package main

import (
	"go/ast"
	"go/parser"
	"go/token"
	"testing"
	"time"
)

// R-363 / R-547: the fill watcher ran once a day (plus once after start), so a filesystem that filled
// right after the 03:30 run went unannounced for ~24 h, and a disk held at 96 % for ten minutes raised
// nothing. The consequence pinned here: main.go registers the SAME fillWatcher.Check on a periodic
// job whose interval is no longer than the shortest measured silent window (10 min), so any such
// window contains a check. Edge-triggering (no repeat mails at a faster cadence) is pinned in
// internal/fillwatch (TestWarnsOnceThenIsSilent, TestEdgeStateSurvivesARestart).
func TestFillWatchRunsOnAnInterval(t *testing.T) {
	const measuredSilentWindow = 10 * time.Minute // R-547, chaos night 2026-09-17
	if fillWatchInterval <= 0 || fillWatchInterval > measuredSilentWindow {
		t.Errorf("fillWatchInterval = %s; it must be >0 and <= %s, or a fill window like R-547's can pass unseen", fillWatchInterval, measuredSilentWindow)
	}

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "main.go", nil, 0)
	if err != nil {
		t.Fatal(err)
	}
	periodic := 0
	ast.Inspect(f, func(n ast.Node) bool {
		call, ok := n.(*ast.CallExpr)
		if !ok {
			return true
		}
		sel, ok := call.Fun.(*ast.SelectorExpr)
		if !ok || sel.Sel.Name != "Every" || len(call.Args) != 3 {
			return true
		}
		iv, ok := call.Args[1].(*ast.Ident)
		if !ok || iv.Name != "fillWatchInterval" {
			return true
		}
		// The job body must call fillWatcher.Check — the same edge-triggered check, not a new one.
		ast.Inspect(call.Args[2], func(m ast.Node) bool {
			if c, ok := m.(*ast.CallExpr); ok {
				if s, ok := c.Fun.(*ast.SelectorExpr); ok && s.Sel.Name == "Check" {
					if x, ok := s.X.(*ast.Ident); ok && x.Name == "fillWatcher" {
						periodic++
					}
				}
			}
			return true
		})
		return true
	})
	if periodic != 1 {
		t.Errorf("R-363: main.go registers fillWatcher.Check on a periodic (sched.Every, fillWatchInterval) job %d times, want 1 — without it the fill check is daily only", periodic)
	}
}