# Library functions

print_powerline() {
	local side="$1"
	local upper_side=$(echo "$1" | tr '[:lower:]' '[:upper:]')
	eval "local input_segments=(\"\${TMUX_POWERLINE_${upper_side}_STATUS_SEGMENTS[@]}\")"
	local powerline_segments=()
	local powerline_segment_contents=()

	__check_platform

	__process_segment_defaults
	__process_scripts
	__process_colors

	__process_powerline
}

__process_segment_defaults() {
	for segment_index in "${!input_segments[@]}"; do
		local input_segment=(${input_segments[$segment_index]})
		eval "local default_separator=\$TMUX_POWERLINE_DEFAULT_${upper_side}SIDE_SEPARATOR"

		powerline_segment_with_defaults=(
			${input_segment[0]:-"no_script"} \
			${input_segment[1]:-$TMUX_POWERLINE_DEFAULT_BACKGROUND_COLOR} \
			${input_segment[2]:-$TMUX_POWERLINE_DEFAULT_FOREGROUND_COLOR} \
			${input_segment[3]:-$default_separator} \
		)

		powerline_segments[$segment_index]="${powerline_segment_with_defaults[@]}"
	done
}

__process_scripts() {
	for segment_index in "${!powerline_segments[@]}"; do
		local powerline_segment=(${powerline_segments[$segment_index]})

		if [ -n "$TMUX_POWERLINE_DIR_USER_SEGMENTS" ] && [ -f "$TMUX_POWERLINE_DIR_USER_SEGMENTS/${powerline_segment[0]}.sh" ] ; then
			local script="$TMUX_POWERLINE_DIR_USER_SEGMENTS/${powerline_segment[0]}.sh"
		else
			local script="$TMUX_POWERLINE_DIR_SEGMENTS/${powerline_segment[0]}.sh"
		fi

		export TMUX_POWERLINE_CUR_SEGMENT_BG="${powerline_segment[1]}"
		export TMUX_POWERLINE_CUR_SEGMENT_FG="${powerline_segment[2]}"
		source "$script"
		local output
		output=$(run_segment)
		local exit_code="$?"
		unset -f run_segment

		if [ "$exit_code" -ne 0 ] && debug_mode_enabled ; then
			local seg_name="${script##*/}"
			echo "Segment '${seg_name}' exited with code ${exit_code}. Aborting."
			exit 1
		fi

		if [ -n "$output" ]; then
			powerline_segment_contents[$segment_index]=" $output "
		else
			unset -v powerline_segments[$segment_index]
		fi
	done
}

__process_colors() {
	for segment_index in "${!powerline_segments[@]}"; do
		local powerline_segment=(${powerline_segments[$segment_index]})
	 	# Find the next segment that produces content (i.e. skip empty segments).
		for next_segment_index in $(eval echo {$(($segment_index + 1))..${#powerline_segments}}) ; do
			[[ -n ${powerline_segments[next_segment_index]} ]] && break
		done
		local next_segment=(${powerline_segments[$next_segment_index]})

		if [ $side == 'left' ]; then
			powerline_segment[4]=${next_segment[1]:-$TMUX_POWERLINE_DEFAULT_BACKGROUND_COLOR}
		elif [ $side == 'right' ]; then
			powerline_segment[4]=${previous_background_color:-$TMUX_POWERLINE_DEFAULT_BACKGROUND_COLOR}
		fi

		if __segment_separator_is_thin; then
			powerline_segment[5]=${powerline_segment[2]}
		else
			powerline_segment[5]=${powerline_segment[1]}
		fi

		local previous_background_color=${powerline_segment[1]}

		powerline_segments[$segment_index]="${powerline_segment[@]}"
	done
}

__process_powerline() {
	for segment_index in "${!powerline_segments[@]}"; do
		local powerline_segment=(${powerline_segments[$segment_index]})

		local background_color=${powerline_segment[1]}
		local foreground_color=${powerline_segment[2]}
		local separator=${powerline_segment[3]}
		local separator_background_color=${powerline_segment[4]}
		local separator_foreground_color=${powerline_segment[5]}

		eval "__print_${side}_segment ${segment_index} ${background_color} ${foreground_color} ${separator} ${separator_background_color} ${separator_foreground_color}"
	done
}

__print_left_segment() {
	local content=${powerline_segment_contents[$1]}
	local content_background_color=$2
	local content_foreground_color=$3
	local separator=$4
	local separator_background_color=$5
	local separator_foreground_color=$6

	__print_colored_content "$content" $content_background_color $content_foreground_color
	__print_colored_content $separator $separator_background_color $separator_foreground_color
}

__print_right_segment() {
	local content=${powerline_segment_contents[$1]}
	local content_background_color=$2
	local content_foreground_color=$3
	local separator=$4
	local separator_background_color=$5
	local separator_foreground_color=$6

	__print_colored_content $separator $separator_background_color $separator_foreground_color
	__print_colored_content "$content" $content_background_color $content_foreground_color
}

__segment_separator_is_thin() {
	[[ ${powerline_segment[3]} == $TMUX_POWERLINE_SEPARATOR_LEFT_THIN || \
		${powerline_segment[3]} == $TMUX_POWERLINE_SEPARATOR_RIGHT_THIN ]];
}

__check_platform() {
	if [ "$SHELL_PLATFORM" == "unknown" ] && debug_mode_enabled; then
		 echo "Unknown platform; modify config/shell.sh"  &1>&2
	fi
}