package jevdecide

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

var (
	flagsMu    sync.RWMutex
	activeMode = defaultMode()
)

func defaultMode() Mode {
	return ParseMode(os.Getenv("JEV_DECIDE_MODE"))
}

// ParseMode maps env string to Mode; unknown → off (fail-closed).
func ParseMode(raw string) Mode {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "", "off", "0", "false", "no":
		return ModeOff
	case "shadow":
		return ModeShadow
	case "assist":
		return ModeAssist
	default:
		return ModeOff
	}
}

// CurrentMode returns the active integration mode.
func CurrentMode() Mode {
	flagsMu.RLock()
	defer flagsMu.RUnlock()
	return activeMode
}

// SetModeForTest overrides mode in tests.
func SetModeForTest(m Mode) {
	flagsMu.Lock()
	activeMode = m
	flagsMu.Unlock()
}

// ResetModeForTest restores mode from the process environment.
func ResetModeForTest() {
	flagsMu.Lock()
	activeMode = defaultMode()
	flagsMu.Unlock()
}

// Enabled reports whether shadow or assist is active.
func Enabled() bool {
	m := CurrentMode()
	return m == ModeShadow || m == ModeAssist
}