package activator

import (
	"path/filepath"

	"github.com/carlosframework/platform/internal/provision"
	"github.com/carlosframework/platform/internal/registry"
)

// instancePaths is every per-host path the exec backend touches, resolved
// once per call by layout so that no method builds a path from DataDir and
// the host on its own. Flat and foreign rows keep today's flat names; a
// nested row's files live in its instance directory with the same names
// (design §3.1).
type instancePaths struct {
	layout     Layout
	reason     string
	dataDir    string // the directory that holds the four files
	runDir     string // the directory that holds app.sock and the control socket
	dbPath     string
	envFile    string
	sidecarEnv string
	configEnv  string
}

// Layout is ExecBackend's Classifier implementation: the same
// classification pathsFor already computes, exposed so doWake can check it
// before Acquire or Restore ever run.
func (b *ExecBackend) Layout(rt registry.Route) (Layout, string) {
	return Classify(rt, b.layoutInputs())
}

func (b *ExecBackend) pathsFor(rt registry.Route) instancePaths {
	l, reason := Classify(rt, b.layoutInputs())
	p := instancePaths{layout: l, reason: reason, dataDir: b.DataDir, runDir: provision.SocketDir}
	if l == LayoutNested {
		p.dataDir = provision.InstanceDir(b.DataDir, rt.Host)
		if b.RunDirOverride != "" {
			// Test-only: a test points the nested run dir at a temp dir
			// rather than /run/carlos, exactly as it points DataDir at one.
			p.runDir = filepath.Join(b.RunDirOverride, "instances", provision.InstanceID(rt.Host))
		} else {
			p.runDir = provision.InstanceRunDir(rt.Host)
		}
	}
	p.dbPath = rt.DBPath
	if p.dbPath == "" {
		p.dbPath = provision.DefaultDBPath(b.DataDir, rt.Host)
	}
	p.envFile = filepath.Join(p.dataDir, rt.Host+".env")
	p.sidecarEnv = filepath.Join(p.dataDir, rt.Host+"-sidecar.env")
	p.configEnv = filepath.Join(p.dataDir, rt.Host+".config.env")
	return p
}

// layoutInputs is the backend's LayoutInputs with DataDir filled in. A
// non-empty RunDirOverride also steers the socket dir Classify tests
// against, so a route built against the override dir still classifies as
// nested through Task 2's sockets() helper.
func (b *ExecBackend) layoutInputs() LayoutInputs {
	in := b.LayoutFacts
	in.DataDir = b.DataDir
	if b.RunDirOverride != "" {
		in.SocketDir = b.RunDirOverride
	}
	return in
}