#!/bin/bash
#  functions - Bash function support

set -e


######
# Function API

# is_function() - Returns success if $1 names a function
is_function() {
	has_args 1 "$@"
	declare -pf "$1" >/dev/null 2>&1
}

# func_deprecate() - Declares the given function ($1) as an
# alias to another function ($2) that prints a deprecation warning.
# $1 - Name of deprecated/renamed function
# $2 - Name of new function to call
func_deprecate() {
	has_args 2 "$@"
	local old=$1
	local new=$2
	eval "$old() { warn \"$old: deprecated, use $new\"; $new \"\$@\"; }"
}

# func_copy() - Makes a copy of named function ($1) as a new name ($2)
func_copy() {
	has_args 2 "$@"
	local src=$1
	local dst=$2
	local scode=$(declare -f $src)
	local dcode="$dst${scode#$src}"
	eval "$dcode"
}

# func_chain() - Overrides an existing function with a new body, copying
# the original function such that it can be called by the new function.
# e.g. 'func chain a b' installs 'a_b' as 'b'; 'a_b' can use 'a_b_next'
# to call the original 'b' (which may itself be a chained function).
func_chain() {
	min_args 2 "$@"
	local name=$1
	shift

	local func
	for func in "$@"; do
		func_copy "$func" "${name}_${func}_next"
		func_copy "${name}_${func}" "$func"
	done
}

# func_delete() - Delets the name function ($1)
func_delete() { min_args 1 "$@"; unset -f "$@"; }

# func_save() - Saves a copy of the function ($1) using a new name ($2).
# Currently, this is an alias for func_copy(), but that may change.
func_save() { func_copy "$@"; }

# func_restore() - Restores the function ($1) using a saved copy ($2),
# deleting the copy when finished.
func_restore() { func_copy "$2" "$1"; unset -f "$2"; }

# func_trace() - Prints debug string of the caller function and arguments ($@)
func_trace() {
	local -a args=( "$@" )
	list_quote args
	debug "FUNC: ${FUNCNAME[1]} ${args[*]}"
}


######
# Boolean Function Wrappers

# func_bool() - Executes arguments ($@) and prints a boolean command
# that produces the same result: ``true`` or ``false``.  This function
# $1 - Command
# $@ - Command arguments (optional)
func_bool() { "$@" && echo "true" || echo "false"; }

# func bool_not() - Like ``func_bool()``, executes a command ($@), but
# prints a boolean command that produces the complement of its result.
# $1 - Command
# $@ - Command arguments (optional)
func_bool_not() { "$@" && echo "false" || echo "true"; }