package sprigx

import (
	`os`
	`path`
	`path/filepath`
)

/*
	//
	// GENERIC
	//
*/

/*
pathPipeJoin wraps path.Join with the root element at the *end* instead of the beginning.

	{{ pathPipeJoin "b" "c" "a" }}

is equivalent to

	path.Join("a", "b", "c")

This order variation is better suited for pipelines that pass the root path.
*/
func pathPipeJoin(elems ...string) (out string) {

	var rootIdx int

	if elems == nil || len(elems) == 0 {
		return
	}

	rootIdx = len(elems) - 1
	out = elems[rootIdx]

	if len(elems) == 1 {
		return
	}

	out = pathSubJoin(out, elems[:rootIdx]...)

	return
}

// pathSliceJoin joins a slice of path segments.
func pathSliceJoin(sl []string) (out string) {

	out = path.Join(sl...)

	return
}

/*
pathSlicePipeJoin behaves like a mix of pathPipeJoin (in that it accepts the root element last)
and pathSliceJoin (in that it accepts a slice of subpath segments).

It's essentially like pathSubJoin in reverse, and with an explicit slice.
*/
func pathSlicePipeJoin(sl []string, root string) (out string) {

	out = pathSubJoin(root, sl...)

	return
}

/*
pathSubJoin is like path.Join except it takes an explicit root
and additional slice of subpaths to sequentially join to it.
*/
func pathSubJoin(root string, elems ...string) (out string) {

	if elems == nil || len(elems) == 0 {
		out = root
		return
	}

	out = path.Join(
		root,
		path.Join(
			elems...,
		),
	)

	return
}

/*
	//
	// OS/PLATFORM
	//
*/

/*
osPathPipeJoin is like pathPipeJoin but uses the rendering OS' path separator (os.PathSeparator).
*/
func osPathPipeJoin(elems ...string) (out string) {

	var rootIdx int

	if elems == nil || len(elems) == 0 {
		return
	}

	rootIdx = len(elems) - 1
	out = elems[rootIdx]

	if len(elems) == 1 {
		return
	}

	out = osPathSubJoin(out, elems[:rootIdx]...)

	return
}

// osPathSep returns os.PathSeparator.
func osPathSep() (out string) {

	out = string(os.PathSeparator)

	return
}

// osPathSliceJoin is the OS-specific implementation of pathSliceJoin.
func osPathSliceJoin(sl []string) (out string) {
	out = filepath.Join(sl...)
	return
}

// osPathSlicePipeJoin is the OS-specific implementation of pathSlicePipeJoin.
func osPathSlicePipeJoin(sl []string, root string) (out string) {

	out = osPathSubJoin(root, sl...)

	return
}

// osPathSubJoin is the OS-specific implementation of pathSubJoin.
func osPathSubJoin(root string, elems ...string) (out string) {

	if elems == nil || len(elems) == 0 {
		out = root
		return
	}

	out = filepath.Join(
		root,
		filepath.Join(
			elems...,
		),
	)

	return
}