#!/usr/bin/env bash

CURRENT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

is_osx() {
	local platform=$(uname)
	[ "$platform" == "Darwin" ]
}

option_value_not_changed() {
	local option="$1"
	local default_value="$2"
	local option_value=$(tmux show-option -gv "$option")
	[ "$option_value" == "$default_value" ]
}

server_option_value_not_changed() {
	local option="$1"
	local default_value="$2"
	local option_value=$(tmux show-option -sv "$option")
	[ "$option_value" == "$default_value" ]
}

key_binding_not_set() {
	local key="$1"
	if $(tmux list-keys | grep -q "bind-key[[:space:]]\+${key}"); then
		return 1
	else
		return 0
	fi
}

main() {
	# OPTIONS

	# enable utf8
	tmux set-option -g utf8 on

	# enable utf8 in tmux status-left and status-right
	tmux set-option -g status-utf8 on

	# set Ctrl-a as Tmux prefix
	if option_value_not_changed "prefix" "C-b"; then
		tmux set-option -g prefix C-a
		tmux unbind-key C-b
	fi

	# address vim mode switching delay (http://superuser.com/a/252717/65504)
	if server_option_value_not_changed "escape-time" "500"; then
		tmux set-option -s escape-time 0
	fi

	# increase scrollback buffer size
	if option_value_not_changed "history-limit" "2000"; then
		tmux set-option -g history-limit 50000
	fi

	# tmux messages are displayed for 4 seconds
	if option_value_not_changed "display-time" "750"; then
		tmux set-option -g display-time 4000
	fi

	# refresh 'status-left' and 'status-right' more often
	if option_value_not_changed "status-interval" "15"; then
		tmux set-option -g status-interval 5
	fi

	# required (only) on OS X
	if is_osx && option_value_not_changed "default-command" ""; then
		tmux set-option -g default-command "reattach-to-user-namespace -l $SHELL"
	fi

	# upgrade $TERM
	if option_value_not_changed "default-terminal" "screen"; then
		tmux set-option -g default-terminal "screen-256color"
	fi

	# enable all mouse features for terminals that support it
	tmux set-window-option -g mode-mouse on
	tmux set-option -g mouse-resize-pane on
	tmux set-option -g mouse-select-pane on
	tmux set-option -g mouse-select-window on

	# emacs key bindings in tmux command prompt (prefix + :) are better than
	# vi keys, even for vim users
	tmux set-option -g status-keys emacs

	# DEFAULT KEY BINDINGS

	# Ctrl-a + a   send `Ctrl-a` to the shell
	if key_binding_not_set "a"; then
		tmux bind-key a send-prefix
	fi

	# Ctrl-a + Ctrl-a   switch between alternate windows
	if key_binding_not_set "C-a"; then
		tmux bind-key C-a last-window
	fi

	# easier switching between next/prev window
	if key_binding_not_set "C-p"; then
		tmux bind-key C-p previous-window
	fi
	if key_binding_not_set "C-n"; then
		tmux bind-key C-n next-window
	fi

	# source `.tmux.conf` file - as suggested in `man tmux`
	if key_binding_not_set "R"; then
		tmux bind-key R run-shell -b ' \
			tmux source-file ~/.tmux.conf > /dev/null; \
			tmux display-message "Sourced .tmux.conf!"'
	fi
}
main