package graph

import (
	"fmt"
	"strings"
)

// The words of a want held on an edge of ADR 0614 (novox/hq ADR 0614 §2, §4, §5): no reader knows a rule number of its own for
// either yet, so the assigner holds them under the provisions' and the composition's rules, and these words are the one
// place they are written and read. The assigner writes them (VerbWaitWords, ReaderWaitWords, BusStateWaitWords); the delivery view names
// the edge a want waits on from them (EdgeOfWords).

const (
	verbOpen   = "the verb "
	verbClose  = " invokes is served by no running build"
	readerOpen = "the node-engine of "
	readerMid  = " does not read "
	readerTail = ", which the manifest of "
	busOpen    = "bus state: "
)

// BusStateWaitWords are the words of a want of module on node held until a build of a module offering bus-state runs
// healthy on a node present (ADR 0614 §5, through ADR 0603 §5's count of the provider's own have).
func BusStateWaitWords(module, node string) string {
	return fmt.Sprintf("%s%s asks bus state, and no build of a module offering %s runs healthy on a node present: its want on %s waits for one (ADR 0614 §5)",
		busOpen, module, BusState, node)
}

// VerbWaitWords are the words of a want of module on node held until a build serving verb runs healthy (ADR 0614 §2).
func VerbWaitWords(verb, module, node string) string {
	return fmt.Sprintf("%s%s %s%s: its want on %s waits until a build serving it runs healthy (ADR 0614 §2)", verbOpen, verb,
		module, verbClose, node)
}

// ReaderWaitWords are the words of a want of module at fp held on node until its node-engine states the reader
// capabilities missing (ADR 0614 §4).
func ReaderWaitWords(node string, missing []string, module, fp string) string {
	return fmt.Sprintf("%s%s%s%s%s%s at %s needs: the want moves once that engine states it", readerOpen, node, readerMid,
		strings.Join(missing, ", "), readerTail, module, fp)
}

// EdgeOfWords is the edge a held want's words name: `verb <verb>` for a verb wait, `reader capability <capabilities>` for
// a reader capability's hold, `bus state` for a bus-state wait, or "" for words of none of them.
func EdgeOfWords(words string) string {
	if strings.HasPrefix(words, busOpen) {
		return "bus state"
	}
	if rest, ok := strings.CutPrefix(words, verbOpen); ok {
		if verb, _, ok := strings.Cut(rest, " "); ok && strings.Contains(rest, verbClose) {
			return "verb " + verb
		}
	}
	if rest, ok := strings.CutPrefix(words, readerOpen); ok {
		if _, rest, ok := strings.Cut(rest, readerMid); ok {
			if missing, _, ok := strings.Cut(rest, readerTail); ok {
				return "reader capability " + missing
			}
		}
	}
	return ""
}