anc" && [ "$2" ] && ln -s "../../${2##*/}" "$1/.dv/anc"
	rsync ${vopt:+"$vopt"} -a ${2:+--link-dest="$2"} --mkpath "$1/" "$dvlib/$3/$3-$4/"

	# After save, clone ancestor points to new saved version.
	rm -f "$1/.dv/anc" && ln -s "$dvlib/$3/$3-$4" "$1/.dv/anc"
}

# status - prints dv informations.
status() {
	echo "lib:  $dvlib"
	set -- "$(dvdir)" "$(anc)"
	[ "$1" ] || die "not a dv item, no .dv found"
	echo "root: $1"
	[ "$2" ] || die "no ancestor found, please save it first"
	echo "anc:  $2"
	command diff -q -x .dv "$2" "$1"
}

# sync [url] - synchronize a remote dvlib.
sync() {
	set -- "${1:-$(cat "$dvlib/.url" 2>/dev/null)}"
	[ "$1" ] || die "missing url"
	[ "$(cat "$dvlib/.url" 2>/dev/null)" = "$1" ] || echo "$1" > "$dvlib/.url"
	rsync ${vopt:+"$vopt"} ${nopt:+"$nopt"} -aH --mkpath "$1/" "$dvlib/"
	rsync ${vopt:+"$vopt"} ${nopt:+"$nopt"} -aH --mkpath "$dvlib/" "$1/"
}

# version - prints the current version of dv.
version() {
	echo "$version"
}

# Main program starts here.
[ "$DVDEBUG" ] && set -x ||
	case $1 in
		(anc|clone|desc|diff|head|help|init|ls|path|save|status|sync|version) ;;
		(*) help; exit 1;;
	esac
cmd="$1"
shift
while getopts :a:nv opt; do
	case $opt in
	(a) aopt="$OPTARG" ;;
	(n) nopt=-n ;;
	(v) vopt=-v ;;
	(*) help; exit ;;
	esac
done
shift $((OPTIND - 1))
$cmd "$@"

# Todo:
# * a function to squash a branch in the trunk
# * merge another ancestor (use anc0, anc1, ...)
# * vendor management
# * show graphs (dot)
# * sync: dvlib sync / mirror: resolve conflict by branching
# * rename version.
# * .dvignore
# * make dvlib versions immutable.