#!/bin/sh
set -eu

MSGS=''
add_msg() {
	MSGS="$MSGS $1"
}


MSG_USAGE="$(cat <<-'EOF'
	Usage:
	  @NAME@ [-c] [-m MESSAGE] [-t TYPE] [-s STATE]
	  @NAME@ [-HlL]
	  @NAME@ [-hV]
EOF
)"
add_msg USAGE

MSG_HELP1="$(cat <<-'EOF'

	Options:
	  -c                commit directly only with the title, without
	                    adding a description.  Assumes -m
	  -m MESSAGE_TITLE  the title message of the entry
	  -t TYPE           the type of entry to be added (default: |TYPE|)
	  -s STATE          the state of entry to be added (default: |STATE|)
	  -l                list the supported values for $TD_USE_BUILTIN_HOOKS
	  -L                lint the issues file
	  -H                pre-process issues file before generating HTML
	  -h, --help        show this help message
	  -V, --version     print the version number

	Examples:
	  Create a new entry with the default type with a custom title:
	    $ td -cm 'An entry title'

	  Create a new entry with a custom type and state:
	    $ td -cm 'Another title' -t bug -s DONE

	States of an entry:
EOF
)"
add_msg HELP1

MSG_HELP2="$(cat <<-'EOF'
	Types of entry:
EOF
)"
add_msg HELP2

MSG_HELP3="$(cat <<-'EOF'
	See "man @NAME@.tutorial" for getting started.
EOF
)"
add_msg HELP3

MSG_UNEDITED_ENTRY="$(cat <<-'EOF'
	Abandoning unedited entry.
EOF
)"
add_msg UNEDITED_ENTRY

MSG_UNREGISTERED_TYPE="$(cat <<-'EOF'
	Unregistered type: %s
EOF
)"
add_msg UNREGISTERED_TYPE

MSG_UNREGISTERED_STATE="$(cat <<-'EOF'
	Unregistered state: %s
EOF
)"
add_msg UNREGISTERED_TYPE

MSG_ADDED_LOG="$(cat <<-'EOF'
	%s added to %s.
EOF
)"
add_msg ADDED_LOG

MSG_COMMIT_MSG="$(cat <<-'EOF'
	$TD_FILE: Add $TD_IDREF
EOF
)"
add_msg COMMIT_MSG

MSG_TYPE_DOESNT_EXIST_CREATING="$(cat <<-'EOF'
	Type "%s" doesn't exist yet, creating new section with it.
EOF
)"
add_msg TYPE_DOESNT_EXIST_CREATING

MSG_FILE_DOESNT_EXIST_CREATING="$(cat <<-'EOF'
	File "%s" doesn't exist yet, creating a brand new one.
EOF
)"
add_msg FILE_DOESNT_EXIST_CREATING

#
# End translatable strings
#



dump_translatable_strings() {
	for msg in $MSGS; do
		eval "echo \"\$MSG_$msg\"" > src/locale/"$msg".en.txt
	done

	cat <<-'EOF'
		#!/bin/sh
		# shellcheck disable=2034
		set -eu

	EOF
	for msg in $MSGS; do
		printf 'MSG_%s="$(cat @LOCALEDIR@/@LANG@/LC_MESSAGES/@NAME@/%s.@LANG@.txt)"\n' \
			"$msg" "$msg"
	done
}

if [ -n "${TD_DUMP_TRANSLATABLE_STRINGS:-}" ]; then
	dump_translatable_strings
	exit
fi

if [ -r '@LIBEXECDIR@/@NAME@/load-messages.sh' ]; then
	. '@LIBEXECDIR@/@NAME@/load-messages.sh'
fi



#
# Documentation functions
#

usage() {
	printf '%s\n' "$MSG_USAGE"
}

help() {
	printf '%s\n' "$MSG_HELP1" |
		sed -e "s/|TYPE|/$DEFAULT_TYPE/" \
		    -e "s/|STATE|/$DEFAULT_STATE/"
	echo "$TD_STATES" | sed -e 's/^/  /'

	printf '\n%s\n' "$MSG_HELP2"
	echo "$TD_TYPES"  | awk -F: '{ printf "  %s\n", $1 }'

	printf '\n%s\n' "$MSG_HELP3"
}

version() {
	printf '@NAME@-@VERSION@ @DATE@\n'
}


#
# Utilities
#

uuid() {
	# Taken from:
	# https://serverfault.com/a/799198
	od -xN20 /dev/urandom |
		head -n 1 |
		awk '{OFS="-"; print $2$3,$4,$5,$6,$7$8$9}'
}

mkstemp() {
	F="${TMPDIR:-/tmp}/td-${1:-$(uuid)}"
	touch "$F"
	echo "$F"
}

mkdtemp() {
	F="${TMPDIR:-/tmp}/td-${1:-$(uuid)}"
	mkdir -p "$F"
	echo "$F"
}


#
# Core functions
#

optimal_line_for_type() {
	GOAL_TYPE="$1"
	GOAL_INDEX="$(echo "$TD_TYPES" | awk "/^$GOAL_TYPE:/ { printf NR }")"
	TYPE_HEADINGS="$(mkstemp)"
	echo "$TD_TYPES" | cut -d: -f2- | sed 's/^/# /' > "$TYPE_HEADINGS"
	IN_TD_SECTION=false
	IN_TD_ENTRY=false
	LINE_NUMBER=0
	LAST_MATCH=0
	IN_TD_REGION=false
	while read -r line; do
		LINE_NUMBER=$((LINE_NUMBER + 1))
		if ! echo "$line" | grep -Eq '^# .+$'; then
			continue
		fi
		MATCH="$(grep -nF "$line" "$TYPE_HEADINGS" ||:)"
		if [ -n "$MATCH" ]; then
			MATCH_N="$(echo "$MATCH" | cut -d: -f1)"
			MATCH_LINE="$(echo "$MATCH" | cut -d: -f2-)"
			if [ "$line" = "$MATCH_LINE" ]; then
				IN_TD_REGION=true
				if [ "$MATCH_N" -lt "$GOAL_INDEX" ]; then
					LAST_MATCH="$MATCH_N"
				else
					echo $((LINE_NUMBER - 1))
					return
				fi
			fi
		elif [ "$IN_TD_REGION" = true ]; then
			echo $((LINE_NUMBER - 1))
			return
		fi
	done < "$TD_FILE"
	echo $((LINE_NUMBER))
}

insert_at_line() {
	N="$1"
	F="$2"
	TYPE="$3"
	TMPF="$(mkstemp)"

	if [ ! -e "$F" ]; then
		printf "$MSG_FILE_DOESNT_EXIST_CREATING\n" "$TD_FILE" >&2
		cat - > "$TMPF"
	elif [ "$N" = 0 ]; then
		DESIRED_N="$(optimal_line_for_type "$TYPE")"
		printf "$MSG_TYPE_DOESNT_EXIST_CREATING\n" "$TYPE" >&2
		printf '%s\n\n\n%s\n\n\n%s\n' \
			"$(head -n "$DESIRED_N" "$F")" \
			"$(cat -)" \
			"$(tail -n +$((DESIRED_N+1)) "$F")" \
			> "$TMPF"
	else
		printf '%s\n\n%s\n\n%s\n' \
			"$(head -n "$N" "$F")" \
			"$(cat -)" \
			"$(tail -n +$((N+1)) "$F")" \
			> "$TMPF"
	fi

	cp "$TMPF" "$F"
}

name_for_type() {
	TYPE="$1"
	echo "$TD_TYPES" | awk -F: "/^$TYPE:/ { print \$2; exit }"
}

linenumber_for_type() {
	TYPE="$1"
	if [ ! -e "$TD_FILE" ]; then
		echo ''
	else
		NAME="$(name_for_type "$TYPE")"
		awk -F: "/^# $NAME\$/ {print NR; exit}" "$TD_FILE"
	fi
}


GIT_BUILTIN_PRE_ADD_HOOK="$(cat <<-EOF
	if ! git diff --exit-code --quiet          -- "\$TD_FILE" ||
	   ! git diff --exit-code --quiet --staged -- "\$TD_FILE"
	then
		git stash push --quiet -- "\$TD_FILE"
		touch "\$TD_HOOKS_DIR/has-diff"
	fi
EOF
)"
GIT_BUILTIN_POST_ADD_HOOK="$(cat <<-EOF
	git add "\$TD_FILE"
	git commit -m "$MSG_COMMIT_MSG"
	if [ -e "\$TD_HOOKS_DIR/has-diff" ]; then
		git stash pop --quiet
	fi
EOF
)"
load_hooks() {
	case "${TD_USE_BUILTIN_HOOKS:-}" in
		git)
			export TD_PRE_ADD_HOOK="${TD_PRE_ADD_HOOK:-$GIT_BUILTIN_PRE_ADD_HOOK}"
			export TD_POST_ADD_HOOK="${TD_POST_ADD_HOOK:-$GIT_BUILTIN_POST_ADD_HOOK}"
			;;
		*)
			;;
	esac
}

list_hooks() {
	for t in git; do
		TD_USE_BUILTIN_HOOKS="$t"
		load_hooks
		printf '%s:\n' "$t"
		printf '  TD_PRE_ADD_HOOK:\n'
		printf '%s\n' "$TD_PRE_ADD_HOOK"  | sed 's/^/    /'
		printf '  TD_POST_ADD_HOOK:\n'
		printf '%s\n' "$TD_POST_ADD_HOOK" | sed 's/^/    /'
	done
}

pre_add_hook() {
	sh -c "${TD_PRE_ADD_HOOK:-}"
}

post_add_hook() {
	sh -c "${TD_POST_ADD_HOOK:-}"
}



#
# HTML pre-processing
#

html_inject_checkboxes() {
	awk '{
		if (match($0, /^(-|[0-9]*.) \[( |x)\] /)) {
			printf \
				"%s <input type=\"checkbox\" disabled %s/> %s\n",
				$1,
				substr($2, 2, 1) == "x" ? "checked " : "",
				substr($0, 1 + length($1) + length(" [ ] "))
		} else {
			print
		}
	}'
}

html_process_tags() {
	sed 's|tag:\([^ ]*\)|<span class="tag">\1</span>|g'
}

html_process_ids() {
	STATES_REGEX="$(
		echo "$TD_STATES" |
			grep .          |
			paste -sd '|'   |
			sed 's/|/\\|/g' |
			printf '\(%s\)' "$(cat -)"
	)"

	sed 's:^## '"$STATES_REGEX"' \(.*\) {#\(.*\)}\(.*\)$:## <a href="#\3"><span class="\1">\1</span> \2</a>\4\
<pre class="header-anchor" id="\3">#\3</pre>\
:g'
}

html_pre_process() {
	html_inject_checkboxes |
		html_process_tags |
		html_process_ids
}



#
# Linting
#

lint_assert_order() {
	GREP_FLAGS="$(echo "$TD_TYPES" | cut -d: -f2- | sed 's/\(.*\)/-e "\1"/' | tr '\n' ' ')"
	echo eval "grep -F $GREP_FLAGS $TD_FILE"
}

known_heading() {
	line="$1"
	TYPE_HEADINGS="$2"
	while read -r heading; do
		if [ "$heading" = "$line" ]; then
			return 0
		fi
	done < "$TYPE_HEADINGS"
	return 1
}

warning() {
	echo "$1" "$2" "$3"
}

lint() {
	return 0
	TYPE_HEADINGS="$(mkstemp)"
	echo "$TD_TYPES" | cut -d: -f2- | sed 's/^/# /' > "$TYPE_HEADINGS"
	IN_TD_SECTION=false
	IN_TD_ENTRY=false
	LINE_NUMBER=0
	while read -r line; do
		LINE_NUMBER=$((LINE_NUMBER + 1))
		if [ "$IN_TD_SECTION" = false ]; then
			if known_heading "$line" "$TYPE_HEADINGS"; then
				IN_TD_SECTION=true
			fi
		fi

		if [ "$IN_TD_SECTION" = false ]; then
			continue
		fi

		if echo "$line" | grep -q '^# .*' &&
				! known_heading "$line" "$TYPE_HEADINGS"; then
			break
		else
			IN_TD_ENTRY=false
			echo "$line" | grep -q '^#.*'
			# continue
		fi

		if echo "$line" | grep -q '^## .*'; then
			IN_TD_ENTRY=true
		fi

		if [ "$IN_TD_ENTRY" = false ] && [ "$line" != '' ]; then
			warning "$TD_FILE" "$LINE_NUMBER" \
				'Content outside of td entry'
		fi
	done < "$TD_FILE"
}



#
# Default values, config "run commands" file and derived values
#

ID="$(uuid)"
export TD_IDREF="#td-$ID"
export TD_FILE='TODOs.md'
export TD_TYPES="$(cat <<-'EOF'
	task:Tasks
	bug:Bugs
	improvement:Improvements
	question:Questions
	decision:Decisions
	idea:Ideas
	proposal:Proposals
EOF
)"
export TD_STATES="$(cat <<-'EOF'
	TODO
	DOING
	WAITING
	INACTIVE
	NEXT
	CANCELLED
	DONE
	WONTFIX
EOF
)"
export TD_HOOKS_DIR="$(mkdtemp)"

if [ -r "$PWD/.tdrc" ]; then
	. "$PWD/.tdrc"
fi

DEFAULT_TYPE="$(echo  "$TD_TYPES"  | awk -F: '{ print $1; exit }')"
DEFAULT_STATE="$(echo "$TD_STATES" | awk -F: '{ print $1; exit }')"
TYPE="$DEFAULT_TYPE"
STATE="$DEFAULT_STATE"
NAME="$(name_for_type "$TYPE")"

load_hooks



#
# Main
#

for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		--version)
			version
			exit
			;;
		*)
			;;
	esac
done

SHORT=false
MESSAGE=FIXME
while getopts 'cm:t:s:lLHhV' flag; do
	case "$flag" in
		c)
			SHORT=true
			;;
		m)
			MESSAGE="$OPTARG"
			;;
		t)
			TYPE="$OPTARG"
			NAME="$(name_for_type "$TYPE")"
			if [ -z "$NAME" ]; then
				printf "$MSG_UNREGISTERED_TYPE\n" "$TYPE" >&2
				exit 1
			fi
			;;
		s)
			STATE="$OPTARG"
			if ! echo "$TD_STATES" | grep -q "$STATE"; then
				printf "$MSG_UNREGISTERED_STATE\n" "$STATE" >&2
				exit 1
			fi
			;;
		l)
			list_hooks
			exit
			;;
		L)
			lint
			exit
			;;
		H)
			html_pre_process < "$TD_FILE"
			exit
			;;
		h)
			usage
			help
			exit
			;;
		V)
			version
			exit
			;;
		*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))


TYPE_LINE="$(linenumber_for_type "$TYPE")"
if [ -z "$TYPE_LINE" ]; then
	TYPE_LINE=-1
	PREAMBLE="# $(name_for_type "$TYPE")"'

'
fi
INSERT_LINE=$((TYPE_LINE + 1))
TITLE_LINE="${PREAMBLE:-}$(printf '## %s %s {%s}\n- %s in %s\n' "$STATE" "$MESSAGE" "$TD_IDREF" "$STATE" "$(date -I)")"

if [ "$SHORT" = 'true' ] && [ "$MESSAGE" != 'FIXME' ]; then
	pre_add_hook
	echo "$TITLE_LINE" | insert_at_line "$INSERT_LINE" "$TD_FILE" "$TYPE"
	post_add_hook
else
	TMPFILE_ORIG="$(mkstemp)"
	TMPFILE_COPY="$(mkstemp)"
	printf '%s\n\n---\n\nFIXME\n' "$TITLE_LINE" > "$TMPFILE_ORIG"
	cp "$TMPFILE_ORIG" "$TMPFILE_COPY"
	CMD="${VISUAL:-${EDITOR:-vi}}"
	$CMD "$TMPFILE_ORIG"
	if diff "$TMPFILE_ORIG" "$TMPFILE_COPY" > /dev/null; then
		echo "$MSG_UNEDITED_ENTRY" >&2
		exit 1
	fi

	pre_add_hook
	insert_at_line "$INSERT_LINE" "$TD_FILE" "$TYPE" < "$TMPFILE_ORIG"
	post_add_hook
fi

printf "$MSG_ADDED_LOG\n" "$TD_IDREF" "$TD_FILE" >&2