package docrevision

import (
	"os"
	"strings"
	"sync"
)

// EnvPIChangeReportNarrative gates optional PI change-report narrative enrichment.
// Default off: deterministic fallback only.
const EnvPIChangeReportNarrative = "PI_CHANGE_REPORT_NARRATIVE"

var (
	flagsMu     sync.RWMutex
	narrativeOn = envBool(EnvPIChangeReportNarrative, false)
)

func envBool(key string, def bool) bool {
	v := strings.TrimSpace(os.Getenv(key))
	if v == "" {
		return def
	}
	return v == "1" || strings.EqualFold(v, "true") || strings.EqualFold(v, "yes")
}

// PIChangeReportNarrativeEnabled reports whether PI narrative enrichment is on.
func PIChangeReportNarrativeEnabled() bool {
	flagsMu.RLock()
	defer flagsMu.RUnlock()
	return narrativeOn
}

// SetPIChangeReportNarrativeForTest overrides the flag in tests.
func SetPIChangeReportNarrativeForTest(on bool) {
	flagsMu.Lock()
	narrativeOn = on
	flagsMu.Unlock()
}

// ResetPIChangeReportNarrativeForTest restores the flag from the process environment.
func ResetPIChangeReportNarrativeForTest() {
	flagsMu.Lock()
	narrativeOn = envBool(EnvPIChangeReportNarrative, false)
	flagsMu.Unlock()
}