package apps

import (
	"path/filepath"
	"strings"
)

// AppAvailableAt reports whether app's virtual HTML can be served at
// requestDir. Rules (case-insensitive on canonical folder names):
//
//   - archive: every directory (multi-project, project, archive, party)
//   - browse: every directory (generic file listing — also the default
//     served at folder URLs without an index.html; see directory.go)
//   - classifier: requestDir is, or descends from, a folder named
//     "working", "staging", or "incoming" (the directories where
//     in-flight files get classified)
//   - mdedit: requestDir is, or descends from, a "working" folder
//     (where markdown drafts are written and edited, including review
//     responses drafted in working/<rs-name>/)
//   - transmittal: requestDir is, or descends from, a "staging" folder
//     (where outgoing transmittals are prepared)
//   - landing: only at the deployment root (the project picker)
//
// Operators can always drop a real <name>.html file at any path to
// override — that path is served by the static handler regardless of
// this function's result. AppAvailableAt is consulted only when no
// real file exists.
//
// In the canonical layout, "incoming" only appears at
// archive/<party>/incoming/, so checking "any ancestor named incoming"
// is equivalent to checking "under a per-party incoming folder."
func AppAvailableAt(root, requestDir, app string) bool {
	root = filepath.Clean(root)
	requestDir = filepath.Clean(requestDir)

	switch app {
	case "archive", "browse":
		return true
	case "landing":
		return requestDir == root
	case "classifier":
		return inAncestorWithName(root, requestDir, "working", "staging", "incoming")
	case "mdedit":
		return inAncestorWithName(root, requestDir, "working")
	case "transmittal":
		return inAncestorWithName(root, requestDir, "staging")
	}
	return false
}

// inAncestorWithName reports whether requestDir is, or has an ancestor
// (not including root itself), whose last segment case-folds to one
// of names. Match is on segment names, case-insensitively.
func inAncestorWithName(root, requestDir string, names ...string) bool {
	if requestDir == root {
		return false
	}
	rel, err := filepath.Rel(root, requestDir)
	if err != nil || strings.HasPrefix(rel, "..") {
		return false
	}
	for _, part := range strings.Split(rel, string(filepath.Separator)) {
		for _, n := range names {
			if strings.EqualFold(part, n) {
				return true
			}
		}
	}
	return false
}